CTX-M-15/27-positive Escherichia coli and VIM-2-producing Pseudomonas putida in free-living pigeons (Columba livia) in Tunisia.

OBJECTIVES: Wild birds are vectors of antimicrobial resistance. Birds living in close contact with humans or other animals, like feral pigeons (Columba livia), might be especially prone to acquire resistance genes such as those encoding extended-spectrum beta-lactamases (ESBLs) and carbapenemases. METHODS: Cloacal samples (n = 206) of free-living feral pigeons (C. livia) were collected in Sousse and Monastir, Tunisia. Antimicrobial susceptibility profiles were determined by disc-diffusion, and resistant isolates were short- and long-read whole-genome sequenced. Sequence analysis was performed using tools of the Centre for Genomic Epidemiology, and Phylogenetic analysis was performed based on the core-genome MLST. RESULTS: Fourteen (14/206, 6.8%) pigeons harboured Enterobacterales resistant to last-generations cephalosporins, of which 10 were CTX-M-15- or CTX-M-27-producers, while two (1.0%) carried a VIM-2-producing Pseudomonas putida. Positive pigeons lived on four different livestock farms. Three STs (ST206, ST5584, ST8149) were identified among E. coli, of which ST5584 and ST8149 were found in two different farms. Genetic diversity was also observed in Enterobacter cloacae and P. putida isolates. The blaCTX-M-27 genes were chromosomally encoded, while the blaCTX-M-15 genes were carried on highly similar IncF/F-:A-:B53 plasmids. The blaVIM-2 gene was located on a class 1 integron co-harbouring several resistance genes. CONCLUSION: Pigeons living on livestock farms carried clinically important resistance genes encoding ESBLs and carbapenemases. Our results evidenced that both clonal (ST8149 and ST5584) and plasmidic (IncF/F-:A-:B53) transfers played a role in the spread of resistance genes among pigeons. Further studies are needed to identify factors favouring the transfer and persistence of resistance genes within the pigeon communities.

Multiple host colonization and differential expansion of multidrug-resistant ST25-Acinetobacter baumannii clades.

The Acinetobacter baumannii clonal lineage ST25 has been identified in humans and animals and found associated with outbreaks globally. To highlight possible similarities among ST25 A. baumannii of animal and human origins and to gather clues on the dissemination and evolution of the ST25 lineage, we conducted a phylogenetic analysis on n = 106 human and n = 35 animal A. baumannii ST25 genomes, including 44 sequenced for this study. Resistance genes and their genetic background were analyzed, as well. ST25 genomes are clustered into four clades: two are widespread in South America, while the other two are largely distributed in Europe, Asia and America. One particular clade was found to include the most recent strains and the highest number of acquired antibiotic resistance genes. OXA-23-type carbapenemase was the most common. Other resistance genes such as blaNDM-1, blaPER-7, and armA were found embedded in complex chromosomal regions present in human isolates. Genomic similarity among multidrug resistant ST25 isolates of either animal or human origin was revealed, suggesting cross-contaminations between the two sectors. Tracking the clonal complex ST25 between humans and animals should provide new insights into the mode of dissemination of these bacteria, and should help defining strategies for preserving global health.

Healthcare Equipment and Personnel Reservoirs of Carbapenem-Resistant Acinetobacter baumannii Epidemic Clones in Intensive Care Units in a Tunisian Hospital.

Carbapenem-resistant Acinetobacter baumannii (CRAB) strains can cause severe and difficult-to-treat infections in patients with compromised general health. CRAB strains disseminate rapidly in nosocomial settings by patient-to-patient contact, through medical devices and inanimate reservoirs. The occurrence of CRAB in patients residing in the intensive care units (ICUs) of the Sahloul University hospital in Sousse, Tunisia is high. The objective of the current study was to determine whether the surfaces of items present in five ICU wards and the medical personnel there operating could serve as reservoirs for CRAB strains. Furthermore, CRAB isolates from patients residing in the ICUs during the sampling campaign were analyzed for genome comparison with isolates from the ICUs environment. Overall, 206 items were screened for CRAB presence and 27 (14%) were contaminated with a CRAB isolate. The items were located in several areas of three ICUs. Eight of the 54 (15%) screened people working in the wards were colonized by CRAB on the hands. Patients residing in the ICUs were infected with CRAB strains sharing extensive genomic similarity with strains recovered in the nosocomial environment. The strains belonged to three sub-clades of the internationally disseminated clone (ST2). A clone emerging in the Mediterranean basin (ST85) was detected as well. The strains were OXA-23 or NDM-1 producers and were also pan-aminoglycoside resistant due to the presence of the armA gene. Hygiene measures are urgent to be implemented in the Sahloul hospital to avoid further spread of difficult-to-treat CRAB strains and preserve health of patients and personnel operating in the ICU wards.

Pilot testing the EARS-Vet surveillance network for antibiotic resistance in bacterial pathogens from animals in the EU/EEA.

Introduction: As part of the EU Joint Action on Antimicrobial Resistance (AMR) and Healthcare-Associated Infections, an initiative has been launched to build the European AMR Surveillance network in veterinary medicine (EARS-Vet). So far, activities included mapping national systems for AMR surveillance in animal bacterial pathogens, and defining the EARS-Vet objectives, scope, and standards. Drawing on these milestones, this study aimed to pilot test EARS-Vet surveillance, namely to (i) assess available data, (ii) perform cross-country analyses, and (iii) identify potential challenges and develop recommendations to improve future data collection and analysis. Methods: Eleven partners from nine EU/EEA countries participated and shared available data for the period 2016-2020, representing a total of 140,110 bacterial isolates and 1,302,389 entries (isolate-antibiotic agent combinations). Results: Collected data were highly diverse and fragmented. Using a standardized approach and interpretation with epidemiological cut-offs, we were able to jointly analyze AMR trends of 53 combinations of animal host-bacteria-antibiotic categories of interest to EARS-Vet. This work demonstrated substantial variations of resistance levels, both among and within countries (e.g., between animal host species). Discussion: Key issues at this stage include the lack of harmonization of antimicrobial susceptibility testing methods used in European surveillance systems and veterinary diagnostic laboratories, the absence of interpretation criteria for many bacteria-antibiotic combinations of interest, and the lack of data from a lot of EU/EEA countries where little or even surveillance currently exists. Still, this pilot study provides a proof-of-concept of what EARS-Vet can achieve. Results form an important basis to shape future systematic data collection and analysis.

Spread of the blaOXA-48/IncL Plasmid within and between Dogs in City Parks, France.

The blaOXA-48/IncL plasmid is increasingly reported in dogs, even in the absence of carbapenem use in animals. In this study, we witnessed the spread of this plasmid within and between dogs sharing the same relaxing area. This indicates a very dynamic situation where carbapenem resistance can be transmitted between dogs and expanded in the dogs' gut. As a consequence, picking up dog feces may lower both this dynamic and the global antimicrobial resistance burden. IMPORTANCE The use of carbapenems in animals is forbidden in France due to their critical importance to treat human diseases. Nevertheless, blaOXA-48-producing Enterobacterales were sporadically recovered in cats and dogs, most likely as a spill over from the human reservoir. This study highlights the rapid spread of blaOXA-48 once transmitted to dogs, suggesting that companion animals can play a role in the transmission routes of carbapenemase genes.

Impact of Antibiotic Therapies on Resistance Genes Dynamic and Composition of the Animal Gut Microbiota.

Antibiotics are major disruptors of the gastrointestinal microbiota, depleting bacterial species beneficial for the host health and favoring the emergence of potential pathogens. Furthermore, the intestine is a reactor of antibiotic resistance emergence, and the presence of antibiotics exacerbates the selection of resistant bacteria that can disseminate in the environment and propagate to further hosts. We reviewed studies analyzing the effect of antibiotics on the intestinal microbiota and antibiotic resistance conducted on animals, focusing on the main food-producing and companion animals. Irrespective of antibiotic classes and animal hosts, therapeutic dosage decreased species diversity and richness favoring the bloom of potential enteropathogens and the selection of antibiotic resistance. These negative effects of antibiotic therapies seem ineluctable but often were mitigated when an antibiotic was administered by parenteral route. Sub-therapeutic dosages caused the augmentation of taxa involved in sugar metabolism, suggesting a link with weight gain. This result should not be interpreted positively, considering that parallel information on antibiotic resistance selection was rarely reported and selection of antibiotic resistance is known to occur also at low antibiotic concentration. However, studies on the effect of antibiotics as growth promoters put the basis for understanding the gut microbiota composition and function in this situation. This knowledge could inspire alternative strategies to antibiotics, such as probiotics, for improving animal performance. This review encompasses the analysis of the main animal hosts and all antibiotic classes, and highlights the future challenges and gaps of knowledge that should be filled. Further studies are necessary for elucidating pharmacodynamics in animals in order to improve therapy duration, antibiotic dosages, and administration routes for mitigating negative effects of antibiotic therapies. Furthermore, this review highlights that studies on aminoglycosides are almost inexistent, and they should be increased, considering that aminoglycosides are the first most commonly used antibiotic family in companion animals. Harmonization of experimental procedures is necessary in this research field. In fact, current studies are based on different experimental set-up varying for antibiotic dosage, regimen, administration, and downstream microbiota analysis. In the future, shotgun metagenomics coupled with long-reads sequencing should become a standard experimental approach enabling to gather comprehensive knowledge on GIM in terms of composition and taxonomic functions, and of ARGs. Decorticating GIM in animals will unveil revolutionary strategies for medication and improvement of animals' health status, with positive consequences on global health.

An inventory of 44 qPCR assays using hydrolysis probes operating with a unique amplification condition for the detection and quantification of antibiotic resistance genes.

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 blaCTX-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.

Investigation of an XDR-Acinetobacter baumannii ST2 outbreak in an intensive care unit of a Lebanese tertiary care hospital.

Aim: We sought to investigate the genetic epidemiological relatedness of carbapenem-resistant Acinetobacter baumannii (CRAB) strains of a suspected outbreak in a Lebanese tertiary care hospital to implement necessary infection prevention and control measures. Methods: Twenty-eight nonduplicate CRAB isolates detected among hospitalized patients between January 2016 and July 2017 were studied by real-time polymerase chain reaction (PCR), pulsed-field gel electrophoresis and multilocus sequence typing analyses. Results: Twenty-seven isolates harbored blaOXA-23, of which one also carried blaNDM-1. The isolates distributed temporally in two presumably episodes were stratified by pulsed-field gel electrophoresis into many clusters. Although several clones have become endemic in the hospital, we have rapidly implemented appropriate infection prevention and control measures, achieving full eradication from August 2017 to November 2019. Conclusion: We have successfully investigated and controlled a polyclonal outbreak of OXA-23 producing ST2 CRAB.

Scarless Removal of Large Resistance Island AbaR Results in Antibiotic Susceptibility and Increased Natural Transformability in Acinetobacter baumannii.

With a great diversity in gene composition, including multiple putative antibiotic resistance genes, AbaR islands are potential contributors to multidrug resistance in Acinetobacter baumannii However, the effective contribution of AbaR to antibiotic resistance and bacterial physiology remains elusive. To address this, we sought to accurately remove AbaR islands and restore the integrity of their insertion site. To this end, we devised a versatile scarless genome editing strategy. We performed this genetic modification in two recent A. baumannii clinical strains: the strain AB5075 and the nosocomial strain AYE, which carry AbaR11 and AbaR1 islands of 19.7 kbp and 86.2 kbp, respectively. Antibiotic susceptibilities were then compared between the parental strains and their AbaR-cured derivatives. As anticipated by the predicted function of the open reading frame (ORF) of this island, the antibiotic resistance profiles were identical between the wild type and the AbaR11-cured AB5075 strains. In contrast, AbaR1 carries 25 ORFs, with predicted resistance to several classes of antibiotics, and the AYE AbaR1-cured derivative showed restored susceptibility to multiple classes of antibiotics. Moreover, curing of AbaRs restored high levels of natural transformability. Indeed, most AbaR islands are inserted into the comM gene involved in natural transformation. Our data indicate that AbaR insertion effectively inactivates comM and that the restored comM is functional. Curing of AbaR consistently resulted in highly transformable and therefore easily genetically tractable strains. Emendation of AbaR provides insight into the functional consequences of AbaR acquisition.

Co-resistance to Amoxicillin and Tetracycline as an Indicator of Multidrug Resistance in Escherichia coli Isolates From Animals.

OBJECTIVES: To examine the relevance of co-resistance to amoxicillin and tetracycline as an indicator of multidrug resistance (MDR) in animal health. METHODS: Escherichia coli isolates collected between 2012 and 2016 by the French surveillance network for antimicrobial resistance in diseased animals (RESAPATH) were analyzed. The proportions of MDR isolates and the proportions of isolates presenting co-resistance to amoxicillin and tetracycline were calculated for seven animal species (cattle, horse, dog, swine, poultry, duck, and turkey). The degree of agreement between these two proportions was estimated by calculating the kappa value. RESULTS: In total, 55,904 isolates were analyzed. MDR proportions were variable among animal species, ranging from 21.9% [20.2; 23.7] in horses to 56.0% [55.4; 56.7] in cattle. A similar situation was observed for proportions of isolates with co-resistance to amoxicillin and tetracycline, with the highest value for cattle 65.0% [64.3; 65.6]. This co-resistance was also most often associated with resistance to other antibiotics, regardless of the animal species considered. Comparative analysis showed substantial agreement between MDR and this co-resistance, with a kappa value of 0.75, all animal species considered. CONCLUSION: Given the widespread use of penicillins and tetracyclines in animal health, co-resistance to amoxicillin and tetracycline could be an efficient indicator of MDR in E. coli isolates. Based on a specific resistance profile and not an arbitrary number of resistances compared with MDR, this potential indicator is also precise, convenient and suitable for routine use.

Antimicrobial Resistance in Acinetobacter spp. and Pseudomonas spp.

The nonfermenting bacteria belonging to Acinetobacter spp. and Pseudomonas spp. are capable of colonizing both humans and animals and can also be opportunistic pathogens. More specifically, the species Acinetobacter baumannii and Pseudomonas aeruginosa have been recurrently reported as multidrug-resistant and even pandrug-resistant in clinical isolates. Both species were categorized among the ESKAPE pathogens, ESKAPE standing for Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, A. baumannii, P. aeruginosa, and Enterobacter species. These six pathogens are the major cause of nosocomial infections in the United States and are a threat all over the world because of their capacity to become increasingly resistant to all available antibiotics. A. baumannii and P. aeruginosa are both intrinsically resistant to many antibiotics due to complementary mechanisms, the main ones being the low permeability of their outer membrane, the production of the AmpC beta-lactamase, and the production of several efflux systems belonging to the resistance-nodulation-cell division family. In addition, they are both capable of acquiring multiple resistance determinants, such as beta-lactamases or carbapenemases. Even if such enzymes have rarely been identified in bacteria of animal origin, they may sooner or later spread to this reservoir. The goal of this article is to give an overview of the resistance phenotypes described in these pathogens and to provide a comprehensive analysis of all data that have been reported on Acinetobacter spp. and Pseudomonas spp. from animal hosts.

Fluorescence-Based Detection of Natural Transformation in Drug-Resistant Acinetobacter baumannii.

Acinetobacter baumannii is a nosocomial agent with a high propensity for developing resistance to antibiotics. This ability relies on horizontal gene transfer mechanisms occurring in the Acinetobacter genus, including natural transformation. To study natural transformation in bacteria, the most prevalent method uses selection for the acquisition of an antibiotic resistance marker in a target chromosomal locus by the recipient cell. Most clinical isolates of A. baumannii are resistant to multiple antibiotics, limiting the use of such selection-based methods. Here, we report the development of a phenotypic and selection-free method based on flow cytometry to detect transformation events in multidrug-resistant (MDR) clinical A. baumannii isolates. To this end, we engineered a translational fusion between the abundant and conserved A. baumannii nucleoprotein (HU) and the superfolder green fluorescent protein (sfGFP). The new method was benchmarked against the conventional antibiotic selection-based method. Using this new method, we investigated several parameters affecting transformation efficiencies and identified conditions of transformability one hundred times higher than those previously reported. Using optimized transformation conditions, we probed natural transformation in a set of MDR clinical and nonclinical animal A. baumannii isolates. Regardless of their origin, the majority of the isolates displayed natural transformability, indicative of a conserved trait in the species. Overall, this new method and optimized protocol will greatly facilitate the study of natural transformation in the opportunistic pathogen A. baumanniiIMPORTANCE Antibiotic resistance is a pressing global health concern with the rise of multiple and panresistant pathogens. The rapid and unfailing resistance to multiple antibiotics of the nosocomial agent Acinetobacter baumannii, notably to carbapenems, prompt to understand the mechanisms behind acquisition of new antibiotic resistance genes. Natural transformation, one of the horizontal gene transfer mechanisms in bacteria, was only recently described in A. baumannii and could explain its ability to acquire resistance genes. We developed a reliable method to probe and study natural transformation mechanism in A. baumannii More broadly, this new method based on flow cytometry will allow experimental detection and quantification of horizontal gene transfer events in multidrug-resistant A. baumannii.

Spread of blaCTX-M-15-Producing Enterobacteriaceae and OXA-23-Producing Acinetobacter baumannii Sequence Type 2 in Tunisian Seafood.

Bivalves are filter-feeding animals and markers of bacterial pollution. We report a massive spread of blaCTX-M-15 through dominant Escherichia coli and Klebsiella pneumoniae lineages and/or plasmid subtypes (F31:A4:B1) as well as the presence of OXA-23-producing Acinetobacter baumannii sequence type 2 (ST2) in seafood, highlighting a direct risk for the consumer. These findings should urge authorities to consider hospital effluents, and also farm and urban effluents, as important sources of extended-spectrum-beta-lactamase (ESBL)/carbapenemase producers that filter-feeding animals can concentrate and further spread to humans.

Antimicrobial Resistance in Escherichia coli.

Multidrug resistance in Escherichia coli has become a worrying issue that is increasingly observed in human but also in veterinary medicine worldwide. E. coli is intrinsically susceptible to almost all clinically relevant antimicrobial agents, but this bacterial species has a great capacity to accumulate resistance genes, mostly through horizontal gene transfer. The most problematic mechanisms in E. coli correspond to the acquisition of genes coding for extended-spectrum ß-lactamases (conferring resistance to broad-spectrum cephalosporins), carbapenemases (conferring resistance to carbapenems), 16S rRNA methylases (conferring pan-resistance to aminoglycosides), plasmid-mediated quinolone resistance (PMQR) genes (conferring resistance to [fluoro]quinolones), and mcr genes (conferring resistance to polymyxins). Although the spread of carbapenemase genes has been mainly recognized in the human sector but poorly recognized in animals, colistin resistance in E. coli seems rather to be related to the use of colistin in veterinary medicine on a global scale. For the other resistance traits, their cross-transfer between the human and animal sectors still remains controversial even though genomic investigations indicate that extended-spectrum ß-lactamase producers encountered in animals are distinct from those affecting humans. In addition, E. coli of animal origin often also show resistances to other-mostly older-antimicrobial agents, including tetracyclines, phenicols, sulfonamides, trimethoprim, and fosfomycin. Plasmids, especially multiresistance plasmids, but also other mobile genetic elements, such as transposons and gene cassettes in class 1 and class 2 integrons, seem to play a major role in the dissemination of resistance genes. Of note, coselection and persistence of resistances to critically important antimicrobial agents in human medicine also occurs through the massive use of antimicrobial agents in veterinary medicine, such as tetracyclines or sulfonamides, as long as all those determinants are located on the same genetic elements.

Is blaCTX-M-1 Riding the Same Plasmid Among Horses in Sweden and France?

A predominance of the blaCTX-M-1/IncHI1 plasmid combination in horses has been reported in Czech-Republic, Denmark, and The Netherlands. To clarify a possible specific plasmid epidemiology of blaCTX-M-1 in horses in a European perspective, a collection of 74 extended-spectrum beta-lactamase-producing Escherichia coli recovered from diseased horses in France and Sweden during the period 2009-2014 was investigated in respect of their genetic relatedness, plasmid content, and molecular features. Overall, 80% of E. coli isolates from diseased horses harbored blaCTX-M-1 on large IncHI1 plasmids with plasmid sequence type (pST) 2 and pST9 more prevalent in Sweden and France, respectively. In French isolates, IncI1/pST3 plasmids were also identified. The CTX-M-1-producing E. coli belonged principally to the clonal complex 10. ST641, together with its single locus variant, and ST1730 constituted two other major groups. The rep-PCR clustering highlighted a clonal dissemination of E. coli CTX-M-1 producers in different regions of the same country and during several years. The STs found in our isolates were also reported in The Netherlands, suggesting a common source of contamination in Europe, although only further cooperative investigation will clarify this issue. On the other hand, the spread of IncI1/pST3 plasmids among horses constitutes another worrisome issue considering their successful spread in other animal hosts such as chicken or bovines. Monitoring evolution and propagation of antimicrobial resistance in equine environment is a priority to avoid further propagation of antimicrobial resistance mechanisms threatening human and animal health.

Antimicrobial Resistance in Streptococcus spp.

The genus Streptococcus includes Gram-positive organisms shaped in cocci and organized in chains. They are commensals, pathogens, and opportunistic pathogens for humans and animals. Most Streptococcus species of veterinary relevance have a specific ecological niche, such as S. uberis, which is almost exclusively an environmental pathogen causing bovine mastitis. In contrast, S. suis can be considered as a true zoonotic pathogen, causing specific diseases in humans after contact with infected animals or derived food products. Finally, Streptococcus species such as S. agalactiae can be sporadically zoonotic, even though they are pathogens of both humans and animals independently. For clarification, a short taxonomical overview will be given here to highlight the diversity of streptococci that infect animals. Several families of antibiotics are used to treat animals for streptococcal infections. First-line treatments are penicillins (alone or in combination with aminoglycosides), macrolides and lincosamides, fluoroquinolones, and tetracyclines. Because of the selecting role of antibiotics, resistance phenotypes have been reported in streptococci isolated from animals worldwide. Globally, the dynamic of resistance acquisition in streptococci is slower than what is experienced in Enterobacteriaceae, probably due to the much more limited horizontal spread of resistance genes. Nonetheless, transposons or integrative and conjugative elements can disseminate resistance determinants among streptococci. Besides providing key elements on the prevalence of resistance in streptococci from animals, this article will also largely consider the mechanisms and molecular epidemiology of the major types of resistance to antimicrobials encountered in the most important streptococcal species in veterinary medicine.

Emergence of blaCTX-M-55 associated with fosA, rmtB and mcr gene variants in Escherichia coli from various animal species in France.

Objectives: In Asian countries, blaCTX-M-55 is the second most common ESBL-encoding gene. blaCTX-M-55 frequently co-localizes with fosA and rmtB genes on epidemic plasmids, which remain sporadic outside Asia. During 2010-13, we investigated CTX-M-55-producing Escherichia coli isolates and their co-resistance to fosfomycin, aminoglycosides, fluoroquinolones and colistin as part of a global survey of ESBLs in animals in France. Methods: blaCTX-M-55, fosA, rmtB and plasmidic quinolone and colistin resistance genes were characterized by PCR, sequencing and hybridization experiments. Plasmids were classified according to their incompatibility groups and subtypes. Genotyping was performed by MLST and repetitive extragenic palindromic sequence-based PCR. Results: Twenty-one E. coli isolates from bovines (n = 16), dogs (n = 2), horses (n = 2) and a monkey harboured blaCTX-M-55, were MDR and belonged to ST744 (n = 9) and 10 other clones. blaCTX-M-55 was mostly located on IncF (n = 19), but also on IncI1 (n = 2) plasmids. On IncF33:A1:B1 plasmids, blaCTX-M-55 co-localized with the rmtB and aac(6')-Ib genes and in one isolate with the fosA3 allele. Ten IncF46:A-:B20 plasmids, which were found in different clones from unrelated animals, also carried the mcr-3 gene. blaCTX-M-55-carrying IncF18:A-:B1 plasmids were found in different animal species from distinct locations and periods, and one additionally carried the fosA4 gene. One isolate harboured the mcr-1 gene, which did not co-localize with blaCTX-M-55. Conclusions: A large diversity of E. coli clones and plasmid types supported the spread of blaCTX-M-55, together with atypical resistance genes, in various animal species in France. fosA and rmtB genes are emerging among animals in Europe and this issue is of concern for public health.