Academic literature on the topic 'Enteric pathogen'
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Journal articles on the topic "Enteric pathogen"
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Kempf, Florent, Roberto La La Ragione, Barbara Chirullo, Catherine Schouler, and Philippe Velge. "Super Shedding in Enteric Pathogens: A Review." Microorganisms 10, no. 11 (2022): 2101. http://dx.doi.org/10.3390/microorganisms10112101.
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Super shedding occurs when a small number of individuals from a given host population shed high levels of a pathogen. Beyond this general definition, various interpretations of the shedding patterns have been proposed to identify super shedders, leading to the description of the super shedding phenomenon in a wide range of pathogens, in particular enteric pathogens, which are of considerable interest. Several underlying mechanisms may explain this observation, including factors related to the environment, the gut microbiota, the pathogen itself (i.e., genetic polymorphism), and the host (including immune factors). Moreover, data suggest that the interplay of these parameters, in particular at the host–pathogen–gut microbiota interface, is of crucial importance for the determination of the super shedding phenotype in enteric pathogens. As a phenomenon playing an important role in the epidemics of enteric diseases, the evidence of super shedding has highlighted the need to develop various control strategies.
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Tsai, Kevin, Sheillah Simiyu, Jane Mumma, et al. "Enteric Pathogen Diversity in Infant Foods in Low-Income Neighborhoods of Kisumu, Kenya." International Journal of Environmental Research and Public Health 16, no. 3 (2019): 506. http://dx.doi.org/10.3390/ijerph16030506.
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Pediatric diarrheal disease remains the second most common cause of preventable illness and death among children under the age of five, especially in low and middle-income countries (LMICs). However, there is limited information regarding the role of food in pathogen transmission in LMICs. For this study, we examined the frequency of enteric pathogen occurrence and co-occurrence in 127 infant weaning foods in Kisumu, Kenya, using a multi-pathogen PCR diagnostic tool, and assessed household food hygiene risk factors for contamination. Bacterial, viral, and protozoan enteric pathogen DNA and RNA were detected in 62% of the infant weaning food samples collected, with 37% of foods containing more than one pathogen type. Multivariable generalized linear mixed model analysis indicated type of infant food best explained the presence and diversity of enteric pathogens in infant food, while most household food hygiene risk factors considered in this study were not significantly associated with pathogen contamination. Specifically, cow’s milk was significantly more likely to contain a pathogen (adjusted risk ratio = 14.4; 95% confidence interval (CI) 1.78–116.1) and more likely to have higher number of enteric pathogen species (adjusted risk ratio = 2.35; 95% CI 1.67–3.29) than porridge. Our study demonstrates that infants in this low-income urban setting are frequently exposed to diarrhoeagenic pathogens in food and suggests that interventions are needed to prevent foodborne transmission of pathogens to infants.
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Gutema, Fanta D., Bonphace Okoth, John Agira, et al. "Spatial–Temporal Patterns in the Enteric Pathogen Contamination of Soil in the Public Environments of Low- and Middle-Income Neighborhoods in Nairobi, Kenya." International Journal of Environmental Research and Public Health 21, no. 10 (2024): 1351. http://dx.doi.org/10.3390/ijerph21101351.
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Public spaces in countries with limited societal development can be contaminated with feces containing pathogenic microbes from animals and people. Data on contamination levels, spatial distribution, and the diversity of enteric pathogens in the public settings of low- and middle-income neighborhoods are crucial for devising strategies that minimize the enteric infection burden. The objective of this study was to compare spatial–temporal differences in the detection rate and diversity of enteric pathogens in the public spaces of low- and middle-income neighborhoods of Nairobi, Kenya. TaqMan array card (TAC) molecular assays were employed to analyze soil samples for 19 enteropathogens, along with a selective bacterial culture for pathogenic Enterobacteriaceae. An observational assessment was conducted during every site visit to document the hygienic infrastructure and sanitation conditions at the sites. We detected at least one pathogen in 79% (127/160) and ≥2 pathogens in 67.5% (108/160) of the soil samples tested. The four most frequently detected pathogens were EAEC (67.5%), ETEC (59%), EPEC (57.5%), and STEC (31%). The detection rate (91% vs. 66%) and mean number of enteric pathogens (5 vs. 4.7) were higher in low-income Kibera than in middle-income Jericho. The more extensive spatial distribution of pathogens in Kibera resulted in increases in the detection of different enteric pathogens from within-site (area < 50 m2) and across-site (across-neighborhood) movements compared to Jericho. The pathogen detection rates fluctuated seasonally in Jericho but remained at sustained high levels in Kibera. While better neighborhood conditions were linked with lower pathogen detection rates, pathogenic E. coli remained prevalent in the public environment across both neighborhoods. Future studies should focus on identifying how the sources of pathogen contamination are modified by improved environmental sanitation and hygiene and the role of these contaminated public environments in enteric infections in children.
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Gorvel, Jean Pierre, Edgardo Moreno, and Ignacio Moriyón. "Is Brucella an enteric pathogen?" Nature Reviews Microbiology 7, no. 3 (2009): 250. http://dx.doi.org/10.1038/nrmicro2012-c1.
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Altwegg, M. "Aeromonas caviae: An enteric pathogen?" Infection 13, no. 5 (1985): 228–30. http://dx.doi.org/10.1007/bf01667217.
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McNeil, Candice J., Robert D. Kirkcaldy, and Kimberly Workowski. "Enteric Infections in Men Who Have Sex With Men." Clinical Infectious Diseases 74, Supplement_2 (2022): S169—S178. http://dx.doi.org/10.1093/cid/ciac061.
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Abstract Background Enteric pathogens are often associated with exposure to food, water, animals, and feces from infected individuals. However, in sexual networks of men who have sex with men (MSM), transmission of enteric pathogens may occur during direct or indirect oral–anal contact. Methods We performed a scoping review of the literature for studies prior to July 2019 with key terms for gastrointestinal syndromes (“proctitis,” “enteritis,” “proctocolitis”), enteric pathogens or sexually transmitted infections (STIs), and outbreaks using multiple electronic databases. Results We identified 5861 records through database searches, bibliography reviews, and keyword searches, of which 117 references were included in the pathogen-specific reviews. Conclusions The strength of observational data describing enteric pathogens in MSM and possible sexual transmission of enteric pathogens varies by pathogen; however, a robust body of literature describes the sexual transmission of Campylobacter, Giardia lamblia, and Shigella (particularly antimicrobial-resistant strains) in sexual networks of MSM. Providers are encouraged to consider enteritis or proctocolitis in MSM as possibly having been sexually transmitted and encourage targeted STI testing. Risk/harm reduction and prevention messages should also be incorporated, though there is an acknowledged paucity of evidence with regards to effective strategies. Further research is needed to understand the transmission and prevention of enteric pathogens in MSM.
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Potgieter, Natasha, Lee Heine, Jean Pierre Kabue Ngandu, et al. "High Burden of Co-Infection with Multiple Enteric Pathogens in Children Suffering with Diarrhoea from Rural and Peri-Urban Communities in South Africa." Pathogens 12, no. 2 (2023): 315. http://dx.doi.org/10.3390/pathogens12020315.
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Infectious diarrhoea contributes to high morbidity and mortality in young children from sub-Saharan Africa. The aim of this study was to assess the prevalence of single and multiple diarrhoeal-causing pathogen combinations in children suffering from diarrhoea from rural and peri-urban communities in South Africa. A total of 275 diarrhoea stool specimens were collected between 2014 and 2016 from Hospitals and Primary Health Care clinics. The BioFire® FilmArray® Gastrointestinal panel was used to simultaneously detect 22 diarrhoea pathogens (viruses, bacteria, parasites) known to cause diarrhoea. A total of 82% (226/275) enteric pathogens were detected in the stool specimens. The two most detected bacterial, viral and parasitic pathogens each included: EAEC (42%), EPEC (32%), Adenovirus F40/41 (19%), Norovirus (15%), Giardia (8%) and Cryptosporidium (6%), respectively. Single enteric pathogen infections were recorded in 24% (65/275) specimens with EAEC, and Norovirus was found in 26% (17/65) and 14% (9/65) of the specimens, respectively. Multiple enteric pathogen combinations were recorded in 59% (161/275) of the stool specimens with 53% (85/161) containing two pathogens, 22% (35/161) containing three pathogens and 25% (41/161) containing four or more pathogens. The results from this study demonstrated the complex nature of pathogen co-infections in diarrhoeal episodes which could have an impact on treatment effectiveness.
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Gourabathini, Poornima, Maria T. Brandl, Katherine S. Redding, John H. Gunderson, and Sharon G. Berk. "Interactions between Food-Borne Pathogens and Protozoa Isolated from Lettuce and Spinach." Applied and Environmental Microbiology 74, no. 8 (2008): 2518–25. http://dx.doi.org/10.1128/aem.02709-07.
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ABSTRACT The survival of Salmonella enterica was recently shown to increase when the bacteria were sequestered in expelled food vacuoles (vesicles) of Tetrahymena. Because fresh produce is increasingly linked to outbreaks of enteric illness, the present investigation aimed to determine the prevalence of protozoa on spinach and lettuce and to examine their interactions with S. enterica, Escherichia coli O157:H7, and Listeria monocytogenes. Glaucoma sp., Colpoda steinii, and Acanthamoeba palestinensis were cultured from store-bought spinach and lettuce and used in our study. A strain of Tetrahymena pyriformis previously isolated from spinach and a soil-borne Tetrahymena sp. were also used. Washed protozoa were allowed to graze on green fluorescent protein- or red fluorescent protein-labeled enteric pathogens. Significant differences in interactions among the various protist-enteric pathogen combinations were observed. Vesicles were produced by Glaucoma with all of the bacterial strains, although L. monocytogenes resulted in the smallest number per ciliate. Vesicle production was observed also during grazing of Tetrahymena on E. coli O157:H7 and S. enterica but not during grazing on L. monocytogenes, in vitro and on leaves. All vesicles contained intact fluorescing bacteria. In contrast, C. steinii and the amoeba did not produce vesicles from any of the enteric pathogens, nor were pathogens trapped within their cysts. Studies of the fate of E. coli O157:H7 in expelled vesicles revealed that by 4 h after addition of spinach extract, the bacteria multiplied and escaped the vesicles. The presence of protozoa on leafy vegetables and their sequestration of enteric bacteria in vesicles indicate that they may play an important role in the ecology of human pathogens on produce.
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Leu-Burke, Grace, Robert Beacham, and Courtney Bennetts. "Discovery of Enteric Pathogens in the Alaskan Subsistence Diet." American Journal of Clinical Pathology 152, Supplement_1 (2019): S129. http://dx.doi.org/10.1093/ajcp/aqz125.003.
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Abstract Objectives Transmission of enteric pathogens from food ingestion is an ongoing public health concern, with commensal bacteria in ruminant animal species causing human disease. Enteric pathogens Salmonella, Shigella, and Shiga toxin producing Escherichia coli (STEC) have been isolated from domesticated animals. However, the Alaskan subsistence diet relies on wild game, such as reindeer, caribou, and moose for their food supply. Research concerning enteric pathogens in wildlife has not established. Therefore, we conducted a pilot survey on moose and reindeer to determine potential enteric pathogen transfer risk. Methods Between July 2018 and January 2019, we collected 72 fecal samples from reindeer and moose migrating in Fairbanks, Anchorage, and the Matanuska Valley. Samples were cultured for enteric pathogens, including E coli 0157, using standard clinical microbial process. Phenotypic Shiga toxin production was verified by enzyme immunoassay. Results Reindeer were statistically significant for enteric pathogens when compared to moose (P < .05) Eighty percent of the reindeer population were colonized for either Shigella, Yersinia, or Shiga toxin-producing E coli, with 20% positive for multiple pathogens. Non-0157 Shiga toxin production was observed in 30% of reindeer samples, generated by a sorbitol fermenting E coli. In contrast, moose population showed a near absence of enteric pathogens with only 5% positive for Shigella. Salmonella was not identified in either animal. Conclusion Reindeer, moose, and caribou meat are prominent in the Alaskan subsistence diet. Although moose had limited enteric pathogen colonization, reindeer were significant for transmission risk, including non-0157 Shiga toxin producing E coli, which has been linked to hemolytic uremic syndrome. Isolation of a non-0157 STEC in wildlife indicates environmental colonization. Because reindeer and caribou are closely linked in diet and migration, Alaska clinical laboratories should screen for enteric pathogens, including non-0157 Shiga toxins.
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Barker, Troy, Drew Capone, Heather K. Amato, et al. "Public toilets have reduced enteric pathogen hazards in San Francisco." PLOS Water 2, no. 8 (2023): e0000152. http://dx.doi.org/10.1371/journal.pwat.0000152.
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Uncontained fecal wastes in cities may present exposure risks to the public. We collected discarded feces from public spaces in San Francisco, CA for analysis by RT-qPCR for a range of enteric pathogens. Out of 59 samples, we found 12 (20%) were of human origin and 47 (80%) were non-human; 30 of 59 stools were positive for ≥1 of the 35 pathogens assessed, including pathogenic E. coli, Shigella, norovirus, Cryptosporidium, and Trichuris. Using quantitative enteric pathogen estimates and data on observed fecal waste from a public reporting system, we modeled pathogens removed from the environment attributable to a recently implemented program of public toilet construction. We estimated that each new public toilet reduced the annual number of enteric pathogens released into the immediate environment (within 500 m walking distance), including 6.3 x 1012 enteropathogenic E. coli (95% CI: 4.0 x 1012–7.9 x 1012), 3.2 x 1011 enteroaggregative E. coli (95% CI: 1.3 x 1011–6.3 x 1011), and 3.2 x 108 Shigella (6.3 x 107–2.5 x 109). Improving access to public sanitation can reduce enteric pathogen hazards in cities. Interventions must also consider the hygienic disposal of animal waste to reduce microbial hazards with zoonotic infection potential.
Dissertations / Theses on the topic "Enteric pathogen"
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Aljaberi, Suuad Ali. "Molecular epidemiology of the enteric pathogen Campylobacter jejuni." Thesis, London School of Hygiene and Tropical Medicine (University of London), 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.536880.
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Elliott, Paul Ronald. "Structure and function of enteric pathogen glyceraldehyde-3-phosphate dehydrogenases." Thesis, University of Leicester, 2009. http://hdl.handle.net/2381/9541.
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The availability of published genomes from all domains of life has provided insight into biochemical processes for many organisms. Frequently the mapping of classical pathways onto genome-derived data is used to deduce metabolic pathways in an otherwise uncharacterised system. Whilst this method may be sufficient as a prelude to further biochemical analysis, the function of genes may be assigned by extrapolation from homologs, and this may not be correct. This study highlights the dangers of such a process, focusing on the glycolytic/gluconeogenic enzymes glyceraldehyde 3-phosphate dehydrogenase (GAPDH) from the human pathogenic species Helicobacter pylori and Campylobacter jejuni. H. pylori has two genes encoding GAPDH (gapA and gapB). These are both annotated as NAD+- dependent glyceraldehyde 3-phosphate dehydrogenases. This study has demonstrated enzymatically and structurally that gapA encodes a NADP-dependent GAPDH, whilst gapB encodes a NAD+-dependent GAPDH, furthermore GAPDHB is a better phosphorylating erythrose-4-phosphate dehydrogenase. Structural analysis of GAPDHA and GAPDHB showed key residues providing specificity for the coenzyme NADP+ over NAD+ and this finding was used to search for other putative NADP+-dependent GAPDHs within the Campylobacterales order. Other NADP+-dependent GAPDHs were identified; including that of C. jejuni, which has only one annotated GAPDH-encoding gene. Structural and enzymatic analysis confirmed C. jejuni's GAPDH is NADP+ dependent, although dual specificity is observed. This further shows the importance of experimental data to describe a system. Finally, a mutagenic approach was undertaken to determine the mechanism underlying the differing substrate specificities between GAPDHA and GAPDHB. Whilst the structural analysis was unable to provide a determinant of substrate specificity, these structures provided clear evidence for a reaction mechanism used by all phosphorylating GAPDHs. The significance of the findings is discussed in the context of the metabolism of these pathogens. This work demonstrates the importance of the synergy between structural and genomic analysis.
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Choudhry, Naheed. "Interactions between the enteric pathogen cryptosporidium parvum and intestinal epithelial cells." Thesis, Queen Mary, University of London, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.511374.
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Al-Ethari, Aziz Yasir Hasan. "Phosphoglycerate kinase and phosphoenolpyruvate synthase of the enteric pathogen Helicobacter pylori." Thesis, University of Leicester, 2018. http://hdl.handle.net/2381/42872.
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Helicobacter pylori is a globally distributed enteric pathogen implicated in several serious diseases. Understanding the genetics and metabolism of the pathogen is of significant importance to developing new therapies for eradication. However, its metabolism is poorly characterised. The genome lacks coding sequences of some key glycolytic enzymes, however the gluconeogenic enzymes fructose-1,6-bisphosphatase and phosphoenolpyruvate synthase (hpPPSA) are present. This suggests H. pylori uses the glycolytic/gluconeogenic pathway for anabolic biosynthesis rather than for catabolic energy production. This study examines the structure and function of hpPPSA and phosphoglycerate kinase (hpPGK) and investigates the conditional essentiality of these genes, which were identified by in silico double deletion mutational studies of H. pylori. The ppsA and pgk mutants (with controls) were constructed using experimental knock out strategies, and their role in synthetic lethality was investigated. The ppsA-mutated allele alone showed evidence of essentiality. The Krebs cycle in H. pylori deviates from the text book examples such as in humans and E. coli, thus pgk may be essential alone or in combination with other enzymes. The X-ray crystal structure of apo hpPGK was determined and compared to human PGK. Structural superposition showed that both the substrate and the nucleotide binding residues are well conserved. Four sulphate ions were identified bound in the hpPGK dimer. The positions of these molecules allowed the path of phosphoryl transfer during catalysis to be modelled. The enzyme was further characterised using kinetic techniques and compared to homologous enzymes. Prediction of the hpPPSA structure by homology modelling analysis located the essential His and Cys catalytic conserved residues in their respective domains. Superimposition of the N-terminal ATP binding domain superposition showed that these residues forming this binding site are well conserved. Understanding H. pylori metabolism may provide directions for the development of therapeutics.
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Perez, Viana Felipe. "Soil microbial interactions affecting enteric pathogen survival in sewage sludge-amended agricultural soil." Thesis, Imperial College London, 2010. http://hdl.handle.net/10044/1/5872.
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The natural inactivation of enteric pathogens in soil is a critical component of the multi-barrier approach to prevent infectious disease in humans by enteric microorganisms when biosolids are used as a fertiliser and soil conditioner on agricultural land. The addition of biosolids to agricultural soil modifies the soil microbial community and ecological interactions. Ecological processes, especially the activities of predatory protozoa, may have a critical role in reducing the survival of enteric pathogenic bacteria when biosolids are applied to agricultural soil. To test this hypothesis a series of field experiments were established on two soils of contrasting organic matter content and fertility status, amended with different sludge types, to examine the interactions between the soil microbial biomass, total protozoa numbers, environmental and soil factors and their effects on the decay of the enteric indicator bacteria, Escherichia coli, in biosolids-amended soil. Soil microbial biomass carbon (SMBC) concentrations were influenced by soil physico-chemical properties and, in particular, larger background biomass concentrations were measured in unamended control soil containing the largest amount of organic matter. The microbiological content and substrate availability of the supplied materials also influenced the extent of the increases in SMBC. Soil protozoa numbers consistently increased in both experimental field soils from background values of 3-3.5 log10 g-1 ds to 4-4.5 log10 g-1 ds after sludge application. The extent of the increase was consistent with the effect of the organic amendments on SMBC. Laboratory investigations indicated the direct involvement of bacteriophagous protozoa activity in the soil ecological processes responsible for E. coli inactivation in biosolidsamended agricultural soil. This was linked to the addition of an active protozoa population to the soil in sludge, as well as to the stimulation of protozoa indigenous to the soil due to inputs of substrates and microbial biomass in sludge. Consequently, the survival of enteric organisms is a self-limiting process, due to the stimulation of microbial predatory activity in amended soil. Overall, the results provide assurance that assumptions relating to soil decay during waiting periods stipulated for agricultural use of sludge are highly conservative. They also confirm that the cropping/harvesting restrictions prescribed in legislation and guidance controlling the application of biosolids on farmland allow the natural attenuation of pathogens to protect human health with a significant margin of safety.
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Kwa, Sue Fen. "Cellular and structural factors influencing the induction of Th1 mucosal responses against an enteric pathogen." Thesis, University College London (University of London), 2006. http://discovery.ucl.ac.uk/1444909/.
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Secondary lymphoid structures are organised networks which support the generation of efficient immune responses by facilitating antigen presentation between an antigen presenting cell (APC) and an antigen-specific naive T cell. Professional APC such as dendritic cells (DC) are potent primers of T cells and have the capacity to determine the T-helper type 1 or 2 direction of the immune response. Lymphotoxin (LT) is a cytokine of the TNF family which has diverse biological roles, including one as a cytotoxic mediator of immunity. Moreover LT-mediated signals are required for the organogenesis and maintenance of lymphoid structures. The role of various lymphoid structures may have profound effects on the co-ordination of primary immune responses and LT-disruption has been used to examine these requirements. To date, most studies have focussed on systemic infection and here, the roles of LT and various gut-associated lymphoid tissues (GALT) were addressed in the context of enteric infection with the gut-tropic apicomplexan parasite, Eimeria vermiformis. Immunity to infection and the induction of protective gut Th1 responses were dependent upon the rapid recruitment of DC to lymphoid structures. Deficiency in lymphoid structures affected the induction of protective immunity and increased susceptibility to infection. Despite the lack of infection in the PP (E. vermiformis targets crypt enterocytes), a role for PP was established in the rapid induction of immunity. The anti-parasite response required a co-operative interaction between PP and mesenteric lymph nodes (MLN) with the PP influencing the time of induction of responses in the MLN. Examination of DC numbers and phenotypes revealed a delay in accumulation of DC subsets in PP-deficient mice and supports the role for DC traffic between these lymphoid structures in the induction of rapid gut immune responses.
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RAMALHETE, Sara de Castro Gonçalves. "Exploring the relationship between toxin and spore prodution in the human enteric pathogen Clostridium difficile." Master's thesis, Instituto de Higiene e Medicina Tropical, 2015. http://hdl.handle.net/10362/19069.
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Clostridium difficile é presentemente a principal causa de doença gastrointestinal associada à utilização de antibióticos em adultos. C. difficile é uma bactéria Gram-positiva, obrigatoriamente anaeróbica, capaz de formar endósporos. Tem-se verificado um aumento dos casos de doença associada a C. difficile com sintomas mais severos, elevadas taxas de morbilidade, mortalidade e recorrência, em parte, devido à emergência de estirpes mais virulentas, mas também devido à má gestão do uso de antibióticos. C. difficile produz duas toxinas, TcdA e TcdB, que são os principais fatores de virulência e responsáveis pelos sintomas da doença. Estas são codificadas a partir do Locus de Patogenicidade (PaLoc) que codifica ainda para um regulador positivo, TcdR, uma holina, TcdE, e um regulador negativo, TcdC. Os esporos resistentes ao oxigénio são essenciais para a transmissão do organismo e recorrência da doença.
A expressão dos genes do PaLoc ocorre em células vegetativas, no final da fase de crescimento exponencial, e em células em esporulação. Neste trabalho construímos dois mutantes de eliminação em fase dos genes tcdR e tcdE. Mostrámos que a auto-regulação do gene tcdR não é significativa. No entanto, tcdR é sempre necessário para a expressão dos genes presentes no PaLoc.
Trabalho anterior mostrou que, com a exceção de tcdC, os demais genes do PaLoc são expressos no pré-esporo. Mostrámos aqui que TcdA é detectada à superfície do esporo maduro e que a eliminação do tcdE não influencia a acumulação de TcdA no meio de cultura ou em associação às células ou ao esporo. Estas observações têm consequências para o nosso entendimento do processo infecioso: sugeremque o esporo possa ser também um veículo para a entrega da toxina nos estágios iniciais da infecção, que TcdA possa ser libertada durante a germinação do esporo, e que o esporo possa utilizar o mesmo receptor reconhecido por TcdA para a ligação à mucosa do cólon.<br>Clostridium difficileis currently the major cause of antibiotic-associated gastrointestinal diseases in adults. This is a Gram-positive bacterium, endospore-forming and an obligate anaerobe that colonizes the gastrointestinal tract.Recent years have seen a rise in C. difficile associated disease (CDAD) cases, associated with more severe disease symptoms, higher rates of morbidity, mortality and recurrence, which were mostly caused due to the emergence of “hypervirulent” strains but also due to changing patterns of antibiotics use. C. difficile produces two potent toxins, TcdA and TcdB, which are the main virulence factors and the responsible for the disease symptoms. These are codified from a Pathogenicity Locus (PaLoc), composed also by the positive regulator, TcdR, the holin-like protein, TcdE, and a negative regulator, TcdC. Besides the toxins, the oxygen-resistant spores are also essential for transmission of the organism through diarrhea; moreover, spores can accumulate in the environment or in the host, which will cause disease recurrence.The expression of the PaLoc genes occurs in vegetative cells, at the end of the exponential growth phase, and in sporulating cells. In this work, we constructed two in-frame deletion mutants of tcdR and tcdE. We showed that the positive auto regulation oftcdR is not significant. However, tcdR is always necessary for the expression of the PaLoc genes.A previous work showed that, except tcdC, all the PaLoc genes are expressed in the forespore. Here, we detected TcdA at the spore surface. Furthermore, we showed that the in-frame deletion of tcdE does not affect the accumulation of TcdA in the culture medium or in association with cells or spores. This data was important for us to conclude about the infeccious process: it suggests that the spore may be the vehicle for the delivery of TcdA in early stages of infection, that TcdA may be released during spores germination and that this spore may use the same receptor recognized by TcdA to bind to the colonic mucosa.
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Cass, James. "Field and laboratory investigations quantifying the factors responsible for enteric pathogen decay in biosolids amended agricultural soils." Thesis, Imperial College London, 2009. http://hdl.handle.net/10044/1/5507.
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The inactivation of enteric pathogens in soil is a critical component of the multibarrier approach to protect human health when biosolids are applied to agricultural land as a fertiliser. Ecological processes may have a central role in eliminating enteric bacteria applied to soil in biosolids providing an active mechanism for their removal. To test this hypothesis, and to provide long-term decay information on a variety of enteric pathogens, a series of field experiments was established on two soils of contrasting organic matter and fertility status, amended with different sludge types. E. coli population numbers were monitored in soils amended with biosolids and unamended control soils. Inoculation treatments with E. coli O157, Salmonella enterica, Listeria monocytogenes, Campylobacter jejuni, and Clostridium perfringens were also monitored. E. coli were found to be indigenous to both soils and their populations were highly dynamic. Following application of conventionally treated biosolids, E. coli and enteric pathogen numbers increased and subsequently showed a rapid decline within 20-100 days and were not significantly different from numbers in the unamended control soils within 316 days. E. coli content of enhanced treated biosolids was lower than that of unamended control soils prior to application. However, E. coli numbers in soil treated with enhanced biosolids increased compared to the unamended controls in response to substrates input. Laboratory investigations indicate the direct involvement of the soil ecological processes on E. coli inactivation an in particular, bacteriophagous protozoa activity. These complex mechanisms are actively stimulated by biosolids addition and significantly impact on E. coli decay in biosolids-amended agricultural soils. The results provide assurance that assumptions relating to soil decay during waiting periods stipulated for agricultural use of sludge are highly conservative. They confirm that the cropping/harvesting restrictions prescribed in legislation and guidance controlling the application of biosolids on farmland allow for the natural attenuation of pathogens to protect human health with a significant margin of safety.
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Lee, Andrew Seong-tae. "Type 1 diabetes (T1D) in NOD mouse models : the role of toll-like receptor 7 and an enteric bacterial pathogen in accelerating the development of T1D." Thesis, University of British Columbia, 2009. http://hdl.handle.net/2429/13922.
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Enteric viruses, intestinal enteropathies and the subsequent activation of endosomal toll-like receptors (TLRs) have been implicated as triggers of type 1 diabetes (T1D). TLR7 detects single stranded RNA. TLR7 agonists can accelerate diabetes by enhancing islet expression of major histocompatibility complex (MHC) I restricted transgenic antigens but the role and source of TLR7 stimulation in promoting T1D (and reactivity to true self antigens) remains unclear. In addition, recent evidence has suggested that disruption of the intestinal barrier, a ‘leaky gut’, may provide an endogenous TLR source that drives the autoimmune response in T1D. We used non-obese diabetic (NOD) mouse models of human T1D to investigate the role of TLR7 activation and an enteric bacterial pathogen, Citrobacter rodentium, that disrupts the intestinal barrier integrity in the development of T1D.
TLR7 activation with the imidazoquinoline CL097 in NOD mice caused the activation of bone marrow derived dendritic cells in vitro, the general activation of T and B cells in vivo, and the production of proinflammatory cytokines. In vivo antigen-specific cytotoxicity studies revealed enhanced cytotoxicity against IGRP (islet autoantigen) peptide pulsed targets in NOD mice treated with CL097 and anti-CD40 compared to negative controls. This treatment combination accelerated the onset of T1D in NOD 8.3 T cell receptor (TCR) transgenic mice (8.3 NOD mice). This accelerated disease in 8.3 NOD mice was significantly delayed when TLR7 signaling was blocked using the oligodeoxynucleotide (ODN) inhibitor, IRS661.
Pre-diabetic (12-week) NOD mice displayed increased intestinal barrier permeability when compared to C57BL/6 and diabetes resistant NOR mice. Moreover, the development of invasive insulitis is accelerated when young (4-week) NOD mice are infected with C. rodentium. C. rodentium infected NOD mice demonstrate increased colonic permeability, increased activation of polyclonal and diabetogenic cytotoxic T lymphocytes (CTLs) and increased C. rodentium counts in the mesenteric and pancreatic lymph nodes, compared to uninfected NOD mice.
Taken together, these findings demonstrate that TLR7 signaling can modulate the development of T1D and an enteric bacterial pathogen can modulate the development of invasive insulitis. Thus, TLR7 antagonism and maintaining an intact intestinal barrier may provide distinct therapeutic approaches in preventing the development of T1D.
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Tafazoli, Farideh. "Perturbation of the epithelial barrier by enteric pathogens /." Linköping : Univ, 2001. http://www.bibl.liu.se/liupubl/disp/disp2001/med702s.pdf.
Full textBooks on the topic "Enteric pathogen"
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Farrah, Samuel R. Inactivation of enteric pathogens during aerobic digestion of wastewater sludge. U.S. Environmental Protection Agency, Water Engineering Research Laboratory, 1986.
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Farrah, Samuel R. Inactivation of enteric pathogens during aerobic digestion of wastewater sludge. U.S. Environmental Protection Agency, Water Engineering Research Laboratory, 1986.
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Sterling, Charles R., and Rodney D. Adam, eds. The Pathogenic Enteric Protozoa: Giardia, Entamoeba, Cryptosporidium and Cyclospora. Springer US, 2004. http://dx.doi.org/10.1007/b113653.
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S, Paul Prem, Francis David H, and International Rushmore Conference on Mechanisms in the Pathogenesis of Enteric Diseases (2nd : 1998 : Rapid City, S.D.), eds. Mechanisms in the pathogenesis of enteric diseases 2. Kluwer Academic/Plenum Publishers, 1999.
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Heufelder, George R. Survival and transport of enteric bacteria and viruses in the nearshore marine environment: An annotated bibliography. Barnstable County Health and Environmental Department, 1988.
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Friedman, Herman, Mauro Bendinelli, and Lois J. Paradise. Enteric Infections and Immunity. Springer, 2014.
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Friedman, Herman, Mauro Bendinelli, and Lois J. Paradise. Enteric Infections and Immunity. Springer, 2013.
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Sterling, Charles R., and Rodney D. Adam. Pathogenic Enteric Protozoa: Giardia, Entamoeba, Cryptosporidium and Cyclospora. Springer, 2014.
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Sterling, Charles R., and Rodney D. Adam. Pathogenic Enteric Protozoa : : Giardia, Entamoeba, Cryptosporidium and Cyclospora. Springer London, Limited, 2006.
Find full textBook chapters on the topic "Enteric pathogen"
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Malago, Joshua J., and Jos F. J. G. Koninkx. "Probiotic-Pathogen Interactions and Enteric Cytoprotection." In Probiotic Bacteria and Enteric Infections. Springer Netherlands, 2011. http://dx.doi.org/10.1007/978-94-007-0386-5_13.
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Mäkelä, P. Helena, Marianne Hovi, Harri Saxén, et al. "Salmonella as an Invasive Enteric Pathogen." In Molecular Pathogenesis of Gastrointestinal Infections. Springer US, 1991. http://dx.doi.org/10.1007/978-1-4684-5982-1_23.
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Mouricout, Michèle. "Interactions between the Enteric Pathogen and the Host." In Advances in Experimental Medicine and Biology. Springer US, 1997. http://dx.doi.org/10.1007/978-1-4899-1828-4_19.
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Guan, Tiffany T. Y., and Richard A. Holley. "Pathogen Survival in Swine Manure Environments and Transmission of Human Enteric Illness—A Reviewa." In Hog Manure Management, the Environment and Human Health. Springer US, 2003. http://dx.doi.org/10.1007/978-1-4615-0031-5_2.
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Stecher, Bärbel. "The Roles of Inflammation, Nutrient Availability and the Commensal Microbiota in Enteric Pathogen Infection." In Metabolism and Bacterial Pathogenesis. ASM Press, 2015. http://dx.doi.org/10.1128/9781555818883.ch14.
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Rees, Judy R. "Enteric Pathogens." In Sequelae and Long-Term Consequences of Infectious Diseases. ASM Press, 2014. http://dx.doi.org/10.1128/9781555815486.ch4.
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Bhunia, Arun K. "Salmonella enterica." In Foodborne Microbial Pathogens. Springer New York, 2018. http://dx.doi.org/10.1007/978-1-4939-7349-1_15.
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Holtkötter, Peter, and Michael Hensel. "Metabolism of IntracellularSalmonella enterica." In Host - Pathogen Interaction. Wiley-VCH Verlag GmbH & Co. KGaA, 2016. http://dx.doi.org/10.1002/9783527682386.ch3.
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Lan, Ruiting, and Peter R. Reeves. "Evolution of Enteric Pathogens." In Evolution of Microbial Pathogens. ASM Press, 2014. http://dx.doi.org/10.1128/9781555815622.ch15.
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Shrestha, Archana, Francisco A. Uzal, and Bruce A. McClane. "Enterotoxic Clostridia: Clostridium perfringens Enteric Diseases." In Gram-Positive Pathogens. ASM Press, 2019. http://dx.doi.org/10.1128/9781683670131.ch60.
Full textConference papers on the topic "Enteric pathogen"
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Al-Asmar, Jawaher, Sara Rashwan, and Layla Kamareddine. "The use of Drosophila Melanogaster as a Model Organism to study the effect of Bacterial Infection on Host Survival and Metabolism." In Qatar University Annual Research Forum & Exhibition. Qatar University Press, 2020. http://dx.doi.org/10.29117/quarfe.2020.0186.
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Enterobacteriaceae, a large family of facultative anaerobic bacteria, encloses a broad spectrum of bacterial species including Escherichia coli, Salmonella enterica, and Shigella sonnei, that produce enterotoxins and cause gastrointestinal tract diseases. While much is known about the regulation and function of enterotoxins within the intestine of the host; the lack of cheap, practical, and genetically tractable model organisms has restricted the investigation of others facets of this host-pathogen interaction. Our group, among others, has employed Drosophila melanogaster, as a model organism to shed more light on some aspects of host-pathogen interplays. In this project, we addressed the effect of Escherichia coli, Salmonella enterica, and Shigella sonnei infection on altering the metabolic homeostasis of the host. Drosophila melanogaster flies were orally infected with Escherichia coli, Salmonella enterica, or Shigella sonnei, a method that mimics the natural route used by enteric pathogens to gain access to the gastrointestinal tract in humans. The results of our study revealed that both Escherichia coli and Shigella sonnei pathogens were capable of colonizing the host gut, resulting in a reduction in the life span of the infected host. Escherichia coli and Shigella sonnei infected flies also exhibited altered metabolic profiles including lipid droplets deprivation from their fat body (normal lipid storage organ in flies), irregular accumulation of lipid droplets in their gut, and significant elevation of systemic glucose and triglyceride levels. These metabolic alterations could be mechanistically attributed to the differential down-regulation in the expression of metabolic peptide hormones (Allatostatin A, Diuretic hormone 31, and Tachykinin) detected in the gut of Escherichia coli and Shigella sonnei infected flies. Salmonella enterica; however, was unable to colonize the gut of the host; and therefore, Salmonella enterica infected flies exhibited a relatively normal metabolic status as that of non infected flies. Gaining a proper mechanistic understanding of infection-induced metabolic alterations helps in modulating the pathogenesis of gastrointestinal tract diseases in a host and opens up for promising therapeutic approaches for infection induced metabolic disorders
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Gimenez-Gomez, Pablo, Jordi Sacristan-Riquelme, Ferran Pujol-Vila, et al. "Photonic lab-on-a-chip with environmental light correction for in situ determination of enteric pathogen contamination." In 2014 IEEE 9th Ibero-American Congress on Sensors (IBERSENSOR). IEEE, 2014. http://dx.doi.org/10.1109/ibersensor.2014.6995563.
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Mahajan, Rishab, James Uber, and Joseph Eisenberg. "A Simplified Model of Combined Sewer Overflows to Estimate Event Driven Enteric Pathogen Concentrations in Drinking Water Sources." In World Environmental and Water Resources Congress 2009. American Society of Civil Engineers, 2009. http://dx.doi.org/10.1061/41036(342)77.
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Muldoon, Maureen A., Randall J. Hunt, David Owens, et al. "USING AUTOSAMPLER MONITORING TO DETERMINE THE TIMING OF ENTERIC PATHOGEN CONTAMINATION OF THE FRACTURED SILURIAN AQUIFER, NORTHEASTERN WI." In GSA Annual Meeting in Seattle, Washington, USA - 2017. Geological Society of America, 2017. http://dx.doi.org/10.1130/abs/2017am-305877.
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Onyango Awuor, Silas Onyango Awuor. "Long-term Home Enteral Nutrition: Feeding Tube-related Complications and Problems in old age Patients." In 4th International Nutrition and Dietetics Scientific Conference. KENYA NUTRITIONISTS AND DIETICIANS INSTITUTE, 2024. http://dx.doi.org/10.57039/jnd-conf-abt-2024-gioh-06.
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The highest infusion therapy at home nowadays is tube feeding or Home enteral Nutrition (HEN) normally used in patient who have a functional gastrointestinal tract but are unable to meet their nutrient requirement through oral intake. This study aim was to evaluate the long-term complications, pathogens and problems related to gastrostomy and jejunostomy feeding tubes used for home enteral nutrition support and the effect these have on health care use. This was retrospectively study among 50 patients (28 having gastrostomy and 22 with jejunostomy) who have been discharged on long-term (>2 months) enteral nutrition and followed up at regular intervals by a nurse. Data were collected and analyzed on complication associated with tube feeding as well as the intervention for a period of six months. From this study it was found that 28 (55.1%) of the participant frequently removes the tube, 23 (46.6%) tube leakage, and 18 (36.4%) had dermatitis of the stoma. Some of the patient 8 (16.4%) developed diarrhea which was seen due to pathogens causing diarrhoea in which Escherichia coli emerged the highest at 5 (30%) even though it is classified as non-pathogenic organism but can enhance other pathogen infection, followed by Salmonella spp. and Shigella spp. at 4 (25%) and lastly Campylobacter spp. at 2 (12%). From this study it was found that most of our patients receiving long-term home enteral nutrition feeding tube-related complications are frequently expose themselves to common pathogens which may lead to other complication to them. Therefore, further studies are needed to address their optimal prevention modalities and management. Key words: Complications, Gastrostomy, Jejunostomy, pathogens, Home enteral nutrition
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Weigl, B. H., J. Gerdes, P. Tarr, et al. "LAB-ON-A-CARD ASSAY FOR ENTERIC PATHOGENS." In 2006 Solid-State, Actuators, and Microsystems Workshop. Transducer Research Foundation, Inc., 2006. http://dx.doi.org/10.31438/trf.hh2006.45.
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Kolb, J., M. Roof, and D. Walter. "Dramatic reductions of in feed medication via immunization against enteric pathogens." In Fifth International Symposium on the Epidemiology and Control of Foodborn Pathogens in Pork. Iowa State University, Digital Press, 2003. http://dx.doi.org/10.31274/safepork-180809-545.
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Weigl, B. H., J. Gerdes, P. Tarr, et al. "Fully integrated multiplexed lab-on-a-card assay for enteric pathogens." In MOEMS-MEMS 2006 Micro and Nanofabrication, edited by Ian Papautsky and Wanjun Wang. SPIE, 2006. http://dx.doi.org/10.1117/12.644714.
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Shesteperov, A. A., and E. S. Starostina. "PARASITOCENOTIC ASPECTS IN PHYTOPARASITOLOGY." In THEORY AND PRACTICE OF PARASITIC DISEASE CONTROL. VNIIP – FSC VIEV, 2024. http://dx.doi.org/10.31016/978-5-6050437-8-2.2024.25.462-468.
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The term "microparasitocenosis" proposed by A. P. Markevich, who combined parasitizing forms of resident microflora of the organism and parasites that entered from external environment. Viruses, viroids, bacteria, fungi, protozoa, phytohelminths, phytoparasitic mites and insects form the parasitocenosis in a macroorganism (plant) and represent a damaging complex that contributes to pathological changes in the macroorganism. The intention to simplify complex biological processes as much as possible has led to artificial isolation of any single pathogen. This turned out to be necessary and effective in studying causative agents of dangerous plant parasite infections. But it turned out to be inconsistent for associated infections and invasions since complex diseases develop when they are combined with other phytoparasites. Their synergism contributes to high harmfulness of complex diseases. Unfortunately, the problem of plant parasite infection and invasion has not been sufficiently studied in phytoparasitology. As defined, plant parasitism has boundaries from positive to neutral interactions of other types that are precisely outlined by pathogenicity. Harmfulness is exactly what can explain centuries-old hostility towards parasites. We considered the plant parasite cenosis of strawberries that included 27 plant parasites and 25 pathogens. The discovery of relationships between phytopathogens and phytoparasites has resulted in a qualitative change in cognitive tools and the interpretation of various pathogenic process phases. Based on systemic analysis, phytoparasites at different levels (plants, plant populations, biocenosis) are considered not as a mechanical population but as an integral system that functions under specific laws. Systemic quality of the plant parasitic cenosis appears in its interactions with other organisms.
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Khutoryanina, I. V., T. I. Tverdochlebova, L. L. Dimidova, M. P. Chernikova, and I. A. Savchuk. "PARASITOLOGICAL POLLUTION ASSESSMENT OF WASTEWATERS AND SEWAGE SLUDGE IN THE TERRITORIES OF SOUTHERN RUSSIA." In THEORY AND PRACTICE OF PARASITIC DISEASE CONTROL. VNIIP – FSC VIEV, 2024. http://dx.doi.org/10.31016/978-5-6050437-8-2.2024.25.444-450.
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Parasitological monitoring of environmental objects plays an important role in the sanitary and epidemiological surveillance system. To control and ensure biological safety, wastewaters are subject to mandatory research because that is where the maximum concentration of parasitic pathogens that can enter the human body is recorded. Since 2011, the Rostov Research Institute of Microbiology and Parasitology of the Rospotebnadzor has conducted 14,055 sanitary and parasitological studies of (pre- and posttreatment) wastewaters and (liquid and dried) sewage sludge sampled at sewage treatment facilities in various territories of the south of Russia. The specific weight of positive wastewater samples before treatment averaged 60.5%, and after treatment, 46.8%. In the spectrum of parasitic pathogens detected in the wastewaters, eggs of Toxocara, ascarids and whipworms were predominantly found. The number of positive sewage sludge samples was 35.2% in the Republic of Adygea, 30.9% in the Republic of Karachay-Cherkessia, 20.5% in the Rostov Region, 34.0% in the Astrakhan Region, and 34.2% in the Krasnodar Territory. Thus, sewage treatment facilities in the south of Russia are epidemiologically significant objects that cause a risk of parasitic pathogen distribution in external environment.
Reports on the topic "Enteric pathogen"
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Gillor, Osnat, Stefan Wuertz, Karen Shapiro, et al. Science-Based Monitoring for Produce Safety: Comparing Indicators and Pathogens in Water, Soil, and Crops. United States Department of Agriculture, 2013. http://dx.doi.org/10.32747/2013.7613884.bard.
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Using treated wastewater (TWW) for crop irrigation represents an important opportunity for ensuring adequate food production in light of growing freshwater scarcity worldwide. However, the environmentally sustainable approach of using TWW for irrigation can lead to contamination of produce with fecal pathogens that may remain in treated water. The overall goal of this research was to evaluate the correlation between the presence of fecal indicator bacteria (FIB) and that of a suite of human pathogens in TWW, the irrigated soil, and crops. Field experiments were conducted to compare secondary and tertiary TWW with dechlorinated tap water for irrigation of tomatoes, a typical commercial crop, in Israel, a semi-arid country. Human pathogens including bacteria (Salmonella), protozoa (Cryptosporidiumand Giardia), and viruses (Adenovirus [AV Types A, B, C & 40/41] and Enterovirus [EV71 subtypes]) were monitored in two field trials using a combination of microscopic, cultivation-based, and molecular (qPCR) techniques. Results from the field trials indicate that microbial contamination on the surface of tomatoes did not appear to be associated with the source of irrigated waters; FIB contamination was not statistically different on tomatoes irrigated with TWW as compared to tomatoes irrigated with potable water. In fact, Indicator bacteria testing did not predict the presence of pathogens in any of the matrices tested. High concentrations of FIB were detected in water and on tomato surfaces from all irrigation treatment schemes, while pathogen contamination on tomato surfaces (Cryptosporidiumand Salmonella) was only detected on crops irrigated with TWW. These results suggest that regular monitoring for pathogens should take place to accurately detect presence of harmful microorganisms that could threaten consumer safety. A notable result from our study is that the large numbers of FIB in the water did not appear to lead to FIB accumulation in the soil. With the exception of two samples, E. coli that was present at 10³ to 10⁴ cells/100 mL in the water, was not detected in the soil. Other bacterial targets associated with the enteric environment (e. g., Proteusspp.) as well as protozoal pathogens were detected in the TWW, but not in the soil. These findings suggest that significant microbial transfer to the soil from TWW did not occur in this study. The pattern of FIB contamination on the surfaces of tomatoes was the same for all treatment types, and showed a temporal effect with more contamination detected as the duration of the field trial increased. An important observation revealed that water quality dramatically deteriorated between the time of its release from the wastewater treatment plant and the time it was utilized for irrigation, highlighting the importance of performing water quality testing throughout the growing season at the cultivation site.
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Brandl, Maria T., Shlomo Sela, Craig T. Parker, and Victor Rodov. Salmonella enterica Interactions with Fresh Produce. United States Department of Agriculture, 2010. http://dx.doi.org/10.32747/2010.7592642.bard.
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The emergence of food-borne illness outbreaks linked to the contamination of fruits and vegetables is a great concern in industrialized countries. The current lack of control measures and effective sanitization methods prompt the need for new strategies to reduce contamination of produce. Our ability to assess the risk associated with produce contamination and to devise innovative control strategies depends on the identification of critical determinants that affect the growth and the persistence of human pathogens on plants. Salmonella enterica, a common causal agent of illness linked to produce, has the ability to colonize and persist on plants. Thus, our main objective was to identify plant-inducible genes that have a role in the growth and/or persistence of S. enterica on postharvest lettuce. Our findings suggest that in-vitro biofilm formation tests may provide a suitable model to predict the initial attachment of Salmonella to cut-romaine lettuce leaves and confirm that Salmonella could persist on lettuce during shelf-life storage. Importantly, we found that Salmonella association with lettuce increases its acid-tolerance, a trait which might be correlated with an enhanced ability of the pathogen to pass through the acidic barrier of the stomach. We have demonstrated that Salmonella can internalize leaves of iceberg lettuce through open stomata. We found for the first time that internalization is an active bacterial process mediated by chemotaxis and motility toward nutrient produced in the leaf by photosynthesis. These findings may provide a partial explanation for the failure of sanitizers to efficiently eradicate foodborne pathogens in leafy greens and may point to a novel mechanism utilized by foodborne and perhaps plant pathogens to colonize leaves. Using resolvase in vivo expression technology (RIVET) we have managed to identify multiple Salmonella genes, some of which with no assigned function, which are involved in attachment to and persistence of Salmonella on lettuce leaves. The precise function of these genes in Salmonella-leaf interactions is yet to be elucidated. Taken together, our findings have advanced the understanding of how Salmonella persist in the plant environment, as well as the potential consequences upon ingestion by human. The emerging knowledge opens new research directions which should ultimately be useful in developing new strategies and approaches to reduce leaf contamination and enhance the safety of fresh produce.
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Sela, Shlomo, and Michael McClelland. Desiccation Tolerance in Salmonella and its Implications. United States Department of Agriculture, 2013. http://dx.doi.org/10.32747/2013.7594389.bard.
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Salmonella enterica is a worldwide food-borne pathogen, which regularly causes large outbreaks of food poisoning. Recent outbreaks linked to consumption of contaminated foods with low water-activity, have raised interest in understanding the factors that control fitness of this pathogen to dry environment. Consequently, the general objective of this study was to extend our knowledge on desiccation tolerance and long-term persistence of Salmonella. We discovered that dehydrated STm entered into a viable-but-nonculturable state, and that addition of chloramphenicol reduced bacterial survival. This finding implied that adaptation to desiccation stress requires de-novo protein synthesis. We also discovered that dried STm cells develop cross-tolerance to multiple stresses that the pathogen might encounter in the agriculture/food environment, such as high or low temperatures, salt, and various disinfectants. These findings have important implications for food safety because they demonstrate the limitations of chemical and physical treatments currently utilized by the food industry to completely inactivate Salmonella. In order to identify genes involved in desiccation stress tolerance, we employed transcriptomic analysis of dehydrated and wet cells and direct screening of knock-out mutant and transposon libraries. Transcriptomic analysis revealed that dehydration induced expression of ninety genes and down-regulated seven. Ribosomal structural genes represented the most abundant functional group with a relatively higher transcription during dehydration. Other large classes of induced functional groups included genes involved in amino acid metabolism, energy production, ion transport, transcription, and stress response. Initial genetic analysis of a number of up-regulated genes was carried out). It was found that mutations in rpoS, yahO, aceA, nifU, rpoE, ddg,fnr and kdpE significantly compromised desiccation tolerance, supporting their role in desiccation stress response.
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Prusky, Dov, Martin Dickman, and Robert Fluhr. Effect of pH Modulation and ROS Production by Postharvest Pathogens on Postharvest Disease Development. United States Department of Agriculture, 2012. http://dx.doi.org/10.32747/2012.7613876.bard.
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Okumu, Noah, Dishon Muloi, Arshnee Moodley, et al. Antimicrobial resistance in community-acquired enteric pathogens amongst children ≤10-years-old in low- and middle-income settings: a systematic review and meta-analysis. INPLASY - International Platform of Registered Systematic Review and Meta-analysis Protocols, 2024. http://dx.doi.org/10.37766/inplasy2024.2.0051.
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Coplin, David L., Shulamit Manulis, and Isaac Barash. roles Hrp-dependent effector proteins and hrp gene regulation as determinants of virulence and host-specificity in Erwinia stewartii and E. herbicola pvs. gypsophilae and betae. United States Department of Agriculture, 2005. http://dx.doi.org/10.32747/2005.7587216.bard.
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Gram-negative plant pathogenic bacteria employ specialized type-III secretion systems (TTSS) to deliver an arsenal of pathogenicity proteins directly into host cells. These secretion systems are encoded by hrp genes (for hypersensitive response and pathogenicity) and the effector proteins by so-called dsp or avr genes. The functions of effectors are to enable bacterial multiplication by damaging host cells and/or by blocking host defenses. We characterized essential hrp gene clusters in the Stewart's Wilt of maize pathogen, Pantoea stewartii subsp. stewartii (Pnss; formerly Erwinia stewartii) and the gall-forming bacterium, Pantoea agglomerans (formerly Erwinia herbicola) pvs. gypsophilae (Pag) and betae (Pab). We proposed that the virulence and host specificity of these pathogens is a function of a) the perception of specific host signals resulting in bacterial hrp gene expression and b) the action of specialized signal proteins (i.e. Hrp effectors) delivered into the plant cell. The specific objectives of the proposal were: 1) How is the expression of the hrp and effector genes regulated in response to host cell contact and the apoplastic environment? 2) What additional effector proteins are involved in pathogenicity? 3) Do the presently known Pantoea effector proteins enter host cells? 4) What host proteins interact with these effectors? We characterized the components of the hrp regulatory cascade (HrpXY ->7 HrpS ->7 HrpL ->7 hrp promoters), showed that they are conserved in both Pnss and Fag, and discovered that the regulation of the hrpS promoter (hrpSp) may be a key point in integrating apoplastic signals. We also analyzed the promoters recognized by HrpL and demonstrated the relationship between their composition and efficiency. Moreover, we showed that promoter strength can influence disease expression. In Pnss, we found that the HrpXY two-component signal system may sense the metabolic status of the bacterium and is required for full hrp gene expression in planta. In both species, acyl-homoserine lactone-mediated quorum sensing may also regulate epiphytic fitness and/or pathogenicity. A common Hrp effector protein, DspE/WtsE, is conserved and required for virulence of both species. When introduced into corn cells, Pnss WtsE protein caused water-soaked lesions. In other plants, it either caused cell death or acted as an Avr determinant. Using a yeast- two-hybrid system, WtsE was shown to interact with a number of maize signal transduction proteins that are likely to have roles in either programmed cell death or disease resistance. In Pag and Pab, we have characterized the effector proteins HsvG, HsvB and PthG. HsvG and HsvB are homologous proteins that determine host specificity of Pag and Pab on gypsophila and beet, respectively. Both possess a transcriptional activation domain that functions in yeast. PthG was found to act as an Avr determinant on multiple beet species, but was required for virulence on gypsophila. In addition, we demonstrated that PthG acts within the host cell. Additional effector genes have been characterized on the pathogenicity plasmid, pPATHₚₐg, in Pag. A screen for HrpL- regulated genes in Pnsspointed up 18 candidate effector proteins and four of these were required for full virulence. It is now well established that the virulence of Gram-negative plant pathogenic bacteria is governed by Hrp-dependent effector proteins. However; the mode of action of many effectors is still unresolved. This BARD supported research will significantly contribute to the understanding of how Hrp effectors operate in Pantoea spp. and how they control host specificity and affect symptom production. This may lead to novel approaches for genetically engineering plants resistant to a wide range of bacterial pathogens by inactivating the Hrp effectors with "plantabodies" or modifying their receptors, thereby blocking the induction of the susceptible response. Alternatively, innovative technologies could be used to interfere with the Hrp regulatory cascade by blocking a critical step or mimicking plant or quorum sensing signals.
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Rosser, Katy, Iulia Gherman, Erica Kintz, Paul Cook, and Anthony WIlson. Assessment of the risk to consumers as a result of disruption to the cold chain during direct supply of Qurbani meat and offal. Food Standards Agency, 2022. http://dx.doi.org/10.46756/sci.fsa.nuc910.
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Qurbani is a religious practice that takes place during Eid al-Adha. Consumers practicing Qurbani typically wish to collect meat and red offal within a short time after slaughter, which means these products cannot complete normal chilling processes before leaving the slaughterhouse. This could permit greater growth of pathogens and has the potential to increase the risk of consumer illness. The FSA is working with industry and stakeholder groups to ensure that the risk to consumers under these conditions remains at an acceptable level. To help inform these discussions, the FSA commissioned this assessment to understand the difference in risk from allowing meat and offal to be provided to consumers without the normal chilling process. The microbiological team at the FSA have analysed scientific literature, expert opinion and business and consumer survey data to assess the effect of disrupting the cold chain on pathogens in Qurbani meat. The pathogens that were chosen for inclusion in this assessment are non-typhoidal Salmonella enterica, Shiga toxin-producing Escherichia coli, and Clostridium perfringens. Their growth characteristics and prevalence in beef, lamb and goat meat and offal are discussed. The assessment concluded that given the reported variation in the process, there were two important scenarios with distinct outcomes. In the typical scenario, which is the most likely outcome based on the collected data, there is no significant difference in risk to consumer health compared to normal chilling processes, and the risk level was established as Very Low (“very rare but cannot be excluded”). In a reasonably foreseeable worst-case scenario, Salmonella spp. and STEC levels may increase, presenting an increased risk to the consumer. This risk level was established as Low (“rare but does occur”). We also identified several areas where more evidence would be helpful, and as a result identified a High level of uncertainty in our conclusion.
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Dubcovsky, Jorge, Tzion Fahima, and Ann Blechl. Molecular characterization and deployment of the high-temperature adult plant stripe rust resistance gene Yr36 from wheat. United States Department of Agriculture, 2013. http://dx.doi.org/10.32747/2013.7699860.bard.
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Stripe rust, caused by Puccinia striiformis f. sp. tritici is one of the most destructive fungal diseases of wheat. Virulent races that appeared within the last decade caused drastic cuts in yields. The incorporation of genetic resistance against this pathogen is the most cost-effective and environmentally friendly solution to this problem. However, race specific seedling resistance genes provide only a temporary solution because fungal populations rapidly evolve to overcome this type of resistance. In contrast, high temperature adult plant (HTAP) resistance genes provide a broad spectrum resistance that is partial and more durable. The cloning of the first wheat HTAP stripe rust resistance gene Yr36 (Science 2009, 323:1357), funded by our previous (2007-2010) BARD grant, provided us for the first time with an entry point for understanding the mechanism of broad spectrum resistance. Two paralogous copies of this gene are tightly linked at the Yr36 locus (WKS1 and WKS2). The main objectives of the current study were to characterize the Yr36 (WKS) resistance mechanism and to identify and characterize alternative WKSgenes in wheat and wild relatives. We report here that the protein coded by Yr36, designated WKS1, that has a novel architecture with a functional kinase and a lipid binding START domain, is localized to chloroplast. Our results suggest that the presence of the START domain may affect the kinase activity. We have found that the WKS1 was over-expressed on leaf necrosis in wheat transgenic plants. When the isolated WKS1.1 splice variant transcript was transformed into susceptible wheat it conferred resistance to stripe rust, but the truncated variant WKS1.2 did not confer resistance. WKS1.1 and WKS1.2 showed different lipid binding profiling. WKS1.1 enters the chloroplast membrane, while WKS1.2 is only attached outside of the chloroplast membrane. The ascorbate peroxidase (APX) activity of the recombinant protein of TmtAPXwas found to be reduced by WKS1.1 protein in vitro. The WKS1.1 mature protein in the chloroplast is able to phosphorylate TmtAPXprotein in vivo. WKS1.1 induced cell death by suppressing APX activity and reducing the ability of the cell to detoxify reactive oxygen. The decrease of APX activity reduces the ability of the plant to detoxify the reactive H2O2 and is the possible mechanism underlying the accelerated cell death observed in the transgenic plants overexpressing WKS1.1 and in the regions surrounding a stripe rust infection in the wheat plants carrying the natural WKS1.1 gene. WKS2 is a nonfunctional paralog of WKS1 in wild emmer wheat, probably due to a retrotransposon insertion close to the alternative splicing site. In some other wild relatives of wheat, such as Aegilops comosa, there is only one copy of this gene, highly similar to WKS2, which is lucking the retrotransposon insertion. WKS2 gene present in wheat and WKS2-Ae from A. showed a different pattern of alternative splice variants, regardless of the presence of the retrotransposon insertion. Susceptible Bobwhite transformed with WKS2-Ae (without retrotansposon insertion in intron10), which derived from Aegilops comosaconferred resistance to stripe rust in wheat. The expression of WKS2-Ae in transgenic plants is up-regulated by temperature and pathogen infection. Combination of WKS1 and WKS2-Ae shows improved stripe rust resistance in WKS1×WKS2-Ae F1 hybrid plants. The obtained results show that WKS1 protein is accelerating programmed cell death observed in the regions surrounding a stripe rust infection in the wheat plants carrying the natural or transgenic WKS1 gene. Furthermore, characterization of the epistatic interactions of Yr36 and Yr18 demonstrated that these two genes have additive effects and can therefore be combined to increase partial resistance to this devastating pathogen of wheat. These achievements may have a broad impact on wheat breeding efforts attempting to protect wheat yields against one of the most devastating wheat pathogen.
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Citovsky, Vitaly, and Yedidya Gafni. Nuclear Import of the Tomato Yellow Curl Leaf Virus in Tomato Plants. United States Department of Agriculture, 1994. http://dx.doi.org/10.32747/1994.7568765.bard.
Full textAbstract:
Tomato yellow leaf curl geminivirus (TYLCV) is a major pathogen of cultivated tomato, causing up to 100% crop loss in many parts of the world. In Israel the disease is well known and has an economic significance. In recent years viral symptoms were found in countries of the "New World" and since 1997, in Florida. Surprisingly, little is known about the molecular mechanisms of TYLCV interaction with the host plant cells. This proposal was aimed at expanding our understanding of the molecular mechanisms by which TYLCV enters the host cell nucleus. The main objective was to elucidate the TYLCV protein(s) involved in transport of the viral genomic DNA into the host cell nucleus. This goal was best served by collaboration between our laboratories one of which (V.C.) was already investigating the nuclear import of the T-DNA ofAgrobacterium tumefaciens, and the other (Y.G.) was studying the effect of TYLCV capsid protein (CP) in transgenic plants, hypothesizing its involvement in the viral nuclear entry. Three years of our collaborative work have provided signifcant data that strongly support our original hypothesis of the involvement of TYLCtr CP in viral nuclear import. Furthermore, our results have laid a foundation to study fundamental, but as yet practically unresolved, questions about the role ofthe host cell factors in the nuclear import of geminiviruses within their host plant. As a result, this research may lead to development of new approaches for plant protection based on control of TYLCV import to the host plant cell nucleus.
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Wong, E. A., and Z. Uni. Modulating intestinal cellular maturation and differentiation in broilers by in ovo feeding. United States-Israel Binational Agricultural Research and Development Fund, 2018. http://dx.doi.org/10.32747/2018.8134161.bard.
Full textAbstract:
Mortality in a broiler flock will typically range from 4-5% of the population over the course of 6- 7 weeks in the U.S. and 7-8% of the population in Israel. Suboptimal intestinal maturation and functionality are one of the major factors that contribute to early age mortality and hinder flock body weight uniformity. The development of absorptive and secretory functions is orchestrated by differentiation of cells that arise from stem cells. Supplying compounds by in ovo feeding (IOF) during late embryogenesis provides nutrients that may change the dynamics of stem cell differentiation. We hypothesize that the introduction of specific nutrients or probiotics to the late embryonic chick via IOF will result in an acceleration of the maturation of the small intestine as measured by villus/crypt morphology and the number and distribution of absorptive and secretory cells. A chick that can absorb nutrients more efficiently by increasing the number of cells expressing nutrient transporters and resist enteric pathogens by increasing the number of cells expressing mucin and host defense peptides will be healthier at hatch. This chick may have less need for antibiotics and may show reduced early mortality. The objectives of this proposal are to: 1) develop a model for the development of putative stem cells and absorptive/secretory cells in the small intestine of the late embryonic and early post hatch broiler. 2) determine the ability of IOF of nutrients to modulate the population of differentiated cells in the intestine. 3) determine the ability of IOF of probiotics to modulate the population of differentiated cells in the intestine. 4) reduce early mortality and increase body weight uniformity by IOF of selected nutrients or probiotics. This proposal combines the IOF expertise of Zehava Uni (Hebrew University) with the RNAscope in situ hybridization technique of Eric Wong (Virginia Tech). Previous studies using quantitative PCR to examine expression of genes in the intestine were unable to identify specific cells expressing these genes. RNAscope allows the ability to identify putative stem, absorptive and secretory cells in the small intestine. Thus, we will be able to investigate the effect of IOF on the presence of intestinal absorptive and secretory cells at the cellular level. Understanding the mechanisms for intestinal development and function are key to maintaining peak growth and health of chickens and thus would be of great economic benefit to the poultry industry.