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Articles de revues sur le sujet "Sub-Inhibitory concentrations of antibiotics"
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Mojsoska, Biljana, Melanie Ghoul, Gabriel G. Perron, Håvard Jenssen et Fatima AlZahra’a Alatraktchi. « Changes in toxin production of environmental Pseudomonas aeruginosa isolates exposed to sub-inhibitory concentrations of three common antibiotics ». PLOS ONE 16, no 3 (4 mars 2021) : e0248014. http://dx.doi.org/10.1371/journal.pone.0248014.
Texte intégralRésumé :
Pseudomonas aeruginosa is an environmental pathogen that can cause severe infections in immunocompromised patients. P. aeruginosa infections are typically treated with multiple antibiotics including tobramycin, ciprofloxacin, and meropenem. However, antibiotics do not always entirely clear the bacteria from the infection site, where they may remain virulent. This is because the effective antibiotic concentration and diffusion in vitro may differ from the in vivo environment in patients. Therefore, it is important to understand the effect of non-lethal sub-inhibitory antibiotic concentrations on bacterial phenotype. Here, we investigate if sub-inhibitory antimicrobial concentrations cause alterations in bacterial virulence factor production using pyocyanin as a model toxin. We tested this using the aforementioned antibiotics on 10 environmental P. aeruginosa strains. Using on-the-spot electrochemical screening, we were able to directly quantify changes in production of pyocyanin in a measurement time of 17 seconds. Upon selecting 3 representative strains to further test the effects of sub-minimum inhibitory concentration (MICs), we found that pyocyanin production changed significantly when the bacteria were exposed to 10-fold MIC of the 3 antibiotics tested, and this was strain specific. A series of biologically relevant measured pyocyanin concentrations were also used to assess the effects of increased virulence on a culture of epithelial cells. We found a decreased viability of the epithelial cells when incubated with biologically relevant pyocyanin concentrations. This suggests that the antibiotic-induced virulence also is a value worth being enclosed in regular testing of pathogens.
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Jamal, W., B. I. Duerden et V. O. Rotimi. « The influence of exposure to various concentrations of five antimicrobial agents on intracellular cytotoxin B production in <i>Clostridioides difficile</i> ; ». African Journal of Clinical and Experimental Microbiology 24, no 3 (19 juillet 2023) : 266–73. http://dx.doi.org/10.4314/ajcem.v24i3.6.
Texte intégralRésumé :
Background: Clostridioides difficile is an important cause of healthcare-associated diarrhea. Several anti- microbial agents are known to promote C. difficile infection (CDI). The impact of various concentrations of ampicillin (AMP), cefotaxime (CTX), clindamycin (CC), metronidazole (MTZ) and vancomycin (VAN) on intra-cellular cytotoxin B production was investigated in this study.
Methodology: Six clinical strains of C. difficile were grown at minimum inhibitory concentration (MIC) and sub-MIC concentrations of these antibiotics. Inoculum standardization was performed by Miles and Misra method. Intracellular toxin B production was detected using Vero cell cytotoxicity assay in sonicated cultures on days 1, 2, 3, 4, 5 and 7 days of incubation.
Results: There was a heterogeneous relationship between antibiotic exposure and the intra-cellular toxin production by the toxigenic strains. Clinical strains of C. difficile when exposed to MIC and sub-inhibitory concentrations of certain antibiotics produced high cytotoxin levels. All toxigenic isolates produced increased levels of cell-bound cytotoxin after exposure to antibiotics but there was no consistent pattern and the response to different doses varied considerably. Metronidazole was the most potent inducer of cell-bound cytotoxin followed by cefotaxime and clindamycin. Vancomycin induced the least amount of cytotoxin activity.
Conclusion: The effects of sub-inhibitory concentration of antibiotic that predispose to C. difficile infection may partially suppress the normal gut flora, allowing colonization and growth of C. difficile, and may affect the level of toxin produced.
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Casciaro, Bruno, Floriana Cappiello, Walter Verrusio, Mauro Cacciafesta et Maria Luisa Mangoni. « Antimicrobial Peptides and their Multiple Effects at Sub-Inhibitory Concentrations ». Current Topics in Medicinal Chemistry 20, no 14 (11 juin 2020) : 1264–73. http://dx.doi.org/10.2174/1568026620666200427090912.
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The frequent occurrence of multidrug-resistant strains to conventional antimicrobials has led to a clear decline in antibiotic therapies. Therefore, new molecules with different mechanisms of action are extremely necessary. Due to their unique properties, antimicrobial peptides (AMPs) represent a valid alternative to conventional antibiotics and many of them have been characterized for their activity and cytotoxicity. However, the effects that these peptides cause at concentrations below the minimum growth inhibitory concentration (MIC) have yet to be fully analyzed along with the underlying molecular mechanism. In this mini-review, the ability of AMPs to synergize with different antibiotic classes or different natural compounds is examined. Furthermore, data on microbial resistance induction are reported to highlight the importance of antibiotic resistance in the fight against infections. Finally, the effects that sub-MIC levels of AMPs can have on the bacterial pathogenicity are summarized while showing how signaling pathways can be valid therapeutic targets for the treatment of infectious diseases. All these aspects support the high potential of AMPs as lead compounds for the development of new drugs with antibacterial and immunomodulatory activities.
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Browne, Katrina, Rajesh Kuppusamy, William R. Walsh, David StC Black, Mark D. P. Willcox, Naresh Kumar et Renxun Chen. « Antimicrobial Peptidomimetics Prevent the Development of Resistance against Gentamicin and Ciprofloxacin in Staphylococcus and Pseudomonas Bacteria ». International Journal of Molecular Sciences 24, no 19 (6 octobre 2023) : 14966. http://dx.doi.org/10.3390/ijms241914966.
Texte intégralRésumé :
Bacteria readily acquire resistance to traditional antibiotics, resulting in pan-resistant strains with no available treatment. Antimicrobial resistance is a global challenge and without the development of effective antimicrobials, the foundation of modern medicine is at risk. Combination therapies such as antibiotic–antibiotic and antibiotic–adjuvant combinations are strategies used to combat antibiotic resistance. Current research focuses on antimicrobial peptidomimetics as adjuvant compounds, due to their promising activity against antibiotic-resistant bacteria. Here, for the first time we demonstrate that antibiotic–peptidomimetic combinations mitigate the development of antibiotic resistance in Staphylococcus aureus and Pseudomonas aeruginosa. When ciprofloxacin and gentamicin were passaged individually at sub-inhibitory concentrations for 10 days, the minimum inhibitory concentrations (MICs) increased up to 32-fold and 128-fold for S. aureus and P. aeruginosa, respectively. In contrast, when antibiotics were passaged in combination with peptidomimetics (Melimine, Mel4, RK758), the MICs of both antibiotics and peptidomimetics remained constant, indicating these combinations were able to mitigate the development of antibiotic-resistance. Furthermore, antibiotic–peptidomimetic combinations demonstrated synergistic activity against both Gram-positive and Gram-negative bacteria, reducing the concentration needed for bactericidal activity. This has significant potential clinical applications—including preventing the spread of antibiotic-resistant strains in hospitals and communities, reviving ineffective antibiotics, and lowering the toxicity of antimicrobial chemotherapy.
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Nanduri, Bindu, Mark L. Lawrence, Divya Swetha Peddinti et Shane C. Burgess. « Effects of Subminimum Inhibitory Concentrations of Antibiotics on thePasteurella multocidaProteome : A Systems Approach ». Comparative and Functional Genomics 2008 (2008) : 1–12. http://dx.doi.org/10.1155/2008/254836.
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To identify key regulators of subminimum inhibitory concentration (sub-MIC) antibiotic response in thePasteurella multocidaproteome, we applied systems approaches. Using 2D-LC-ESI-MS2, we achieved 53% proteome coverage. To study the differential protein expression in response to sub-MIC antibiotics in the context of protein interaction networks, we inferredP. multocidaPm70 protein interaction network from orthologous proteins. We then overlaid the differential protein expression data onto theP. multocidaprotein interaction network to study the bacterial response. We identified proteins that could enhance antimicrobial activity. Overall compensatory response to antibiotics was characterized by altered expression of proteins involved in purine metabolism, stress response, and cell envelope permeability.
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Portela, Raquel, Filipe Valcovo, Pedro L. Almeida, Rita G. Sobral et Catarina R. Leal. « Antibiotic Activity Screened by the Rheology of S. aureus Cultures ». Fluids 5, no 2 (18 mai 2020) : 76. http://dx.doi.org/10.3390/fluids5020076.
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Multidrug resistant bacteria are one of the most serious public health threats nowadays. How bacteria, as a population, react to the presence of antibiotics is of major importance to the outcome of the chosen treatment. In this study we addressed the impact of oxacillin, a β-lactam, the most clinically relevant class of antibiotics, in the viscosity profile of the methicillin resistant Staphylococcus aureus (MRSA) strain COL. In the first approach, the antibiotic was added, at concentrations under the minimum inhibitory concentration (sub-MIC), to the culture of S. aureus and steady-state shear flow curves were obtained for discrete time points during the bacterial growth, with and without the presence of the antibiotic, showing distinct viscosity progress over time. The different behaviors obtained led us to test the impact of the sub-inhibitory concentration and a concentration that inhibited growth. In the second approach, the viscosity growth curves were measured at a constant shear rate of 10 s−1, over time. The obtained rheological behaviors revealed distinctive characteristics associated to the presence of each concentration of the tested antibiotic. These results bring new insights to the bacteria response to a well-known bacteriolytic antibiotic.
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Trancassini, M., M. I. Brenciaglia, M. C. Ghezzi, P. Cipriani et F. Filadoro. « Modification ofPseudomonas aeruginosaVirulence Factors by Sub-Inhibitory Concentrations of Antibiotics ». Journal of Chemotherapy 4, no 2 (avril 1992) : 78–81. http://dx.doi.org/10.1080/1120009x.1992.11739144.
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Chee, Jessica. « Identifying genes associated with biofilm production in Pseudomonas aeruginosa ». Meducator 1, no 33 (19 juin 2018) : 19–22. http://dx.doi.org/10.15173/m.v1i33.1796.
Texte intégralRésumé :
Pseudomonas aeruginosa is an opportunistic pathogen associated with a variety of life-threatening diseases. Infections caused by P. aeruginosa can be nearly untreatable because of its multidrug-resistance. One of the characteristics of P. aeruginosa that helps it survive in high drug concentrations is its ability to form biofilms–large communities of cells encompassed by extracellular polymeric substances that defend against many antibiotics. In fact, sub-minimum inhibitory concentrations of antibiotics stimulate biofilm production. This project aims to identify genes associated with biofilm induction in P. aeruginosa by screening a transposon mutant library for mutants that fail to show increased biofilm production when exposed to sub-minimum inhibitory concentrations of cefixime, tobramycin, and thiostrepton. So far, we have identified one gene, PA2714, that encodes a predicted molybdopterin oxidoreductase required for biofilm production. Because of the strong association between biofilm production and antibiotic tolerance in P. aeruginosa, the gene identified in this screen may be a useful therapeutic target for novel antimicrobialsthat can disrupt biofilm formation.
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Chow, Louise K. M., Timothy M. Ghaly et Michael R. Gillings. « A survey of sub-inhibitory concentrations of antibiotics in the environment ». Journal of Environmental Sciences 99 (janvier 2021) : 21–27. http://dx.doi.org/10.1016/j.jes.2020.05.030.
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György, Éva, Károly Arnold Unguran et Éva Laslo. « Biocide Tolerance and Impact of Sanitizer Concentrations on the Antibiotic Resistance of Bacteria Originating from Cheese ». Foods 12, no 21 (27 octobre 2023) : 3937. http://dx.doi.org/10.3390/foods12213937.
Texte intégralRésumé :
In this study, we determined and identified the bacterial diversity of different types of artisanal and industrially produced cheese. The antibiotic (erythromycin, chloramphenicol, kanamycin, ampicillin, clindamycin, streptomycin, tetracycline, and gentamicin) and biocide (peracetic acid, sodium hypochlorite, and benzalkonium chloride) resistance of clinically relevant bacteria was determined as follows: Staphylococcus aureus, Macrococcus caseolyticus, Bacillus sp., Kocuria varians, Escherichia coli, Enterococcus faecalis, Citrobacter freundii, Citrobacter pasteurii, Klebsiella oxytoca, Klebsiella michiganensis, Enterobacter sp., Enterobacter cloacae, Enterobacter sichuanensis, Raoultella ornithinolytica, Shigella flexneri, and Salmonella enterica. Also, the effect of the sub-inhibitory concentration of three biocides on antibiotic resistance was determined. The microbiota of evaluated dairy products comprise diverse and heterogeneous groups of bacteria with respect to antibiotic and disinfectant tolerance. The results indicated that resistance was common in the case of ampicillin, chloramphenicol, erythromycin, and streptomycin. Bacillus sp. SCSSZT2/3, Enterococcus faecalis SRGT/1, E. coli SAT/1, Raoultella ornithinolytica MTT/5, and S. aureus SIJ/2 showed resistance to most antibiotics. The tested bacteria showed sensitivity to peracetic acid and a different level of tolerance to benzalkonium chloride and sodium hypochlorite. The inhibition zone diameter of antibiotics against Enterococcus faecalis SZT/2, S. aureus JS11, E. coli CSKO2, and Kocuria varians GRT/10 was affected only by the sub-inhibitory concentration of peracetic acid.
Thèses sur le sujet "Sub-Inhibitory concentrations of antibiotics"
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Subrt, Natalia. « Effects of sub-inhibitory concentrations of cell wall active antibiotics on virulence gene expression in Staphylococcus aureus ». Thesis, University of British Columbia, 2009. http://hdl.handle.net/2429/17417.
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Infections caused by Staphylococcus aureus are a major concern to public health due to multifactorial virulence of the bacteria and increasing resistance to antimicrobial therapy. The bacterial cell wall continues to be the primary target for antibiotics used to treat staphylococcal infections. I have used promoter-lux reporter constructs to study the effects of sub-inhibitory concentrations of cell wall active antibiotics on virulence gene expression in S. aureus. Constructs made for virulence genes encoding Spa, an adhesin, RNAIII, a regulatory RNA molecule, and LukE, a leukotoxin E, were introduced into several strains of S. aureus. It was found that the effects of sub-inhibitory concentrations of antibiotics differed depending on the strain, and antibiotics affected the expression of virulence genes differently in the same strain. Based on the results with S. aureus strains lacking virulence regulators, SarA and SarS, it was concluded that sub-inhibitory concentrations of antibiotics modulate the expression of virulence regulators, which affects transcription of the downstream genes, spa and lukE. A speculative model for the mechanism of transcription modulation by antibiotics was proposed. The effect of sub-inhibitory concentrations of antibiotics on S. aureus biofilm formation was also studied. Finally, promoter-lux reporter constructs were used to investigate effects of various antibiotic combinations on gene expression in S. aureus.
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Masadeh, Majed. « Studies on the effects of sub-minimal inhibitory concentrations of antibiotics on the virulence factors of biofilm bacteria ». Thesis, Abertay University, 2005. https://rke.abertay.ac.uk/en/studentTheses/ee318b1c-d3f5-4357-8165-2bf1caed633d.
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Pseudomonas aeruginosa is a notorious nosocomial opportunist. Planktonic forms of this pathogen have been traditionally studied for its pathogenicity. Such studies have shown that sub-minimal inhibitory concentrations (sub-MICs) of antibiotics are able to negatively modulate pathogenicity. However, more recent findings suggest a biofilm basis of infection. In this study, monospecies and binary biofilms of Pseudomonas aeruginosa ATCC 15692 (PAOl) and Escherichia coli ATCC 10000 were investigated for their pathogenic potential using resistance and virulence as key pathogenic determinants, in the presence of sub-MICs of selected antibiotics (Ampicillin, Nalidixic acid and Streptomycin). MICs of biofilms were observed to be at least 7-fold greater than those of the corresponding planktonic form of the same species (as judged from results obtained from MIC experiments). SDS-PAGE and 2D-PAGE analysis indicate alteration of outer membrane proteins (OMPs) within the envelope of the pathogen in sub-MIC antibiotic treated samples. The observed rearrangement of lipopolysaccharide (LPS; as observed in LPS gel experiments) may also contribute to the pathogens increased tolerance to antibiotics within the biofilm state. While LPS changes may possibly help the biofilm bacteria escape host immune system in vivo, more direct evidence of increases in virulence of the pathogen comes from investigation of its secreted proteases and cytotoxins (leucocidin). Virulence-specific azocasein and micro-culture tetrazolium (MTT) assays against both monospecies and binary biofilms of Pseudomonas aeruginosa indicate significant increases in virulence potential of proteases and cytotoxins, respectively. These results were further substantiated in phase contrast microscopy images showing advanced stages of oncosis in tissue cultured mouse spleen myeloma (Sp2) cells treated with leucocidin isolated from Ps. aeruginosa treated with sub-MIC of ampicillin (8 pg mL'1). The results reported in this thesis provide evidence of observed increases in virulence and pathogenicity in biofilm cells of Pseudomonas aeruginosa in the presence of sub-MICs of selected antibiotics, in vitro. Although these findings are those of in vitro experiments, they may have significant implications regarding the usage and therapeutic control of antibiotics in clinical situations.
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Paul, Terry R. « Influence of iron deprivation and sub-inhibitory concentrations of antifungal antibiotics on surface antigens of candida albicans yeast cells ». Thesis, Aston University, 1988. http://publications.aston.ac.uk/12520/.
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This study examined the effect of iron deprivation and sub-inhibitory concentrations of antifungal agents on yeast cell surface antigen recognition by antibodies from patients with Candida infections. Separation of cell wall surface proteins by sodium dodecyl-polyacrylamide gel electrophoresis (SDS-PAGE) and immunological detection by immunoblotting, revealed that antigenic profiles of yeasts were profoundly influenced by the growth environment. Cells grown under iron-depleted conditions expressed several iron-regulated proteins that were recognized by antibodies from patient sera. An attempt to characterize these proteins by lectin blotting with concanavalin A revealed that some could be glycoprotein in nature. Furthermore, these proteins which were located within cell walls and on yeast surfaces, were barely or not expressed in yeasts cultivated under iron-sufficient conditions. The magnitude and heterogeneity of human antibody responses to these iron-regulated proteins were dependent on the type of Candida infection, serum antibody class and yeast strain. Hydroxamate-type siderophores were also detected in supernatants of iron depleted yeast cultures. This evidence suggests that Candida albicans expresses iron-regulated proteins/glycoproteins in vitro which may play a role in siderophore-mediated iron uptake in Candida albicans. Sequential monitoring of IgG antibodies directed against yeast surface antigens during immunization of rabbits revealed that different antigens were recognized particularly during early and later stages of immunization in iron-depleted cells compared to iron-sufficient cells. In vitro and in vivo adherence studies demonstrated that growth phase, yeast strain and growth conditions affect adhesion mechanisms. In particular, growth under iron-depletion in the presence of sub-inhibitory concentrations of polyene and azole antifungals enhanced the hydrophobicity of C.albicans. Growth conditions also influenced MICs of antifungals, notably that of ketoconazole. Sub-inhibitory concentrations of amphotericin B and fluconazole had little effect on surface antigens, whereas nystatin induced profound changes in surface antigens of yeast cells. The effects of such drug concentrations on yeast cells coupled with host defence mechanisms may have a significant affect on the course of Candida infections.
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Maniveau, Morgane. « Dissémination et évolution des intégrons de résistance : impact du mode de vie bactérien et du stress antibiotique ». Electronic Thesis or Diss., Limoges, 2024. http://www.theses.fr/2024LIMO0118.
Texte intégralRésumé :
Les intégrons de résistance (IR) de classe 1 sont des éléments génétiques bactériens qui permettent l’acquisition et l’expression de gènes de résistance aux antibiotiques. Cette étude examine comment la présence d'un IR chromosomique et le mode de vie bactérien, planctonique ou biofilm, affectent l'évolution des populations bactériennes exposées à des concentrations sub-inhibitrices d'antibiotiques. Pour ce faire, deux IRs synthétiques contenant trois cassettes de gènes, exprimées à partir des variants faible (PcW) ou fort (PcS), ont été intégrés dans la souche de E. coli, R3A. Les souches R3A (sans IR), R3Aw et R3As (avec IR) ont été cultivées en conditions planctonique et biofilm, avec ou sans antibiotiques, sur 15 transferts. Les résultats montrent qu'après 15 passages, l’évolution des 3 souches en planctonique en présence de Tobramycine (Tob) supplémentée ou non de Ciprofloxacine (Cip), a induit une augmentation de la résistance à la Tob. De même, la formation du biofilm a augmenté, pour toutes les populations évoluées (PE) en planctonique, et pour les populations R3As en biofilm. La caractérisation génomique des PE en biofilm, n’a montré aucune mutation fixée chez R3Aw, et une seule (gène srkA) chez R3A exposée à la Tob. Pour les PE en planctonique, une mutation a été fixée chez R3A propagée en Tob +/- Cip (fusA) et une chez R3A évoluée sans Tob (rpoC). Pour R3Aw, toutes les PE en Tob +/- Cip présentaient des mutations identiques dans 5 gènes dont intI1. Dans celui-ci, la présence de deux mutations a permis l'évolution du promoteur PcW vers PcS. La caractérisation génomique des populations R3As est encore en cours. Cette étude met ainsi en lumière des trajectoires évolutives distinctes des populations bactériennes selon la présence d’IR, l'exposition aux antibiotiques et leur mode de vieClass 1 resistance integrons (RI) are bacterial genetic elements that enable the acquisition andexpression of antibiotic resistance genes. This study examines how the presence of a chromosomal RI and the bacterial planktonic or biofilm lifestyle affect the evolution of bacterial populations exposedto sub-inhibitory concentrations of antibiotics. To this end, two synthetic RI containing three genecassettes, expressed from weak (PcW) or strong (PcS) variants, were integrated into the E. coli R3Astrain. Strains R3A (without RE), R3Aw and R3As (with RI) were grown under planktonic and biofilmconditions, with or without antibiotics, over 15 transfers. The results show that after 15 passages, theevolution of the 3 strains in planktonic conditions in the presence of Tobramycin (Tob) supplementedor not with Ciprofloxacin (Cip) induced an increase in resistance to Tob. Similarly, biofilm formationincreased for all evolved population (EP) in planktonic, and for R3As biofilm populations. Genomiccharacterization of EP in biofilm showed no fixed mutations in R3Aw, and only one (srkA gene) in Tobexposed R3A. For planktonic EP, one mutation was fixed in R3A propagated in Tob +/- Cip (fusA) and one in R3A evolved without Tob (rpoC). For R3Aw, all Tob +/- Cip EP had identical mutations in 5 genes, including intI1. In the latter, the presence of two mutations led to the evolution of the PcW promoter towards PcS. Genomic characterization of the R3As populations is still in progress. This study highlights distinct evolutionary trajectories of bacterial populations according to the presence of RI, antibiotic exposure and lifestyle
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Fermér, Elin. « Selection for Antibiotic Resistance Below Minimal inhibitory concentration in Biofilm ». Thesis, Uppsala universitet, Institutionen för biologisk grundutbildning, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-409806.
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Antibiotics are today one of the most important cornerstones in modern healthcare when it comes to treating bacterial infections. It is an asset human kind have been leaning on for the last century, but excessive and widespread misuse of antibiotics have left deep scars in the form of multi resistant pathogenic strains of bacteria that we soon will not be able to treat. A lot of research have been invested in understanding the mechanisms and spread of resistance within bacteria living in planktonic form, overlooking the fact that there are more lifestyles that causes problems. In this study, focus has been put on antibiotic resistance within bacteria living as biofilms, a lifestyle that causes problems in chronic infections and prosthetics/medical implants. By constructing resistant mutants derived from a biofilm forming strain of Escherichia coli, the minimal selection concentration has been investigated in both planktonic and biofilm assays for Streptomycin and Ciprofloxacin. By comparing the results, it is possible to evaluate if and how the antibiotic resistance properties differ between the two lifestyles. Focus has been put on concentrations of antibiotics below the minimal inhibitory concentration with the objective to see how selection of antibiotic resistant mutants take place with the susceptible strain still growing, although with reduced growth rate. The hope is that the results gained in this study will provide a foundation for future research regarding antibiotic resistance in biofilms, and be part of the solution to the excessive resistance problem before it is too late.
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Doroshenko, Natalya. « The biofilm matrix at sub-inhibitory concentrations of vancomycin ». Thesis, University of Southampton, 2014. https://eprints.soton.ac.uk/366538/.
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Staphylococcus epidermidis biofilm formation is a primary cause of medical device infections, which are persistent and difficult to eradicate because biofilms intrinsically exhibit a naturally high level of antibiotic resistance. Although biofilm antibiotic resistance or tolerance is a multifactorial process, some mechanisms such as limited diffusion, low metabolic activity and persister cells, contribute to the failure of antibiotics in the treatment of biofilm infections. Current, antibiotic treatment strategies may provide biofilm infections with intermittent exposure to sub-minimum inhibitory concentrations (sub-MIC) of antibiotics. Biofilms have been shown to display an increase in antibiotic tolerance when exposed to antibiotics at sub-MIC. Such mechanisms of adaptive antibiotic resistance are not well characterized but are of extreme clinical importance. This project showed that exposure to sub-MIC vancomycin increases the virulence of S. epidermidis biofilms because it induces vancomycin tolerance. BODIPY FL-vancomycin (fluorescent vancomycin conjugate) and confocal microscopy were used to show that the penetration of vancomycin through sub-MIC vancomycin pre-treated S. epidermidis biofilms was impeded, when compared to control, untreated biofilms. In addition, the results showed that a wide range of sub-MIC vancomycin concentrations induced an increased amount of extracellular DNA (eDNA) within the matrix of sub-MIC vancomycin treated biofilms. Finally, a set of ex vivo experiments using extracted exogenous S. epidermidis DNA revealed that exogenous S. epidermidis DNA binds vancomycin. Collectively these findings suggest that sub-MIC vancomycin exposure increase the abundance of eDNA in the matrix of S. epidermidis biofilms, which protects the biofilm community from subsequent vancomycin exposure by binding vancomycin as it travels through the matrix. Therefore the work in this project provides details of an eDNA-based mechanism of adaptive antibiotic tolerance in sub-MIC vancomycin treated S. epidermidis biofilms, which might be an important factor in the persistence of biofilms infections.
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Gullberg, Erik. « Selection of Resistance at very low Antibiotic Concentrations ». Doctoral thesis, Uppsala universitet, Institutionen för medicinsk biokemi och mikrobiologi, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-235225.
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The extensive medical and agricultural use and misuse of antibiotics during the last 70 years has caused an enrichment of resistant pathogenic bacteria that now severely threatens our capacity to efficiently treat bacterial infections. While is has been known for a long time that high concentrations of antibiotics can select for resistant mutants, less is known about the lower limit at which antibiotics can be selective and enrich for resistant bacteria. In this thesis we investigated the role of low concentrations of antibiotics and heavy metals in the enrichment and evolution of antibiotic resistance. Selection was studied using Escherichia coli and Salmonella enterica serovar Typhimurium LT2 with different resistance mutations, different chromosomal resistance genes as well as large conjugative multidrug resistance plasmids. Using very sensitive competition experiments, we showed that antibiotic and heavy metal levels more than several hundred-fold below the minimal inhibitory concentration of susceptible bacteria can enrich for resistant bacteria. Additionally, we demonstrated that subinhibitory levels of antibiotics can select for de novo resistant mutants, and that these conditions can select for a new spectrum of low-cost resistance mutations. The combinatorial effects of antibiotics and heavy metals can cause an enrichment of a multidrug resistance plasmid, even if the concentration of each compound individually is not high enough to cause selection. These results indicate that environments contaminated with low levels of antibiotics and heavy metals such as, for example, sewage water or soil fertilized with sludge or manure, could provide a setting for selection, enrichment and transfer of antibiotic resistance genes. This selection could be a critical step in the transfer of resistance genes from environmental bacteria to human pathogens.
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Abu-Elteen, Khalid Hussein. « Effect of sub-inhibitory concentrations of antifungal drugs on adherence of Candida species ». Thesis, Loughborough University, 1991. https://dspace.lboro.ac.uk/2134/33210.
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The adherence of three Candida species to human buccal epithelial cells (BECs) following treatment of the yeast with sub-inhibitory concentrations of amphotericin B, nystatin, miconazole nitrate, 5-fluorocytosine, octenidine and pirtenidine was investigated in vitro. Pre-incubation of C. albicans (two strains), C. tropicalis or C.kefyr with these antifungal drugs inhibited their adherence to varying degrees (reduction between 17% and 78% of the control value). Pre-treatment of yeast for a short period (l hr) had less effect on adhesion than pre-treatment for a long period (24 hr). Furthermore, treating C. albicans with a combination of amphotericin B plus 5-fluorocytosine, both at 1/8 MIC level, led to stronger adherence inhibition than that obtained for yeast pre-treated with either one alone at 1/4 MIC levels. In addition, the pre-treatment of either Candida or BECs or both types of cells with the drugs reduced adherence, the reduction being greatest when both types of cells were pre-treated. No difference in adherence between stationary or exponential phase yeast to BEC was observed and the drugs were effective in reducing the adherence of cells from either growth phase.
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Younson, Justine Sarah. « The paradoxic effects of sub-inhibitory concentrations of ciprofloxacin on pathogenic determinants in coagulase-negative staphylococci ». Thesis, King's College London (University of London), 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.286761.
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Kadurugamuwa, Jagath L. « Influence of sub-inhibitory concentrations of cephalosporins on surface properties of klebsiella pneumoniae important in infection ». Thesis, Aston University, 1985. http://publications.aston.ac.uk/12489/.
Texte intégralLivres sur le sujet "Sub-Inhibitory concentrations of antibiotics"
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Kadurugamuwa, Jagath L. Influence of sub-inhibitory concentrations of cephalosporins on surface properties of klebsiella pneumoniae important in infection. Birmingham : University of Aston. Department of Pharmaceutical Sciences, 1985.
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Domingue, Pierre Alain Gilbert. Influence of sub-inhibitory concentrations of penicillin G on surface properties of iron-deprived staphylococcus aureus NCTC 6571. Birmingham : Aston University. Department of Pharmaceutical Sciences, 1986.
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Abu-Elteen, Khalid Hussein Ahmad. Effect of sub-inhibitory concentrations of antifungal drugs on adherence of Candida species. 1991.
Trouver le texte intégralChapitres de livres sur le sujet "Sub-Inhibitory concentrations of antibiotics"
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Gillissen, G., et B. Melzer. « Influence of Subminimal Inhibitory Concentrations of Antibiotics on Antigen Expression and Metabolic Activity of Salmonella Species ». Dans The Influence of Antibiotics on the Host-Parasite Relationship II, 84–95. Berlin, Heidelberg : Springer Berlin Heidelberg, 1985. http://dx.doi.org/10.1007/978-3-642-70748-3_9.
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Domingue, P. A. G., E. Schwarzinger et M. R. W. Brown. « Growth Rate, Iron Depletion, and a Sub-Minimal Inhibitory Concentration of Penicillin G Affect the Surface Hydrophobicity of Staphylococcus aureus ». Dans The Influence of Antibiotics on the Host-Parasite Relationship III, 50–62. Berlin, Heidelberg : Springer Berlin Heidelberg, 1989. http://dx.doi.org/10.1007/978-3-642-73653-7_7.
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Srivastava, Anmol, Vivek Kumar et Vishnu Agarwal. « Antimicrobial Activity of Some Essential Oils Against Pseudomonas aeruginosa ». Dans Proceedings of the Conference BioSangam 2022 : Emerging Trends in Biotechnology (BIOSANGAM 2022), 27–34. Dordrecht : Atlantis Press International BV, 2022. http://dx.doi.org/10.2991/978-94-6463-020-6_4.
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AbstractThe emergence of multidrug resistance in bacteria due to overuse of antibiotics is becoming an important health concern in recent years, which requires development of novel alternatives to fight against these bacteria. Essential oils (EOs) are secondary metabolites that have different components and chemical compositions which may provide promising solution to the problem of rising number of drug resistant bacteria, as they can effectively kill bacteria. Here, in this study our aim is to determine the efficacy of lemongrass, rosemary, clary sage, geranium and tea tree essential oil against Pseudomonas aeruginosa, using agar well diffusion method. The minimum inhibitory concentration (MIC) of these EOs were also determined. The chemical composition of these essential oils were known by gas chromatography-mass spectrometry (GC-MS) analysis. It was revealed in this study that most of the essential oils show antimicrobial property against the test bacterium. The MIC of lemongrass is 0.25% (v/v), rosemary is 1% (v/v), clary sage is 2% (v/v), geranium is 0.5% (v/v) and for tea tree oil is 1% (v/v). We can infer from this data that lemongrass, rosemary, clary sage, geranium and tree oil can be utilized to treat infections caused by Pseudomonas aeruginosa, which is a gram-negative bacterium.
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Busetto, Gian Maria, Ramadan Saleh, Murat Gül et Ashok Agarwal. « Therapy in Oligozoospermia (Varicocele, Cryptorchidism, Inflammation, and Seminal Tract Infections) ». Dans Practical Clinical Andrology, 185–98. Cham : Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-11701-5_14.
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AbstractThe management of infertile men with varicocele is highly debated. Varicocele repair (VR) can be either surgical (varicolectomy) or through angiographic embolization. Surgical repair of varicocele includes open non-microsurgical techniques whether inguinal (Ivanissevich) or high retroperitoneal ligation (Palomo), open microsurgical techniques (inguinal or sub-inguinal) or laparoscopic. The accumulating evidence suggests that VR can improve conventional sperm parameters (sperm concentration, motility, and morphology), seminal oxidative stress, sperm DNA fragmentation, and serum testosterone concentrations.Treatment of cryptorchism is based on surgical correction. The surgical approach for palpable undescended testis is inguinal orchidopexy with eventual repair of concomitant hernia. Scrotal surgical approach is a viable alternative. For nonpalpable undescended testis, surgical approach can be open or laparoscopic, in one or two stages and possibly with spermatic vessel transection. In some cases, orchiectomy is required (testis abdominal localization, impossibility of mobilization or high neoplastic risk).Male accessory gland infections, including infection and/or inflammation of accessory glands (prostate, seminal vesicles, and Cowper’s glands), and male genital tract infections are characterized by the presence of an elevated number of leukocytes and/or pathogens in semen, together with inflammatory signs. Management is based on different antibiotic therapies.
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Gant, Vanya. « Pharmacology of Anti-infective Drugs in Critical Illness ». Dans Oxford Textbook of Respiratory Critical Care, 377–82. Oxford University PressOxford, 2023. http://dx.doi.org/10.1093/med/9780198766438.003.0040.
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Abstract Summary The disturbed physiology of critical illness considerably impacts blood and tissue concentrations of antimicrobials. In addition, the antimicrobials themselves vary enormously in chemical structure (and therefore charge, solubility, hydrophilicity, etc.), adding yet more complexity to effective and correct calculation of appropriate dose and interval timing. Examples here include on the one hand increased concentrations of hydrophilic beta-lactam antibiotics secondary to poor renal function and/or acute kidney injury, and on the other decreased antibiotic concentrations from increased volumes of distribution, decreased protein binding, and (sometimes artificially augmented by filtration or haemodialysis) renal clearance. Lipophilic antibiotics such as macrolides are less affected by physiological changes—although issues such as obesity influence dosing for optimal outcomes. Some antibiotics also have a narrow efficacy range and therapeutic index. Accordingly, aminoglycosides work best when used in high, once-daily dosing strategies with mandatory therapeutic drug monitoring. On the other hand, beta-lactam antimicrobials often have very short half-lives and are either bactericidal or entirely ineffective when only just below therapeutic concentrations. With such drugs, the most important pharmacodynamic parameter is therefore a ‘time above minimal inhibitory concentration’ optimized with shorter administration regimens, extended or even continuous infusions. None of these considerations should absolve treating physicians from deciding whether individual cases of infection are not better treated by removing the source of infection, as antibiotics alone cannot be expected to deal with large, undrained infected collections for instance.
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Correa, Gabriel Veloso, José Felipe Leite Ferreira Rosa, Stephanie Priscila de Sousa Cezário, Laura Faria Araujo, Ludmilla Louise Cerqueira Maia Prates, Sérgio Avelino Mota Nobre et Luiz Frederico Motta. « TOXICOLOGICAL EVALUATION AND IN SILICO PHARMACOKINETICS OF CEFTIOFUR IN HUMAN AND ENVIRONMENTAL HEALTH ». Dans Science and Connections : The Interdependence of Disciplines. Seven Editora, 2024. https://doi.org/10.56238/sevened2024.037-107.
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Ceftiofur is a broad-spectrum cephalosporin, effective against Gram-positive and Gram-negative pathogens. This antibiotic works by inhibiting the synthesis of the bacterial cell wall. Antibiotics, used in both human and veterinary medicine, are drugs of concern when found in the environment. This is due to the fact that, even at low concentrations, prolonged exposure to these residues can lead to the emergence of resistant bacteria, compromising human health and environmental balance. Direct or indirect contact, whether through the food chain, water resources or animal excreta, represent the main routes of contamination. In the present study, in silico methodologies were employed to predict the molecular properties of the antibiotic Ceftiofur. The in silico environmental toxicology study showed that Ceftiofur is not toxic to bees, but is toxic to fish and crustaceans, and its chemical structure does not degrade in the environment. ADME in silico analysis indicated that the antibiotic does not present a favorable prediction for oral bioavailability, due to violations of the Lipinski criteria and has a moderate intestinal absorption rate and absence of permeability across the blood-brain barrier. In addition, the in silico pharmacokinetic study revealed that Ceftiofur has no inhibitory capacity on any of the five hepatic isoenzymes of cytochrome P450 complex (CYP450). The human in silico toxicology study showed promising results, demonstrating that the antibiotic is non-toxic (non-mutagenic) in the AMES test, has no carcinogenic properties, and is classified in category IV for acute oral toxicity, indicating low toxicity.
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Das, Pranjal P., Simons Dhara et Mihir K. Purkait. « The Anaerobic Ammonium Oxidation Process : Inhibition, Challenges and Opportunities ». Dans Ammonia Oxidizing Bacteria, 56–82. Royal Society of Chemistry, 2023. http://dx.doi.org/10.1039/bk9781837671960-00056.
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The anaerobic ammonium oxidation (anammox) process has been recognized as an efficient nitrogen removal technology. Anammox processes are gaining attention owing to their advantages over the conventional biological nitrogen removal processes. Anammox bacteria are susceptible to various wastewater pollutants, which limits the extensive application of the anammox process worldwide. In general, low-concentration pollutants lead to the promotion of the anammox activity, while high-concentration pollutants show inhibitory effects. Moreover, mainstream anammox processes face a variety of challenges that limit their stable operation, such as difficulty in the out-selection of nitrite-oxidizing bacteria, high organic carbon to nitrogen (C/N) ratio, retention of anammox bacteria, and the influence of high concentrations of ammonia and nitrite compounds. Efficient strategies are necessary to manage high carbon to nitrogen ratios, improve performance in low-intensity wastewater, and retain anammox bacteria. This chapter systemically summarizes the recent advances in the inhibition, mechanism involved and recovery process of conventional and emerging pollutants in the anammox process, such as organics, metals, antibiotics and nanoparticles. The key elements in the operation, and maintenance of mainstream anammox processes in full-scale wastewater treatment plants have also been demonstrated. Moreover, for improving the process performance, the primary influencing factors affecting the anammox process have been identified and discussed in this chapter. Taken together, this chapter effectively illustrates the critical perspective on the challenges and opportunities associated with mainstream anammox processes, which will provide an in-depth understanding for researchers and engineers working in this field.
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Gălăţanu, Mona Luciana, Mariana Panţuroiu, Mariana Popescu et Carmen Marinela Mihăilescu. « Plant Extracts With Antibiotic Effect ». Dans Handbook of Research on Advanced Phytochemicals and Plant-Based Drug Discovery, 49–72. IGI Global, 2022. http://dx.doi.org/10.4018/978-1-6684-5129-8.ch004.
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This chapter tries to describe the most important plant extracts and their bioactive compounds which determine the antibiotic activity. Pharmacological assays performed for each plant extract are presented, including the minimum inhibitory concentration (MIC) as the most used experimental method to determine antimicrobial activity. Also, the effective associations between classic antibiotics and plant extracts with antibacterial are presented. The mechanisms of action are deeply explained to the extent that they are known and discovered by in vitro and in vivo studies. Plant-derived compounds have different mechanism of action as antibiotics. They can have other target sites than traditional antimicrobials and subsequently having different mechanisms of action against microbes. Ultimately, this chapter tries to be an invitation to use plant extract as an alternative to chemical, synthetic antibiotics, or used complementary, synergistic for better therapeutically results.
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Molina-Gallardo, Axel R., Yesica R. Cruz-Martínez, Julieta Orozco-Martínez, Israel Valencia Quiroz et C. Tzasna Hernández-Delgado. « The Roles of Farnesol and Farnesene in Curtailing Antibiotic Resistance ». Dans Biotechnology and Drug Development for Targeting Human Diseases, 52–69. BENTHAM SCIENCE PUBLISHERS, 2024. http://dx.doi.org/10.2174/9789815223163124090005.
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In the extensive domain of “biotechnology and drug development for targeting human diseases”, essential oils have long been revered for their therapeutic potential. Among these, farnesol and farnesene stand out due to their pharmacological attributes. As the challenge of antibiotic resistance intensifies, the scientific community is increasingly exploring the potential of these traditional remedies. Using the KirbyBauer agar diffusion method, a qualitative assessment was conducted on two grampositive and two gram-negative bacterial strains. The broth microdilution technique further determined the Minimum Inhibitory Concentration (MIC), Minimum Bactericidal Concentration (MBC), and the sensitizing impacts of these compounds. Both farnesol and farnesene exhibited antibacterial efficacy against all evaluated strains. Their synergistic potential was highlighted when combined with clavulanic acid, cefuroxime, and cefepime. Among these combinations, farnesene paired with cefepime showed pronounced efficacy against Escherichia coli 82 MR, with an MIC of 0.47 μg/mL. In contrast, in the investigation of Staphylococcus aureus 23MR, it was observed that this particular strain exhibited an increased sensitivity when exposed to combinations containing farnesol. Notably, the Minimum Inhibitory Concentration (MIC) was determined to be 0.03 µg/mL in the presence of both antibiotic agents. To gain deeper molecular insights, docking experiments were performed with the βlactamases of E. coli and S. aureus, focusing on the most effective combinations. All tested compounds—cefuroxime, cefepime, farnesene, and farnesol—acted as noncompetitive inhibitors, suggesting their potential mechanisms of action.
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Middleton, Stephen J., et Raymond J. Playford. « Bacterial overgrowth of the small intestine ». Dans Oxford Textbook of Medicine, sous la direction de Jack Satsangi, 2879–83. Oxford University Press, 2020. http://dx.doi.org/10.1093/med/9780198746690.003.0299.
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Small intestinal bacterial overgrowth can be defined as the presence of excessive bacteria in the small intestine which can interfere with digestion and absorption. Predisposing causes include sustained hypochlorhydria induced by proton pump inhibitors, small intestinal dysmotility and stasis due to anatomical or motor abnormalities, and reduced antibacterial activity as seen in immunological deficiency and chronic pancreatitis. Presentation is predominantly from consequences of malabsorption, including gastrointestinal symptoms (e.g. diarrhoea or steatorrhoea) and features of specific nutrient malabsorption (e.g. osteoporosis, anaemia, neuropathy, and night blindness). Definitive diagnosis is difficult, requiring a properly collected and appropriately cultured aspirate from the proximal small intestine revealing a total concentration of a mixed growth of bacteria generally greater than 105 organisms/ml. Alternative investigations frequently used include glucose/lactulose breath tests or either the 13C- or 14C-xylose breath test, with elevated levels of 13CO2 or 14CO2 found in the breath. There may be low levels of cobalamin (metabolized by Gram-negative anaerobes), increased serum folate (synthesized by overgrowth flora), and increased urinary indicans (intraluminal product of bacterial tryptophan metabolism). Aside from treatment of any nutritional deficiencies, specific treatment is with an antimicrobial that is effective against both aerobic and anaerobic enteric bacteria (e.g. doxycycline, amoxicillin–clavulanic acid, rifaximin, or ciprofloxacin), which can be administered in rotation to reduce antibiotic resistance. Where possible and appropriate, correction of any underlying cause should also be performed.
Actes de conférences sur le sujet "Sub-Inhibitory concentrations of antibiotics"
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Recktenwald, Matthias, Muskanjot Kaur, Mohammed M. Benmassaoud, Aryanna Copling, Tulika Khanna, Michael Curry, Denise Cortes, Gilbert Fleischer, Valerie J. Carabetta et Sebastian L. Vega. « Soluble Antimicrobial Peptide (AMP) Screening to Rationally Design AMP-Hydrogels that Selectively Prevent Biofilm Formation ». Dans 28th Annual Rowan-Virtua Research Day. Rowan University Libraries, 2024. https://doi.org/10.31986/issn.2689-0690_rdw.stratford_research_day.192_2024.
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Staphylococcus aureus is an opportunistic pathogen that lives on surfaces and skin and can cause serious infections once inside the body. While antibiotics effectively kill bacteria, there are a growing number of infections with antibiotic-resistant strains. Antimicrobial peptides (AMPs) are part of the innate immune system and can eliminate pathogens including bacteria, fungi, and viruses, and are a promising alternative to antibiotics. Although studies have reported that AMP-functionalized hydrogels can prevent bacterial adhesion and biofilm formation, these materials generally consist of one AMP at an arbitrary concentration, and AMP dosing and the combined effects of multiple AMPs are not well understood. Here, three AMPs with different antibacterial properties were synthesized and the soluble minimum inhibitory concentrations (MICs) of each AMP against methicillin-susceptible S. aureus (MSSA) and methicillin-resistant S. aureus (MRSA) determined. Hydrogels with immobilized AMPs at their MIC (DD13RIP 27.5 µM; indolicidin 43.8 µM; P10 120 µM) were effective in preventing MRSA adhesion and biofilm formation. Checkerboard array screens identified synergy between indolicidin (3.125 µM) and P10 (12.5 µM) based on soluble fractional inhibitory concentrations (FICs) against MRSA, and hydrogels formed with these AMPs at half of their synergistic FICs (total peptide concentration, 8.5 µM) were highly efficacious in killing MRSA. Mammalian cells cultured atop these hydrogels are also highly viable, demonstrating that the AMP hydrogels developed are biocompatible and selectively eradicate bacteria based on soluble checkerboard screening data.
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M. HASAN, Alaa. « STUDYING THE ANTIMICROBIAL EFFECT OF PHENOLIC COMPOUNDS EXTRACTED FROM CAULIFLOWER BRASSICA OLERACEA VAR. BOTRYTIS AGAINST SOME SPECIES OF PATHOGENIC CANDIDA ». Dans VIII.International ScientificCongressofPure,AppliedandTechnological Sciences. Rimar Academy, 2023. http://dx.doi.org/10.47832/minarcongress8-7.
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Increasing microbial and fungal resistance to antibiotics is one of the biggest challenges facing the scientific community, therefore, finding alternative treatments is one of the ideal options to overcome this problem. The cruciferous family is one of the richest plants worldwide because it contains an important secondary metabolite .Phenolics compound which are known for their antimicrobial properties. The sScop of this work is to estimate the antimicrobial influence of phenolic compound against four Candida spp. (C. albicans, C. tropicales, C. kyfer and C. parasilopses). The activity of five concentrations (200, 400, 600, 800, and 1000 µg/ml) prepared from crud alcoholic phenol extract were investigated. Data showed that the highest antifungal effect of phenol was against C. albicans and C. parasilopses respectively at the concentration 1000 µg/ml, while the lowest inhibitory effect was against C. albicans at the concentration 200 µg/ml, C. kyfer at the concentration 200 µg/ml, and C. tropicales at the concentration 400 µg/ml. In general, it has been noticed that the inhibitory effect for the rest concentrations concerning Candida spp. was concentrationdependent manner
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Popov, Sergey, Aleksey Kuzmin, Tamara Sabgayda et Nataly Vedenina. « Minimum inhibitory concentrations (MIC) determination of TB drugs and broad-spectrum antibiotics inM.tuberculosiswith M/X/TDR ». Dans Annual Congress 2015. European Respiratory Society, 2015. http://dx.doi.org/10.1183/13993003.congress-2015.pa3331.
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A.GHAFIL, Jenan, Nihad Taha Mohammed JADDOA et Marwa shakib ALRAWI. « ACALYPHA AUSTRALIS PLANT PROMISING TREATMENT AGAINST BACTERIA ». Dans VI.International Scientific Congress of Pure,Applied and Technological Sciences. Rimar Academy, 2022. http://dx.doi.org/10.47832/minarcongress6-31.
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The research aimedtoevaluate theantibacterial effect of ethanol extract of Acalypha australisagainst eightbacterialstrains (Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, Klebsiella pneumonia, Pseudomonas aeruginosa, Actinomyces, Proteus mirabilis and Streptococcus pneumonia) with concentrations ranged from 3.90 to 2000 µg/ml. The sensitivity of bacterial isolates to various antibiotics was tested by VITIK2 Densi-Check equipment. The xtricate was made by a soaked powder of Acalypha australis with 80%ethanol in the unit of soxhlet extractions and after that was aseptically sifted. The antibacterial effects of theextricate were surveyed utilizing the agar dissemination strategy and the broth microdilution-method, which was utilized to gauge the extract's minimal inhibitory concentration (MIC). Results appearedthat the ethanol-extricate has antibacterial action in a concentration-dependent way, with the normal distance across zone of hindrance watched against bacterial segragates extending from 15±0.5 mm to 25±0.5 mmThe xtract had the greatest effectagainst E. coli, followed by P. aeruginosa, and the least effect against P. mirabilis. The extract's minimal inhibitory concentration varies from one species to another, ranging from 31.25 to 250 µg/ml.
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Saeed MOHAMMED, Luma. « STUDY THE ANTIBACTERIAL ACTIVITY OF ALCOHOLIC EXTRACT OF ALLIUM SATIVUM ON PSEUDOMONAS AERUGINOSA AND COMPARE WITH SOME ANTIBIOTICS ». Dans V. International Scientific Congress of Pure, Applied and Technological Sciences. Rimar Academy, 2022. http://dx.doi.org/10.47832/minarcongress5-3.
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Twenty isolate of P.aerugiosa isolated from Baghdad hospitals identified morphologically and biochemical tests then vitek system.Disk diffusion method carried out to determined the sensitivity of bacterial isolates to different antibiotics like amoxicillin,ciprofloxacin, meropenem and cefotaxim by using Muller-Hinton agar, the results showed that 100% of isolates had resistance to amoxicillin,40% of resistance to cefotxim, 20% of resistance to ciprofloxacin and meropenem. Agar well method used to determined the minimal inhibitory concentrations for alcoholic extract of Allium sativum which prepared by using aqueous ethanol by soxhlet extractor ,it had inhibition effect in 50, and 25 mg/ml, the diameter of inhibition zone on agar were 15-9 mm.
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BAQER, Batool Abd Al Ameer, et Maysoon Khaleefah ABBAS. « EFFECT OF CEPHALOSPORINS ON ( BIOFILM PRODUCTION AND PROTEASE ) ACTIVITIES BY SOME BACTERIA ISOLATED FROM OTITIS MEDIA ». Dans III.International Scientific Congress of Pure,Appliedand Technological Sciences. Rimar Academy, 2021. http://dx.doi.org/10.47832/minarcongress3-1.
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30 samples (swab) were collected from patients suffering from Otitis media. Swabs were implanted on the culture media blood agar and MacConkey agar to isolate the bacteria and to diagnose them using microscopic, culture and biochemical tests and confirmed by the Vitck-2 system. Of the total, 18 isolates were selected which belong to 8 (26.6%) Staphylococcus aureus, 5 (16.6%) Klebsiella pneumonia, and 4 (13.3%) Escherichia coli. All isolates were investigated for sensitivity to (18) antibiotics, six of them from the cephalosporins group The results showed that all isolates were 100% resistance to Cefotaxime, Ceftazidime, Cefixime, Ceftriaxone, Cefepime, Cefoxitin, Aztronam, Ampenicillin, while the isolates showed the lowest percentage of resistance to Imipenem (4.54) %, while all differences showed a clear difference in some of their resistance. Of the antagonists (Vancomycin, Erythromycin, Rifampin) with a percentage of (95.45, 27.27, 18.18)%, respectively. but for concentrations (4–16)µg/ml were ineffective for some of them. The (Minimal inhibitory concentrations ) MIC test indicated that it ranged between (4–32)µg/ml for Ceftriaxone and (16–32)µg/ml for Ceftazidime. All isolates were shown ability have (100%) activity to produce (Biofilm) was tested on the Congo red agar (CRA) medium, and ability to produce a protease enzyme by (72.22%) on Skim milk agar medium. The results showed a effect of inhibitory concentrations of Ceftriaxone on the activity of biofilm production and the protease enzyme, further the results of this study showed that the following concentrations (1024, 512, 256 and 128)µg/ml were lethal to isolates, while (32–64)µg/ml were inhibitory, Also, the molecular diagnosis shown results of Agarose - gel electrophoresis of both (normal case) S. aureus, E. coli and Kl. pneumonia and heal isolates observed the presence of chromosomal and plasmid DNA bands in the normal status but alone chromosomal DNA bands occur with the isolates deal in Ceftriaxone at levels of (32–128 )µg/ml. In the study of the effect of some Gram-negative bacteria by using IL-2 human. It can be used in the diagnosis of inflammation of the Otitis Media. Key words: Cephalosporins, Otitis media, Biofilm, protease, E. coli, Staphylococcus aureus, Klebsiella pneumonia.
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Rammadan ABDUL, Fatima, Ihsan Ali RAHEEEM, Alaa Laebi ABDULLAH et Batool Abd Al Ameer BAQER. « DETECTION OF SOME VIRULENCE FACTORS AND ANTIBIOTICS RESISTANCE OF KLEBSIELLA PNEUMONIAE ». Dans DETERMINATION OF THE ACTUAL INTENSITY BY CORRECTION OF THE EMISSION SPECTRUM LINES OF HEAVY METALS CONTAINED IN CRUDE OIL USING LASER INDUCED PLASMA –TECHNIQUE. Rimar Academy, 2022. http://dx.doi.org/10.47832/minarcongress4-9.
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Background: Infections of Klebsiella pneumoniae can include; diarrhea, septicemia, pneumonia, urinary tract infection and infections of soft tissues. Many factors are donated to K. pneumoniae pathogenicity particularly production of enzymes and formation of biofilm. Objective: find the relationship between the resistance of K. pneumoniae bacteria to antibiotics of quinolones and their ability to produce enzymes of beta lactamase. Materials and Methods: The Study included isolation and identification of (51) isolate of K. pneumoniae and (94) isolates of other bacteria from different clinical sources in some Baghdad hospitals. Results: The isolation and diagnosis of (51) isolates of K. pneumoniae from infection of urinary tract were 49.1%, infection of wounds were 31.3% and infection of burns were19.6%. All bacterial isolates were identified by the biochemical, cultural and microbial characteristics and confirmed by Api E20 System. I showed of β-lactamase test of Klebsiella pneumoniae revealed that (35) 68.6% isolates were positive. While 16 (31.4%) isolates were able to produce urease. Four groups of quinolones were tested by done the sensitivity test of isolates and results revealed the following percentage of resistant to Norfloxacin, Ofloxacin and ciprofloxacin consequently were (50.1%), (44.5%), (39.4%). whereas, the lower percent of resistant to Levofloxacin was (26.8%). In contrast, the βlactamase positive K. pneumoniae exhibited a high resistance in compare to isolates that negative for β-lactamase. The minimum inhibitory range concentrations of ciprofloxacin were arranged between (4-512 µg\ml). From isolates that resistant to Ciprofloxacin, the DNA plasmid was determined. Single plasmid bands were included in two isolates with same size and other isolates were confined free plasmid
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Soares, Jennifer M., Vanderlei S. Bagnato et Kate C. Blanco. « Synergistic enhancement effects of antibiotic combination with photodynamic inactivation ». Dans Latin America Optics and Photonics Conference. Washington, D.C. : Optica Publishing Group, 2022. http://dx.doi.org/10.1364/laop.2022.w4a.29.
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Antimicrobial resistance is one of the most severe threats to global public health in this century. Photodynamic Inactivation (PDI) is an alternative to antibiotic therapy, a standard treatment for infections because the combination of a photosensitizer with light leads to the production of reactive oxygen species that promote eliminating undesirable cells without bacterial selection and with few side effects for the patient. This work investigates whether PDI can restore bacterial sensitivity to antibiotics. PDI protocols using curcumin and light at 450 nm are applied at regular intervals and new values of minimum inhibitory concentration of antibiotics are obtained. As a result, we observed that PDI treatments can decrease MIC. Thus, the combination of both antimicrobial therapies may result in synergistic effects.
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Takagi, Rika, Junji Fukuda, Hiroaki Suzuki, Keiji Nagata et Nobuhiko Nomura. « Electrochemical microdevice for the determination of the minimum inhibitory concentration of antibiotics ». Dans 2012 IEEE Sensors. IEEE, 2012. http://dx.doi.org/10.1109/icsens.2012.6411101.
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Sarvarova, E. R., E. A. Cherepanova et I. V. Maksimov. « Antifungal activity of lipopeptides from endophytic strains of the genus Bacillus sp. against the fungus Stagonospora nodorum (Berk.) ». Dans 2nd International Scientific Conference "Plants and Microbes : the Future of Biotechnology". PLAMIC2020 Organizing committee, 2020. http://dx.doi.org/10.28983/plamic2020.216.
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The direct antibiotic effect of lipopeptides from four endophytic strains on the germination of spores of the pathogenic fungus Stagonospora nodorum (Berk.) was found and the minimum inhibitory concentration (MIC) of these lipopeptides was determined.
Rapports d'organisations sur le sujet "Sub-Inhibitory concentrations of antibiotics"
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ศรีอุบลมาศ, นงลักษณ์, อารี ลออปักษา et สารี วิรุฬหผล. ฤทธิ์ต้านจุลชีพของน้ำผึ้ง. จุฬาลงกรณ์มหาวิทยาลัย, 1991. https://doi.org/10.58837/chula.res.1991.7.
Texte intégralRésumé :
น้ำผึ้งทดสอบ 10 ตัวอย่าง มีฤทธิ์ยับยั้งการเจริญเติบโตของ Trichophyton mentagrophytes, Microsporum gypseum, และ Epidermophyton flocccosum โดยมีค่าเฉลี่ยเส้นผ่าศูนย์กลางของโซนใสอยู่ในช่วง 19.58 ? 0.29, 17.00 ? 0.61 ถึง 29.62 ? 0.29 และ 20.40 ? 1.59 ถึง 46.36 ? 1.06 มิลิลิตร ตามลำดับ น้ำผึ้งจากต่างประเทศมีฤทธิ์ยับยั้งการเจริญต่ำสุด ในขณะที่น้ำผึ้งตัวอย่างจากจังหวัดชุมพรให้ค่าสูงสุดจากตัวอย่างน้ำผึ้งอื่นๆ อย่างมีนัยสำคัญทางสถิติ ตัวอย่างน้ำผึ้งทั้งหมดไม่มีผลยับยั้งการเจริญเติบโตของ Aspergillus niger และเชื้อยีสต์ 2 ชนิด Saccharomyces cerevisiae และ Candida albicans เมื่อเปรียบเทียบกับกลุ่มควบคุมซึ่งประกอบด้วยกลูโคส : ฟรักโทส ในอัตราส่วน 1 : 1 พบว่า ไม่มีฤทธิ์ต้านเชื้อทดสอบทุกชนิดในการหาความเข้มข้นต่ำสุดที่สามารถยับยั้งการเจริญเติบโต (MICs) โดยใช้น้ำผึ้ง 2 ตัวอย่าง ได้ค่า MICs ต่อ Trichophyton mentagrophytes เท่ากับ Microsporum gypseum คือ อยู่ในช่วง 10-30 มิลลิกรัม/มิลลิลิตร ส่วน MIC ต่อเชื้อ Epidermophyton floccosum มีค่า 10-20 -มิลลิกรัม/มิลลิลิตรThe antifungal activity of ten honey samples against Trichophyton mentagrophytes, Microsporum gypseum and Epidermophyton floccousum was studied. The average inhibition zones were found to be in the range of 19.58 1.05 to 31.00 0.92, 17.00 0.61 to 29.62 0.29 and 20.40 1.59 to 46.36 1.06 mullimeters, respectively. The imported honey provided the lowest antifungal activity whereas the sample from Chumporn provided the highest activity. All samples had no effect on Aspergillus niger and the two yeasts : Saccharomyces cerevisiae and Candida albicans. The control sugar (Glucose : Fructose in ratio 1 : 1X showed no antifungal effect against all test organisms. The minimal inhibitory concentrations (MICs) of the two selected honey samples against Trichophyton mentagrophytes and Microsporum gypseum were both in the range of 10 - 30 milligrams/milliter while the MICs against Epidermophyton floccosum were in the range of 10 - 20 milligrams/milliliterการศึกษาฤทธิ์ต้านแบคทีเรียของน้ำผึ้ง 10 ตัวอย่าง โดยเปรียบเทียบความแรงกับยาเพนิซิลลิน และเตตราซัยคลิน พบว่า ฤทธิ์ต้านเชื้อ Staphy lococcus aureus ของน้ำผึ้งสมมูลกับเพนิซิลลินความแรง 0.675 - 1.45 หน่วย/มิลลิลิตร และฤทธิ์ต้านเชื้อ Escherichia coli ของน้ำผึ้งสมมูลกับเตตราซัยคลินความแรง <14.7 - 28.1 ไมโครกรัม/มิลลิลิตร เลือกน้ำผึ้งมา 5 ตัวอย่าง ทีมีฤทธิ์สมมูลกับความแรงของเพนิซิลลินในช่วงต่างๆ ต่อเชื้อ Staphy lococcus aureus นำมาหาค่าความเข้มข้นต่ำสุดที่ยับยั้งการเจริญของเชื้อ Staphy lococcus aureus และ Escherichia coli ชนิดละ 30 สายพันธุ์ รวมทั้งสายพันธุ์มาตรฐาน เชื้อทดสอบส่วนใหญ่เป็นสายพันธุ์ที่ต้านยาปฏิชีวนะ ความเข้มข้นต่ำสุดของน้ำผึ้งที่ยับยั้งการเจริญของเชื่อ Staphy cococcus aureus และ Escherichia coli มีค่าอยู่ระหว่าง 0.1 - 0.3 กรัม/มิลลิลิตร และ 0.15 - 0.35 กรัม/มิลลิลิตร ตามลำดับ สำหรับกลุ่มควบคุมซึ่งประกอบด้วยน้ำตาล 80% คือ กลูโคส : ฟรักโทสในอัตราส่วน 1 : 1 ไม่สามารถยับยั้งการเจริญของแบคทีเรียได้ จากผลการทดลองแสดงให้เห็นว่าน้ำผึ้งต้วอย่างต่างๆ มีฤทธิ์ต้านแบคทีเรียใกล้เคียงกัน และมีฤทธิ์ต้านแบคทีเรียสายพันธุ์ที่ดื้อยาปฏิชีวนะTen samples of honey were studied for the antibiotic equivalent potency. The antibacterial activity of honey was equivalent to 0.675 - 1.45 units/ml of pencillin against Staphylococcus aurenus and to <14.7 - 28.1 mcg/ml of tetracycline against Escherichia coli. Five selected samples, having low to high equivalent potency of penicillin against Staphylococcus aureus, were determined for MICs against 30 strains of Staphylococcus aureus and Escherichio coli including standard strains. Most strains were antibiotic - resistant organisms. The MICs against Staphylococcus sureus and Escherichia coli of honey samples were 0.1 - 0.3 g/ml and 0.15 - 0.35 g/ml, respectively. For control solution containing 80% of glucose and fructose in the ratio of 1 : 1, the growth of test organisms was not inhibited. Our study showed that the various samples of honey had approximately the same antibacterial activity.น้ำผึ้ง 10 ตัวอย่าง และกลุ่มควบคุมซึ่งประกอบด้วยน้ำตาล 80% โดยมีกลูโคสและฟรักโทสในอัตราส่วน 1 : 1 ทำให้ร้อนที่อุณหภูมิ 63 องศาเซียเซียส, 80 องศาเซียเซียส, 100 องศาเซียเซียส และ 121 องศาเซียเซียส เป็นเวลา 30 นาที วัดความหนืด และหาฤทธิ์ด้านแบคทีเรียโดยวิธีดัดแปลงจาก disc susceptibility test ตัวอย่างน้ำผึ้งที่ไม่ได้ทำให้ร้อน มีความหนืดแตกต่างกันมาก คือ ระหว่าง 80.43 - 7,507.77 cps แต่เส้นผ่าศูนย์กลางของโซนใส่เชื้อไม่ขึ้นของน้ำผึ้งส่วนใหญ่แตกต่างกัน ความร้อนมีผลต่อ ฤทธิ์ต้านแบคทีเรียของน้ำผึ้ง โดยเฉพาะความร้อนที่อุณหภูมิ 100 องศาเซียเซียส และ 121 องศาเซียเซียส ผลนี้อาจเกิดจากการที่ความร้อนทำลายสารต้านแบคทีเรียบางชนิดในน้ำผึ้ง ความร้อนทำให้น้ำผึ้งมีความหนืดมากขึ้น อย่างไรก็ตามความหนืดไม่มีความสัมพันธ์กับฤทธิ์ต้านแบคทีเรียของน้ำผึ้ง