Dissertations / Theses: 'Bacterial diseases in fishes'

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Leung, Ka-ming, and 梁家銘. "Isolation, identification and establishment of bacterial culture collection of fish pathogens in Hong Kong." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2014. http://hdl.handle.net/10722/207649.

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The importance of fish culture has been increasing since 1990’s. The steady growth of fish culture helps to ensure a stable supply of fish for human consumption. However, when compared with capture fisheries, production from fish culture is greatly influenced by fish diseases. Outbreaks of fish diseases have caused great economic loss to fish culture. Research has been conducted to understand and reduce the occurrence of fish diseases in fish culture. In Hong Kong, bacterial infection is the most common cause of fish diseases. This project is therefore directed to isolate and identify the causative bacterial pathogen of some fish disease cases with the aim of setting up a local fish disease database for assisting the identification of diseases and improving the understanding of fish diseases in fish farms in Hong Kong. In this project, seven fish disease cases caused by bacteria were investigated with the AFCD officials in Hong Kong. Nine fish disease bacterial pathogens were isolated and identified using different methods (including commercial biochemical test kits, automated system and DNA sequencing). The bacteria identified included Aeromonas hydrophila, Lactococcus garvieae, Streptococcus agalactiae, Streptococcus dysgalactiae, Streptococcus iniae, Vibrio vulnificus and Aeromonas salmonicida. Sensitivity tests to 10 common antibiotics conducted for the identified bacteria showed that spectinomycin is the most broad spectrum antibiotics. In addition, a long-term physical storage of bacterial stock with glycerol and glass beads was established for further research of the identified bacteria. For efficient data analysis, an electronic database using Microsoft Access to hold the identification results and case history of each isolated bacteria was developed. Different data entry forms and reports were also constructed to facilitate easy data entry and data access for users. The three bacteria identification methods were compared for their efficiency and accuracy. Some limitations encountered in this project including time constraints and low accuracy of some biochemical identification tests were discussed and recommendations to overcome these limitations and improvements to the constructed database were made.
published_or_final_version
Environmental Management
Master
Master of Science in Environmental Management

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Al-Ghabshi, Alya. "Bacteria recovered from aquaculture in Oman, with emphasis on Aeromonas Spp." Thesis, University of Stirling, 2015. http://hdl.handle.net/1893/22154.

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Aquaculture is being seriously considered as a promising sustainable industry in the Sultanate of Oman. Fish farming commenced in Oman in 1986, but it was only in 2011 that it became a more commercially driven sector. While worldwide aquaculture production is expected to rise to meet the shortage in capture fisheries, there is a parallel requirement to identify potential threats to the health and welfare of existing aquatic farmed stocks and to take appropriate steps to mitigate them. As aquaculture in Oman is in an early stage of development, it is important to acquire baseline data on the existence and prevalence of aquatic diseases and pathogens to help the Government make policy decisions to develop health management regimes applicable for Omani aquaculture. Therefore, this study was conducted to evaluate current farming practices of tilapia in Oman, to investigate the bacterial species composition and distribution from different sites in some of the economically important fish species, and to study the characteristics and pathogenicity of Aeromonas species. The current practices were studied for 9 Nile tilapia (Oreochromis niloticus) farms from four areas (Al Batinah, Ad Dhahirah, Ad Dakhiliyah and Ash Sharqiyah North) during the period of September to November 2012 by using questionnaires and interviews with the farm owners and staff. In total 417 fish representing 5 target species were chosen on the basis of the commercial importance and their potential for aquaculture in Oman, including red spot emperor (Lethrinus lentjan), king soldier bream (Argyrops spinifer), white spotted rabbit fish (Siganus canaliculatus), abalone (Haliotis mariae) and tilapia (Oreochromis niloticus). The fish were collected from 5 main sampling areas in Oman (Muscat, Mudhaibi, Manah, Sohar and Salalah) based on the Atlas of suitable sites for aquaculture in Oman to investigate the bacterial species composition and distribution. The animals were examined for clinical signs of disease prior to routine bacteriology. Bacterial isolates were recovered using traditional methods and identified to species level using phenotypic and molecular approaches using 16S rDNA, 16S rDNA RFLP and 16S rDNA sequencing. Experimental fish challenge studies were also conducted using both live bacterial cells and ECP protein to investigate the pathogenicity of Aeromonas isolates. In addition, the presence of some virulence factors was investigated using both phenotypic and genotypic methods. The results of this study showed that, the most farms in the Oman follow very similar farming practices. The major proportion of the tilapia is consumed within the local communities. A number of farmers have experienced mortalities, which were considered to be attributable to poor water quality, overcrowding or due to excessive feeding. Farmers facing fish mortalities tended not to record the problems due to a lack of understanding of the concept of fish farm management. There is a regulation about aquaculture and related quality control, but it has not yet been implemented in an appropriate manner in Oman. From the diverse group of bacteria recovered from wild and farmed fish, 83% of the total isolates comprised Gram negative, rod-shaped bacteria. The most frequently isolated groups from marine and cultured fish were Aeromonas spp., Vibrio spp., Sphingobacterium spp., Micrococcus spp. and Staphylococcus spp., with Aeromonas spp. being the predominant group representing 25% of the isolates recovered in this study. Identification of the Aeromonas spp. showed 57% agreement between the results of phenotypic and genotypic methodologies, and determined 6 species as the dominant organisms, i.e. A. veronii, A. jandaei, A. caviae, A. trota, A. encheleia and A. salmonicida. 65% of the iso-lates shared 99% 16S rDNA sequence similarity with the closest sequences in GenBank, and the dominant species was A. veronii. In conclusion, the Aeromonas isolates recovered from fish with clinical signs of disease showed heterogeneity in their identification profiles and their pathogenicity.

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Bromage, Erin. "The humoral immune response of Lates calcarifer to Streptococcus iniae." Thesis, Townsville, Qld, 2004. https://researchonline.jcu.edu.au/1007/1/01front.pdf.

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This study characterises various aspects of barramundi (Lates calcarifer) humoral immunity, including ontogeny, temperature modulation and kinetics following challenge with Streptococcus iniae. It was discovered that Staphylococcal protein A (SpA) was able to efficiently isolate antibody from serum, and that all barramundi Ig found in serum is tetrameric with a weight of approximately 800 kDa. This tetramer is composed of 8 heavy chains (72 kDa) and 8 light chains (28 kDa). Denaturing, non-reducing electrophoresis demonstrated differential disulfide polymerization (redox forms) of the tetrameric Ig which was consistent with those observed with other species. Polyclonal and monoclonal antibodies were produced against the protein A purified barramundi Ig, and various ELISA formats were developed. These serological tools were used to investigate aspects of barramundi humoral immunity. Examination of ontogeny of humoral immunity, revealed that barramundi possess minimal maternal antibody (<10 μg/ml wet weight) post-hatch, which is depleted rapidly (within 3 days). By day 8 systemic Ig is able to be detected, which continues to increase over the following months. However, it is not until seven week post-hatch that barramundi fingerlings are able to mount a prolonged immune response following vaccination with S. iniae. Environmental temperature was also found to significantly impact the ability of barramundi to respond to vaccination with S. iniae. Barramundi maintained at low temperatures (<230C) displayed a diminished, delayed and highly variable humoral immune response following vaccination, with many of the experimental animals failing to respond to primary vaccination. These responses could be mediated by either administering a booster vaccine or by elevating the environmental temperature. This study also demonstrated that there was a relationship with specific serum antibody and protection against S. iniae, with fish possessing high levels of specific Ig being protected from lethal challenge, while those with low titres being more susceptible to disease. Specific antibody in barramundi could be generated through natural exposure to the bacterium from the environment or through vaccination. Thus bath vaccination of fish (50,000) held at two facilities resulted in elevated systemic antibody levels and lower observed mortality, when compared to the unvaccinated control fish. Infections due to S. iniae were determined to be associated with elevated water temperatures. Laboratory trials and field data indicated that water temperatures between 24 and 280C resulted in the highest barramundi mortality. A weak association was also determined with low pH and mortality, with fish exposed to low pH’s (<6.0) being more susceptible to infection. No association was observed with mortality and salinity. Four monoclonal antibodies (Mab’s) were also generated against a 21 kDa protein from cell wall of S. iniae. The Mab’s displayed a high level of specificity for S. iniae, including those from Australia, Israel and America, and minimal cross-reactivity with other bacterial species tested. The Mab’s were used in an immunohistochemical study that confirmed the neurotropic nature of S. iniae infections, as well as demonstrating the presence of the bacterium in the intestine of infected fish.

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Bromage, Erin. "The humoral immune response of Lates calcarifer to Streptococcus iniae." Townsville, Qld, 2004. http://eprints.jcu.edu.au/1007/1/01front.pdf.

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This study characterises various aspects of barramundi (Lates calcarifer) humoral immunity, including ontogeny, temperature modulation and kinetics following challenge with Streptococcus iniae. It was discovered that Staphylococcal protein A (SpA) was able to efficiently isolate antibody from serum, and that all barramundi Ig found in serum is tetrameric with a weight of approximately 800 kDa. This tetramer is composed of 8 heavy chains (72 kDa) and 8 light chains (28 kDa). Denaturing, non-reducing electrophoresis demonstrated differential disulfide polymerization (redox forms) of the tetrameric Ig which was consistent with those observed with other species. Polyclonal and monoclonal antibodies were produced against the protein A purified barramundi Ig, and various ELISA formats were developed. These serological tools were used to investigate aspects of barramundi humoral immunity. Examination of ontogeny of humoral immunity, revealed that barramundi possess minimal maternal antibody (<10 μg/ml wet weight) post-hatch, which is depleted rapidly (within 3 days). By day 8 systemic Ig is able to be detected, which continues to increase over the following months. However, it is not until seven week post-hatch that barramundi fingerlings are able to mount a prolonged immune response following vaccination with S. iniae. Environmental temperature was also found to significantly impact the ability of barramundi to respond to vaccination with S. iniae. Barramundi maintained at low temperatures (<230C) displayed a diminished, delayed and highly variable humoral immune response following vaccination, with many of the experimental animals failing to respond to primary vaccination. These responses could be mediated by either administering a booster vaccine or by elevating the environmental temperature. This study also demonstrated that there was a relationship with specific serum antibody and protection against S. iniae, with fish possessing high levels of specific Ig being protected from lethal challenge, while those with low titres being more susceptible to disease. Specific antibody in barramundi could be generated through natural exposure to the bacterium from the environment or through vaccination. Thus bath vaccination of fish (50,000) held at two facilities resulted in elevated systemic antibody levels and lower observed mortality, when compared to the unvaccinated control fish. Infections due to S. iniae were determined to be associated with elevated water temperatures. Laboratory trials and field data indicated that water temperatures between 24 and 280C resulted in the highest barramundi mortality. A weak association was also determined with low pH and mortality, with fish exposed to low pH’s (<6.0) being more susceptible to infection. No association was observed with mortality and salinity. Four monoclonal antibodies (Mab’s) were also generated against a 21 kDa protein from cell wall of S. iniae. The Mab’s displayed a high level of specificity for S. iniae, including those from Australia, Israel and America, and minimal cross-reactivity with other bacterial species tested. The Mab’s were used in an immunohistochemical study that confirmed the neurotropic nature of S. iniae infections, as well as demonstrating the presence of the bacterium in the intestine of infected fish.

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Djainal, Winarti Achmad Sarmin. "Effect of algal-derived compounds on growth and survival of the fish pathogen Francisella noatunensis subsp. orientalis." Thesis, University of Stirling, 2018. http://hdl.handle.net/1893/27682.

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Piscine francisellosis, caused by Francisella noatuenensis subsp orientalis (Fno), is an emerging infectious disease in the tilapia industry, but no effective commercial treatments or vaccines are available. The use of immunostimulants is a promising method to control diseases in aquaculture, and various algae and algal-derived compounds are potent immunostimulants for improving immune status. Algae produce a great variety of secondary metabolites that exert a broad spectrum of biological activities. The aim of this thesis was to evaluate the effectiveness of algal compounds against Fno in vitro and in vivo and determine their potential to control francisellosis infection in Nile tilapia Oreochromis niloticus L. under experimental conditions, and in an alternative host, namely the greater wax moth Galeria mellonella. Some of the algae and their compounds (Chlorella sp., alginic acid, and ß-glucan) exerted antimicrobial activity in vitro against Fno, Aeromonas hydrophila and Streptococcus agalactiae and stimulated responses of Nile tilapia macrophages (Chapter 2). An immersion challenge model for Fno STIR-GUS-F2f7 was developed in two genetic groups of Nile tilapia, and the homo gold strain was more susceptible to infection than wild type (Chapter 3). In vivo trials were conducted in Nile tilapia homo gold where fish were fed diets supplemented with 10% Scenedesmus quaricauda, 10% Haematococcus pluvialis, and 0.1% or 0.2% alginic acid or ß-glucan, and then challenged with Fno and co-infected with S. agalactiae (Chapter 4). The Fno challenge failed to produce mortality; however, co-infection resulted in high mortalities in all groups. As the in vivo trial in tilapia could not be to repeated, a G. mellonella model for Fno was validated. Fno doses between 0.7–1.7 x 108 CFU mL-1 killed G. mellonella, while tetracycline, alginic acid and ß-glucan rescued the wax moth from lethal doses of bacteria (Chapter 5).

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Pradhan, Kalyan. "Studies on the bacterial involvement in the ulcerative disease of fishes." Thesis, University of North Bengal, 1992. http://hdl.handle.net/123456789/1110.

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Palm, Roger Carl. "Specific humoral response of rainbow trout (Onchorhynchus mykiss) to injection, immersion, and oral immunization against Vibrio anguillarum /." Thesis, Connect to this title online; UW restricted, 1996. http://hdl.handle.net/1773/5349.

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Manfredi, Eugene Trent. "Immunodiagnostic methods for the detection of bacterial kidney disease in salmonid fishes /." Thesis, Connect to this title online; UW restricted, 1986. http://hdl.handle.net/1773/5282.

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Griffin, Matt J. "Development and application of a real-time polymerase chain reaction assay for the myxozoan parasite Henneguya ictaluri." Diss., Mississippi State : Mississippi State University, 2008. http://library.msstate.edu/etd/show.asp?etd=etd-07102008-165508.

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Jacobs, Anelet. "Investigation and comparison of adherence- and biofilm-forming capacities of yellow-pigmented Chryseobacterium, Elizabethkingia and Myroides spp. isolated from South African aquaculture systems." Thesis, Stellenbosch : Stellenbosch University, 2007. http://hdl.handle.net/10019.1/19634.

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Thesis (MSc)--University of Stellenbosch, 2007.
ENGLISH ABSTRACT: In the aquaculture setting, opportunistic pathogens are present as part of the normal aquatic microflora, colonizing surfaces in fish tanks as part of biofilm communities, and often causing severe economic losses to the aquacultural industry. Isolates belonging to the genera Chryseobacterium, Elizabethkingia, Myroides and Empedobacter have been isolated from diseased fish, and are responsible for causing secondary fish infections, fish- and food-product spoilage, and have been described as etiological agents of various human diseases. Thirty-four Chryseobacterium and Elizabethkingia spp. and five Myroides and Empedobacter spp. isolates, obtained from various diseased fish species and biofilm growth in South African aquaculture systems, were characterised genetically using 16S rRNA gene PCR restriction fragment length polymorphism (RFLP), randomly amplified polymorphic DNA (RAPD) PCR, whole cell protein (WCP) and outer membrane protein (OMP) analyses. Genetic heterogeneity was displayed by the Myroides and Empedobacter spp. study isolates following OMP analysis, although 16S rRNA gene RFLP, RAPD-PCR and WCP analysis did not allow for differentiation of these isolates. A high degree of genetic heterogeneity was displayed by the Chryseobacterium and Elizabethkingia spp. study isolates following OMP analysis, 16S rRNA gene RFLP with MspI, and RAPD-PCR with primer P2. However, based on the results obtained by WCP analysis, 16S rRNA gene RFLP with CfoI and TaqI, and RAPD-PCR with primer P1 the isolates appeared genetically very homogeneous. High MAR indices and potential multi-drug resistance phenotypes were obtained for the Myroides and Empedobacter spp. and some of the Chryseobacterium and Elizabethkingia spp. isolates by antimicrobial susceptibility testing. Primary adherence and the influence of environmental changes on adherence was investigated by a modified microtitre-plate adherence assay. Nutrient composition, temperature and hydrodynamic incubation conditions were observed to influence adherence abilities of all study isolates. In addition, adherence varied greatly among isolates of the genera Chryseobacterium and Elizabethkingia, as opposed to a consistent strong adherence profile observed for the Myroides and Empedobacter spp. isolates. The influence of cell surface properties such as capsule presence and cell surface hydrophobicity, on primary adherence of the isolates was also investigated. Quantitative analysis of capsular material revealed the presence of thick capsular material surrounding the Myroides and Empedobacter spp. and some of the Chryseobacterium and Elizabethkingia spp. isolates, but could not be directly associated with adherence. Hydrophobicity were investigated using the salt aggregation assay (SAT) and bacterial adherence to hydrocarbon test (BATH). A very hydrophilic cell surface was observed for all of the Myroides and Empedobacter spp. isolates, and majority (74%) of the Chryseobacterium and Elizabethkingia spp. isolates. Cell surface hydrophobicity could not be correlated to the adherence of the Myroides and Empedobacter spp. isolates, and only SAT-determined hydrophobicity could be positively correlated to adherence of Chryseobacterium and Elizabethkingia spp. isolates under certain conditions. Coaggregation studies were performed between the study isolates and various important clinical and aquacultural microorganisms. High coaggregation indices were observed between the Myroides and Empedobacter spp. isolates and E. faecalis and S. aureus, and between E. faecalis, S. enterica serovar Arizonae, S. aureus and Listeria spp. and the Chryseobacterium and Elizabethkingia spp. isolates. Biofilm-forming capacity of the study isolates in an environment simulating their natural environment was investigated microscopically using a flow cell system. Typical ‘cone-like’ biofilm structures were observed for selected strains of both Myroides and Empedobacter spp. and Chryseobacterium and Elizabethkingia spp. isolates. The effect of increased hydrodynamics on biofilm architecture was seen through the narrowing of the biofilm structures and the formation of single cell chains towards the increased hydrodynamic area of the flow chambers. Chryseobacterium and Elizabethkingia spp. and Myroides and Empedobacter spp. appear to be potential primary biofilm-formers associating with a variety of microbes thus perpetuating their survival in a variety of aquatic habitats.
AFRIKAANSE OPSOMMING: Opportunistiese patogene kom gereeld in akwakultuur sisteme voor as deel van die akwatiese mikroflora wat dikwels biofilms vorm op oppervlaktes in hierdie sisteme. Visinfeksies veroorsaak deur hierdie patogene lei tot ernstige ekonomiese verliese vir akwakultuur industrieë. Chryseobacterium, Elizabethkingia, Myroides en Empedobacter spp. is reeds voorheen van verskeie geïnfekteerde visspesies geïsoleer hierdie bakterieë is verantwoordelik vir sekondere visinfeksies, die bederf van vis- en kosprodukte, asook menslike siektes. Vier-en-dertig Chryseobacterium en Elizabethkingia spp. en 5 Myroides en Empedobacter spp. isolate, geïsoleer vanaf verskeie geïnfekteerde visspesies en biofilm-groei in Suid Afrikaanse akwakultuur-sisteme, is geneties met behulp van 16S rRNS geen PKR restriksie fragment lengte polimorfisme (RFLP), toevallig geamplifiseerde polimorfiese DNS (TGPD) PKR, heel-sel protein (HSP) en buitemembraan protein (BMP) analise gekarakteriseer. BMP analise het getoon dat die Myroides en Empedobacter spp. isolate geneties heterogeen is, alhoewel 16S rRNS TGPD-PKR, TGPD-PKR en HSP analise nie tussen die isolate kon onderskei nie. BMP analise, 16S rRNS TGPD-PKR met MspI en TGPD-PKR met inleier P2 was meer suksesvol as HSP analise, 16S rRNS TGPD-PKR met CfoI en MspI, en TGPD-PKR met inleier P1, om onderskeid te tref tussen die Chryseobacterium en Elizabethkingia spp. isolate en het gedui op ‘n hoë vlak van genetiese heterogeniteit tussen hierdie isolate. Beide die Chryseobacterium en Elizabethkingia spp. en Myroides en Empedobacter spp. isolate het ‘n hoë vlak van antibiotika weerstand getoon wat dui op ‘n menigvuldigde antibiotika weerstands-fenotiepe. Primêre vashegting vermoëns en die invloed van omgewingsfaktore op vashegting is met behulp van ‘n gemodifiseerde mikrotiterplaat vashegtings toets ondersoek. Vashegting van die isolate is beïnvloed deur variasies in die samestelling van die medium, temperatuurveranderings en verskillende hidrodinamiese inkubasie kondisies. Inteenstelling met die sterk vashegtingsvermoë van die Myroides en Empedobacter spp. isolate, het die vermoë om vas te heg grootliks tussen die Chryseobacterium en Elizabethkingia spp. isolate gevarieer. Verder is ondersoek ingestel op die invloed van seloppervlak eienskappe soos die teenwoordigheid van kapsules en hidrofobisiteit op die isolate se vermoë om aan oppervlaktes te heg. Die Myroides en Empedobacter spp. isolate en verskeie Chryseobacterium en Elizabethkingia spp. isolate is omring deur dik kapsules, maar geen verband tussen vashegting en die teenwoordigheid van kapsules kon bepaal word nie. Die sout aggregasie toets (SAT) en bakteriële vashegting aan koolwaterstowwe (BVAK) toets was gebruik om die hidrofobisiteit van die isolate se seloppervlaktes te bepaal. Die Myroides en Empedobacter spp. isolate en 74% van die Chryseobacterium en Elizabethkingia spp. isolate het ‘n baie hidrofiliese seloppervlak getoon. Slegs die hidrofobisiteit bepaal deur die SAT toets het ‘n positiewe verwantskap met die aanhegtingsvermoë van die Chryseobacterium en Elizabethkingia spp. isolate getoon. Mede-aggregasie tussen die isolate en verskeie belangrike mediese en akwakultuur mikroörganismes is ook ondersoek. Die Myroides en Empedobacter spp. isolate het ‘n sterk assosiasie met E. faecalis en S. aureus getoon Die Chryseobacterium en Elizabethkingia spp. isolate het sterk met E. faecalis, S. aureus, S. enterica serovar Arizonae en Listeria spp. geassosieer. Vloei-sel studies is uitgevoer om die biofilm-vormingsvermoë van die isolate te ondersoek. Vir beide die Myroides en Empedobacter spp. en Chryseobacterium en Elizabethkingia spp. isolate is tipiese kegelagtige biofilm stukture waargeneem. Die invloed van verhoogde hidrodinamiese kondisies in die vloei-sel het vernouing van die biofilm strukture en die vorming van enkel-sel kettings tot gevolg gehad. Vanuit hierdie studie is afgelei dat die Myroides en Empedobacter spp. en Chryseobacterium en Elizabethkingia spp. isolate onder verskeie kondisies aan oppervlaktes kan vasheg en dus potensiële primêre biofilm-vormings organismses is. Hierdie organismes besit ook die vermoë om met ‘n verskeidenheid ander organismes te assosieer, wat waarskynlik hulle suksesvolle oorlewing in akwakultuursisteme verseker.

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Soto, Esteban. "Genetic and virulence diversity of Flavobacterium columnare." Master's thesis, Mississippi State : Mississippi State University, 2007. http://library.msstate.edu/etd/show.asp?etd=etd-05292007-091752.

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McMillan, Stuart. "Virulence and required genes in the fish pathogen Vibrio anguillarum." Thesis, University of Stirling, 2016. http://hdl.handle.net/1893/25417.

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Vibrio anguillarum infects many fish species in aquaculture, reducing farm productivity and negatively impacting fish welfare. Deeper understanding of the biology of V. anguillarum, particularly during infections in vivo, will help to improve disease prevention and control. Thus, the aim of this thesis was to provide further insight into the infection biology of V. anguillarum with a view to identifying better ways to reduce the impact of this pathogen in aquaculture. Conventional studies on virulence, particularly those aiming to identify novel virulence factors, often employ transposon mutagenesis where the functions of individual genes in the bacterium are disrupted. These mutant libraries are screened to identify those with attenuated virulence, allowing subsequent identification of the gene responsible. Usually the native fish host would be used but such studies are increasingly difficult to perform due to regulations on vertebrate experiments and ethical concerns. As a result, alternative invertebrate hosts are now an important means to studying microbial infections, but few models have been assessed for bacterial pathogens of fish. In this thesis, larvae of the greater wax moth Galleria mellonella were evaluated as an alternative host to investigate V. anguillarum virulence. Wild-type V. anguillarum isolates killed larvae in a dose-dependent manner, replicated in the haemolymph, and larvae infected with a lethal dose of bacteria could be rescued by antibiotic therapy, thus indicating that V. anguillarum established an infection in G. mellonella. Crucially, virulence of 11 wild-type V. anguillarum isolates correlated significantly between larva and Atlantic salmon infection models, and studies with isogenic mutants knocked out for various virulence determinants revealed conserved roles for some in larva and fish infections, including the pJM1 virulence plasmid and rtxA toxin. Thereafter, 350 strains from a V. anguillarum random transposon insertion library were screened for attenuated virulence in G. mellonella. In total, 12 strains had reduced virulence and in these mutants the transposon had inserted into genes encoding several recognised and putative virulence factors, including a haemolytic toxin (vah1) and proteins involved in iron sequestration (angB/G and angN). Importantly, the transposon in one strain had inserted into an uncharacterised hypothetical protein. Preliminary investigations found this putative novel virulence factor to contain a GlyGly-CTERM sorting domain motif, with sequence similarity to VesB of Vibrio cholerae which is involved in post-translational processing of cholera toxin. Finally, three transposon insertion libraries were mass sequenced on a MiSeq platform to identify V. anguillarum genes lacking transposon insertions. These genes were assumed to be ‘required’ for viability in the conditions under which the mutants were selected, in this case tryptone soya agar. In total, 248 genes lacked a transposon insertion and were the putative ‘required’ genes, and these may be important chemotherapeutic targets for new approaches to combat V. anguillarum infections. This thesis has furthered our understanding of the biology of the important fish pathogen V. anguillarum using an ethically acceptable approach, and the findings may assist with new ways to reduce the burden of this bacterium in aquaculture.

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Fukushima, Hirla Costa Silva [UNESP]. "Eficácia de duas formulações de vacinas autógenas para o controle da lactococose em surubins híbridos Pseudoplatystoma corruscans x Pseudoplatystoma reticulatum." Universidade Estadual Paulista (UNESP), 2014. http://hdl.handle.net/11449/115894.

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Identificou-se no presente estudo o agente patogênico causador de surtos de estreptococose em cachara e surubins como sendo a Lactococcus garvieae. Considerando que a lactococose é uma doença emergente de importância econômica mundial, que gera surtos de mortalidade em massa em diversas espécies de peixes, avaliamos a possibilidade de prevenção e controle desta patogenia com o uso de vacinas. Após confirmação da patogenicidade da bactéria pelo Postulado de Koch, foram formuladas duas bacterinas inativadas com formalina, uma aquosa e uma oleosa, com emprego de adjuvante. Surubins híbridos foram imunizados via intraperitoneal com ambas bacterinas e com PBS. Para avaliar a eficiência das vacinas foi comparada a potência dos imunobiológicos desenvolvidos na sobrevivência dos animais, na cinética de anticorpos 15, 30 e 60 dias após a vacinação e na modulação da resposta imune após desafio bacteriano. Melhores níveis de proteção foram observados com a imunização com bacterina oleosa, onde foi observado maior nível de anticorpos circulantes e cujo valor de porcentagem relativa de sobrevivência foi de 81,7%. O presente fez o primeiro registro de surto de septicemia hemorrágica causada por Lactococcus garvieae em surubins híbridos e cacharas, e demonstrou que a imunidade dos surubins pode ser estimulada com emprego de vacinas, e que a bacterina oleosa proporciona proteção mais eficaz contra a lactococose
The present study identified the pathogen causing outbreaks of estreptococose in cachara and surubins as being the Lactococcus garvieae. Whereas lactococose as an emerging disease of worldwide economic importance, that generates outbreaks of mass mortality in several species of fish, we evaluated the possibility of prevention and control of this pathogen with the use of vaccines. After confirming the pathogenicity of the bacterium by Koch postulate, two inactivated bacterins with formalin, an aqueous and an oily, with the use of adjuvant, were formulated. Surubins hybrids were immunized intraperitoneally with PBS and both bacterins. To evaluate the efficacy of the vaccines was compared the potency of the biopharmaceuticals developed in survival of the animals, on the kinetic of antibody 15, 30 and 60 days after vaccination and in the modulation of the immune response after bacterial challenge. Best levels of protection were observed with immunization with oily bacterin, where were observed higher level of circulating antibodies and whose value relative survival percentage was 81.7 %. This work made the first recorded outbreak of haemorrhagic septicemia caused by Lactococcus garvieae in hybrid surubins and cacharas, and demonstrated that the immunity of surubins can be stimulated through the use of vaccines, and oily bacterin provides more effective protection against lactococose

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Fukushima, Hirla Costa Silva. "Eficácia de duas formulações de vacinas autógenas para o controle da lactococose em surubins híbridos Pseudoplatystoma corruscans x Pseudoplatystoma reticulatum /." Jaboticabal, 2014. http://hdl.handle.net/11449/115894.

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Orientador: Maria José Tavares Ranzani de Paiva
Banca: Eduardo Makoto Onaka
Banca: Antenor Aguiar Santos
Banca: Paulo Teixeira Lacava
Banca: Ricardo Carneiro Borra
Resumo: Identificou-se no presente estudo o agente patogênico causador de surtos de estreptococose em cachara e surubins como sendo a Lactococcus garvieae. Considerando que a lactococose é uma doença emergente de importância econômica mundial, que gera surtos de mortalidade em massa em diversas espécies de peixes, avaliamos a possibilidade de prevenção e controle desta patogenia com o uso de vacinas. Após confirmação da patogenicidade da bactéria pelo Postulado de Koch, foram formuladas duas bacterinas inativadas com formalina, uma aquosa e uma oleosa, com emprego de adjuvante. Surubins híbridos foram imunizados via intraperitoneal com ambas bacterinas e com PBS. Para avaliar a eficiência das vacinas foi comparada a potência dos imunobiológicos desenvolvidos na sobrevivência dos animais, na cinética de anticorpos 15, 30 e 60 dias após a vacinação e na modulação da resposta imune após desafio bacteriano. Melhores níveis de proteção foram observados com a imunização com bacterina oleosa, onde foi observado maior nível de anticorpos circulantes e cujo valor de porcentagem relativa de sobrevivência foi de 81,7%. O presente fez o primeiro registro de surto de septicemia hemorrágica causada por Lactococcus garvieae em surubins híbridos e cacharas, e demonstrou que a imunidade dos surubins pode ser estimulada com emprego de vacinas, e que a bacterina oleosa proporciona proteção mais eficaz contra a lactococose
Abstract: The present study identified the pathogen causing outbreaks of estreptococose in cachara and surubins as being the Lactococcus garvieae. Whereas lactococose as an emerging disease of worldwide economic importance, that generates outbreaks of mass mortality in several species of fish, we evaluated the possibility of prevention and control of this pathogen with the use of vaccines. After confirming the pathogenicity of the bacterium by Koch postulate, two inactivated bacterins with formalin, an aqueous and an oily, with the use of adjuvant, were formulated. Surubins hybrids were immunized intraperitoneally with PBS and both bacterins. To evaluate the efficacy of the vaccines was compared the potency of the biopharmaceuticals developed in survival of the animals, on the kinetic of antibody 15, 30 and 60 days after vaccination and in the modulation of the immune response after bacterial challenge. Best levels of protection were observed with immunization with oily bacterin, where were observed higher level of circulating antibodies and whose value relative survival percentage was 81.7 %. This work made the first recorded outbreak of haemorrhagic septicemia caused by Lactococcus garvieae in hybrid surubins and cacharas, and demonstrated that the immunity of surubins can be stimulated through the use of vaccines, and oily bacterin provides more effective protection against lactococose
Doutor

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15

Sirimanapong, Wanna. "Characterisation of the immune response of the striped catfish (Pangasianodon hypophthalmus, Sauvage) following immunomodulation and challenge with bacteria pathogens." Thesis, University of Stirling, 2013. http://hdl.handle.net/1893/19277.

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In Southeast Asia, the family Pangasiidae is important for commercial fisheries and aquaculture. Pangasianodon hypophthalmus (striped catfish) is the most economically important species farmed in Vietnam, with a total export value of 1.7 billion USD in 2012. Intensive aquaculture can lead to problems with major outbreaks of disease and Edwardsiella ictaluri and Aeromonas hydrophila represent two important bacterial pathogens in P. hypophthalmus aquaculture. Immunostimulants have proven to be a very useful food additive for the aquaculture industry, since they can be easily fed to fish to enhance their immune response at times of stress and to improve resistance to disease. The immune system of pangasius catfish has not been fully described, despite the recent growth in aquaculture for this species, and little is known about the effects of immunostimulants on disease resistance. Understanding the immune response is very important in order to evaluate the health status of the fish and assist in control of disease (including prevention) so that production levels by the aquaculture industry can be sustained. The aims of this thesis were to develop and standardise methods to elucidate and measure immune responses in P. hypophthalmus and then to use these with relevant disease models (A. hydrophila and E. ictaluri) and immunomodulators (β-glucans from different sources and at different doses) to determine if bacterial diseases can be controlled, and which functional immune responses and immune genes could be correlated with disease resistance. As a variety of different species from family Pangasiidae are economically important for aquaculture, initial work focused on the characterisation of the immunoglobulin IgM molecule in these species, and anti-P. hypophthalmus IgM mAbs were tested to determine if they cross-reacted between different Pangasiidae species (Chapter 2). Although affinity purification of IgM from the different fish species resulted in a purer preparation ammonium sulphate precipitation (14% w/w), the latter proved faster and easier to perform. The heavy (H) and light (L) chains of IgM from P. hypophthalmus were estimated to be 70-72 kDa and 25-26 kDa, respectively, using SDS-PAGE (12.5%). The L chains of IgM in the other Asian fish species examined were similar in molecular weight to P. hypophthalmus, while the H chains varied (P. gigas and P. larnaudii 76kDa, P. sanitwongsei 69kDa, H. filamentus 73kDa, P. borcoti and H. wyckioides 75kDa, C. bactracus 74kDa, C. macrocephalus 73kDa and C. carpio 70kDa), as did the native IgM molecules. Sedimentation velocity ultracentrifugation was used to determine the molecular weight of the whole IgM molecule from P. hypophthalmus as an alternative to the more commonly used native gels that are run under non-denaturing conditions, although this technique proved more complex. Anti–P. hypophthalmus IgM monoclonal antibodies (mAbs) cross reacted with all of the Pangasiidae species and were successfully applied in an enzyme-linked immunosorbent assay (ELISA) using mAb 23 to measure serum antibody response of P. hypoophthalmus following experimental infection with A. hydrophila by interperitoneal (I.P.) injection in Chapter 3 and E. ictaluri by immersion in Chapter 4. As P. hypophthalmus is a relatively new aquaculture species, there are few reports evaluating its immune response to pathogens. Thus, functional assays were standardised to evaluate both innate and adaptive immune responses of this species and then these assays used to compare immune response following stimulation with live and killed A. hydrophila. (Chapter3). Four treatment groups of 40 fish per group (53.2 ± 14.8g.) consisting of an untreated control group, a group injected I.P. with adjuvant (Montanide ISA 760 VG) only, a group injected with heat-killed A. hydrophila (1 x109 cfu ml-1 mixed with adjuvant), and a group injected with a subclinical dose of live A. hydrophila 2.7 x105 cfu ml-1 were used in the study. Samples were collected 0, 1, 3, 7, 14 and 21 days post injection (d.p.i.) to assess the immune response of fish. The results indicated that challenge with live or/and dead bacteria stimulated the immune response in P. hypophthalmus significantly above control groups with respect to specific antibody titre, lysozyme activity, phagocytosis and plasma peroxidase at 7 or/and 14 d.p.i. Moreover, on 21 d.p.i. total IgM, specific antibody titre and lysozyme activity from both live and dead A. hydrophila challenge groups were significantly different to the control groups. Differential immune responses between live and dead bacterial challenges were also observed as only live A. hydrophila significantly stimulated WBC counts and plasma peroxidase at 3 d.p.i. with the greatest increase in WBC counts noted at 21 d.p.i. and in phagocytosis at 14 d.p.i. By 21 d.p.i. only the macrophages from fish challenged with dead A. hydrophila showed significantly stimulated respiratory burst activity. Immunostimulants are food additives used by the aquaculture industry to enhance the immune response, and β-glucan is now commonly used for this purpose in aquaculture. In Chapter 4 the effect of the prebiotic β-glucan on the immune response and disease resistance of P. hypophthalmus was evaluated. The fish (60.3 ± 11.7 g.) were fed with a basal diet (control) or diets supplemented with fungal derived β-glucan at concentrations of 0.05 %, 0.1 %, or 0.2 % g/kg for four weeks. Fish fed 0.1 % commercial yeast derived β-glucan were also included as a positive control group. Samples were collected from fish on Days 0, 1, 3, 7, 14, 21 and 28. The results showed that fish fed with the highest two levels of fungal derived β-glucan had enhanced immune responses compared to the control group, with respiratory burst activity on all days examined and lysozyme activity on 7 days post feeding (d.p.f.) being significantly elevated (P<0.05) in the group fed with 0.2 % fungal derived β-glucan, while plasma anti-protease activity on 21 d.p.f., natural antibody titre on 3 d.p.f. and complement activity 7 d.p.f. and 14 d.p.i. were significantly enhanced (P<0.05) in the group fed 0.1 % fungal derived β-glucan. The lowest dose of fungal derived β-glucan (0.05 %) appeared insufficient to effectively stimulate the fish’s immune response. WBC count, respiratory burst, lysozyme activity and complement were useful as an early indication of immunostimulation (1 to 7 days). Four weeks after feeding with the different diets, the fish were experimentally infected with E. ictaluri by immersion using 8 x104 cfu ml-1 for 1 h and mortalities were monitored for 14 days. There was a great deal of variation in the level of mortalities within the four replicate tanks for each dietary group. Although the in vivo challenge results showed no statistical differences between the groups fed on the different diets, the highest mortalities were observed in group fed with the control diet and the lowest mortalities were observed in the groups fed with commercial yeast derived β-glucan and 0.2 % fungal derived β glucan. Immune gene expression following stimulation with β-glucan and challenge with E. ictaluri was investigated in Chapter 5.

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16

Mazur, Carl François. "Growth, incidence of bacterial kidney disease and immunological function of salmonids reared in captivity." Thesis, University of British Columbia, 1991. http://hdl.handle.net/2429/30127.

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Pacific salmon reared commercially off of the Coast of British Columbia suffer great mortality losses to Bacterial Kidney Disease (BKD), caused by the diplobacillus bacterium Renibacterium salmqninarum. This thesis investigates the effects of environmental conditions on the growth performance and disease susceptibility of salmonids reared in captivity. I found that growth rate of chinook salmon was significantly higher in fish fed to 100 compared to 67 % of satiation during the first 175 days of saltwater rearing but not during the first winter. Feed coversion rate was significantly higher for fish fed at 100 % of satiation compared to 67 % of satiation and higher during the winter compared to summer and fall, irrespective of feeding level. Mortality rates were significantly higher during the summer than during the fall or winter, irrespective of experimental treatment. The last BKD sampling period (day 263) revealed that infection rates were directly proportional to stocking densities of 1.5 to 4 kg.m⁻₃. Hatchery-reared chinook salmon held in freshwater aquaria had significantly lower hematocrit and plasma cortisol concentration increases in response to increased stocking density than did their wild counterparts. Crowding of hatchery-reared and wild chinook salmon resulted in equally increased mortality rates for both groups of fish. Day 33 plasma cortisol concentrations in Atlantic salmon held at three stocking densities were directly proportional to stocking densities of 8 to 64 kg.m⁻₃. The ability of anterior kidney lymphocytes from these fish to produce antibody-producing cells was inversely proportional to the density at which the fish were held.
Land and Food Systems, Faculty of
Graduate

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17

Ajitha, S. "Investigations on the effect of probionts as a tool against bacterial infestation in Penaeus (Fenneropenaeus indicus H. Milne Edwards) juveniles." Thesis, Central Marine Fisheries Research Institute, 1997. http://eprints.cmfri.org.in/11023/1/Ajitha%20S..pdf.

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The family Vibrionacea plays an ambiguous part m marine fish and shellfish as it includes bacterial strains that have been reported to proliferate and cause mass mortalities in semi intensive and intensive culture systems.) Gram negative bacterial septicemias disease or Vibriosis has been observed in captured as well as cultured marine crustaceans exposed to stress where it has resulted in severe mortalities. Systemic infection or septicemis have also been reviewed. The infections are usually caused by Vibrio parahaemolyticus. Vibrio alginolyticus or the odd Aeromonas spp. Although there are many reports of vibriosis among marine crustaceans none have been studied in detail.

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18

Gonzalez, Jorge Del Pozo. "A study of the aetiology and control of rainbow trout gastroenteritis." Thesis, University of Stirling, 2009. http://hdl.handle.net/1893/1081.

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Disease has been identified as a major problem in the aquaculture industry for the welfare of the fish stocked as well as for its economic impact. The number of diseases affecting cultured fish has increased significantly during recent years with the emergence of several conditions that have added to the overall impact of disease on the industry. Frequently, a lack of scientific knowledge about these diseases is compounded by an absence of effective treatment and control strategies. This has been the case with rainbow trout gastroenteritis (RTGE), an emerging disease of rainbow trout (Oncorhynchus mykiss Walbaum). This study investigated several aspects related to its aetiology and control. A retrospective survey of UK rainbow trout farmers was undertaken to ascertain the extent and severity of RTGE in the UK as well as to identify RTGE risk factors at the site level. Participants in this study accounted for over 85% of UK rainbow trout production in 2004. It was found that the total number of RTGE-affected sites had risen from 2 in the year 2000 to 7 in 2005. The disease was only reported from sites producing more than 200 tonnes of trout/year for the table market. Analysis of risk factors associated with RTGE at the site level showed that this syndrome was associated with large tonnage and rapid production of rainbow trout for the table market. The data collected during this study enabled the identification of those sites that were most likely to present with RTGE the following year and this information was used to study the epidemiology of RTGE at the unit level. A prospective longitudinal study was undertaken in 12 RTGE-affected UK sites. It described in detail the impact, presentation, current control strategies and spread pattern of RTGE within affected UK sites. The risk factors associated with RTGE presence and severity were also investigated. Data were collected for each productive unit (i.e. cage, pond, raceway or tank) on the mortalities, fish origin, site management and environmental factors. RTGE was identified using a case definition based on gross pathological lesions. Analysis of these data revealed that RTGE behaved in an infectious manner. This conclusion was supported by the presence of a pattern typical of a propagating epidemic within affected units. Also, the risk of an unaffected unit becoming RTGE positive was increased if it had received fish from or was contiguous to a RTGE-affected unit. The presentation also suggested an incubation period of 20-25 days. Risk factor analysis identified management and environmental risk factors for RTGE, including high feed input and stressful events, which could be used to generate a list of control strategies. A study of the histopathological and ultrastructural presentation of RTGE was conducted. The location of segmented filamentous bacteria (SFB) and pathological changes found in affected fish were examined. Pyloric caeca were the digestive organ where SFB were found more frequently and in higher numbers, suggesting that this was the best location to detect SFB in RTGE-affected trout. Scanning and transmission electron microscopy revealed a previously undescribed interaction of SFB with the mucosa of distal intestine and pyloric caeca and this included the presence of attachment sites and SFB engulfment by enterocytes, as previously described in other host species. The SFB were not always adjacent to the pathological changes observed in the digestive tract of RTGE-affected trout. Such changes included cytoskeletal damage and osmotic imbalance of enterocytes, with frequent detachment. These observations suggested that if SFB are indeed the cause of RTGE their pathogenesis must involve the production of extracellular products. Analysis of the gross presentation and blood biochemistry in RTGE-affected fish was used to examine the patho-physiologic mechanisms of RTGE. To enable identification of positive RTGE cases for this study, a case definition was created from the information available on RTGE gross presentation in the literature. This case definition was assessed in a sample including 152 fish cases and 152 fish controls from 11 RTGE-affected UK sites, matched by unit of origin. The analysis of these fish using bacteriology, packed cell volume (PCV) and histopathology revealed that RTGE occurred simultaneously with other parasitic and bacterial diseases in a percentage of fish identified with this case definition. With the information gained after analysing the gross presentation, RTGE-affected fish without concurrent disease were selected for the study of the pathogenesis, which included blood biochemical analyses. These analyses revealed a severe osmotic imbalance, and a reduced albumin/globulin ratio suggesting selective loss of albumin, typical for a protein losing enteropathy. The role of the SFB “Candidatus arthromitus” in the aetiology of RTGE was assessed using a newly developed “C. arthromitus”-specific polymerase chain reaction assay (PCR) in conjunction with histological detection. This technique was applied to eight different groups of trout, including an RTGE-affected group and seven negative control groups. This analysis was conducted on DNA extracted from paraffin wax-embedded tissues as well as fresh intestinal contents. The results revealed the presence of “C. arthromitus” DNA in apparently healthy fish from sites where RTGE had never been reported. Additionally, SFB were observed histologically in two trout from an RTGE-free hatchery. These findings do not permit the exclusion of “C. arthromitus” as the aetiological agent for RTGE, although they suggest that the presence of these organisms in the digestive system of healthy trout is not sufficient to cause clinical disease, and therefore other factors are necessary. In conclusion, this study has used a multidisciplinary approach to the study of RTGE which has generated scientific information related to the epidemiology, pathogenesis and aetiology of this syndrome. The results of this project have suggested priority areas where further work is required, including experimental transmission of RTGE, field assessment of the control strategies proposed and further investigation into the aetiology of RTGE.

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Ramirez, Paredes J. G. "The fish pathogen Francisella orientalis : characterisation and vaccine development." Thesis, University of Stirling, 2015. http://hdl.handle.net/1893/21822.

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Piscine francisellosis in an infectious emerging bacterial disease that affects several marine and fresh water fish species worldwide, including farmed salmon, wild and farmed cod, farmed tilapia and several ornamental species, for which no commercial treatment or vaccine exists. During 2011 and the first semester of 2012, chronic episodes of moderate to high levels of mortality with nonspecific clinical signs, and widespread multifocal white nodules as the most consistent gross pathological lesion were experienced by farmed tilapia fingerlings at two different locations in Northern Europe. In this study such outbreaks of granulomatous disease were diagnosed as francisellosis with a genus-specific PCR, and 10 new isolates of the bacterium including the one named STIR-GUS-F2f7, were recovered on a new selective “cysteine blood-tilapia” agar and cysteine heart agar with bovine haemoglobin. Ultrastructural observations of the pathogen in Nile tilapia (O. niloticus) tissues suggested the secretion of outer membrane vesicles (OMVs) by the bacterial cells during infection in these fish. This represented the first documented report of isolation of pathogenic Francisella strains from tilapia in Europe. The phenotypic characterisation indicated that isolates recovered were able to metabolise dextrin, N-acetyl-D glucosamine, D-fructose, α-D-glucose, D-mannose, methyl pyruvate, acetic acid, α-keto butyric acid, L-alaninamide, L-alanine, L-alanylglycine, L-asparagine, L-glutamic acid, L-proline, L-serine, L-threonine, inosine, uridine, glycerol, D L-α-glycerol phosphate, glucose-1-phosphate and glucose-6-phosphate. The predominant structural fatty acids of the isolates were 24:1 (20.3%), 18:1n-9 (16.9%), 24:0 (13.1%) 14:0 (10.9%), 22:0 (7.8%), 16:0 (7.6%) and 18:0 (5.5%). Anti-microbial resistance analyses indicated that STIR-GUS-F2f7 was susceptible to neomycin, novobiocin, amikacin, ciprofloxacin, imipenem, gatifloxacin, meropenem, tobramycin, nitrofurantoin, and levofloxacin using the quantitative broth micro-dilution method, while the qualitative disc diffusion method indicated susceptibility to enrofloxacin, kanamycin, gentamicin, tetracycline, oxytetracycline, florfenicol, oxolinic acid and streptomycin. The use of the following housekeeping genes: mdh, dnaA, mutS, 16SrRNA-ITS-23SrRNA, prfB putA rpoA, rpoB and tpiA indicated 100% similarity with other isolates belonging to the subspecies F. noatunensis orientalis (Fno). Koch’s postulates were successfully fulfilled by establishing an intraperitoneal injection (IP) challenge model with STIR-GUS-F2f7 in Nile tilapia. Moreover, the challenge model was used to investigate the susceptibility of 3 genetic groups of tilapia to STIR-GUS-F2f7. The lowest amount of bacteria required to cause mortality was 12 CFU/ml and this was seen as early as only 24 hours post infection in the red Nile tilapia and in the wild type after 26 days, no mortalities were seen in the species O. mossambicus with this dose. The mortality in red O. niloticus was significantly higher than that of the other two tilapia groups when 12 and 120 CFU/fish were injected. It was also observed that when a dose of 1200 CFU/ml was used, the mortality in O. niloticus wild type was significantly lower than that of the other two tilapia groups and no differences were seen among the 3 groups when the highest dose (1.2 x105 CFU/fish) was used. The median lethal dose (LD50) of O. niloticus wild type was the most stable during the experiment (values around 104 CFU/ml) and the highest of the three groups after day 25 post infection. At the end of the experiment (day 45) the LD50 was 30 CFU/ml in the red Nile tilapia, 2.3x104 CFU/ml for the wild type and 3.3x102 CFU/ml for O. mossambicus. This pattern, where the LD50 of the red tilapia was lower than that of the other two groups, was observed during the whole experiment. The outcomes of these experiments suggested that the red Nile tilapia family appeared to be the most susceptible while the wild type Nile tilapia family the most resistant. The complete genome of STIR-GUS-F2f7 was sequenced using next generation sequencing (NGS) Illumina Hi-Seq platform™, and the annotation of the assembled genome predicted 1970 protein coding sequences and 63 non-coding rRNA sequences distributed in 328 sub-systems. The taxonomy of the species Francisella noatunensis was revised using genomic-derived parameters form STIR-GUS-F2f7 and other strains in combination with a polyphasic approach that included ecologic, chemotaxonomic and phenotypic analyses. The results indicated that STIR-GUS-F2f7 and all the other strains from warm water fish represent a new bacterial species for which the name Francisella orientalis was assigned. Moreover the description of F. noatunensis was emended and the creation of a new subspecies within this taxon i.e. Francisella noatunensis subsp. chilense was proposed. The results of this study led to the development of a highly efficacious vaccine to protect tilapia against francisellosis.

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20

Roberts, S. J. "Bacterial diseases of woody ornamental plants." Thesis, University of Leeds, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.375533.

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21

Zhang, Xiao-Hua. "Studies on the pathogenicity mechanisms of the fish pathogen Vibrio harveyi." Thesis, Heriot-Watt University, 2001. http://hdl.handle.net/10399/544.

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22

Olfat, Farzad. "Helicobacter pylori : bacterial adhesion and host response." Doctoral thesis, Umeå universitet, Odontologi, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-133.

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The gastric pathogen Helicobacter pylori infects more than half of the population worldwide. H. pylori manage to establish persistent infection, which would be life-long if not treated. In order to establish such an infection, this pathogen has to deal with the host immune system. H. pylori has certain characteristics which make the bacteria less announced to the host immune system. Additionally, for remaining in the harsh and acidic environment of the stomach with peristaltic movements and a high frequency of turnover of epithelial cells, H. pylori has developed different binding modes to structures present both in the mucus and on the surface of gastric cells and also to extracellular matrix proteins. Evidently, adhesion has a determinant role for a successful colonization by H. pylori. It has been shown that a small fraction of the H. pylori infection is in intimate contact and attached to the host epithelium. Despite its small proportion, this group maintains the persistency of infection. As there is no suitable in vitro system to mimic the human stomach for studies of H. pylori infection, we have developed the In Vitro Explant Culture technique (IVEC). By using this model we could show that H. pylori use the Lewis b blood group antigen to bind to the host gastric mucosa, during experimental conditions most similar to the in vivo situation. Furthermore, we could show that the host tissue responses to the bacterial attachment by expression of Interleukin 8 (IL- ), which will guide the inflammatory processes. Interestingly, by inhibition of bacterial adhesion through receptor competition i.e., by use of soluble Lewis b antigen, IL-8 production was hampered in the IVEC system, which further validates the presence of a tight relation between bacterial adhesion and induction of host immune responses. One of the inflammation signaling cursors in vivo is the upregulated sialylated Lewis x (sLex) antigen, an inflammation associated carbohydrate structure well established as a binding site for the selectin family of adhesion molecules. We could show that during chronic gastric inflammation, which is actually caused by the persistent H. pylori infection, the bacterial cells adapt their binding mode, and preferentially bind to sLex, which will provide an even more intimate contact with the host cells. This interaction is mediated by SabA, the H. pylori adhesin for sialylated oligosaccharides/glycoconjugates. By employing red blood cells as a model we could further demonstrate that SabA is identical to the “established” H. pylori hemagglutinin. We could also show that SabA binds to sialylated glycolipids (gangliosides) rather than glycoproteins on cell surfaces. Our result also revealed that SabA also binds to and activates human neutrophils. Such effect was unrelated to BabA and the H. pylori Neutrophil Activating Protein (HP- AP), which were not directly involved in the activation of neutrophils. Furthermore, phagocytosis of bacteria by neutrophils was demonstrated to be mainly dependent on presence of SabA. Interestingly, HP-NAP showed a possible role in guiding the bacterial adhesion during conditions of limited sialylation, i.e. equivalent to mild gastritis, when the tissue would be less inflamed and sialylated. In conclusion, H. pylori adhesion causes host tissue inflammation, then the bacteria will adapt to the new condition and bind to epithelial cells in a tighter mode by synergistic activities of BabA and SabA. Additionally, SabA bind to and activate human neutrophils, which will exacerbate inflammation responses and cause damage to host tissue. Thus, BabA and SabA are potential candidates to be targeted for therapeutic strategies against H. pylori and gastric disease.

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23

Rector, Trent. "Genomic Organization of Infectious Salmon Anemia Virus." Fogler Library, University of Maine, 2001. http://www.library.umaine.edu/theses/pdf/RectorT2001.pdf.

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24

Hamel, Owen Sprague. "The dynamics and effects of bacterial kidney disease in Snake River spring Chinook salmon (Oncorhynchus tshawytscha) /." Thesis, Connect to this title online; UW restricted, 2001. http://hdl.handle.net/1773/6364.

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25

Wondimagegne, Eshetu. "Bacterial wilt of potato in Ethiopia." Thesis, University of East Anglia, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.335193.

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26

Packer, Samantha. "Bacterial-epithelial cell interactions in the periodontal diseases." Thesis, University College London (University of London), 2005. http://discovery.ucl.ac.uk/1445766/.

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Periodontal diseases result from a complex interaction between a biofilm containing commensal and periopathogenic bacteria and the host innate and acquired defense systems. The interaction of oral commensal and pathogenic bacteria and their effect on ' cell behaviour, particularly the synthesis of antibacterial and inflammatory molecules, has been the focus of this project. The messenger RNA (mRNA) and protein expression of human beta-defensin and pro-inflammatory cytokine mRNA in the gingiva of patients suffering from the periodontal diseases was also determined. Patients suffering periodontal diseases showed increased mRNA expression of human beta-defensins and cytokines compared to controls, however, there was no difference in human beta-defensin protein expression between diseased and control tissue samples. Further studies were then carried out to determine the effect of oral commensal and periopathogenic bacteria and their surface components on oral epithelial cells (OECs). An oral squamous carcinoma cell line was found to produce IL-8 protein and express mRNA for human beta-defensin 2 (hpD-2), both of which were induced by several oral bacterial cell surface components, including LPS. The stimulatory effect of LPS was subsequently found to involve the LPS receptor, CD 14. The presence of toll-like receptor mRNA was also demonstrated and results showed that their expression may be regulated by bacteria associated molecular patterns. Both live- and heat-killed oral bacterial pathogens, A. actinomycetemcomitans and P. gingivalis induced production of IL-8 protein and hpD-2 mRNA from OECs. Exposure to the oral commensals S. sanguis and S. gordonii resulted in a decrease in the production of IL-8 mRNA from OECs, whilst heat-killed S. sanguis upregulated hpD-2 mRNA. A highly invasive strain of A. actinomycetemcomitans was shown to adhere to OECs to a greater degree, and also led to a greater induction of hpD-2 mRNA and IL-8 protein compared to a non-invasive strain. Further, isogenic mutants of the oral commensal S. gordonii DL1 Challis, deficient in the production of antigen I/II-family proteins SspA and SspB and the fibrillar cell surface proteins CshA and CshB, showed reduced adhesion to OECs. All strains had comparable effects on IL-8 protein and hpD-2 mRNA expression in OECs. The results presented in this thesis demonstrate the expression profile of human beta- defensins and cytokines in healthy and diseased gingival tissue. hpD-2 has been shown to be upregulated in oral epithelial cells by a range of oral commensal and pathogenic bacteria and their products. It has also been shown that the invasive nature of oral bacteria may contribute to increased expression of hpD-2 messenger RNA in oral epithelial cells. The upregulation of hpD-2 mRNA by a wide variety of components, bacterial or otherwise in oral epithelial cells may have therapeutic potential, however further studies would need to be carried out to determine the correlation between mRNA and protein expression of hpD-2.

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27

Teschke, Miriam. "Prävalenz von Arcobacter spp. in Puten- und Schweinefleisch aus dem Berliner Einzelhandel und Vergleich von drei kulturellen Arcobacter-Nachweisverfahren /." Berlin : Mbv, 2008. http://d-nb.info/990056414/04.

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28

Bérubé, Michel. "La transmission de Diphyllobothrium ditremum à l'omble chevalier (Salvelinus alpinus) dans deux lacs sub-arctiques du Québec /." Thesis, McGill University, 1985. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=64488.

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29

Young, Hugh. "Laboratory diagnosis and epidemiology of bacterial sexually transmitted diseases." Thesis, University of Edinburgh, 1997. http://hdl.handle.net/1842/27730.

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This thesis brings together 118 published studies on the microbiology of sexually transmitted diseases resulting from work performed in the University of Edinburgh Department of Medical Microbiology between 1973 and 1995. The main aim of these studies was to improve microbiological aspects of the diagnosis and management of syphilis and gonorrhoea. The earliest publication on syphilis serology was the first to recommend the use of a specific treponemal antigen test, the Treponema pallidum haemagglutination assay (TPHA) for routine screening. As a result of this study a screening schedule comprising the Venereal Diseases Research Laboratory (VDRL) and TPHA tests was introduced into routine practice in late 1973. Soon the same screening schedule was widely adopted in the United Kingdom and Europe. Appreciating the importance of computerised and automation I validated and standardised a prototype commercial enzyme immunoassay (EIA) as a single serological screening test and demonstrated that this gave a performance comparable to screening with the VDRL and TPHA tests while being suitable for automation and electronic report generation. Screening for syphilis by EIA is now becoming widespread throughout Europe. Because false positive EIA reactions may also show reactivity in the FTA-abs test, immunoblotting was evaluated as a confirmatory test. The possibility of syphilis reactivation and loss of treponemal markers in patients co-infected with HIV were also studied.

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30

Ndungu, Anne. "Rare genetic variants and susceptibility to severe bacterial diseases." Thesis, University of Oxford, 2015. https://ora.ox.ac.uk/objects/uuid:9c5745f9-50f9-469a-8771-2e49e75db7ac.

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Infectious diseases are a major cause of morbidity and mortality worldwide. Streptococcus pneumoniae and Neisseria meningitidis are major causes of severe bacterial disease which can manifest as invasive disease such as bacteraemia and meningitis. Exposure to these pathogens is relatively widespread, yet only a minority of individuals develop invasive disease. A host genetic component to infectious disease susceptibility has been implied from twin and adoptee studies. A role for rare large effect genetic variants in predisposition to infection has been demonstrated through the study of individuals with primary immunodeficiencies. However, a majority of these studies have been undertaken in individuals with a history of recurrent disease or in multi-case families. The relative role of rare genetic variants of moderate to large effect at the population level has not been widely explored. This thesis presents effort made using next generation sequencing methods to identify rare genetic variants that lead to increased susceptibility to bacterial disease focussing on meningococcal disease, pleural infection(empyema), pneumococcal disease and sepsis phenotypes. Using an exome sequencing approach in 13 cases with invasive meningococcal disease, a novel mutation leading to a complement deficiency and increased risk of meningococcal infection was identified and functionally validated in one individual. This mutation in the CFP gene was demonstrated as leading to impaired properdin secretion. Further analysis implicated loss of function mutations in CD4 and ZAP70 as novel loci for meningococcal disease susceptibility. A case control association analysis for sepsis susceptibility highlighted the possible role for small Rho GTPases in sepsis pathology. By aggregating all rare predicted deleterious mutations in a gene, four genes in this pathway, (ROCK2, ARHGAP18, FYN and CDC42BPG) were implicated as having an excess of rare deleterious variants in sepsis samples compared to population controls. A similar approach identified low frequency genetic variants in the CD109 gene as predisposing to empyema susceptibility in children. Finally, preliminary evidence from adult individuals with invasive pneumococcal disease points to a potential role of the RNASE7 gene in invasive pneumococcal disease susceptibility. This association was primarily due to a predicted deleterious missense mutation present in cases and absent in controls. Taken together, these results have identified a number of potential loci with rare variants associated with susceptibility to severe phenotypes of bacterial diseases.

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31

Campos-Perez, Juan Jose. "The role of reactive oxygen and nitrogen species in the immune response of rainbow trout to Renibacterium salmoninarum." Thesis, University of Aberdeen, 1998. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU112258.

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The role of reactive oxygen and nitrogen intermediates in the immune response of rainbow trout to R.s. was investigated. The early events occurring when the pathogen interacted with trout macrophages were assessed in terms of the respiratory burst elicited. Live R.s. elicited a respiratory burst, which was enhanced by heat-killed microorganism. This phenomenon, though, was not observed using UV-killed bacteria. Both responses were enhanced when a combination of LPS and TNF was used to activate the macrophages prior to contact R.s. Further studies demonstrated that both compounds synergised to enhance superoxide (O2) production, and that this was correlated with the ability to kill the pathogen. Opsonisation of R.s. with serum factors also increased the respiratory burst, but no difference was found between normal serum and heat-inactivated serum. The role of NO in the immune response of rainbow trout is also studied. Though no evidence of NO production was found in vitro, i.p. injection of live R.s. produced higher NO levels in serum as compared to controls. Fish injected with a virulent strain showed higher levels of NO than controls and than fish injected with an avirulent strain and other strains of unknown virulence. Fish vaccinated with killed R.s. and FIA also showed a significant increase in NO levels, but only four days after vaccination, decreasing thereafter, at both doses of vaccine tested. Injected of Brivax II, an attenuated strain of Aeromonas salmonicida, did not produce a significant increase of NO. RT-PCR was used to detect the expression of the iNOS in different tissues of rainbow trout. iNOS expression was seen only in gill and kidney after i.p. injection. iNOS was detected in the gills 6 h after injecting live R.s. and the expression was still present at day 5. iNOS was detected in the kidney 24 h after injection but was switched off at day 3. After bath challenge with the bacterium, iNOS was expressed in gill, gut and kidney, but the expression varied in each fish. No iNOS expression was found in macrophages isolated from challenged fish.

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32

Jones, Angela M. "Aspects of the biology of some marine ascaridoid nematodes." Thesis, University of Stirling, 1994. http://hdl.handle.net/1893/1498.

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Larval Anisakis simplex, Pseudoterranova decipiens, Contracaecum osculatum and larvae and adults of Hysterothylacium aduncum were recovered from specimens of cod, haddock, blue whiting and bull rout; however, only A.simplex were retrieved from long rough dab. The epidemiology of infection by these four nematode species was examined both in whole fish, and in individual host tissues and organs. Frequency distributions of nematodes were found to be generally overdispersed in fish. Preliminary investigations revealed no strong evidence to suggest that competi tive interactions occurred between ascaridoid nematodes wi thin fish. Stomach lesions in gadoids were associated with single (partially penetrated) and mul tiple (throughout stomach wall) worm infections of larval A.simplex; such lesions were discrete and raised in appearance. Lesions associated with 1-3 larval P.decipiens in an open cavity within the stomach of angler fish were diffuse and not significantly raised. Histological examination of each form of ulcer revealed general similarities in pathology, with infil tration of inflamatory cells being the initial response to the nematode\s. Changes in the cephalic morphology of A.simplex, P.decip1ens, C.osculatum and H.aduncu were examined at different life cycle stages under scanning electron microscopy. Due to their small size, newly hatched third stage larvae of P .decip1ens were cultured in a bacterial mat prior to fixation for S.E.M., and the external ultrastructure of these larvae is described. The most prominent external feature at this stage is the cephalic boring tooth. Aspects of the internal ultrastructure of A. simplex, P.decipiens, C.osculatum and H.aduncu were examined using transmission electron microscopy. Newly hatched third stage larvae of P.decipiens show little differentiation of internal organs. The ultrastructure of sensory amphids in H.aduncum and A. simplex is cons i stent wi th that of a chemoreceptor, that of the single papilla in P.decipiens a mechanoreceptor. The ultrastructure of the digestive tract, excretory gland and body wall of marine ascaridoids were also examined.

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33

Hahn, Scott Thomas. "Toxinology of ciguatera." Thesis, Queensland University of Technology, 1991.

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34

Wang, Xiangdong. "Bacterial translocation after major liver resection." Lund : Dept. of Surgery, Lund University, 1993. http://catalog.hathitrust.org/api/volumes/oclc/39793360.html.

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35

Behzad, Kasravi F. "Bacterial translocation in acute liver injury." Lund : Dept. of Surgery, Lund University, 1995. http://books.google.com/books?id=I39sAAAAMAAJ.

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36

Davies, Robert L. "Biochemical and cell-surface characteristics of Yersinia ruckeri in relation to the epizootiology and pathogenesis of infections in fish." Thesis, University of Stirling, 1989. http://hdl.handle.net/1893/11897.

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Isolates of Yersinia ruckeri were obtained from Europe, North America, Australia and South Africa. The biochemical and serological characteristics of the isolates were investigated. Biochemically the isolates were extremely uniform although motile, Tween positive isolates could be differentiated from non-motile, Tween negative isolates; these were designated biotypes 1 and 2 respectively. With the exception of two isolates, biotype 2 isolates were confined to the U. K. Five 0-serotypes were recognised and an O-serotyping scheme is proposed; the relation of this scheme to previously described schemes is discussed. The geographic distribution of the different serotypes is also discussed. The lipopolysaccharide (LPS) and outer membrane protein (OMP) profiles of isolates were analysed by SDS-PAGE and Western-blotting using both rabbit and rainbow trout antisera. The relation of LPS-type to 0- serotype, as well as variation within LPS-types, is discussed. Based on interstrain variation in the molecular weight of a heat-modifiable protein and of peptidoglycan-associated (porin) proteins, an OMP-typing scheme was developed. Three major OMP-types comprised 95% of the isolates studied. Variation in biotype, serotype and OMP-type was used as an epizootiological tool, and six serotype 01 clonal groups were recognised which differed in their geographic distribution. The production of iron-regulated OMPs and siderophores was investigated. Four iron-regulated OMPs were produced in all of the isolates examined; siderophores appeared not to be produced by any of the isolates. Production of iron-regulated OMPs was not an important virulence determinant and appears to be a chromosomally-mediated factor. Resistance to the bactericidal effects of normal rainbow trout serum and virulence were also investigated. Serum-resistance was associated principally with two serotype 01 clonal groups and virulence was associated with the same two clonal groups. Other serotype 01 clonal groups and other serotypes were iii generally serum-sensitive and avirulent. Thus, serum-resistance is an important virulence determinant in this organism. The role of outer membrane components in serum-resistance and virulence is discussed.

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37

Bluvas, Peter J. (Peter Jan) 1979. "Identification of viral and bacterial triggers for human autoimmune diseases." Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/87184.

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Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2002.
Includes bibliographical references (leaf 31).
by Peter J. Bluvas, Jr.
M.Eng.

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38

Schorer, Marianne [UNESP]. "Utilização do 'beta' - glucano sobre o desempemho produtivo, indicadores de estresse, perfil hematológico e sobrevivência do pacu (Piaractus mesopotamicus)." Universidade Estadual Paulista (UNESP), 2008. http://hdl.handle.net/11449/86719.

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Made available in DSpace on 2014-06-11T19:22:23Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-07-25Bitstream added on 2014-06-13T19:07:49Z : No. of bitstreams: 1 schorer_m_me_jabo.pdf: 422367 bytes, checksum: 37206debb94744d658461678b9bf1e34 (MD5)
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Em peixes, o 'beta'- glucano apresenta uma potente função imunoestimulante sendo cada vez maior a sua utilização como suplemento alimentar, aumentando significantemente a resistência à exposição infecciosa. Este prebiótico tem função de prevenir a colonização de patógenos por intensificar a ativação de macrófagos, proporcionando benefícios ao trato gastrointestinal e resultando em melhor desempenho e resistência a doenças. Este estudo teve a finalidade de avaliar os efeitos do 'beta' - glucano adicionado às rações peletizadas e extrusadas sobre o desempenho produtivo, indicadores de estresse, perfil hematológico e sobrevivência do pacu. Este experimento foi conduzido no Laboratório de peixes ornamentais, do Centro de Aqüicultura da UNESP (CAUNESP), em Jaboticabal, São Paulo. Foram utilizados 640 juvenis de pacu, com 24,7 ± 2,0 g, distribuídos em 32 aquários de vidro (130L). Os parâmetros físico – químicos da água foram mensurados quinzenalmente. Os peixes foram alimentados duas vezes ao dia, uma pela manhão e outra ao fim do dia. Os experimentos apresentaram um delineamento experimental inteiramente casualizado em esquema fatorial 2 x 4, utilizando níveis de inclusão do 'beta'– glucano de: 0 (controle), 0,1%, 0,2% e 0,3% por kg/ ração. Os níveis de'beta'-glucano avaliados neste estudo, não proporcionaram ganhos significativos no desempenho produtivo de juvenis de pacu, porém o tratamento 0,3% apresentou melhores resultados no GP, PF e TCE. A administração do 'beta'- glucano na dieta, durante todo período experimental, provocou alterações nos parâmetros hematológicos e indicadores de estresse do pacu. Os peixes alimentados com o 'beta'-glucano apresentaram maior resistência à infecção da bactéria A. hidrophila. Sendo assim, o tratamento 0,1% apresenta um custo/kg inferior e garante eficácia na saúde de juvenis de pacu.
In fish, glucano has shown a potent immunostimulant function. The use of glucano is increasing significantly the resistance to diseases after infectious exposition. This prebiotic may be prevent the bacterial colonization, and activated macrophages, been beneficial to the digestive tract, resulting in better performance and disease resistance. This study will evaluate the glucano effects added in palletized and extruded diets of fish, analyzing fish perfOrmance, stress indicators, hematological profile and survival of pacu. This study was driven in Laboratory of ornamental fish, on Centro de Aqüicultura of UNESP (CAUNESP), in Jaboticabal, São Paulo. Were used 640 pacu juveniles, with 24,7 ± 2,0 g, distributed in 32 aquarium (130 L). The physical and chemical water parameters were measured every two weeks. Fish were fed twice a day, in the morning and another at the end of the day. In this trial were used 640 pacu juveniles (24.7 ± 2.0 g) distribuided in 32 aquariums (20 fish/aquarium). Throughout the experimental period, water remained at 26.5 oC and the others limnological parameters (dissolved oxygen, pH, alkalinity, ammonia and conductivity) stayed within normal values for the specie. The experimental trial design was entirely casualized in factorial scheme 2 x 4, evaluating two proceeding of diets (extruded and pelletized) and four 'beta' - glucan levels in diets: 0 (control), 0.1%, 0.2% and 0.3% with four repetitions. In this study,'beta' – glucan levels do not provide significant gains on pacu juveniles performance, but treatment with 0,3% – glucan showed better results of weight gain, weight final and specific growth rate. The administration of glucan in the diet, caused changes in hematological parameters and stress indicators in pacu. The fishes fed with glucan showed greater resistance to infection with A. hidrophila. Thus, treatment with 0,1% of glucan presented a lower cost/kg and shows efficiency in health of pacu juveniles.

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39

Xu, Zinan. "Isolation, characterisation and application of bacteriophages in aquaculture." Thesis, University of Stirling, 2016. http://hdl.handle.net/1893/23740.

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The increasing incidence of infections due to antibiotic resistant bacteria has led to renewed interest in bacteriophages (= phages) and phage therapy. Although phage therapy has been applied to control bacterial diseases in plants, poultry, livestock and humans, its application in aquaculture is still relatively limited. The emergence of phage-resistant bacterial mutants has been considered to be one of the major limitations of phage therapy. This study aimed to (i) isolate and characterise phages; (ii) select phages and their bacterial hosts to set up in vivo phage therapy models with aquaculture animals, and estimate the efficiency of phage therapy; (iii) investigate the generation and characteristics of phage-resistant mutants, and thus estimate the consequence of applying phage therapy when phage-resistant mutants emerge; and (iv) discuss the prospects for application of phages in aquaculture. Two Vibrio isolates and their phages were isolated from a Scottish marine fish farm. Based on the results of conventional phenotype testing and 16S rRNA gene sequencing analysis, the two vibrios, V9 and V13, were identified as Vibrio splendidus and Vibrio cyclitrophicus, respectively. The bacterial characteristics including morphology, temperature and salinity range of growth, production of extracellular enzymes, and the possession of virulence genes were examined. According to the morphological characteristics observed using transmission electron microscopy by negative staining, phage PVS9 of V. splendidus V9 was identified as a myophage, while phage PVC13 of V. cyclitrophicus V13 was identified as a siphophage. The phages could only lyse one bacterial host strain and their genomic DNA was double stranded with a size of ~46 kb. The two Vibrio isolates were found to be non- or of low virulence to rainbow trout, goldsinny wrasse and Artemia in pathogenicity experiments. Thus an in vivo phage therapy model could not be set up using these Vibrio isolates and their phages. Two phages pAS-3 and pAS-6 were isolated using the Aeromonas salmonicida subsp. salmonicida Hooke strain as the host. Phages pAS-3 and pAS-6 had a similar genome size of ~50 kb, and the same relatively narrow host range within A. salmonicida subsp. salmonicida strains. The siphophage pAS-3 formed clear plaques and inhibited A. salmonicida Hooke growth in vitro completely for at least 18 hours when using MOI = 1,000, whereas the podophage pAS-6 formed turbid plaques and weakly inhibited Hooke growth. Rainbow trout exposed by intraperitoneal injection with 0.1 mL of the raw phage preparations at a concentration of 108 PUF mL-1 showed no adverse effects over 14 days. In the phage therapy trial, fish were firstly injected with 1 x 102 CFU fish-1 of A. salmonicida Hooke, then immediately injected with phage preparations of pAS-3 and pAS-6, respectively, using MOI = 10,000. Compared with the control group (which did not receive phage treatment), phage treated groups showed a delay in the time to death, and lower mortalities. However, the mortalities and time to death between phage treated and non-treated groups were not significantly different. Phage-resistant mutants of pathogenic A. salmonicida strain Hooke were induced by repeatedly challenging with phage pAS-3. One of the mutants, termed HM, was chosen to compare the characteristics with the parental wild-type strain Hooke. Test results including the formation of ‘smooth’ colonies on TSA, autoagglutination negative, the formation of creamy colonies on Coomassie Brilliant Blue agar, and the degradation of a thick/furry layered structure on the cell surface indicated a deficiency of the A-layer in the phage-resistant mutant HM. Therefore, it was deduced that the A-layer either directly acted as the receptor of A. salmonicida phage pAS-3, or was affected indirectly by the change of an unknown phage receptor. The greater wax moth larvae model was used to compare the virulence of the phage-resistant mutant HM and the parental wild-type strain Hooke, as it is an ethically acceptable animal model, which has the advantages of being low cost and convenient for injection, and is also a recognised alternative model for bacterial pathogens of fish. The results showed that virulence of the phage-resistant mutant HM did not decline in the greater wax moth larvae model compared with that of the parental wild-type strain Hooke. In conclusion, different approaches were used to isolate and characterise phages from different aquaculture environments for potential use in phage therapy. A rainbow trout model was set up using pathogenic A. salmonicida strain Hooke and two A. salmonicida phages pAS-3 and pAS-6. The use of phage treatment led to lower cumulative mortalities and delay to the time of death, although the differences between the groups were not significant, futher work is required to determine if these phages have potential in phage therapy. The consequence of applying phage therapy when phage-resistant mutants emerge was estimated based on their characteristics and virulence, and no decline in virulence of the phage-resistant mutant from this study indicates the importance of fully testing the virulence of phage-resistant mutants before carrying out large scale field trials of phage therapy. It appears feasible to use phage therapy as an alternative approach to control bacterial infections in aquaculture, but further studies are required to focus on improving effectiveness, and also to overcome the concrete limitations and hurdles in application and commercialisation. Moreover, a broader range of applications of phages in aquaculture should be explored.

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40

Kanchanakhan, Somkiat. "Field and laboratory studies of rhabdoviruses associated with epizootic ulcerative syndrome (EUS) of fishes." Thesis, University of Stirling, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.319799.

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41

Aboagye, Daniel Larbi Daniels William H. "Evaluation of the commercially-available probiotic Lymnozyme as an effective control of bacterial infections in channel catfish." Auburn, Ala, 2008. http://repo.lib.auburn.edu/EtdRoot/2008/SPRING/Fisheries_and_Allied_Aquacultures/Thesis/Aboagye_Daniel_41.pdf.

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42

Williams, Chris F. "Impact assessment of non-native parasites in freshwater fisheries in England and Wales." Thesis, University of Stirling, 2007. http://hdl.handle.net/1893/410.

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Non-native parasites pose a significant threat to aquatic bio-diversity and fishery development. Many factors have facilitated the introduction of non-native parasites into England and Wales. Identifying the effects of these parasites and the importance of any changes to wild fish populations represents a considerable challenge. However, in order for the Environment Agency to identify future disease threats, effectively manage resources and implement practical and sustainable control measures, the risks posed by these parasites to fisheries must be better understood. A structured, risk-assessment process for non-native freshwater parasites is proposed. This approach includes procedures for hazard identification, impact assessment, risk management and communication. A quantitative approach to hazard identification provides an initial prediction of impact at the time of introduction to inform decisionmaking and guide preliminary control measures. This is followed by a more comprehensive framework for impact assessment that promotes understanding of changes at host, population and fishery levels. These are placed into context with the economic and ecological value of native resources. An independent 'non-native parasite review group' has been convened to ensure consistency of policy decisions and clear communication of disease risks to interested bodies. It is hoped that this wil assist the management of future invasions and provide a scientifically robust foundation on which to base proportionate control measures. The Category 2 parasites are defined as "species having a significant disease potential when introduced into waters where they do not already exist, or are non-indigenous species with unknown pathogenicity and distribution". Understanding of the dangers posed by these parasites varies considerably. Ergasilus sieboldi, Anguilicola crassus, Bothriocephalus acheilognathi and Lernaea cyprinacea, are well recognised non-native fish pathogens that pose a considerable threat to fisheries. Conversely, the effects of other introduced parasites remain poorly understood. In many cases, a paucity of published literature at the time of introduction has limited a reliable assessment of impact. Four non-native parasites were considered a priority for further study. These were Paraergasilus longidigitus (Copepoda: Poecilostomatoida), Ergasilus briani (Copepoda: Caryophylldae) Poecilostomatoida ), Atractolytocestus huronensis (Cestoda: and Philometroides sanguinea (Nematoda: Philometridae). Pathological, epidemiological and experimental investigations were undertaken to assess the effects of these parasites at host and population levels. P. longidigitus can cause pronounced pathological changes to the olfactory epithelium of infected fish. Although this damage provides the potential for disruption to spawning through reduced sensitivity to reproductive chemical cues, experimental observations combined with seasonality studies suggest that the parasite is unlikely to disrupt reproduction within infected cyprinid fisheries. Similarly, studies conducted on the caryophylidean cestode A. huronensis provide little evidence to suggest that the parasites poses a threat to car fisheries. Damage within the intesinal tract was characterised by relatively mild mechanical and inflammatory changes. Infections of up 213 parasites had no adverse affect upon the conditon of common carp. Based on these findings and the application of the aformentioned risk model, P. longidigitus and A. huronensis are considered to be of low disease risk to fisheries. The pathology of E. briani and P. sanguinea are described for the first time. Literature suggests that both parasites are pathogenic to juvenile fIsh. E. briani causes a number of pathological changes within the gils of juvenile cyprinids, although these remain localised due to the very strict site specificity of the parasite. Migrations of the nematode P. sanguinea causes damage to the fins and caudal musculature of juvenile crucian car. For both parasites, the extent and severity of pathological changes are inversely proprtional to host size. Further studies at the population level are needed before an assessment of impact to fisheries can be made. The difficulties associated with studying the effects of introduced parasites to juvenile fish populations in the wild are recognised. Recommendations for further study are given.

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43

Collins, Ann. "A review and retrospective study of some major bacterial orofacial infections." Thesis, The University of Sydney, 1990. http://hdl.handle.net/2123/4209.

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History has recorded the antiquity of serious infections in the region of the head and neck. Today, our community still experiences major life-threatening infections in these anatomical locations, which pose significant management difficulties to the oral and maxillofacial surgeon. The aim of this thesis is to review the aetiology, diagnosis and treatment of some bacterial infections involving structures of the head and neck. Such infections may spread, causing serious complications with severe morbidity and occasionally death. This theses deals only with infections of bacterial origin and does not attempt to cover viral, or fungal agents or the chronic specific diseases of tuberculosis and syphilis, and makes no attempt to address the old question of focal infection. The literature review relates especially to Ludwig’s Angina which was first described so dramatically in 1836. To this day it remains as a clinically potentially lethal disease despite the progress of modern medicine. Numerous descriptions in the literature warn of the rapid appearance of symptoms and the danger of respiratory obstruction when management of the airway is not satisfactorily undertaken. Both odontogenic and non-odontogenic causes of orofacial and neck infections are reviewed. Odontogenic problems are given special emphasis as they are now of major concern. The significance of the potential fascial spaces in the face and neck which allow the spread of dental infections is also highlighter. A thorough knowledge of these anatomical relationships is still of the utmost importance to the surgeon if he is to be successful in treatment. The principle of surgical drainage of pus is as important in 1990 as it was 150 years ago. The biological basis for the onset and progress of such fulminating infections in the head and neck region is still poorly understood. One constant need is that the bacteria, both aerobic and anaerobic, be correctly identified. Microbiological techniques are constantly improving and provide an important adjuvant investigation, which then allows the surgeon to provide the most appropriate antimicrobial therapy. Principal to the many aspects of treatment is the ability to maintain the airway of the patient and to provide the depth of anaesthesia necessary to undertake the required surgery. Major bacterial orofacial infections may have severe local and far-reaching systemic effects. Such complications are discussed in all their ramifications. It should be realised that the presentation of these patients at a late stage, when complications have already supervened, may make diagnosis difficult. There is always a necessity to ensure that the underlying cause of the disease is accurately defined and that complication are not allowed to progress further. Finally, a retrospective study of the management of 90 patients with major bacterial orofacial infections who have been treated at Westmead Hospital is presented. The outcome of this study of some major bacterial orofacial infections of the head and neck is the need to stress the importance of urgent surgical management and maintenance of the airway, together with the microbiological determination of the causative organisms and their sensitivities, so that other than empirical antibiotics can be instituted early. This must be combined with an upgrading of the patients’ medical and dental status. It was demonstrated that, in the majority of these patients, ignorance and fear combined with a lack of routine dental care resulted in major infections arising from relatively simple odontogenic causes such as dental caries, periodontal disease and pericoronal infection related to impacted teeth. Without doubt, the immediate care of these patients demanded intensive management. However, it is important to recognise that dental education forms an integral part not only of the recovery programme for the afflicted patient, but also as a community health preventive measure of profound significance.

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44

Collins, Ann. "A review and retrospective study of some major bacterial orofacial infections." University of Sydney, 1990. http://hdl.handle.net/2123/4209.

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Master of Dental Surgery
History has recorded the antiquity of serious infections in the region of the head and neck. Today, our community still experiences major life-threatening infections in these anatomical locations, which pose significant management difficulties to the oral and maxillofacial surgeon. The aim of this thesis is to review the aetiology, diagnosis and treatment of some bacterial infections involving structures of the head and neck. Such infections may spread, causing serious complications with severe morbidity and occasionally death. This theses deals only with infections of bacterial origin and does not attempt to cover viral, or fungal agents or the chronic specific diseases of tuberculosis and syphilis, and makes no attempt to address the old question of focal infection. The literature review relates especially to Ludwig’s Angina which was first described so dramatically in 1836. To this day it remains as a clinically potentially lethal disease despite the progress of modern medicine. Numerous descriptions in the literature warn of the rapid appearance of symptoms and the danger of respiratory obstruction when management of the airway is not satisfactorily undertaken. Both odontogenic and non-odontogenic causes of orofacial and neck infections are reviewed. Odontogenic problems are given special emphasis as they are now of major concern. The significance of the potential fascial spaces in the face and neck which allow the spread of dental infections is also highlighter. A thorough knowledge of these anatomical relationships is still of the utmost importance to the surgeon if he is to be successful in treatment. The principle of surgical drainage of pus is as important in 1990 as it was 150 years ago. The biological basis for the onset and progress of such fulminating infections in the head and neck region is still poorly understood. One constant need is that the bacteria, both aerobic and anaerobic, be correctly identified. Microbiological techniques are constantly improving and provide an important adjuvant investigation, which then allows the surgeon to provide the most appropriate antimicrobial therapy. Principal to the many aspects of treatment is the ability to maintain the airway of the patient and to provide the depth of anaesthesia necessary to undertake the required surgery. Major bacterial orofacial infections may have severe local and far-reaching systemic effects. Such complications are discussed in all their ramifications. It should be realised that the presentation of these patients at a late stage, when complications have already supervened, may make diagnosis difficult. There is always a necessity to ensure that the underlying cause of the disease is accurately defined and that complication are not allowed to progress further. Finally, a retrospective study of the management of 90 patients with major bacterial orofacial infections who have been treated at Westmead Hospital is presented. The outcome of this study of some major bacterial orofacial infections of the head and neck is the need to stress the importance of urgent surgical management and maintenance of the airway, together with the microbiological determination of the causative organisms and their sensitivities, so that other than empirical antibiotics can be instituted early. This must be combined with an upgrading of the patients’ medical and dental status. It was demonstrated that, in the majority of these patients, ignorance and fear combined with a lack of routine dental care resulted in major infections arising from relatively simple odontogenic causes such as dental caries, periodontal disease and pericoronal infection related to impacted teeth. Without doubt, the immediate care of these patients demanded intensive management. However, it is important to recognise that dental education forms an integral part not only of the recovery programme for the afflicted patient, but also as a community health preventive measure of profound significance.

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45

Tucker, Carl Steven. "Larval settlement and epidemiology of Lepeophtheirus salmonis Kroyer, 1837 (Copepoda: Caligidae)." Thesis, University of Stirling, 1998. http://hdl.handle.net/1893/2199.

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This study has been carried out to investigate the biological and environmental parameters influencing the settlement and post-settlement survival of the infective stages of Lepeophtheirus salmonis Kroyer 1837. The abiotic factors investigated were temperature and salinity. Temperature was found to have a significant effect on the settlement success of the copepodids with an inverse relationship between temperature and settlement. Survival of the louse at 10 days post infection showed a decrease at the reduced temperature. Temperature was also shown to have a direct relationship on lice development; higher seawater temperatures resulted in faster development. Regression analysis of temperature and settlement shows a significant correlation. A constant reduced salinity, 24%, resulted in a reduced ability of the copepodid to infect its host compared with 34%. Post-settlement survival in 24%, at approximately 13°C resulted in 5.8% survival of lice to day 10 post-infection compared to 79% in 34% salinity. When this experiment was repeated but with elevated seawater temperatures of up to 18°C, survival at the reduced salinity was found to be 75.3%, higher than the ambient control group. The developmental rate at day 10 post-infection of L.salmonis larva at 24% was shown to be slower than development at 34%o. Distribution of the L.salmonis copepodid on its host showed the highest settlement on the gills and on the fins, particularly the pectoral and dorsal fins. Examination of L.salmonis survival at day 10 post-infection indicated the highest losses on the gills and the pelvic, caudal and dorsal fins. Settlement on the pectoral fins showed the highest settlement and the greatest survival. The infective copepodid has a reduced ability to infect its host after 7 days following the moult from nauplius 2, compared to copepodids aged 1 and 3 days following the nauplius 2 moult. For copepodids of all ages, once settlement had been achieved, survival at 10 days post-infection was approximately 50% in all groups. Copepodids of all ages did not show any difference in the development rate at 10 days post infection. Highest settlement was found to be on the gills and pectoral and dorsal fins. The effects of varying dose rates of copepodids, has shown that a finite percentage of lice settle and survive the first five days post-infection. Settlement distribution was found to be highest on the body, gills and pectoral and dorsal fins. In serial infections of fish there was a reduced settlement count with second infections, possibly through intraspecific competition. Experiments using different host stocking densities showed that with an increased number of hosts the intensity of the infection of individual fish was reduced. Smaller fish appear more susceptible to settlement of L.salmonis than larger fish, and this is associated with the relatively greater fin area of those fish compared to larger fish. L.salmonis exhibits a preference for the fins as an area of settlement in all sizes of fish. Comparison of copepodid settlement on salmon and sea trout showed that in single populations of fish salmon had the highest intensities of infection whilst in mixed populations of fish sea trout had a higher intensity. Settlement distribution of L.salmonis on salmon showed greatest settlement on the body, pectoral and dorsal fins, whilst on sea trout settlement was highest on the body, pectoral, pelvic, caudal and dorsal fins. The comparative development of L.salmonis between the two species of host fish showed an increased rate of development on salmon. The calculated energy levels for L.salmonis larval stages show a decrease in available energy within each developmental stage. After 6 days from the nauplius 2 moult the copepodid starts to show a sharp decline in energy levels which coincides with the reduced ability of the copepodid to infect the host. Post-settlement energy levels remain constant even though the copepodid is actively feeding, as seen by SEM examination at 2 days postinfection. The principal lipid class found within L.salmonis larval stages as energy reserve is triacylgylcerol (37.6% of the total lipid). A preliminary epidemiological model for sea lice population dynamics is proposed. This is a differential equation compartmental model that has been designed to examine the flow of L.salmonis developmental stages on the host. The model was able to predict the timing of the maximum number of pre-adult 1 lice stages to within one day. The difference between the observed data and the model output is probably due to the considerable variability in the parameters used in the model construction.

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46

Swangchan-Uthai, Theerawat. "Molecular response of the endometrium to bacterial infection in dairy cattle." Thesis, Royal Veterinary College (University of London), 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.572492.

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47

Banja, Wakweya Dugassa. "Antibiotic use in two hospitals in West Wollega, Ethiopia." Thesis, Nelson Mandela Metropolitan University, 2010. http://hdl.handle.net/10948/1263.

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In the last decades, there has been an escalating consumption of antibiotics with the number of antibiotic prescriptions increasing worldwide. Overuse or inappropriate use of antibiotics has resulted in a major increase in the development of multi-drug resistant pathogens. Antimicrobial resistance is one of the world’s most serious public health problems with great implication in terms of morbidity, mortality, and costs. To date, there has been no formal antibiotic use study conducted in the West Wollega zone of Ethiopia to assess antibiotic utilization. The objective of this study was to determine the pattern of antibiotic use in two hospitals in the West Wollega zone of Ethiopia, namely Gimbie Adventist Hospital and Nedjo Hospitals, using drug utilization metrics and the costs associated. In addition it was to assess the correlation between diagnosed infectious diseases and antibiotic prescriptions. This study was a cross-sectional, retrospective, descriptive review of antibiotic usage in the two hospitals in the year 2007. Prescriptions dispensed in the first month of each quarter of 2007 were reviewed. The number of prescriptions screened, antibiotic courses started, antibiotic days by specific agent and overall, the cost of individual and all antibiotics, the number and type of infectious diseases diagnosed were collected from which core drug use indicators were calculated. The correlation between infectious disease diagnosed and the antibiotic days prescribed were analyzed. A total of 18568 antibiotic and non-antibiotic prescriptions were reviewed retrospectively in the four months of the study period, 47 percent of which contained at least one antibiotic. The average number of antibiotics per prescription was 1.33 and 1.09 whilst the percentage of injectable antibiotics prescribed was 83.2 percent and 3.76 percent to outpatients and inpatients respectively. Antibiotics prescribed from the Essential Drug List (EDL) and List of Drugs for District Hospital (LDDH) were 63.0 percent, 74.8 percent, and 90.8 percent and 76.1 percent for outpatients and inpatients respectively. 98.6 percent of outpatient and 97.0 percent inpatient prescribed antibiotics were actually dispensed. Penicillins and quinolones were the most prescribed antibiotics in both inpatient and outpatient departments constituting 43.46 percent and 24.08 percent respectively. The antibiotic utilization ratio, incidence of outpatient antibiotic use, incidence of inpatient antibiotic use, the number of Defined Daily Doses (DDD)/1000inhabitants/year and DDD/100 Occupied Bed Days (OBD) for the zone was 0.16, 17.25, 23.56, 158.61, and 70 respectively. Antibiotic cost constituted 33.7 percent of all expenditure on drug, cost of antibiotic per patient care day and cost per antibiotic day was 3.84 Ethiopian Birr (ETB) ($0.40) and 6.29 ETB ($0.66) respectively. The correlation between infectious diseases diagnosed and antibiotic prescription shows significant variation. At outpatient departments alone an average number of antibiotic courses started was 2.7 at Gimbie Adventist Hospital and 7.6 for Nedjo Hospital. When overall antibiotic days prescribed and required was compared in both hospitals, there were 2.4 and 5 times more antibiotic days prescribed than were required for Gimbie and Nedjo Hospitals respectively. This suggests that the overuse of antibiotic is worse in the government hospital (Nedjo Hospital) than in the mission hospital (Gimbie Adventist Hospital). This study suggested that there was overuse of antibiotics in the West Wollega hospitals although further investigation is needed to identify its underlying causes and nature. It is recommended that the health personnel, the hospital management, the zonal and regional Health Bureau, the regulatory bodies and Non-Governmental Organizations (NGOs) work hand-in-hand to promote the rational use of antibiotics in this region so that the consequences and financial cost of antimicrobial resistance can be prevented.

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48

Thompson, Matthew James. "Predicting serious bacterial infections in children in primary care." Thesis, University of Oxford, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.670104.

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49

Nuorala, Emilia. "Molecular palaeopathology : ancient DNA analyses of the bacterial diseases tuberculosis and leprosy /." Stockholm : Archaeological Research Laboratory [Arkeologiska forskningslaboratoriet], Univ, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-231.

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50

ROSSI, PAOLO. "Bacterial symbiosis in mosquitoes: from basic research to mosquito borne diseases control." Doctoral thesis, Università degli Studi di Camerino, 2011. http://hdl.handle.net/11581/401854.

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Dissertations / Theses on the topic 'Bacterial diseases in fishes'

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