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• Colistin is considered a critical antibiotic for human medicine. • The emergence of bacterial resistance to colistin is a major concern. • The mcr-1 gene led to a significant fitness cost in enterobacterial species. • The ban of colistin as a feed additive has had an encouraging outcome. • Colistin is a paradigmatic example of the success of a One Health intervention. Antimicrobial resistance (AMR) poses a serious threat to human, animal and environmental health worldwide. Colistin has regained importance as a last-resort treatment against multi-drug-resistant Gram-negative bacteria. However, colistin resistance has been reported in various Enterobacteriaceae species isolated from several sources. The 2015 discovery of the plasmid-mediated mcr-1 (mobile colistin resistance) gene conferring resistance to colistin was a major concern within the scientific community worldwide. The global spread of this plasmid – as well as the subsequent identification of 10 MCR-family genes and their variants that catalyse the addition of phosphoethanolamine to the phosphate group of lipid A – underscores the urgent need to regulate the use of colistin, particularly in animal production. This review traces the history of colistin resistance and mcr -like gene identification, and examines the impact of policy changes regarding the use of colistin on the prevalence of mcr-1- positive Escherichia coli and colistin-resistant E. coli from a One Health perspective. The withdrawal of colistin as a livestock growth promoter in several countries reduced the prevalence of colistin-resistant bacteria and its resistance determinants (e.g. mcr-1 gene) in farm animals, humans and the environment. This reduction was certainly favoured by the significant fitness cost associated with acquisition and expression of the mcr-1 gene in enterobacterial species. The success of this One Health intervention could be used to accelerate regulation of other important antimicrobials, especially those associated with bacterial resistance mechanisms linked to high fitness cost. The development of global collaborations and the implementation of sustainable solutions like the One Health approach are essential to manage AMR. [ABSTRACT FROM AUTHOR]

• Feeding calves with CEF-spicked milk selects ESBL-positive E. coli in gut. • Impact of CEF ingestion depends on the initial magnitude of ESBL shedding. • For ESBL-positive E. coli , the genetic diversity increases after CEF ingestion. • Two E. coli lineages initially present in gut persist after CEF ingestion. • A unique bla CTX-M-1 gene systematically located on a IncI1/ST3 plasmid is found. In the bovine sector, the spread of Enterobacterales producing extended-spectrum and AmpC β-lactamases (ESBL/AmpC) mostly concerns veal calves, and the use of waste milk containing antibiotic residues has been recurrently incriminated. In this study, calves were experimentally fed with milk containing either 2,000 μg/L or 20,000 μg/L of the critically important antibiotic cefquinome. The total counts of enterobacterales and ESBL-producing E. coli were monitored using non-selective and selective media. Our data highlighted the important combination of two main factors (cefquinome exposure and initial ESBL colonization level) in the ESBL selection and amplification process in the gut of calves. Results also proved the dose-independent effect of cefquinome administration on the selection and amplification of ESBL-producing E. coli. Finally, the bla CTX-M-1 /IncI1 ST3 plasmid was systematically recovered after cefquinome exposure, highlighting its epidemic success. Altogether, this work is one of the rare experimental studies providing quantitative information on the impact of waste milk containing antimicrobials on the ESBL load in calves' microbiota, and the first one using cefquinome. These data emphasise the need for global guidelines on the use of waste milk on dairy farms in order to decrease the antimicrobial resistance burden in this sector. [ABSTRACT FROM AUTHOR]

Dissemination of antimicrobial resistance in food animals is a One Health concern, but sheep production has been overlooked. This study aimed to explore the dissemination of Escherichia coli resistant to extended-spectrum cephalosporins (ESC) in feedlot lambs. Two pens were sampled on two occasions, and carcasses and other mammals living around were also tested. E. coli were recovered and antibiotic resistance determined. bla CTX-M/CMY genes and their genetic localization were characterized. Whole genome sequencing (WGS) was performed to confirm clonal relationship. The most prevalent ESC-resistance genes in the 108 E. coli isolates were bla CTX-M-55 (53.7 %), bla CTX-M-2 (14.8 %) and bla CMY-2 (13.9 %). Most bla CTX-M-55 genes were found on the chromosome, but IncA/C, IncHI1, IncHI2 and IncF plasmids were also identified. Genetic diversity was observed even though ST6448 was by far the most frequent ST. WGS analysis showed high similarity among isolates recovered from feedlot lambs, animals in the surroundings and lambs' carcasses, proving the clonal and plasmidic dissemination. • 10 %-37 % of lambs intended for human consumption carried ESC-resistant E. coli. • The ST6448-B1 clone was highly prevalent (50/108 isolates). • Plasmidic transfers were suspected for IncHI2-ST2/ bla CTX-M- and IncC-ST3/ bla CMY-2. • Identical isolates were identified in lambs, carcasses and surrounding animals. [ABSTRACT FROM AUTHOR]

• Resistances of P. multocida were almost all below 20% over the period 2012-2017. • Resistance to florfenicol was less than 1%, regardless of the animal species. • Resistance to fluoroquinolones increased in cattle isolates from 2012 to 2017. • Similarly in cattle, other resistance trends continuously increased over the period. Surveillance of Pasteurella multocida resistance in food-producing animals is essential to guide the first-line treatment of respiratory diseases and to limit economic losses. Since Pasteurella are the most common bacteria isolated from dog and cat bites, this surveillance is also needed to guide treatment in humans in case of bites. The aim of this study was to characterize the phenotypic resistance of P. multocida strains isolated from respiratory infections in animals, including both food-producing animals and pets. Data collected between 2012 and 2017 by the French national surveillance network for antimicrobial resistance referred to as RESAPATH were analyzed. The proportions of resistance to antimicrobials of relevance in veterinary and human medicines were estimated for each animal species. For cattle, resistance trends over the period were investigated using non-linear analysis applied to time-series. In total, 5356 P. multocida isolates were analyzed. Proportions of resistance of P. multocida were almost all below 20% over the period, and, more precisely, all resistance proportions were below 10% for rabbits, sheep and dogs. The highest resistance proportions to enrofloxacin were identified for cattle (4.5%) and dogs (5.2%). Despite its frequent use in livestock, resistance to florfenicol was less than 1% in P. multocida strains, regardless of the animal species considered. Time series analyses revealed continuous increases in resistance to tetracycline, tilmicosin, flumequine and fluoroquinolones in P. multocida strains isolated from cattle. These trends contrast with the decrease in use of antibiotics in cattle in France and with the decrease in resistance observed in E. coli isolated from diseased cattle. [ABSTRACT FROM AUTHOR]

In dairy cattle, mastitis is the most frequent bacterial disease, and the routine use of antibiotics for treatment and prevention can drive antimicrobial resistance (AMR). The aim of our study was to estimate the levels of AMR of the 3 main bacteria isolated from dairy cattle with mastitis in France (Streptococcus uberis, Escherichia coli, and coagulase-positive staphylococci) and to investigate their changes over time. Data collected between 2006 and 2016 by the French surveillance network for AMR in pathogenic bacteria of animal origin (called RESAPATH) were analyzed. The proportions of mono- and multidrug resistance were calculated and the trends were investigated using nonlinear analyses applied to time series. Over the whole period, the lowest proportions of resistance in S. uberis isolates were observed for oxacillin (2.2%) and gentamicin (2.4%) and most resistance levels were below 20%. The trends in resistance showed some significant variation, mainly for S. uberis, but without a common pattern across the various antibiotics examined. For only 2 combinations of bacteria-antibiotic the trend in resistance showed a continuous increase from 2006 to 2016: tetracycline resistance in S. uberis isolates and third-generation cephalosporin resistance in E. coli isolates. In E. coli, the highest proportions of resistance were observed for amoxicillin (28.1%) and tetracycline (23.1%). Resistance to third-generation cephalosporins in E. coli from dairy cattle was almost nil in 2006, but reached 2.4% in December 2016. This increase is particularly concerning because these antibiotics constitute one of the latest therapeutic alternatives to fight severe infectious diseases in humans. Except for penicillin (33.9%), the proportions of resistance in coagulase-positive staphylococci were below 11% during the whole study period. Multidrug resistance (isolates with acquired resistance to at least one antibiotic in 3 or more antibiotic classes) ranged from 2.4% for coagulase-positive staphylococci to 9.9% for S. uberis. These findings can serve as guidelines for practitioners in the choice of the most appropriate antibiotic according to the prevailing epidemiological context. Ultimately, our results contribute to risk assessment of AMR and provide a baseline for setting up and evaluating control measures and designing strategies to limit AMR. [ABSTRACT FROM AUTHOR]

Extended-spectrum beta-lactamase (ESBL)- and plasmid-mediated AmpC (pAmpC)-carrying Enterobacteriaceae have widely disseminated in human, animal and environmental reservoirs. Pets have been recognized as a source of ESBL/pAmpC worldwide, and are possibly also a source of human contamination. The aim of this study was to document to what extent cats and dogs may act as a driving force in the spread of ESBLs and pAmpCs in Brazil. A total of 113 healthy stray cats and dogs and 74 sick pets were sampled, and extended-spectrum cephalosporin-resistant Enterobacteriaceae (ESC-R) were detected in 28/113 (24.8%) and 8/74 (10.8%) tested animals, respectively. Different Enterobacteriaceae isolates (mostly E. coli ), a large number of E. coli clones (with ST90, ST457, ST973 and ST2541 being predominant), and several ESBL/pAmpC genes and plasmids were characterized, highlighting the ability of stray and pet cats and dogs to further spread a wide range of ESC-resistance determinants. The ESBL phenotype was due to the bla CTX-M-2 and bla CTX-M-8 genes, as found in human epidemiology in Brazil, but bla CTX-M-9 and bla CTX-M-15 were also identified. The pAmpC phenotype was systematically due to the presence of the bla CMY-2 gene, mostly carried by IncI1 ST12 plasmids. Our results showed that pets can be considered a significant reservoir of multidrug-resistant bacteria in Brazil. This is especially true for healthy stray dogs that displayed the highest prevalence (24.8%) of ESBLs/pAmpC resistance determinants, which can then be further spread both to the environment and to other animals or humans by contact. [ABSTRACT FROM AUTHOR]

Extended-spectrum beta-lactamases (ESBLs) have been recurrently reported in both human and veterinary medicine, and carbapenemases have also emerged in these two sectors. Such resistance phenotypes were increasingly reported in the environment, which both receives and further disseminates multidrug-resistant (MDR) bacteria. Here, we report the high contamination of water samples (68.2%; 15/22) collected in estuaries in Lebanon. From these 15 contaminated sites, a total of 21 ESBL-producing (mostly harbouring the bla CTX-M-15 gene) and four carbapenemase-producing (two bla OXA-48 and two bla OXA-244 ) Enterobacteriaceae were recovered. ESBL contamination was also identified in water samples collected from rural wells and spring water, although at a lower frequency. Indeed, 1.9% (3/155) and 6.1% (7/115) of the wells and springs were contaminated, respectively, and all identified isolates were CTX-M-15-producing E. coli . Interestingly, sequence types (STs) previously associated both with animal and human reservoirs were detected (ST38, ST10 and ST131), suggesting a complex source of contamination. This situation is alarming since water drawn from wells or springs is directly intended for human consumption in Lebanon without any further treatment. Moreover, even though water from estuaries is not intended for human consumption, it is used to water animals and irrigate crops. Consequently, water contamination by ESBLs and carbapenemases in Lebanon is potentially a major risk to public health. Part of this work was presented at the 7th Symposium on Antimicrobial Resistance in Animals and the Environment (ARAE). [ABSTRACT FROM AUTHOR]

The Rapid Polymyxin NP test has been recently developed to rapidly detect polymyxin resistance in Enterobacteriaceae. Here we evaluated this test for detecting MCR-1/MCR-2-producing Enterobacteriaceae using a collection of 70 non-redundant strains either recovered from the environment, animals, or humans. Sensitivity and specificity were found to be 100%. [ABSTRACT FROM AUTHOR]

Extended-spectrum cephalosporins (ESCs) are critically important antibiotics for humans and their use in animals poses a potential threat for public health. Chicken represents an increasing part of the human diet and has also been regarded as a source of ESC-resistant Enterobacteriaceae because of the worldwide off-label use of ceftiofur, a broad-spectrum cephalosporin. Thus, numerous studies pointed out chicken as a reservoir of ESBL/pAmpC genes, plasmids and/or clones at risk for humans. In France, late 2011, strong political pressure led to a drastic reduction of ceftiofur use and all other antibiotics in chicken production. Here, we ascertained the potential impact of those efforts on the prevalence of ESC-resistant E. coli in retail chicken. From October 2015 to January 2016, of 48 unrelated pieces of meat (chicken legs) belonging to four different brands, 44 (91.7%) were positive for ESC-resistant E. coli . The bla CTX-M-1 gene was highly prevalent (68/74, 91.9%), mostly located on IncI1/ST3 plasmids (65/68, 95.6%). Other ESBL/pAmpC genes ( bla TEM-52 , bla SHV-12 , bla CMY-2 ) were carried by IncX1, IncI1/ST36, IncI1/ST95, IncA/C or IncK plasmids. The positive isolates were non-clonal, suggesting a horizontal spread of the ESBL/pAmpC genes. Obviously, the strong decrease of antimicrobial use in chicken farms had no impact yet on the ESBL/pAmpC prevalence in retail chicken meat in France. A human source of these ESBL/pAmpC genes is unlikely as bla CTX-M-1 IncI1/ST3 plasmids are dominant in animals and rare in humans. Our data question the real impact of the decrease of antimicrobial use in chicken production on ESBL contamination of chicken meat and point out the risk of ESBL/AmpCs human transfer through the food chain. [ABSTRACT FROM AUTHOR]

The spread of Extended-Spectrum β-Lactamases (ESBLs) or AmpC β-Lactamases (AmpC) encoding genes in healthy human populations is of major concern. The role of the food chain has been questioned since numerous studies reported surface contamination of retail meat or crude vegetables with ESBL/AmpC-producing Enterobacteriaceae (ESBL/AmpC-E). Nonetheless, these food products are intended to be cooked or washed before consumption so that the risk of human transfer might be low. Here, the presence of ESBL/AmpC-E was investigated in ready-to-eat (RTE) sandwiches purchased in the street in the city of Bejaia, Algeria. Thirty ESBL/AmpC-producing E. coli (n = 18), K. pneumoniae (n = 11) and K. oxytoca (n = 1) were recovered from 21 sandwiches purchased in 14 of the 100 shops that were visited (14%). Twenty-four isolates (13 E. coli , 10 K. pneumoniae , 1 K. oxytoca ) produced one or two ESBLs, while 5 E. coli and 1 K. pneumoniae isolates produced an AmpC. Among those, 12 E. coli harbored bla CTX-M-1 (n = 7), bla CTX-M-15 (n = 3), bla CTX-M-14 (n = 1) or bla CTX-M-2 (n = 1) and one E. coli co-harbored the bla CTX-M-15 and bla SHV-2 genes. The 10 K. pneumoniae displayed bla CTX-M-15 (n = 7), bla SHV-2 (n = 3), bla SHV-12 (n = 1) or bla CTX-M-1 (n = 1), including two isolates presenting a bla CTX-M-15 /bla SHV-2 or bla CTX-M-1 /bla SHV-2 combination. The K. oxytoca harbored the bla SHV-2 gene, and one K. pneumoniae and four E. coli displayed bla DHA and bla CMY-2 , respectively. Most isolates (26/30, n = 87%) also possessed the aac(6′)-Ib-cr gene. Identical ESBL/AmpC-producing E. coli or K. pneumoniae clones were detected at different places across the city. This may reflect cross-contamination through poor handling practices, contaminated equipment, common ingredients or environmental factors. Of note, the emergent ST405 K. pneumoniae human clone was identified as a CTX-M-15 producer. This study highlights the presence of ESBL/AmpC-E in RTE sandwiches, which are a source of direct transfer to the human gut. These data indicate that fast food shops should be regarded as ESBL/AmpC reservoirs, and a risk for humans. Major efforts should be made in Algeria through guidelines on good practices in the food chain, and more globally in all countries sharing similar poor levels of food hygiene worldwide. [ABSTRACT FROM AUTHOR]

Resistant Enterobacterales of avian intestinal origin can contaminate carcasses during broiler processing and thereby spread through the human food chain. This study aimed at assessing the prevalence, diversity and genomic characteristics of ESBL/AmpC Enterobacterales in poultry flocks from different farms and cities in the state of Paraná, Brazil. Enterobacterales isolated from cloacal samples were subjected to antimicrobial susceptibility testing (AST). ESBL/AmpC isolates were whole-genome sequenced and subjected to S1-nuclease pulsed-field gel electrophoresis (S1-PFGE) followed by Southern blotting to determine the location of resistant genes on plasmids. A surprisingly high proportion of E. coli (40.6 %) collected on non-selective plates presented an ESBL/AmpC phenotype. Multidrug resistance was statistically not higher in ESBL/AmpC E. coli having the potential to be Avian Pathogenic (APEC-like) compared to non-APEC-like ESBL/AmpC E. coli isolates. Resistance to antibiotics not authorized for use in poultry in the State of Paraná was observed, suggesting that antimicrobial resistance (AMR) is co-selected by the use of veterinary-licensed antibiotics. Phylogenetic analyzes revealed the presence of identical or highly similar ESBL/AmpC E. coli clones on farms distant up to 100 km of each other; this strongly suggests that the centralization and verticalization of the poultry industry can facilitate the spread of resistant bacteria among different farms, companies, and cities. The molecular characterization of clones and plasmids proved the dominance of the ST224 E. coli lineage and the IncF/ bla CTX-M-55 plasmid, possibly indicating the emergence of successful clones and plasmids adapted to the chicken host. Our data contribute to the epidemiological tracking of resistance mechanisms in Enterobacterales from poultry and to knowledge for further One Health studies to control the spread of resistant bacteria from food animals to humans. • ESBL/pAmpC-positive E. coli were found in all farms and 40.6 % of all samples. • A high genetic diversity was observed, with the dominance of ST224. • The IncF/CTX-M-15 plasmid was found in 7/8 farms and in 31 samples. • Seventeen (26.2 %) E. coli isolates were characterized as APEC. [ABSTRACT FROM AUTHOR]

This study investigated the molecular features of extended-spectrum β-lactamase (ESBL)–producing Klebsiella pneumoniae from hospital- and community-acquired (HA/CA) infections in the region of Mahdia, Tunisia. Among 336 K. pneumoniae isolates recovered from both clinical contexts between July 2009 and December 2011, 49 and 15 were ESBL producers and originated from clinical and community sources, respectively. All isolates produced the CTX-M-15 enzyme. As shown by Southern blot on S1 nuclease treatment followed by pulsed-field gel electrophoresis (PFGE) gels, the bla CTX-M-15 gene was carried on IncFII (n = 4), IncFIIk (n = 25), IncL/M (n = 4), IncK (n = 1), or untypeable (n = 15) plasmids in HA isolates. In CA isolates, the bla CTX-M-15 gene was carried on IncFIIk (n = 6), IncFII (n = 1), IncHI1 (n = 1), or untypeable (n = 7) plasmids. In all, 23 and 11 PFGE types were found among the HA and CA isolates. Multilocus sequence typing on representative isolates shows diverse sequence types (STs), such as ST307, ST101, ST39, ST4, ST140, ST15, and ST307 in HA isolates and ST101, ST664, and ST323 in CA isolates. This study is the first comprehensive report of ESBL plasmids in K. pneumoniae from HA and CA infections in Tunisia. [ABSTRACT FROM AUTHOR]

We have developed a phenotypic method suited to the systematic screening of resistance to colistin in E . coli , including those with the mcr -1 gene, by the absence of an inhibition zone after an application of a single drop of 8 mg/L colistin solution on a previously inoculated Mueller-Hinton agar. [ABSTRACT FROM AUTHOR]

Abstract: Clinical Escherichia coli strains with resistance or variable susceptibility to third-generation cephalosporins were detected in cattle, swine and poultry in France. These strains were shown to produce extended-spectrum β-lactamases (ESBLs), with CTX-M-1- and CTX-M-15-type β-lactamases being responsible for this phenotype. The bla CTX-M-1 gene was encountered most commonly and was characterised in seven E. coli strains isolated from cattle, swine and poultry, whereas bla CTX-M-15 was identified in one E. coli isolated from cattle. These genes were located on a conjugative plasmid and were linked to the insertion sequence ISEcp1, which could have contributed to dissemination of the resistance gene. No epidemiological link between the strains was determined by pulsed-field gel electrophoresis, although two plasmids were identical in two strains isolated from swine and in two strains isolated from cattle and poultry. Thus, this study describes the emergence of ESBLs in animals in France, with a probable similar prevalence rate to that observed in humans. This is a major concern because of the possibility of transfer of these genes between animal species as well as to humans, leading to treatment failures in veterinary and human medicine. [Copyright &y& Elsevier]

Early antibiotic resistance determinants (ARDs) detection in humans or animals is crucial to counteract their propagation. The ARDs quantification is fundamental to understand the perturbation caused by disruptors, such as antibiotics, during therapies. Forty-three qPCRs on the most diffused ARDs and integrons among human and animal Enterobacterales , and one on the 16S rDNA for bacteria quantification, were developed. The qPCRs, using hydrolysis probes, operated with a unique amplification condition and were tested analytically and diagnostically performing 435 reactions on five positive and negative controls for each qPCR. Diagnostic sensitivity and specificity were confirmed by PCR and genome sequencing of control isolates, demonstrating 100% performance for all qPCRs. An easy and rapid discrimination method for the epidemiologically relevant bla CTX-Ms is provided. This large, noncommercial qPCRs inventory could serve for precise quantification of ARDs, but also as a rapid screening tool for surveillance purposes, providing the basis for further high-throughput developments. [ABSTRACT FROM AUTHOR]

The ermB gene was identified in 111 erythromycin resistant isolates of Streptococcus uberis from cases of bovine mastitis associated either with a constitutive (47/111 ) or an inducible (64/111 ) phenotype, as well as a phenotypic resistance to all macrolides tested. Resistance to lincosamides was identified in 14 other isolates of S. uberis from bovine mastitis cases and was mainly mediated by the linB gene; resistance conferred by a combination of two genes (linB-InuD, ermB-linB) was also detected. [ABSTRACT FROM AUTHOR]

Abstract: The Red recombinase system of bacteriophage Lambda has been used to inactivate chromosomal genes in bacteria using PCR products. In this study, we describe the replacement of the ampicillin resistance marker of helper plasmids pKD46 and pCP20 by a gentamicin resistance gene to disrupt chromosomal genes and then to eliminate FRT flanked resistance gene in multiple antibiotic-resistant Salmonella enterica strains. [Copyright &y& Elsevier]

• We report the long-lasting outbreak of chlorhexidine-resistant S. marcescens. • This outbreak was a source of hospital-acquired infections in cats and dogs. • Two clones were identified, one in 2009 and the second over the 2014-2018 period. Healthcare-associated infections (HAIs) are often overlooked in veterinary medicine. Serratia marcescens isolates were recovered over a ten-year period from companion animals in a French veterinary hospital. The pets were sampled either for diagnostic purposes or to monitor colonization. A retrospective study showed that 32 S. marcescens isolates were identified as HAI cases and a further 22 cases were associated with colonization of the surgical site. Two S. marcescens lineages were responsible for two different outbreaks during the study period. Chlorhexidine solution (1%) used to impregnate gauze was found to be the source of the second S. marcescens outbreak and all isolates had high MIC values for chlorhexidine (MIC = 128 mg/L). This study reports, for the first time to our knowledge, the nosocomial spread of chlorhexidine-resistant S. marcescens in a veterinary setting and highlights consequences of the improper use of disinfectants. [ABSTRACT FROM AUTHOR]

• 34/191 animals (17.8 %) from 15/22 farms (68.2 %) were positive for ESBL-producing E. coli. • The bla CTX-M-8 gene was the most frequent (62.5 %) gene from ESBL-producing E. coli. • CTX-M-8 was localized on the IncI1/pST113 plasmid in various E. coli backgrounds. • IncI1/pST113/ bla CTX-M-8 plasmid was found associated to the human epidemic ST155 and ST648 clones. • First report from Brazilian cattle of bla SHV-2a , bla CTX-M-2 and bla CTX-M-15 genes. The prevalence of Extended-Spectrum Beta-Lactamase (ESBL)-producing Enterobacteriaceae is increasing worldwide and the Agri-Food sector acts as a reservoir of clinically relevant ESBL genes. Our study aimed at detecting and characterizing ESBL-producing Enterobacteriaceae responsible for intestinal colonization of Brazilian bovines. ESBL-producing E. coli isolates were recovered from fecal samples of healthy cattle in Northwest Brazil. Antimicrobial susceptibility was determined by disk diffusion. Resistance and virulence genes were identified by PCR and amplicons were sequenced, clonality was assessed by PFGE and MLST, and plasmids were characterized by replicon typing, S1-PFGE and Southern blot hybridizations. Transferability of ESBL genes was assessed by conjugation assay. A total of 40 ESBL-producing E. coli were characterized, which originated from 34/191 animals (17.8 %) and 15/22 farms (68.2 %). The bla CTX-M-8 gene was the most frequent ESBL gene (62.5 %), followed by bla SHV-2a (20.0 %), bla CTX-M-2 (10.0 %), and bla CTX-M-15 (7.5 %). The bla CTX-M-8 gene was localized on the IncI1/pST113 plasmid in multiple E. coli sequence types across unrelated animals and farms. We report the first characterization and a high prevalence of ESBL-producing E. coli in the beef cattle sector in Brazil, which is mainly supported by the spread of an epidemic IncI1/pST113/ bla CTX-M-8 plasmid. Since Brazil is one of the biggest beef meat exporters worldwide, the spread of this ESBL plasmid across other sectors, countries and continents should be considered with attention. [ABSTRACT FROM AUTHOR]