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Abstract Background Formyl peptide receptor 2 (Fpr2) plays a crucial role in colon homeostasis and microbiota balance. Commensal E. coli is known to promote the regeneration of damaged colon epithelial cells. The aim of the study was to investigate the connection between E. coli and Fpr2 in the recovery of colon epithelial cells. Results The deficiency of Fpr2 was associated with impaired integrity of the colon mucosa and an imbalance of microbiota, characterized by the enrichment of Proteobacteria in the colon. Two serotypes of E. coli, O22:H8 and O91:H21, were identified in the mouse colon through complete genome sequencing. E. coli O22:H8 was found to be prevalent in the gut of mice and exhibited lower virulence compared to O91:H21. Germ-free (GF) mice that were pre-orally inoculated with E. coli O22:H8 showed reduced susceptibility to chemically induced colitis, increased proliferation of epithelial cells, and improved mouse survival. Following infection with E. coli O22:H8, the expression of Fpr2 in colon epithelial cells was upregulated, and the products derived from E. coli O22:H8 induced migration and proliferation of colon epithelial cells through Fpr2. Fpr2 deficiency increased susceptibility to chemically induced colitis, delayed the repair of damaged colon epithelial cells, and heightened inflammatory responses. Additionally, the population of E. coli was observed to increase in the colons of Fpr2 −/− mice with colitis. Conclusion Commensal E. coli O22:H8 stimulated the upregulation of Fpr2 expression in colon epithelial cells, and the products from E. coli induced migration and proliferation of colon epithelial cells through Fpr2. Fpr2 deficiency led to an increased E. coli population in the colon and delayed recovery of damaged colon epithelial cells in mice with colitis. Therefore, Fpr2 is essential for the effects of commensal E. coli on colon epithelial cell recovery.

Commensal Escherichia coli has the potential to easily acquire resistance to a broad range of antimicrobials, making it a reservoir for its transfer to other microorganisms, including pathogens. The aim of this study was to determine the prevalence of resistant commensal Escherichia coli isolated from dairy cows' feces. Phenotypic resistance profiles and categorization were determined by minimum inhibitory concentration (MIC) testing with the broth microdilution method, while the PCR method was used to determine the presence of resistant genes. Out of 159 commensal E. coli isolates, 39 (24.5%) were confirmed to have resistance. According to the MIC values, 37 (97.3%) and 1 (2.7%) isolate were phenotypically categorized as ESBL and ESBL/AmpC, respectively. All isolates showed resistance to ampicillin, while 97.4%, 56.4%, and 36% showed resistance to cefotaxime, ciprofloxacine, and azitromycine, respectively. Not all isolates that showed phenotypic resistance were found to be carrying the corresponding gene. The most prevalent resistant genes were gyrA, tetA, sul2, and tetB, which were present in 61.5%, 64%, 54%, and 49% of the isolates, respectively. The results clearly indicate that, besides their resistance to multiple antimicrobials, the commensal E. coli isolates did not necessarily carry any genes conferring resistance to that particular antimicrobial. [ABSTRACT FROM AUTHOR]

Background: Formyl peptide receptor 2 (Fpr2) plays a crucial role in colon homeostasis and microbiota balance. Commensal E. coli is known to promote the regeneration of damaged colon epithelial cells. The aim of the study was to investigate the connection between E. coli and Fpr2 in the recovery of colon epithelial cells. Results: The deficiency of Fpr2 was associated with impaired integrity of the colon mucosa and an imbalance of microbiota, characterized by the enrichment of Proteobacteria in the colon. Two serotypes of E. coli, O22:H8 and O91:H21, were identified in the mouse colon through complete genome sequencing. E. coli O22:H8 was found to be prevalent in the gut of mice and exhibited lower virulence compared to O91:H21. Germ-free (GF) mice that were pre-orally inoculated with E. coli O22:H8 showed reduced susceptibility to chemically induced colitis, increased proliferation of epithelial cells, and improved mouse survival. Following infection with E. coli O22:H8, the expression of Fpr2 in colon epithelial cells was upregulated, and the products derived from E. coli O22:H8 induced migration and proliferation of colon epithelial cells through Fpr2. Fpr2 deficiency increased susceptibility to chemically induced colitis, delayed the repair of damaged colon epithelial cells, and heightened inflammatory responses. Additionally, the population of E. coli was observed to increase in the colons of Fpr2−/− mice with colitis. Conclusion: Commensal E. coli O22:H8 stimulated the upregulation of Fpr2 expression in colon epithelial cells, and the products from E. coli induced migration and proliferation of colon epithelial cells through Fpr2. Fpr2 deficiency led to an increased E. coli population in the colon and delayed recovery of damaged colon epithelial cells in mice with colitis. Therefore, Fpr2 is essential for the effects of commensal E. coli on colon epithelial cell recovery. [ABSTRACT FROM AUTHOR]

Healthy host-microbial mutualism with our intestinal microbiota relies to a large degree on compartmentalization and careful regulation of adaptive mucosal and systemic anti-microbial immune responses. However, commensal intestinal bacteria are never exclusively or permanently restricted to the intestinal lumen and regularly reach the systemic circulation. This results in various degrees of commensal bacteremia that needs to be appropriately dealt with by the systemic immune system. While most intestinal commensal bacteria, except for pathobionts or opportunistic pathogen, have evolved to be non-pathogenic, this does not mean that they are non-immunogenic. Mucosal immune adaptation is carefully controlled and regulated to avoid an inflammatory response, but the systemic immune system usually responds differently and more vigorously to systemic bacteremia. Here we show that germ-free mice have increased systemic immune sensitivity and display anti-commensal hyperreactivity in response to the addition of a single defined T helper cell epitope to the outer membrane porin C (OmpC) of a commensal Escherichia coli strain demonstrated by increased E. coli-specific T cell-dependent IgG responses following systemic priming. This increased systemic immune sensitivity was not observed in mice colonized with a defined microbiota at birth indicating that intestinal commensal colonization also regulates systemic, and not only mucosal, anti-commensal responses. The observed increased immunogenicity of the E. coli strain with the modified OmpC protein was not due to a loss of function and associated metabolic changes as a control E. coli strain without OmpC did not display increased immunogenicity. [ABSTRACT FROM AUTHOR]

Community-acquired urinary tract infections (UTIs) are one of the most common bacterial infections worldwide. Escherichia coli is the most common cause of community-acquired UTI. In general, UTI results from E. coli in the intestine that enters the bladder via the urethra. However, whether these E. coli strains that cause UTI represent members of the intestinal commensal E. coli or a distinct subgroup of pathogenic E. coli remains unestablished. Here, we analyzed E. coli isolates from fecal samples of healthy volunteers and urine samples of UTI patients obtained from a university-affiliated health center. The E. coli isolates were genotyped by multilocus sequence typing (MLST). From May to October 2018, we analyzed 89 E. coli isolates from 76 (75%) rectal swabs from 113 unique healthy volunteers. We also analyzed 106 (27%) E. coli isolates from 398 unique urine samples collected between August and October 2018. Fecal and urine E. coli isolates each contained 31 distinct sequence types (STs). Nine STs were shared by fecal and urine E. coli isolates, which accounted for approximately 50% of urine isolates typed by MLST. Among the shared genotypes, ST10 and ST131 were significantly more frequently found in fecal samples, whereas ST95 and ST127 were significantly more frequently recovered from UTI samples. ST73 was found only among urine samples. These E. coli genotypes clustered and fluctuated over time. These observations suggest that E. coli genotypes found to cause UTI transiently colonize the intestine and that their primary reservoir may reside outside of the human intestine.

Recent studies have found limited associations between antimicrobial resistance (AMR) in domestic animals (and animal products), and AMR in human clinical settings. These studies have primarily used Escherichia coli, a critically important bacterial species associated with significant human morbidity and mortality. E. coli is found in domestic animals and the environment, and it can be easily transmitted between these compartments. Additionally, the World Health Organization has highlighted E. coli as a "highly relevant and representative indicator of the magnitude and the leading edge of the global antimicrobial resistance (AMR) problem". In this paper, we discuss the weaknesses of current research that aims to link E. coli from domestic animals to the current AMR crisis in humans. Fundamental gaps remain in our understanding the complexities of E. coli population genetics and the magnitude of phenomena such as horizontal gene transfer (HGT) or DNA rearrangements (transposition and recombination). The dynamic and intricate interplay between bacterial clones, plasmids, transposons, and genes likely blur the evidence of AMR transmission from E. coli in domestic animals to human microbiota and vice versa. We describe key factors that are frequently neglected when carrying out studies of AMR sources and transmission dynamics.

Healthy host-microbial mutualism with our intestinal microbiota relies to a large degree on compartmentalization and careful regulation of adaptive mucosal and systemic anti-microbial immune responses. However, commensal intestinal bacteria are never exclusively or permanently restricted to the intestinal lumen and regularly reach the systemic circulation. This results in various degrees of commensal bacteremia that needs to be appropriately dealt with by the systemic immune system. While most intestinal commensal bacteria, except for pathobionts or opportunistic pathogen, have evolved to be non-pathogenic, this does not mean that they are non-immunogenic. Mucosal immune adaptation is carefully controlled and regulated to avoid an inflammatory response, but the systemic immune system usually responds differently and more vigorously to systemic bacteremia. Here we show that germ-free mice have increased systemic immune sensitivity and display anti-commensal hyperreactivity in response to the addition of a single defined T helper cell epitope to the outer membrane porin C (OmpC) of a commensal Escherichia coli strain demonstrated by increased E. coli-specific T cell-dependent IgG responses following systemic priming. This increased systemic immune sensitivity was not observed in mice colonized with a defined microbiota at birth indicating that intestinal commensal colonization also regulates systemic, and not only mucosal, anti-commensal responses. The observed increased immunogenicity of the E. coli strain with the modified OmpC protein was not due to a loss of function and associated metabolic changes as a control E. coli strain without OmpC did not display increased immunogenicity.

In social animals, affiliative behaviours bring many benefits, but also costs such as disease risk. The ways in which affiliation may affect the risk of infectious agent transmission remain unclear. Moreover, studies linking variation in affiliative interactions to infectious agent incidence/diversity have speculated that disease transmission may have occurred, rather than revealing that transmission did occur. We address these gaps using the phylogenetics of commensal gut Escherichia coli to determine whether affiliative grooming and huddling social networks mediated microbial transmission among rhesus macaques. We collected behavioural and microbial data from adult macaques across a 12-week period that was split into two 6-week phases to better detect dyadic transmission. We reconstructed undirected social networks from affiliative interactions and reconstructed microbial transmission networks from the pairwise phylogenetic similarity of E. coli pulsotypes from macaques within and across adjacent sampling events. Macaque E. coli pulsotypes were more phylogenetically similar to each other than to environmental isolates, which established a premise for socially mediated transmission. Dyadic grooming and huddling frequencies strongly influenced the likelihood of E. coli transmission during the second data collection phase, but not the first. Macaques that were more central/well connected in both their grooming and huddling networks were also more central in the E. coli transmission networks. Our results confirmed that affiliative grooming and huddling behaviours mediate the transmission of gut microbes among rhesus macaques, particularly among females and high-ranking individuals. The detectability of socially mediated E. coli transmission maybe partially masked by environmental acquisition in males, or by high frequencies of interactions in captivity. Predicting the potential transmission pathways of gastrointestinal parasites and pathogens, our findings add to current knowledge of the coevolutionary relationships between affiliative behaviour and health and may be used to identify 'superspreader' individuals as potential targets for disease control strategies.

Goutam Chowdhury,1,2 Thandavarayan Ramamurthy,1 Bhabatosh Das,3 Debjani Ghosh,1 Keinosuke Okamoto,2 Shin-ichi Miyoshi,2,4 Shanta Dutta,1 Asish K Mukhopadhyay1 1Division of Bacteriology, ICMR-National Institute of Cholera and Enteric Diseases, Kolkata, India; 2Collaborative Research Centre of Okayama University for Infectious Diseases, ICMR-National Institute of Cholera and Enteric Diseases, Kolkata, India; 3Department of Infection and Immunology, Translational Health Science and Technology Institute, Faridabad, India; 4Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama, JapanCorrespondence: Goutam Chowdhury; Asish K Mukhopadhyay, Division of Bacteriology, ICMR-National Institute of Cholera and Enteric Diseases, P-33, CIT Road, Scheme XM, Beliaghata, Kolkata, 700010, India, Email goutambiotech@gmail.com; asish_mukhopadhyay@yahoo.comPurpose: The multidrug resistance Enterobacteriaceae cause many serious infections resulting in prolonged hospitalization, increased treatment charges and mortality rate. In this study, we characterized blaNDM-5-positive multidrug resistance commensal Escherichia coli (CE) isolated from diarrheal patients in Kolkata, India.Methods: Three CE strains were isolated from diarrheal stools, which were negative for different pathogroups of diarrheagenic E. coli (DEC). The presence of carbapenemases encoding genes and other antimicrobial resistance genes (ARGs) was detected using PCR. The genetic arrangement adjoining blaNDM-5 was investigated by plasmid genome sequencing. The genetic relatedness of the strains was determined by pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST) methods.Results: In addition to colistin, the blaNDM-5-positive CE strains showed resistance to most of the antibiotics. Higher MICs were detected for ciprofloxacin (> 32 mg/L) and imipenem (8 mg/L). Molecular typing revealed that three CE strains belonged to two different STs (ST 101 and ST 648) but they were 95% similar in the PFGE analysis. Screening for ARGs revealed that CE strains harbored Int-1, blaTEM, blaCTX-M3, blaOXA-1, blaOXA-7, blaOXA-9, tetA, strA, aadA1, aadB, sul2, floR, mph(A), and aac(6´)-Ib-cr. In conjugation experiment, transfer frequencies ranged from 2.5× 10− 3 to 8.4x10− 5. The blaNDM-5 gene was located on a 94-kb pNDM-TC-CE-89 type plasmid, which is highly similar to the IncFII plasmid harboring an IS26-IS30-blaNDM-5-bleMBL-trpF-dsbd-IS 91-dhps structure.Conclusion: To the best of our knowledge, this is the first report on carbapenem resistance involving the blaNDM-5 gene in CE from diarrheal patients. The circulation of blaNDM-5 gene in CE is worrisome, since it has the potential to transfer blaNDM-5 gene to other enteric pathogens.Keywords: antimicrobial resistance, carbapenem-resistance, commensal E. coli, plasmid; blaNDM-5

In group-living animals, heterogeneity in individuals' social connections may mediate the sharing of microbial infectious agents. In this regard, the genetic relatedness of individuals' commensal gut bacterium Escherichia coli may be ideal to assess the potential for pathogen transmission through animal social networks. Here we use microbial phylogenetics and population genetics approaches, as well as host social network reconstruction, to assess evidence for the contact-mediated sharing of E. coli among three groups of captively housed rhesus macaques (Macaca mulatta), at multiple organizational scales. For each group, behavioral data on grooming, huddling, and aggressive interactions collected for a six-week period were used to reconstruct social network communities via the Data Cloud Geometry (DCG) clustering algorithm. Further, an E. coli isolate was biochemically confirmed and genotypically fingerprinted from fecal swabs collected from each macaque. Population genetics approaches revealed that Group Membership, in comparison to intrinsic attributes like age, sex, and/or matriline membership of individuals, accounted for the highest proportion of variance in E. coli genotypic similarity. Social network approaches revealed that such sharing was evident at the community-level rather than the dyadic level. Specifically, although we found no links between dyadic E. coli similarity and social contact frequencies, similarity was significantly greater among macaques within the same social network communities compared to those across different communities. Moreover, tests for one of our study-groups confirmed that E. coli isolated from macaque rectal swabs were more genotypically similar to each other than they were to isolates from environmentally deposited feces. In summary, our results suggest that among frequently interacting, spatially constrained macaques with complex social relationships, microbial sharing via fecal-oral, social contact-mediated routes may depend on both individuals' direct connections and on secondary network pathways that define community structure. They lend support to the hypothesis that social network communities may act as bottlenecks to contain the spread of infectious agents, thereby encouraging disease control strategies to focus on multiple organizational scales. Future directions includeincreasing microbial sampling effort per individual to better-detect dyadic transmission events, and assessments of the co-evolutionary links between sociality, infectious agent risk, and host immune function.

Either extracts, cell-free suspensions or bacterial suspensions are used to study bacterial lipid peroxidation processes. Along with gas chromatography-mass spectrometry, liquid chromatography-mass spectrometry, and several other strategies, the thiobarbituric acid test is used for the determination of malondialdehyde (MDA) as the basis for the commercial test kits and the colorimetric detection of lipid peroxidation. The aim of the current study was to evaluate lipid peroxidation processes levels in the suspensions, extracts and culture supernatants of Escherichia coli and Salmonella Derby strains. The dependence of the formation of thiobarbituric acid-reactive substances levels in the cell extracts, the suspensions and cell-free supernatants on bacterial species, and their concentration and growth phase were revealed. The effect of bacterial concentrations on MDA formation was also found to be more pronounced in bacterial suspensions than in extracts, probably due to the dynamics of MDA release into the intercellular space. This study highlights the possible importance of MDA determination in both cell-free suspensions and extracts, as well as in bacterial suspensions to elucidate the role of lipid peroxidation processes in bacterial physiology, bacteria–host interactions, as well as in host physiology. [ABSTRACT FROM AUTHOR]

Purpose: The multidrug resistance Enterobacteriaceae cause many serious infections resulting in prolonged hospitalization, increased treatment charges and mortality rate. In this study, we characterized blaNDM-5-positive multidrug resistance commensal Escherichia coli (CE) isolated from diarrheal patients in Kolkata, India. Methods: Three CE strains were isolated from diarrheal stools, which were negative for different pathogroups of diarrheagenic E. coli (DEC). The presence of carbapenemases encoding genes and other antimicrobial resistance genes (ARGs) was detected using PCR. The genetic arrangement adjoining blaNDM-5 was investigated by plasmid genome sequencing. The genetic relatedness of the strains was determined by pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST) methods. Results: In addition to colistin, the blaNDM-5-positive CE strains showed resistance to most of the antibiotics. Higher MICs were detected for ciprofloxacin (> 32 mg/L) and imipenem (8 mg/L). Molecular typing revealed that three CE strains belonged to two different STs (ST 101 and ST 648) but they were 95% similar in the PFGE analysis. Screening for ARGs revealed that CE strains harbored Int-1, blaTEM, blaCTX-M3, blaOXA-1, blaOXA-7, blaOXA-9, tetA, strA, aadA1, aadB, sul2, floR, mph(A), and aac(6´)-Ib-cr. In conjugation experiment, transfer frequencies ranged from 2.5× 10− 3 to 8.4x10− 5. The blaNDM-5 gene was located on a 94-kb pNDM-TC-CE-89 type plasmid, which is highly similar to the IncFII plasmid harboring an IS26-IS30-blaNDM-5-bleMBL-trpF-dsbd-IS 91-dhps structure. Conclusion: To the best of our knowledge, this is the first report on carbapenem resistance involving the blaNDM-5 gene in CE from diarrheal patients. The circulation of blaNDM-5 gene in CE is worrisome, since it has the potential to transfer blaNDM-5 gene to other enteric pathogens. [ABSTRACT FROM AUTHOR]

Aims: Antimicrobial resistance (AMR) is a significant public health concern of modern civilization. The potential risk of AMR is significant in terms of both human and animal health. This study aims to assess the antimicrobial resistance pattern of selected antimicrobials against Escherichia coli of animal, poultry and human origin in the Cumilla district of Bangladesh. Methodology and results: A total of 200 samples were collected from different sources. Isolation and identification of commensal E. coli were performed following standard bacteriological and molecular techniques. Antimicrobial susceptibility testing was performed following the Kirby-Bauer disc diffusion technique. Ampicillin, tetracycline and sulfamethoxazole-trimethoprim resistance genes were detected by polymerase chain reactions (PCR). A total of 152 (76%; 95% confidence interval (CI) 70-81%) E. coli were isolated from cattle, sheep, chicken and human, where 37.5% of isolates were found to be multidrug-resistant (MDR). In the cultural sensitivity test, E. coli showed the highest resistance to sulfamethoxazole-trimethoprim (71%), tetracycline (63%), ampicillin (62%), where gentamicin (23%) showed the lowest resistance, followed by ceftriaxone (26%). The prevalence of resistance genes like blaTEM, tetA, tetB, tetC, sul1 and sul2 were 100%, 95%, 11%, 8%, 58% and 52%, respectively. Conclusion, significance and impact of study: The emergence of multidrug-resistant commensal E. coli and resistance genes circulating in animals, poultry and humans limit the treatment options for serious infections. [ABSTRACT FROM AUTHOR]

Introduction: Commensal Escherichia coli is defined as bacteria without known virulence factors that could be playing a specific role in some diseases; however, they could be responsible to disseminate antimicrobial resistance genes to other microorganisms. This study aimed to characterize the commensal E. coli isolates obtained from slaughtered sheep in the central region of Mexico. Methodology: Isolates were classified as commensal E. coli when distinctive genes related to diarrheagenic pathotypes (stx1, stx2, eae, bfp, LT, stp, ipaH, and aggR) were discarded by PCR. Identification of serotype, phylogenetic group, and antimicrobial resistance was also performed. Results: A total of 41 isolates were characterized. The phylogenetic groups found were B1 in 37 isolates (90.2%), A in 2 (4.8%), and 1 isolate (2.4%) for C and D groups. Serotypes associated with diarrhea in humans (O104:H2 and O154:NM) and hemolytic uremic syndrome (O8:NM) were detected. Thirty-three isolates (80%) were resistant to ceftazidime, 23 (56%), to tetracycline 8 (19.5%) to ampicillin, and 1 to amikacin. Six isolates (14.6%) were multidrug-resistant. Conclusions: This study provides new information about commensal E. coli in slaughtered sheep, high percentages of resistance to antibiotics, and different profiles of antimicrobial resistance were found, their dissemination constitute a risk factor towards the consuming population. [ABSTRACT FROM AUTHOR]

Objective: The aim of this study was to detect potential animal reservoirs of Escherichia coli carrying the mcr-1 gene in an Ecuadorian household. Methods: The mobile colistin-resistance gene, mcr-1, was first detected in Ecuador in a commensal E. coli isolate from a boy. A cross-sectional study was performed to detect the possible source of colistin-resistant E. coli in the boy’s household. Faecal swabs and soil faecal samples were collected from companion animals. Samples were plated on selective media to isolate colistin-resistant E. coli and isolates were submitted to PCR detection of mcr-1, pulsed field gel electrophoresis (PFGE), and multi-locus sequences typing (MLST). Moreover, the genomes of all the isolates were sequenced. Results: Three different colistin-resistant E. coli sequence types (ST3941, 1630 and 2170), corresponding to three PFGE patterns, were obtained from a chicken and two dogs; these isolates were different from the human isolate (ST609). By whole-genome sequencing, the mcr-1.1 gene was found on IncI2 plasmids with very high nucleotide identity. Conclusions: Our results indicate a polyclonal dissemination of mcr-1.1 in the environment surrounding the first MCR-producing E. coli strain reported in Ecuador. Our findings support the idea of lateral dissemination of mcr-1.1 gene between unrelated E. coli isolates.

Abstract Community‐acquired urinary tract infections (UTIs) are one of the most common bacterial infections worldwide. Escherichia coli is the most common cause of community‐acquired UTI. In general, UTI results from E. coli in the intestine that enters the bladder via the urethra. However, whether these E. coli strains that cause UTI represent members of the intestinal commensal E. coli or a distinct subgroup of pathogenic E. coli remains unestablished. Here, we analyzed E. coli isolates from fecal samples of healthy volunteers and urine samples of UTI patients obtained from a university‐affiliated health center. The E. coli isolates were genotyped by multilocus sequence typing (MLST). From May to October 2018, we analyzed 89 E. coli isolates from 76 (75%) rectal swabs from 113 unique healthy volunteers. We also analyzed 106 (27%) E. coli isolates from 398 unique urine samples collected between August and October 2018. Fecal and urine E. coli isolates each contained 31 distinct sequence types (STs). Nine STs were shared by fecal and urine E. coli isolates, which accounted for approximately 50% of urine isolates typed by MLST. Among the shared genotypes, ST10 and ST131 were significantly more frequently found in fecal samples, whereas ST95 and ST127 were significantly more frequently recovered from UTI samples. ST73 was found only among urine samples. These E. coli genotypes clustered and fluctuated over time. These observations suggest that E. coli genotypes found to cause UTI transiently colonize the intestine and that their primary reservoir may reside outside of the human intestine.

ABSTRACT: The transmission of antimicrobial resistance bacteria from animals to humans has become an important concern. The extended-spectrum beta-lactamase (ESBL) -AmpC- producing Escherichia coli (ESBL-AmpC EC) and quinolones resistant E. coli are of particular interest. The present study aimed to evaluate the load and prevalence of antibiotic-resistant commensal E. coli along the goose production cycle on 2 free-range farms in central Italy. On A farm, oxytetracycline was administered, while the B farm did not use antibiotics during the geese productive cycle. One hundred geese of 1-day-old from the same batch were divided into the two farms. At hatching, the animals showed an average of E. coli loads was 6.83 ± 0.48 log CFU/g, and 0.28 ± 0.28, 0, 5.12 ± 0.54 log CFU/g for E. coli resistant to nalidixic acid (E. colinal), to cefotaxime (E. colicef) and to tetracyclines (E. colitet), respectively. The loads of E. coli, E. colinal, E. colicef and E. colitet on 224 environmental faecal pools were determined at 8 time points. Antimicrobial susceptibility and molecular characterization of E. colicef isolates were performed. The ANOVA was used to assess the difference in bacterial loads between the two farms. We described more than 50% of resistances for tetracyclines in both farms, and sulphonamides and cephazolin in the A farm. The loads of E. coli and E. colinal in faeces were estimated at approximately 6–7 log (CFU/g) and 5–6 log (CFU/g) in the two farms, respectively. The average load of extended-spectrum beta-lactamase Escherichia coli (ESBL EC) in goose faeces varied broadly along the production cycle: in the first weeks, a sharp increase was observed in both farms, while later on A farm, the burden of ESBL EC remained steady until the end of the production cycle and on B farm the load dramatically decreased from 6 wk of age onward. An increase in the proportion of E. colinal was observed on A farm shortly after the antibiotic administration. Our study shows that the dynamics of antibiotic-resistant E. coli in farmed geese are similar to the ones observed in broilers. However, the risk of the emergence of antibiotic-resistant commensal E. coli, might be mitigated by the adoption of good management practices, including prudent use of antibiotics.

Either extracts, cell-free suspensions or bacterial suspensions are used to study bacterial lipid peroxidation processes. Along with gas chromatography-mass spectrometry, liquid chromatography-mass spectrometry, and several other strategies, the thiobarbituric acid test is used for the determination of malondialdehyde (MDA) as the basis for the commercial test kits and the colorimetric detection of lipid peroxidation. The aim of the current study was to evaluate lipid peroxidation processes levels in the suspensions, extracts and culture supernatants of Escherichia coli and Salmonella Derby strains. The dependence of the formation of thiobarbituric acid-reactive substances levels in the cell extracts, the suspensions and cell-free supernatants on bacterial species, and their concentration and growth phase were revealed. The effect of bacterial concentrations on MDA formation was also found to be more pronounced in bacterial suspensions than in extracts, probably due to the dynamics of MDA release into the intercellular space. This study highlights the possible importance of MDA determination in both cell-free suspensions and extracts, as well as in bacterial suspensions to elucidate the role of lipid peroxidation processes in bacterial physiology, bacteria–host interactions, as well as in host physiology.

Globally, urban water bodies have emerged as an environmental reservoir of antimicrobial resistance (AMR) genes because resistant bacteria residing here might easily disseminate these traits to other waterborne pathogens. In the present study, we have investigated the AMR phenotypes, prevalent plasmid-mediated AMR genes, and integrons in commensal strains of Escherichia coli, the predominant fecal indicator bacteria isolated from a major urban river of northern India Yamuna. The genetic environment of blaCTX–M–15 was also investigated. Our results indicated that 57.5% of the E. coli strains were resistant to at least two antibiotic classes and 20% strains were multidrug resistant, i.e., resistant to three or more antibiotic classes. The multiple antibiotic resistance index of about one-third of the E. coli strains was quite high (>0.2), reflecting high contamination of river Yamuna with antibiotics. With regard to plasmid-mediated AMR genes, blaTEM–1 was present in 95% of the strains, followed by qnrS1 and armA (17% each), blaCTX–M–15 (15%), strA-strB (12%), and tetA (7%). Contrary to the earlier reports where blaCTX–M–15 was mostly associated with pathogenic phylogroup B2, our study revealed that the CTX-M-15 type extended-spectrum β-lactamases (ESBLs) were present in the commensal phylogroups A and B1, also. The genetic organization of blaCTX–M–15 was similar to that reported for E. coli, isolated from other parts of the world; and ISEcp1 was present upstream of blaCTX–M–15. The integrons of classes 2 and 3 were absent, but class 1 integron gene intI1 was present in 75% of the isolates, denoting its high prevalence in E. coli of river Yamuna. These evidences indicate that due to high prevalence of plasmid-mediated AMR genes and intI1, commensal E. coli can become vehicles for widespread dissemination of AMR in the environment. Thus, regular surveillance and management of urban rivers is necessary to curtail the spread of AMR and associated health risks.

Globally, urban water bodies have emerged as an environmental reservoir of antimicrobial resistance (AMR) genes because resistant bacteria residing here might easily disseminate these traits to other waterborne pathogens. In the present study, we have investigated the AMR phenotypes, prevalent plasmid-mediated AMR genes, and integrons in commensal strains of Escherichia coli , the predominant fecal indicator bacteria isolated from a major urban river of northern India Yamuna. The genetic environment of bla CTX–M– 15 was also investigated. Our results indicated that 57.5% of the E. coli strains were resistant to at least two antibiotic classes and 20% strains were multidrug resistant, i.e., resistant to three or more antibiotic classes. The multiple antibiotic resistance index of about one-third of the E. coli strains was quite high (>0.2), reflecting high contamination of river Yamuna with antibiotics. With regard to plasmid-mediated AMR genes, bla TEM– 1 was present in 95% of the strains, followed by q nr S1 and arm A (17% each), bla CTX–M– 15 (15%), str A -str B (12%), and tet A (7%). Contrary to the earlier reports where bla CTX–M– 15 was mostly associated with pathogenic phylogroup B2, our study revealed that the CTX-M-15 type extended-spectrum β-lactamases (ESBLs) were present in the commensal phylogroups A and B1, also. The genetic organization of bla CTX–M– 15 was similar to that reported for E. coli , isolated from other parts of the world; and IS Ecp1 was present upstream of bla CTX–M– 15. The integrons of classes 2 and 3 were absent, but class 1 integron gene intI1 was present in 75% of the isolates, denoting its high prevalence in E. coli of river Yamuna. These evidences indicate that due to high prevalence of plasmid-mediated AMR genes and intI1 , commensal E. coli can become vehicles for widespread dissemination of AMR in the environment. Thus, regular surveillance and management of urban rivers is necessary to curtail the spread of AMR and associated health risks. [ABSTRACT FROM AUTHOR]

Carriage of resistant bacteria and spread of antimicrobial resistance (AMR) in the environment through animal manure pose a potential risk for transferring AMR from poultry and poultry products to the human population. Managing this risk is becoming one of the most important challenges in livestock farming. This study focused on monitoring the prevalence of multi-drug resistance (MDR) bacteria and development of AMR depending on flooring. In two experiments (2 × 15,000 birds), broilers were always divided in two different stables. In the control group, the entire floor pen was covered with litter material and in the experimental group, the flooring system was partly modified by installing elevated slat platforms equipped with water lines and feed pans. Over the whole fattening period, excreta and manure samples were taken (days 2, 22, and 32). In total, 828 commensal E. coli isolates were collected. The development and prevalence of resistance against four different antibiotic classes (quinolones, β-lactams, tetracyclines, and sulfonamides) were examined by using broth microdilution. At the end of the trials, the amount of manure per square metre was twice as high below the elevated platforms compared to the control group. Approximately 58% of E. coli isolates from excreta showed resistance against at least one antibacterial agent at day 2. During and at the end of the fattening period, resistant E. coli isolates at least against one of the four antibacterial agents were observed in excreta (46 and 46%, respectively), and manure samples (14 and 42%, respectively), despite the absence of antibacterial agent usage. In spite of less contact to manure in the experimental group, the prevalence of resistant E. coli isolates was significantly higher. Birds preferred the elevated areas which inevitably led to a local high population density. Animal-to-animal contact seems to be more important for spreading antimicrobial resistant bacteria than contact to the litter-excreta mixture. Therefore, attractive areas in poultry housing inducing crowding of animals might foster transmission of AMR. In poultry farming, enrichment is one of the most important aims for future systems. Consequently, there is a need for keeping birds not carrying resistant bacteria at the start of life.

Carriage of resistant bacteria and spread of antimicrobial resistance (AMR) in the environment through animal manure pose a potential risk for transferring AMR from poultry and poultry products to the human population. Managing this risk is becoming one of the most important challenges in livestock farming. This study focused on monitoring the prevalence of multi-drug resistance (MDR) bacteria and development of AMR depending on flooring. In two experiments (2 × 15,000 birds), broilers were always divided in two different stables. In the control group, the entire floor pen was covered with litter material and in the experimental group, the flooring system was partly modified by installing elevated slat platforms equipped with water lines and feed pans. Over the whole fattening period, excreta and manure samples were taken (days 2, 22, and 32). In total, 828 commensal E. coli isolates were collected. The development and prevalence of resistance against four different antibiotic classes (quinolones, β-lactams, tetracyclines, and sulfonamides) were examined by using broth microdilution. At the end of the trials, the amount of manure per square metre was twice as high below the elevated platforms compared to the control group. Approximately 58% of E. coli isolates from excreta showed resistance against at least one antibacterial agent at day 2. During and at the end of the fattening period, resistant E. coli isolates at least against one of the four antibacterial agents were observed in excreta (46 and 46%, respectively), and manure samples (14 and 42%, respectively), despite the absence of antibacterial agent usage. In spite of less contact to manure in the experimental group, the prevalence of resistant E. coli isolates was significantly higher. Birds preferred the elevated areas which inevitably led to a local high population density. Animal-to-animal contact seems to be more important for spreading antimicrobial resistant bacteria than contact to the litter-excreta mixture. Therefore, attractive areas in poultry housing inducing crowding of animals might foster transmission of AMR. In poultry farming, enrichment is one of the most important aims for future systems. Consequently, there is a need for keeping birds not carrying resistant bacteria at the start of life. [ABSTRACT FROM AUTHOR]

The spread of resistant bacteria from livestock to the food industry promoted an increase of alternative poultry production systems, such as organic and antibiotic-free ones, based on the lack of antimicrobial use, except in cases in which welfare is compromised. We aimed to investigate the antibiotic susceptibility of commensal Escherichia coli isolated from organic, antibiotic-free, and conventional broiler farms and slaughterhouses toward several antimicrobials critically important for human health. To assess antimicrobial susceptibility, all E. coli isolates and extended spectrum beta-lactamase (ESBL) E. coli were analysed by the microdilution method. The prevalence of tigecycline, azithromycin and gentamicin E. coli-resistant strains was highest in organic samplings. Conversely, the lowest prevalence of resistant E. coli strains was observed for cefotaxime, ceftazidime and ciprofloxacin in organic systems, representing a significant protective factor compared to conventional systems. All E. coli strains were colistin-susceptible. Contamination of the external environment by drug-resistant bacteria could play a role in the presence of resistant strains detected in organic systems. Of interest is the highest prevalence of cephalosporin resistance of E. coli in conventional samplings, since they are not permitted in poultry. Our results suggest that monitoring of antibiotic resistance of the production chain may be helpful to detect “risks” inherent to different rearing systems.

We analyzed and compared genomes of Extended Spectrum Beta-Lactamase (ESBL)-producing Escherichia coli from pigs and pig farm workers at 116 farms in Vietnam. Analyses revealed the presence of blaCTX-M-55, blaCTX-M-27, blaCTX-M-15, blaCTX-M-14, blaCTX-M-3, blaCTX-M-65, blaCTX-M-24, blaDHA-1, and blaCMY2 in both hosts. Most strains from pigs contained quinolones (qnr) and colistin resistance genes (mcr-1 and mcr-3). Isolates predominantly harbored more than one plasmid replicon and some harbored plasmid replicons on the same contigs as the ESBL genes. Five strains from farm workers of ST38 (2), ST69 (1), and ST1722 (2) were classified as either uropathogenic E. coli (UPECHM)/extraintestinal pathogenic E. coli (ExPECJJ) or UPECHM, and the remaining were genetically distinct commensals. A high heterogeneity was found among the ESBL-producing E. coli from pigs and workers, with most isolates belonging to unrelated phylogroups, serogroups, and sequence types with >4046 Single-Nucleotide Polymorphisms-(SNPs). In comparing the genomes of pig isolates to those from humans, it appeared that ESBL-producing E. coli in workers did not predominantly originate from pigs but were rather host-specific. Nevertheless, the occurrence of ESBL-producing E. coli carrying plasmid-mediated colistin and quinolone resistance genes in pigs could represent a potential source for horizontal transmission to humans through food rather than direct contact.

Intensive pig production systems often rely on the use of antimicrobials and heavy metal feed additives to maintain animal health and welfare. To gain insight into the carriage of antimicrobial resistance genes (ARGs) in the faecal flora of commercially reared healthy swine, we characterised the genome sequences of 117 porcine commensal E. coli that carried the class 1 integrase gene (intI1+). Isolates were sourced from 42 healthy sows and 126 of their offspring from a commercial breeding operation in Australia in 2017. intI1+ E. coli was detected in 28/42 (67%) sows and 90/126 (71%) piglets. Phylogroup A, particularly clonal complex 10, and phylogroup B1 featured prominently in the study collection. ST10, ST20, ST48 and ST361 were the dominant sequence types. Notably, 113/117 isolates (96%) carried three or more ARGs. Genes encoding resistance to β-lactams, aminoglycosides, trimethoprim, sulphonamides, tetracyclines and heavy metals were dominant. ARGs encoding resistance to last-line agents, such as carbapenems and third generation cephalosporins, were not detected. IS26, an insertion sequence noted for its ability to capture and mobilise ARGs, was present in 108/117 (92%) intI1+ isolates, and it played a role in determining class 1 integron structure. Our data shows that healthy Australian pig faeces are an important reservoir of multidrug resistant E. coli that carry genes encoding resistance to multiple first-generation antibiotics and virulence-associated genes.

Colicins are specific and potent toxins produced by Enterobacteriaceae that result in the rapid elimination of sensitive cells. Colicin production is commonly found throughout microbial populations, suggesting its potential importance for bacterial survival in complex microbial environments. Nonetheless, as colicin biology has been predominately studied using synthetic models, it remains unclear how colicin production contributes to survival and fitness of a colicin-producing commensal strain in a natural environment. To address this gap, we took advantage of MP1, an E. coli strain that harbors a colicinogenic plasmid and is a natural colonizer of the murine gut. Using this model, we validated that MP1 is competent for colicin production and then directly interrogated the importance of colicin production and immunity for MP1 survival in the murine gut. We showed that colicin production is dispensable for sustained colonization in the unperturbed gut. A strain lacking colicin production or immunity shows minimal fitness defects and can resist displacement by colicin producers. This report extends our understanding of the role that colicin production may play for E. coli during gut colonization and suggests that colicin production is not essential for a commensal to persist in its physiologic niche in the absence of exogenous challenges.

Escherichia coli is a facultative anaerobic symbiont found widely among mammalian gastrointestinal tracts. Several human studies have reported increased commensal E. coli abundance in the intestine during inflammation; however, host immunological responses toward commensal E. coli during inflammation are not well-defined. Here, we show that colonization of gnotobiotic mice with different genotypes of commensal E. coli isolated from healthy conventional microbiota mice and representing distinct populations of E. coli elicited strain-specific disease phenotypes and immunopathological changes following treatment with the inflammatory stimulus, dextran sulfate sodium (DSS). Production of the inflammatory cytokines GM-CSF, IL-6, and IFN-γ was a hallmark of the severe inflammation induced by E. coli strains of Sequence Type 129 (ST129) and ST375 following DSS administration. In contrast, colonization with E. coli strains ST150 and ST468 caused mild intestinal inflammation and triggered only low levels of pro-inflammatory cytokines, a response indistinguishable from that of E. coli-free control mice treated with DSS. The disease development observed with ST129 and ST375 colonization was not directly associated with their abundance in the GI tract as their levels did not change throughout DSS treatment, and no major differences in bacterial burden in the gut were observed among the strains tested. Data mining and in vivo neutralization identified IL-6 as a key cytokine responsible for the observed differential disease severity. Collectively, our results show that the capacity to exacerbate acute intestinal inflammation is a strain-specific trait that can potentially be overcome by blocking the pro-inflammatory immune responses that mediate intestinal tissue damage.

Intestinal colonization by the foodborne pathogen Escherichia coli O157:H7 leads to serious disease symptoms, including hemolytic uremic syndrome (HUS) and hemorrhagic colitis (HC). Synthesis of one or more Shiga toxins (Stx) is essential for HUS and HC development. The genes encoding Stx, including Stx2a, are found within a lambdoid prophage integrated in the E. coli O157:H7 chromosome. Enhanced Stx2a expression was reported when specific non-pathogenic E. coli strains were co-cultured with E. coli O157:H7, and it was hypothesized that this phenotype required the non-pathogenic E. coli to be sensitive to stx-converting phage infection. We tested this hypothesis by generating phage resistant non-pathogenic E. coli strains where bamA (an essential gene and Stx phage receptor) was replaced with an ortholog from other species. Such heterologous gene replacement abolished the ability of the laboratory strain E. coli C600 to enhance toxin production when co-cultured with E. coli O157:H7 strain PA2, which belongs to the hypervirulent clade 8. The extracellular loops of BamA (loop 4, 6, 7) were further shown to be important for infection by stx2a-converting phages. However, similar gene replacement in another commensal E. coli, designated 1.1954, revealed a bamA-independent mechanism for toxin amplification. Toxin enhancement by 1.1954 was not the result of phage infection through an alternative receptor (LamB or FadL), lysogen formation by stx2a-converting phages, or the production of a secreted molecule. Collectively, these data suggest that non-pathogenic E. coli can enhance toxin production through at least two mechanisms.

In group-living animals, heterogeneity in individuals’ social connections may mediate the sharing of microbial infectious agents. In this regard, the genetic relatedness of individuals’ commensal gut bacterium Escherichia coli may be ideal to assess the potential for pathogen transmission through animal social networks. Here we use microbial phylogenetics and population genetics approaches, as well as host social network reconstruction, to assess evidence for the contact-mediated sharing of E. coli among three groups of captively housed rhesus macaques (Macaca mulatta), at multiple organizational scales. For each group, behavioral data on grooming, huddling, and aggressive interactions collected for a six-week period were used to reconstruct social network communities via the Data Cloud Geometry (DCG) clustering algorithm. Further, an E. coli isolate was biochemically confirmed and genotypically fingerprinted from fecal swabs collected from each macaque. Population genetics approaches revealed that Group Membership, in comparison to intrinsic attributes like age, sex, and/or matriline membership of individuals, accounted for the highest proportion of variance in E. coli genotypic similarity. Social network approaches revealed that such sharing was evident at the community-level rather than the dyadic level. Specifically, although we found no links between dyadic E. coli similarity and social contact frequencies, similarity was significantly greater among macaques within the same social network communities compared to those across different communities. Moreover, tests for one of our study-groups confirmed that E. coli isolated from macaque rectal swabs were more genotypically similar to each other than they were to isolates from environmentally deposited feces. In summary, our results suggest that among frequently interacting, spatially constrained macaques with complex social relationships, microbial sharing via fecal-oral, social contact-mediated routes may depend on both individuals’ direct connections and on secondary network pathways that define community structure. They lend support to the hypothesis that social network communities may act as bottlenecks to contain the spread of infectious agents, thereby encouraging disease control strategies to focus on multiple organizational scales. Future directions includeincreasing microbial sampling effort per individual to better-detect dyadic transmission events, and assessments of the co-evolutionary links between sociality, infectious agent risk, and host immune function.

Escherichia coli is a facultative anaerobic symbiont found widely among mammalian gastrointestinal tracts. Several human studies have reported increased commensal E. coli abundance in the intestine during inflammation; however, host immunological responses toward commensal E. coli during inflammation are not well-defined. Here, we show that colonization of gnotobiotic mice with different genotypes of commensal E. coli isolated from healthy conventional microbiota mice and representing distinct populations of E. coli elicited strain-specific disease phenotypes and immunopathological changes following treatment with the inflammatory stimulus, dextran sulfate sodium (DSS). Production of the inflammatory cytokines GM-CSF, IL-6, and IFN-γ was a hallmark of the severe inflammation induced by E. coli strains of Sequence Type 129 (ST129) and ST375 following DSS administration. In contrast, colonization with E. coli strains ST150 and ST468 caused mild intestinal inflammation and triggered only low levels of pro-inflammatory cytokines, a response indistinguishable from that of E. coli -free control mice treated with DSS. The disease development observed with ST129 and ST375 colonization was not directly associated with their abundance in the GI tract as their levels did not change throughout DSS treatment, and no major differences in bacterial burden in the gut were observed among the strains tested. Data mining and in vivo neutralization identified IL-6 as a key cytokine responsible for the observed differential disease severity. Collectively, our results show that the capacity to exacerbate acute intestinal inflammation is a strain-specific trait that can potentially be overcome by blocking the pro-inflammatory immune responses that mediate intestinal tissue damage. [ABSTRACT FROM AUTHOR]

Intestinal colonization by the foodborne pathogen Escherichia coli O157:H7 leads to serious disease symptoms, including hemolytic uremic syndrome (HUS) and hemorrhagic colitis (HC). Synthesis of one or more Shiga toxins (Stx) is essential for HUS and HC development. The genes encoding Stx, including Stx2a, are found within a lambdoid prophage integrated in the E. coli O157:H7 chromosome. Enhanced Stx2a expression was reported when specific non-pathogenic E. coli strains were co-cultured with E. coli O157:H7, and it was hypothesized that this phenotype required the non-pathogenic E. coli to be sensitive to stx-converting phage infection. We tested this hypothesis by generating phage resistant non-pathogenic E. coli strains where bamA (an essential gene and Stx phage receptor) was replaced with an ortholog from other species. Such heterologous gene replacement abolished the ability of the laboratory strain E. coli C600 to enhance toxin production when co-cultured with E. coli O157:H7 strain PA2, which belongs to the hypervirulent clade 8. The extracellular loops of BamA (loop 4, 6, 7) were further shown to be important for infection by stx2a-converting phages. However, similar gene replacement in another commensal E. coli, designated 1.1954, revealed a bamA-independent mechanism for toxin amplification. Toxin enhancement by 1.1954 was not the result of phage infection through an alternative receptor (LamB or FadL), lysogen formation by stx2a-converting phages, or the production of a secreted molecule. Collectively, these data suggest that non-pathogenic E. coli can enhance toxin production through at least two mechanisms. [ABSTRACT FROM AUTHOR]

Ethanolamine (EA) is a substrate naturally present in the human gut and its catabolism by bacteria relies on the presence of eut genes encoding specific metabolic enzymes and accessory proteins. To date, EA utilization has been mostly investigated in gut bacterial pathogens. The aim of this study was to evaluate the ability of human gut commensal Escherichia coli isolates to utilize EA as a nitrogen and/or carbon sources. Although the capacity to consume EA is heterogeneous between the 40 strains of our collection, we determined that most of them could degrade EA to generate ammonia, a useful nitrogen resource for growth. Three isolates were also able to exploit EA as a carbon source. We also revealed that the inability of some strains to catabolize EA is explained either by mutations in the eut locus or by a defect in gene transcription. Finally, we demonstrated the importance of EA utilization for an optimal fitness of commensal E. coli in vivo. Our study provides new insights on the diversity of commensal E. coli strains to utilize EA as a nutrient in the gut and opens the way for new research in the field of interactions between host, gut microbiota and pathogens. [ABSTRACT FROM AUTHOR]

Enterohemorrhagic E. coli (EHEC) is a food-borne pathogen that causes disease ranging from uncomplicated diarrhea to life-threatening hemolytic uremic syndrome (HUS) and nervous system complications. Shiga toxin 2 (Stx2) is the major virulence factor of EHEC and is critical for development of HUS. The genes encoding Stx2 are carried by lambdoid bacteriophages and the toxin production is tightly linked to the production of phages during lytic cycle. It has previously been suggested that commensal E. coli could amplify the production of Stx2-phages and contribute to the severity of disease. In this study we examined the susceptibility of commensal E. coli strains to the Stx2-converting phage ϕ734, isolated from a highly virulent EHEC O103:H25 (NIPH-11060424). Among 38 commensal E. coli strains from healthy children below five years, 15 were lysogenized by the ϕ734 phage, whereas lytic infection was not observed. Three of the commensal E. coli ϕ734 lysogens were tested for stability, and appeared stable and retained the phage for at least 10 cultural passages. When induced to enter lytic cycle by H2O2 treatment, 8 out of 13 commensal lysogens produced more ϕ734 phages than NIPH-11060424. Strikingly, five of them even spontaneously (non-induced) produced higher levels of phage than the H2O2 induced NIPH-11060424. An especially high frequency of HUS (60%) was seen among children infected by NIPH-11060424 during the outbreak in 2006. Based on our findings, a high Stx2 production by commensal E. coli lysogens cannot be ruled out as a contributor to the high frequency of HUS during this outbreak.

Enterohemorrhagic E. coli (EHEC) is a food-borne pathogen that causes disease ranging from uncomplicated diarrhea to life-threatening hemolytic uremic syndrome (HUS) and nervous system complications. Shiga toxin 2 (Stx2) is the major virulence factor of EHEC and is critical for development of HUS. The genes encoding Stx2 are carried by lambdoid bacteriophages and the toxin production is tightly linked to the production of phages during lytic cycle. It has previously been suggested that commensal E. coli could amplify the production of Stx2-phages and contribute to the severity of disease. In this study we examined the susceptibility of commensal E. coli strains to the Stx2-converting phage φ734, isolated from a highly virulent EHEC O103:H25 (NIPH-11060424). Among 38 commensal E. coli strains from healthy children below 5 years, 15 were lysogenized by the φ734 phage, whereas lytic infection was not observed. Three of the commensal E. coli φ734 lysogens were tested for stability, and appeared stable and retained the phage for at least 10 cultural passages. When induced to enter lytic cycle by H2O2 treatment, 8 out of 13 commensal lysogens produced more φ734 phages than NIPH-11060424. Strikingly, five of them even spontaneously (non-induced) produced higher levels of phage than the H2O2 induced NIPH-11060424. An especially high frequency of HUS (60%) was seen among children infected by NIPH-11060424 during the outbreak in 2006. Based on our findings, a high Stx2 production by commensal E. coli lysogens cannot be ruled out as a contributor to the high frequency of HUS during this outbreak. [ABSTRACT FROM AUTHOR]

The objective of the study was to examine the characteristics of the resistance profiles of Escherichia coli isolated from healthy pigs from three farms in Western Poland. The sensitivity to 13 antimicrobial agents was tested by a disk diffusion method, and the presence of 13 resistance genes was determined by PCR. The majority of the isolates were multi-resistant. The most common multi-resistance patterns were streptomycin, trimethoprim, sulfisoxazole, ampicillin, tetracycline. Although some resistance genes, such as strA/strB, blaTEM, sul1, sul2, and tetA, were equally represented in isolates from each farm, differences in the distribution of tetB and tetC, hfrV, dhfrXII, and sul1 resistance genes were observed among the isolates from different farms. Approximately one-third (35.9%) of the isolates possessed a class 1 integron. The four major different variable regions of the class 1 integron contained streptomycin (aadA1, aadA2, and aadA5) and/or trimethoprim (dhfrI, dhfrV and dhfrXVII), and/or sulphonamides (sul1) resistance genes. The results of this study emphasise that uncontrolled use of antibiotics causes the development of resistance and provides the evidence of frequent occurrence of more than one gene encoding the resistance to the same antimicrobial agent in the multi-resistant strains. [ABSTRACT FROM AUTHOR]

Purpose: The multidrug resistance Enterobacteriaceae cause many serious infections resulting in prolonged hospitalization, increased treatment charges and mortality rate. In this study, we characterized bla NDM-5 -positive multidrug resistance commensal Escherichia coli (CE) isolated from diarrheal patients in Kolkata, India., Methods: Three CE strains were isolated from diarrheal stools, which were negative for different pathogroups of diarrheagenic E. coli (DEC). The presence of carbapenemases encoding genes and other antimicrobial resistance genes (ARGs) was detected using PCR. The genetic arrangement adjoining bla NDM-5 was investigated by plasmid genome sequencing. The genetic relatedness of the strains was determined by pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST) methods., Results: In addition to colistin, the bla NDM-5 -positive CE strains showed resistance to most of the antibiotics. Higher MICs were detected for ciprofloxacin (>32 mg/L) and imipenem (8 mg/L). Molecular typing revealed that three CE strains belonged to two different STs (ST 101 and ST 648) but they were 95% similar in the PFGE analysis. Screening for ARGs revealed that CE strains harbored Int-1, bla TEM , bla C TX-M3 , bla OXA-1 , bla OXA-7 , bla OXA-9 , tetA, strA, aadA1, aadB, sul2, floR, mph(A) , and aac(6´)-Ib-cr . In conjugation experiment, transfer frequencies ranged from 2.5×10 -3 to 8.4x10 -5 . The bla NDM-5 gene was located on a 94-kb pNDM-TC-CE-89 type plasmid, which is highly similar to the IncFII plasmid harboring an IS26-IS30- bla NDM-5 - ble MBL - trpF-dsbd -IS 91-dhps structure., Conclusion: To the best of our knowledge, this is the first report on carbapenem resistance involving the bla NDM-5 gene in CE from diarrheal patients. The circulation of bla NDM-5 gene in CE is worrisome, since it has the potential to transfer bla NDM-5 gene to other enteric pathogens., Competing Interests: The authors report no conflicts of interest in relation to this work., (© 2022 Chowdhury et al.)

The spread of resistant bacteria from livestock to the food industry promoted an increase of alternative poultry production systems, such as organic and antibiotic-free ones, based on the lack of antimicrobial use, except in cases in which welfare is compromised. We aimed to investigate the antibiotic susceptibility of commensal Escherichia coli isolated from organic, antibiotic-free, and conventional broiler farms and slaughterhouses toward several antimicrobials critically important for human health. To assess antimicrobial susceptibility, all E. coli isolates and extended spectrum beta-lactamase (ESBL) E. coli were analysed by the microdilution method. The prevalence of tigecycline, azithromycin and gentamicin E. coli-resistant strains was highest in organic samplings. Conversely, the lowest prevalence of resistant E. coli strains was observed for cefotaxime, ceftazidime and ciprofloxacin in organic systems, representing a significant protective factor compared to conventional systems. All E. coli strains were colistin-susceptible. Contamination of the external environment by drug-resistant bacteria could play a role in the presence of resistant strains detected in organic systems. Of interest is the highest prevalence of cephalosporin resistance of E. coli in conventional samplings, since they are not permitted in poultry. Our results suggest that monitoring of antibiotic resistance of the production chain may be helpful to detect "risks" inherent to different rearing systems. [ABSTRACT FROM AUTHOR]