Overcoming Multidrug Resistance in E. coli and Salmonella Isolates from Nile Tilapia: Synergistic Effects of Novel Antibiotic Combinations. - Related Documents




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472601.0000Overcoming Multidrug Resistance in E. coli and Salmonella Isolates from Nile Tilapia: Synergistic Effects of Novel Antibiotic Combinations. Escherichia coli and Salmonella are significant foodborne zoonotic pathogens, causing serious human illness. The rising global prevalence of antimicrobial resistance (AMR) in these species exacerbates their public health risk, complicating the treatment of bacterial infection. This study investigates its prevalence, resistant genes, and treatment strategy against antibiotic-resistant bacteria, focusing on E. coli and Salmonella isolates from Nile tilapia. Prevalence of E. coli and Salmonella was found to be 32 and 22% respectively. Antibiotic susceptibility testing revealed resistance to five antibiotics in E. coli and four in Salmonella. Physiochemical properties of antibiotic resistance genes (ABRGs) indicated that the TetB gene has the highest aliphatic index in both bacteria, suggesting greater stability. All Bla proteins were hydrophobic as indicated by negative GRAVY values, which may contribute to antibiotic efflux or modification of antibiotic targets. Motif analysis identified functional domains, and cellular localization prediction showed that TetA and TetB genes are primarily expressed in the cell membrane. To combat this resistance, a checkerboard method was used to explore novel antibiotic combinations. For E. coli, one synergistic and two additive combinations were identified, while for Salmonella, two synergistic and one additive combination were effective. These results highlight the importance of regularly evaluating antibiotic combinations to combat resistance and preserve antibiotic efficacy.202540581898
472710.9998Biodegradation of plastics and pesticides by soil bacteria in Bangladesh: Insights into antibiotic resistance and potential therapeutic targets. Soil bacteria exhibit varying degrees of tolerance to different concentrations of pesticides and plastics, and some possess the ability to degrade them, which is crucial for bioremediation. However, the multidrug-resistant properties of these bacteria pose challenges for their potential applications. Hence, this study aims to separate and characterize plastics and pesticide-degrading bacteria fromnon-contaminated and contaminated sites in Bangladesh and evaluate their antibiotic-resistant patterns to identify safety issues and discover promising therapeutic targets for combating multidrug-resistant infections. In the current study, a total of 90 soil samples were collected from different agricultural and dumped sites of Bangladesh, and bacterial isolates were screened for pesticides and plastics-degrading capabilities. Antibiotic sensitivity patterns of the potential isolates were evaluated using 16 different antibiotics. Biochemical, molecular, and genomic analyses were conducted to characterize the bacteria and identify antimicrobial resistance (AMR) genes. Our study screened out 122 plastic and 60 pesticide-tolerant bacterial isolates. Among them, 3 pesticide and 3 plastic-degrading isolates were found to be more promising and identified as Acinetobacter baumannii with pesticide-degrading capabilities from non-contaminated sites, and Klebsiella pneumoniae with plastic-degrading capabilities from contaminated sites. Antibiotic sensitivity test exhibited that most of the isolates were resistance to commonly used antimicrobials. The genomics and proteomics analysis uncovered the efflux pump-related genes responsible for the resistant mechanism and highlighted the involvement of genes that respond to antibiotics and transmembrane transport activities. Phylogenetic analysis confirmed the conservation of 2 common resistance genes adeF and gyrA, across diverse multidrug-resistant pathogens. Therefore, targeting conserved genes adeF and gyrA, to disrupt resistance mechanisms and combat persistent and clinically significant multidrug-resistant pathogens could be a promising strategy for developing combination therapies in medical science.202540854651
567420.9998Evaluation of Resistance by Clinically Pathogenic Bacteria to Antimicrobials and Common Disinfectants in Beijing, China. BACKGROUND: Antibiotic resistance of pathogenic bacteria is well recognized among clinicians; however, studies that directly evaluate the bacterial resistance to commonly used disinfectants in clinical settings are lacking. Currently available reports focus on the resistance of single strains to single disinfectants and do not adequately examine the degree of resistance and cross-resistance to antimicrobials in the large-scale clinical use of disinfectants. METHODS: We investigated the resistance capacity to 11 antibiotics and 7 chemical disinfectants by bacterial strains collected from body fluids of patients in 10 hospitals in Beijing, China over a 1-year period. Bacterial resistance to disinfectants was tested using minimum inhibitory concentration and minimum bactericidal concentration using agar dilution methods based on commercially available reference strains. RESULTS: A total of 1,104 pathogenic strains were identified, of which 23% were Gram-positive bacteria, 74% were Gram-negative bacteria, and 3% were fungi. Overall, resistance to antibiotics for the most common strains was significantly higher than their resistance to disinfectants. The least effective antibiotics and disinfectants were aztreonam and glutaral, respectively, exhibiting the highest overall resistance rates; while amikacin and alcohol had the lowest resistance rates. Consistently, Acinetobacter baumannii exhibited the most resistance, while Escherichia coli had the least resistance for both antibiotics and disinfectants. CONCLUSIONS: Based on the pathogen spectrum for bacterial infective pathogens evaluated in this study, as well as the status quo of their resistance to antimicrobial agents and common clinical disinfectants, it is essential for healthcare professionals to pay attention not only to the standardized use of antimicrobial agents but also to the rational application of disinfectants.201830568055
481630.9998Sub-inhibitory concentrations of colistin and imipenem impact the expression of biofilm-associated genes in Acinetobacter baumannii. Acinetobacter baumannii is an opportunistic pathogen that is responsible for nosocomial infections. Imipenem and colistin are drugs that are commonly used to treat severe infections caused by A. baumannii, such as sepsis, ventilator-associated pneumonia, and bacteremia. However, some strains of A. baumannii have become resistant to these drugs, which is a concern for public health. Biofilms produced by A. baumannii increase their resistance to antibiotics and the cells within the inner layers of biofilm are exposed to sub-inhibitory concentrations (sub-MICs) of antibiotics. There is limited information available regarding how the genes of A. baumannii are linked to biofilm formation when the bacteria are exposed to sub-MICs of imipenem and colistin. Thus, this study's objective was to explore this relationship by examining the genes involved in biofilm formation in A. baumannii when exposed to low levels of imipenem and colistin. The study found that exposing an isolate of A. baumannii to low levels of these drugs caused changes in their drug susceptibility pattern. The relative gene expression profiles of the biofilm-associated genes exhibited a change in their expression profile during short-term and long-term exposure. This study highlights the potential consequences of overuse and misuse of antibiotics, which can help bacteria become resistant to these drugs.202438489041
481740.9998Relationship Between Biofilm Formation and Antimicrobial Resistance in Gram-Negative Bacteria. Gram-negative microorganisms are a significant cause of infection in both community and nosocomial settings. The increase, emergence, and spread of antimicrobial resistance among bacteria are the most important health problems worldwide. One of the mechanisms of resistance used by bacteria is biofilm formation, which is also a mechanism of virulence. This study analyzed the possible relationship between antimicrobial resistance and biofilm formation among isolates of three Gram-negative bacteria species. Several relationships were found between the ability to form biofilm and antimicrobial resistance, being different for each species. Indeed, gentamicin and ceftazidime resistance was related to biofilm formation in Escherichia coli, piperacillin/tazobactam, and colistin in Klebsiella pneumoniae, and ciprofloxacin in Pseudomonas aeruginosa. However, no relationship was observed between global resistance or multidrug-resistance and biofilm formation. In addition, compared with other reported data, the isolates in the present study showed higher rates of antimicrobial resistance. In conclusion, the acquisition of specific antimicrobial resistance can compromise or enhance biofilm formation in several species of Gram-negative bacteria. However, multidrug-resistant isolates do not show a trend to being greater biofilm producers than non-multiresistant isolates.201930142035
467650.9998Probiotic Lactobacillus and the potential risk of spreading antibiotic resistance: a systematic review. BACKGROUND AND PURPOSE: Lactobacillus, the most popular probiotic, has recently gained more attention because it is a potential reservoir of antibiotic resistance. This review summarized and discussed the phenotypic-genotypic characteristics of antibiotic resistance. EXPERIMENTAL APPROACH: Google Scholar, PubMed, Web of Science, and Scopus were searched up to February 2022. The inclusion criteria were all studies testing antibiotic resistance of probiotic Lactobacillus strains present in human food supplementation and all human/animal model studies in which transferring antibiotic-resistant genes from Lactobacillus strains to another bacterium were investigated. FINDINGS/RESULTS: Phenotypic and genotypic characterization of Lactobacillus probiotics showed that the most antibiotic resistance was against protein synthesis inhibitors (fourteen studies, 87.5%) and cell wall synthesis inhibitors (ten studies, 62.5%). Nine of these studies reported the transfer of antibiotic resistance from Lactobacillus probiotic as donor species to pathogenic bacteria and mostly used in vitro methods for resistance gene transfer. CONCLUSION AND IMPLICATIONS: The transferability of resistance genes such as tet and erm in Lactobacillus increases the risk of spreading antibiotic resistance. Further studies need to be conducted to evaluate the potential spread of antibiotic resistance traits via probiotics, especially in elderly people and newborns.202337842520
472360.9998Impact of Sublethal Disinfectant Exposure on Antibiotic Resistance Patterns of Pseudomonasaeruginosa. OBJECTIVE: The problem of hospital cross-infection due to contamination of disinfectants has been recognized elsewhere. The passage of bacteria through diluted disinfectants may not only bring about phenotypic changes in their antibiograms but also changes in phage susceptibility patterns. Contact with disinfectants in sublethal concentrations allows survival and multiplication of bacteria. METHODS AND MATERIALS: Serial passage, through disinfectants at subminimal inhibitory concentrations, induced antibiotic resistance in 18% of derived phenotypic variants of fifty strains of Pseudomonas aeruginosa which were isolated from diarrheal stools of infants in children's hospital. RESULTS: A proportion of these strains became susceptible to an increased number of antibiotics. The present study revealed that all the isolates were resistant to tetracycline and carbenicillin and 40% of these isolates became sensitive to both antibiotics after exposure to disinfectants. The exposure to disinfectants induced neomycin resistance among two isolates. The resistance patterns were three before disinfectants exposure which increased to be nine different patterns after exposure. No antibiotic resistance was transferred between P. aeruginosa and Escherichia coli K12 as a recipient strain. CONCLUSIONS: Almost 50% of the isolates tested became sensitive to tetracycline, carbenicillin and co-trimoxazole after exposure to disinfectants. The resistance patterns among the 50 isolates were three which changed to be nine different patterns after exposure to disinfectants. Unjustifiable use of disinfectants might give a chance for survival and multiplication of pathogenic bacteria to develop new resistance patterns to antibiotics in use with a short time. These new resistance variants of bacteria which multiply in hospital environment could lead to serious epidemic conflicts particularly the epidemiological reporting and management. OBJECTIVE: The problem of hospital cross-infection due to contamination of disinfectants has been recognized elsewhere. The passage of bacteria through diluted disinfectants may not only bring about phenotypic changes in their antibiograms but also changes in phage susceptibility patterns. Contact with disinfectants in sublethal concentrations allows survival and multiplication of bacteria. METHODS AND MATERIALS: Serial passage, through disinfectants at subminimal inhibitory concentrations, induced antibiotic resistance in 18% of derived phenotypic variants of fifty strains of Pseudomonas aeruginosa which were isolated from diarrheal stools of infants in children's hospital. RESULTS: A proportion of these strains became susceptible to an increased number of antibiotics. The present study revealed that all the isolates were resistant to tetracycline and carbenicillin and 40% of these isolates became sensitive to both antibiotics after exposure to disinfectants. The exposure to disinfectants induced neomycin resistance among two isolates. The resistance patterns were three before disinfectants exposure which increased to be nine different patterns after exposure. No antibiotic resistance was transferred between P. aeruginosa and Escherichia coli K12 as a recipient strain. CONCLUSIONS: Almost 50% of the isolates tested became sensitive to tetracycline, carbenicillin and co-trimoxazole after exposure to disinfectants. The resistance patterns among the 50 isolates were three which changed to be nine different patterns after exposure to disinfectants. Unjustifiable use of disinfectants might give a chance for survival and multiplication of pathogenic bacteria to develop new resistance patterns to antibiotics in use with a short time. These new resistance variants of bacteria which multiply in hospital environment could lead to serious epidemic conflicts particularly the epidemiological reporting and management.202539536720
575970.9998The Relationship between Antibiotic Susceptibility and pH in the Case of Uropathogenic Bacteria. Urinary tract infections (UTIs) are common bacterial infections caused mainly by enteric bacteria. Numerous virulence factors assist bacteria in the colonization of the bladder. Bacterial efflux pumps also contribute to bacterial communication and to biofilm formation. In this study, the phenotypic and genetic antibiotic resistance of clinical UTI pathogens such as Escherichia coli, Klebsiella pneumoniae, and Proteus mirabilis were determined by disk diffusion method and polymerase chain reaction (PCR). Following this, different classes of antibiotics were evaluated for their antibacterial activity at pH 5, 6, 7 and 8 by a microdilution method. Gentamicin (GEN) was the most potent antibacterial agent against E. coli strains. The effect of GEN on the relative expression of marR and sdiA genes was evaluated by quantitative PCR. The slightly acidic pH (pH 6) and GEN treatment induced the upregulation of marR antibiotic resistance and sdiA QS activator genes in both E. coli strains. Consequently, bacteria had become more susceptible to GEN. It can be concluded that antibiotic activity is pH dependent and so the artificial manipulation of urinary pH can contribute to a more effective therapy of multidrug resistant bacterial infections.202134943643
472280.9998Ciprofloxacin, amoxicillin, and aminoglycosides stimulate genetic and phenotypic changes in uropathogenic Escherichia coli strains. Antibiotic therapy and its consequences in bacterial and human aspects are widely investigated. Despite this, the emergence of new multidrug resistant bacteria is still a current problem. The scope of our work included the observation of changes among uropathogenic Escherichia coli strains after the treatment with a subinhibitory concentration of different antibiotics. The sensitive strains with or without virulence factors were incubated with amoxicillin, ciprofloxacin, gentamycin, or tobramycin. After each passage, the E. coli derivatives were compared to their wild types based on their susceptibility profiles, virulence genes, biofilm formations and the fingerprint profiles of PCR products amplified with using the (N)(6)(CGG)(4) primer. It turned out that antibiotics caused significant changes in the repertoire of bacterial virulence and biofilm formation, corresponding to acquired cross-resistance. The genomic changes among the studied bacteria were reflected in the changed profiles of the CGG-PCR products. In conclusion, the inappropriate application of antibiotics may cause a rapid rise of Multidrug Resistant (MDR) strains and give bacteria a chance to modulate their own pathogenicity. This phenomenon has been easily observed among uropathogenic E. coli strains and it is one of the main reasons for recurrent infections of the urinary tract.201930938219
472090.9998Augmentation of antibiotic resistance in Salmonella typhimurium DT104 following exposure to penicillin derivatives. Antibiotic resistance in pathogenic bacteria has been a problem in both developed and developing countries. This problem is especially evident in Salmonella typhimurium, one of the most prevalent foodborne pathogens. While performing in vitro gentamicin protection-based invasion assays, we found that certain isolates of multiresistant S. typhimurium can be 'induced' to exhibit new resistance profiles. That is, bacteria become resistant to a wider range of antibiotics and they also exhibit quantitative increases in MIC values for antibiotics that were part of their pre-induction antibiograms. This 'induction' process involves growing the bacteria to stationary phase in the presence of antibiotics such as ampicillin, amoxicillin or ticarcillin. Since the isolates studied exhibited resistance to ampicillin, amoxicillin and ticarcillin prior to exposing the bacteria to these antibiotics, the observed phenomenon suggests that resistant Salmonella not only have a selective advantage over non-resistant Salmonella but their resistance phenotypes can be accentuated when an inappropriate antibiotic is used therapeutically.200010731615
5671100.9998Biofilms and antibiotic susceptibility of multidrug-resistant bacteria from wild animals. BACKGROUND: The "One Health" concept recognizes that human health and animal health are interdependent and bound to the health of the ecosystem in which they (co)exist. This interconnection favors the transmission of bacteria and other infectious agents as well as the flow of genetic elements containing antibiotic resistance genes. This problem is worsened when pathogenic bacteria have the ability to establish as biofilms. Therefore, it is important to understand the characteristics and behaviour of microorganisms in both planktonic and biofilms states from the most diverse environmental niches to mitigate the emergence and dissemination of resistance. METHODS: The purpose of this work was to assess the antibiotic susceptibility of four bacteria (Acinetobacter spp., Klebsiella pneumoniae, Pseudomonas fluorescens and Shewanella putrefaciens) isolated from wild animals and their ability to form biofilms. The effect of two antibiotics, imipenem (IPM) and ciprofloxacin (CIP), on biofilm removal was also assessed. Screening of resistance genetic determinants was performed by PCR. Biofilm tests were performed by a modified microtiter plate method. Bacterial surface hydrophobicity was determined by sessile drop contact angles. RESULTS: The susceptibility profile classified the bacteria as multidrug-resistant. Three genes coding for β-lactamases were detected in K. pneumoniae (TEM, SHV, OXA-aer) and one in P. fluorescens (OXA-aer). K. pneumoniae was the microorganism that carried more β-lactamase genes and it was the most proficient biofilm producer, while P. fluorescens demonstrated the highest adhesion ability. Antibiotics at their MIC, 5 × MIC and 10 × MIC were ineffective in total biofilm removal. The highest biomass reductions were found with IPM (54% at 10 × MIC) against K. pneumoniae biofilms and with CIP (40% at 10 × MIC) against P. fluorescens biofilms. DISCUSSION: The results highlight wildlife as important host reservoirs and vectors for the spread of multidrug-resistant bacteria and genetic determinants of resistance. The ability of these bacteria to form biofilms should increase their persistence.201829910986
5672110.9998Antibiotic Resistance, Biofilm Formation, and Presence of Genes Encoding Virulence Factors in Strains Isolated from the Pharmaceutical Production Environment. The spread of bacterial resistance to antibiotics affects various areas of life. The aim of this study was to assess the occurrence of Pseudomonas aeruginosa, and other bacteria mainly from orders Enterobacterales and Staphylococcus in the pharmaceutical production sites, and to characterize isolated strains in the aspects of antibiotic resistance, biofilm formation, and presence of genes encoding virulence factors. Genes encoding selected virulence factors were detected using PCR techniques. Antimicrobial susceptibility testing was applied in accordance with the EUCAST recommendations. A total of 46 P. aeruginosa strains were isolated and 85% strains showed a strong biofilm-forming ability. The qualitative identification of genes taking part in Quorum Sensing system demonstrated that over 89% of strains contained lasR and rhlI genes. An antimicrobial susceptibility testing revealed nine strains resistant to at least one antibiotic, and two isolates were the metallo-β-lactamase producers. Moreover, the majority of P. aeruginosa strains contained genes encoding various virulence factors. Presence of even low level of pathogenic microorganisms or higher level of opportunistic pathogens and their toxic metabolites might result in the production inefficiency. Therefore, the prevention of microbial contamination, effectiveness of sanitary and hygienic applied protocols, and constant microbiological monitoring of the environment are of great importance.202133513933
3401120.9998Heavy metal resistance and virulence profile in Pseudomonas aeruginosa isolated from Brazilian soils. Pseudomonas aeruginosa is an opportunistic pathogen, which can have several virulence factors that confer on it the ability to cause severe, acute and chronic infections. Thus, the simultaneous occurrence of resistance to antibiotics and heavy metals associated with the presence of virulence genes is a potential threat to human health and environmental balance. This study aimed to investigate the resistance profile to heavy metals and the correlation of this phenotype of resistance to antimicrobials and to investigate the pathogenic potential of 46 P. aeruginosa isolates obtained from the soil of five Brazilian regions. The bacteria were evaluating for antimicrobial and heavy metal resistance, as well as the presence of plasmids and virulence genes. The isolates showed resistance to four different antibiotics and the majority (n = 44) had resistance to aztreonam or ticarcillin, furthermore, 32 isolates showed concomitant resistance to both of these antibiotics. A high prevalence of virulence genes was found, which highlights the pathogenic potential of the studied environmental isolates. Moreover, a high frequency of heavy metal resistance genes was also detected, however, the phenotypic results indicated that other genes and/or mechanisms should be related to heavy metal resistance.201627197940
3929130.9997Genetic basis of antibiotic resistance in bovine mastitis and its possible implications for human and ecological health. Bovine mastitis is a mammary gland inflammation that can occur due to infectious pathogens, Staphylococcus aureus and Escherichia coli, which are, respectively, the most prevalent Gram-positive and Gram-negative bacteria associated with this disease. Currently, antibiotic treatment has become more complicated due to the presence of resistant pathogens. This review, therefore, aims to identify the most common resistance genes reported for these strains in the last four years. During the review, it was noted that bla(Z), bla(SHV,) bla(TEM), and bla(ampC) are the most reported genes for S. aureus and E. coli, associated with drug inactivation, mainly β-lactamases. They are characterized by generating bacterial resistance to β-lactam antibiotics, the most common treatment in animal and human bacterial treatments (penicillins and cephalosporins, among others). Genes associated with efflux systems were also present in the two strains and included norA, tetA, tetC, and tetK, which generate resistance to macrolide and tetracycline antibiotics. Additionally, the effects of spreading resistance between animals and humans through direct contact (such as consumption of contaminated milk) or indirect contact (through environmental contamination) has been deeply discussed, emphasizing the importance of having adequate sanitation and antibiotic control and administration protocols.202538916977
3407140.9997The culturable soil antibiotic resistome: a community of multi-drug resistant bacteria. Understanding the soil bacterial resistome is essential to understanding the evolution and development of antibiotic resistance, and its spread between species and biomes. We have identified and characterized multi-drug resistance (MDR) mechanisms in the culturable soil antibiotic resistome and linked the resistance profiles to bacterial species. We isolated 412 antibiotic resistant bacteria from agricultural, urban and pristine soils. All isolates were multi-drug resistant, of which greater than 80% were resistant to 16-23 antibiotics, comprising almost all classes of antibiotic. The mobile resistance genes investigated, (ESBL, bla NDM-1, and plasmid mediated quinolone resistance (PMQR) resistance genes) were not responsible for the respective resistance phenotypes nor were they present in the extracted soil DNA. Efflux was demonstrated to play an important role in MDR and many resistance phenotypes. Clinically relevant Burkholderia species are intrinsically resistant to ciprofloxacin but the soil Burkholderia species were not intrinsically resistant to ciprofloxacin. Using a phenotypic enzyme assay we identified the antibiotic specific inactivation of trimethoprim in 21 bacteria from different soils. The results of this study identified the importance of the efflux mechanism in the soil resistome and variations between the intrinsic resistance profiles of clinical and soil bacteria of the same family.201323776501
4738150.9997Detection and evaluation of susceptibility to antibiotics in non-hydrogen sulfide-producing antibiotic-resistant soil microbe: Pseudomonas guariconensis. Antimicrobial resistance in bacteria is a global threat that can make antibacterial treatments ineffective. One well-known method of antibiotic resistance and a common defensive mechanism in many harmful bacteria is the synthesis of endogenous hydrogen sulfide (H(2)S) in bacteria. In this study, soil bacteria were screened using the lead acetate agar test and the triple sugar iron test to determine that they were non-endogenous H(2)S producers. This was further validated by full genome analysis of the identified organism against the gene sequences of H(2)S-producing genes. Antibacterial resistance of the bacteria was phenotypically analyzed using the Kirby-Bauer disk diffusion method. Then, the effect of exogenous H(2)S on the antibiotic-resistant bacteria was checked in sodium sulfide, leading to antibiotic re-sensitization.202538767682
4739160.9997Indirect resistance to several classes of antibiotics in cocultures with resistant bacteria expressing antibiotic-modifying or -degrading enzymes. OBJECTIVES: Indirect resistance (IR), the ability of an antibiotic-resistant population of bacteria to protect a susceptible population, has been previously observed for β-lactamase-producing bacteria and associated with antimicrobial treatment failures. Here, we determined whether other resistance determinants could cause IR in the presence of five other classes of antibiotics. METHODS: A test was designed to detect IR and 14 antibiotic resistance genes were tested in the presence of 13 antibiotics from six classes. A bioassay was used to measure the ability of resistance-causing enzymes to decrease the concentration of active antibiotics in the medium. RESULTS: We confirmed IR in the presence of β-lactam antibiotics (ampicillin and mecillinam) when TEM-1A was expressed. We found that bacteria expressing antibiotic-modifying or -degrading enzymes Ere(A), Tet(X2) or CatA1 caused IR in the presence of macrolides (erythromycin and clarithromycin), tetracyclines (tetracycline and tigecycline) and chloramphenicol, respectively. IR was not observed with resistance determinants that did not modify or destroy antibiotics or with enzymes modifying aminoglycosides or degrading fosfomycin. IR was dependent on the resistance enzymes decreasing the concentration of active antibiotics in the medium, hence allowing nearby susceptible bacteria to resume growth once the antibiotic concentration fell below their MIC. CONCLUSIONS: IR was not limited to β-lactamase-producing bacteria, but was also caused by resistant bacteria carrying cytoplasmic antibiotic-modifying or -degrading enzymes that catalyse energy-consuming reactions requiring complex cellular cofactors. Our results suggest that IR is common and further emphasizes that coinfecting agents and the human microflora can have a negative impact during antimicrobial therapy.201626467993
4728170.9997Antibiotic Resistance Profile, Outer Membrane Proteins, Virulence Factors and Genome Sequence Analysis Reveal Clinical Isolates of Enterobacter Are Potential Pathogens Compared to Environmental Isolates. Outer membrane proteins (OMPs) of gram-negative bacteria play an important role in mediating antibacterial resistance, bacterial virulence and thus affect pathogenic ability of the bacteria. Over the years, prevalence of environmental antibiotic resistant organisms, their transmission to clinics and ability to transfer resistance genes, have been studied extensively. Nevertheless, how successful environmental bacteria can be in establishing as pathogenic bacteria under clinical setting, is less addressed. In the present study, we utilized an integrated approach of investigating the antibiotic resistance profile, presence of outer membrane proteins and virulence factors to understand extent of threat posed due to multidrug resistant environmental Enterobacter isolates. Also, we investigated clinical Enterobacter isolates and compared the results thereof. Results of the study showed that multidrug resistant environmental Enterobacter isolates lacked OmpC, lacked cell invasion abilities and exhibited low reactive oxygen species (ROS) production in neutrophils. In contrast, clinical isolates possessed OmpF, exhibited high invasive and adhesive property and produced higher amounts of ROS in neutrophils. These attributes indicated limited pathogenic potential of environmental Enterobacter isolates. Informations obtained from whole genome sequence of two representative bacterial isolates from environment (DL4.3) and clinical sources (EspIMS6) corroborated well with the observed results. Findings of the present study are significant as it highlights limited fitness of multidrug resistant environmental Enterobacter isolates.202032154188
9919180.9997An In Vitro Chicken Gut Model Demonstrates Transfer of a Multidrug Resistance Plasmid from Salmonella to Commensal Escherichia coli. The chicken gastrointestinal tract is richly populated by commensal bacteria that fulfill various beneficial roles for the host, including helping to resist colonization by pathogens. It can also facilitate the conjugative transfer of multidrug resistance (MDR) plasmids between commensal and pathogenic bacteria which is a significant public and animal health concern as it may affect our ability to treat bacterial infections. We used an in vitro chemostat system to approximate the chicken cecal microbiota, simulate colonization by an MDR Salmonella pathogen, and examine the dynamics of transfer of its MDR plasmid harboring several genes, including the extended-spectrum beta-lactamase bla(CTX-M1) We also evaluated the impact of cefotaxime administration on plasmid transfer and microbial diversity. Bacterial community profiles obtained by culture-independent methods showed that Salmonella inoculation resulted in no significant changes to bacterial community alpha diversity and beta diversity, whereas administration of cefotaxime caused significant alterations to both measures of diversity, which largely recovered. MDR plasmid transfer from Salmonella to commensal Escherichia coli was demonstrated by PCR and whole-genome sequencing of isolates purified from agar plates containing cefotaxime. Transfer occurred to seven E. coli sequence types at high rates, even in the absence of cefotaxime, with resistant strains isolated within 3 days. Our chemostat system provides a good representation of bacterial interactions, including antibiotic resistance transfer in vivo It can be used as an ethical and relatively inexpensive approach to model dissemination of antibiotic resistance within the gut of any animal or human and refine interventions that mitigate its spread before employing in vivo studies.IMPORTANCE The spread of antimicrobial resistance presents a grave threat to public health and animal health and is affecting our ability to respond to bacterial infections. Transfer of antimicrobial resistance via plasmid exchange is of particular concern as it enables unrelated bacteria to acquire resistance. The gastrointestinal tract is replete with bacteria and provides an environment for plasmid transfer between commensals and pathogens. Here we use the chicken gut microbiota as an exemplar to model the effects of bacterial infection, antibiotic administration, and plasmid transfer. We show that transfer of a multidrug-resistant plasmid from the zoonotic pathogen Salmonella to commensal Escherichia coli occurs at a high rate, even in the absence of antibiotic administration. Our work demonstrates that the in vitro gut model provides a powerful screening tool that can be used to assess and refine interventions that mitigate the spread of antibiotic resistance in the gut before undertaking animal studies.201728720731
4721190.9997Antimicrobial resistances do not affect colonization parameters of intestinal E. coli in a small piglet group. BACKGROUND: Although antimicrobial resistance and persistence of resistant bacteria in humans and animals are major health concerns worldwide, the impact of antimicrobial resistance on bacterial intestinal colonization in healthy domestic animals has only been rarely studied. We carried out a retrospective analysis of the antimicrobial susceptibility status and the presence of resistance genes in intestinal commensal E. coli clones from clinically healthy pigs from one production unit with particular focus on effects of pheno- and/or genotypic resistance on different nominal and numerical intestinal colonization parameters. In addition, we compared the occurrence of antimicrobial resistance phenotypes and genotypes with the occurrence of virulence associated genes typical for extraintestinal pathogenic E. coli. RESULTS: In general, up to 72.1% of all E. coli clones were resistant to ampicillin, chloramphenicol, kanamycin, streptomycin, sulfamethoxazole or tetracycline with a variety of different resistance genes involved. There was no significant correlation between one of the nominal or numerical colonization parameters and the absence or presence of antimicrobial resistance properties or resistance genes. However, there were several statistically significant associations between the occurrence of single resistance genes and single virulence associated genes. CONCLUSION: The demonstrated resistance to the tested antibiotics might not play a dominant role for an intestinal colonization success in pigs in the absence of antimicrobial drugs, or cross-selection of other colonization factors e.g. virulence associated genes might compensate "the cost of antibiotic resistance". Nevertheless, resistant strains are not outcompeted by susceptible bacteria in the porcine intestine.200919814790