The phylogroups and antibiotic susceptibilities of Escherichia coli isolates from the feces of Anatolian Ground Squirrels (Spermophilus xanthoprymnus)

The current study was conducted to determine the phylogroups and antibiotic susceptibilities of Escherichia coli isolates recovered from fecal samples of Anatolian Ground Squirrels (Spermophilus xanthoprymnus) and to examine the relationship between them. Eighty-two E. coli isolates obtained from 150 fecal samples were investigated. The quadruplex polymerase chain reaction (PCR), phylogroup C-, and E-specific mPCR were subjected to phylogenetic typing of the isolates. The susceptibilities to fifteen antibiotics of the isolates were detected by the disk diffusion method. In the result of phylogenetic typing, phylogroup B2 was most predominant (58.6 %), followed by B1 (25.6 %), E (8.5 %), C (4.9 %), and D (2.4 %). The phylogroup A, F, and Escherichia clades were not detected. The antibiotic susceptibility test revealed that 59.8 % (49/82) and 19.5 % (16/82) of E. coli isolates were resistant to at least one antibiotic and multidrug-resistant (MDR), respectively. Twenty-six (31.7 %), 19 (23.2 %), 11 (13.4 %), and 10 (12.2 %) of the isolates were found to be resistant to gentamicin, tetracycline, amoxicillin-clavulanic acid, and cefoxitin. Of the 49 E. coli isolates that were found to be resistant to any antibiotic analyzed, 30, 13, 4, and 2 were located in phylogroup B2, B1, E, and D, respectively. MDR isolates were mostly located in both phylogroup B1 (31.3 %) and B2 (31.3 %). In conclusion, data from the current study suggest that the isolates may potentially have pathogenic properties, since the majority (69.5 %) of E. coli isolates from fecal samples of Spermophilus xanthoprymnus were located in the pathogenic phylogroup and resistance to various antibiotics was detected.

Antimicrobial resistance and phylogenetic relatedness of extended-spectrum ß-lactamase (ESBL)-producing Escherichia coli in peridomestic rats (Rattus norvegicus and Rattus tanezumi) linked to city areas and animal farms in Hong Kong

Extended-spectrum β-lactamase-producing Escherichia (E.) coli (ESBL-EC) in the clinical setting have emerged as a major threat to public and animal health. Wildlife, including Rattus spp. may serve as reservoirs and spreaders of ESBL-EC in the environment. Peridomestic rats are well adapted to living in proximity to humans and animals in a variety of urban and agricultural environments and may serve as sentinels to identify variations of ESBL-EC within their different habitats. In this study, a set of 221 rats (Rattus norvegicus, R. tanezumi, R. andamanensis, and Niviventer huang) consisting of 104 rats from city areas, 44 from chicken farms, 52 from pig farms, and 21 from stables of horse-riding schools were screened for ESBL-EC. Overall, a total of 134 ESBL-EC were isolated from the caecal samples of 130 (59%) rats. The predominant blaESBL genes were blaCTX-M-14, blaCTX-M-15, blaCTX-M-55, and blaCTX-M-65. Phylogenetic analysis revealed a total of 62 sequence types (STs) and 17 SNP clusters. E. coli ST10 and ST155 were common to ESBL-EC from city areas and chicken farms, and ST44 were found among ESBL-EC from city areas and pig farms. Extra-intestinal pathogenic E. coli (ExPEC) ST69, ST131 and ST1193 were found exclusively among rats from city areas, and avian pathogenic E. coli (APEC) ST177 was restricted to ESBL-EC originating from chicken farms. Phylogenetic analysis showed that the populations of rodent ESBL-EC from city areas, chicken farms and pig farms were genetically different, suggesting a certain degree of partitioning between the human and animal locations. This study contributes to current understanding of ESBL-EC occurring in rats in ecologically diverse locations.

Synanthropic rodents and shrews are reservoirs of zoonotic bacterial pathogens and act as sentinels for antimicrobial resistance spillover in the environment: A study from Puducherry, India

Antimicrobial resistance (AMR) is a global public health concern and needs to be monitored for control. In this study, synanthropic rodents trapped from humans and animal habitats in Puducherry, India, were screened as sentinels for bacterial pathogens of public health importance and antimicrobial resistance spillover. From the trapped rodents and shrews (n = 100) pathogens viz., Staphylococcus sp, E. coli and Salmonella sp were isolated from oropharyngeal and rectal swabs on Mannitol salt, Mac Conkey and Xylose lysine deoxycholate media respectively. The AMR genes in these isolates were screened by PCR. A total of 76, S. aureus and 19, Staphylococcus non aureus were isolated. E. coli was isolated in 89 samples and among the Salmonella sp (n = 59), 16, were S. enteritidis and 29, were S. typhimurium. A total of 46 MRSA isolates with mec A (n = 40) and mec C (n = 6) were detected. Also, 36.84% and 5.3% Staphylococcus non aureus isolates were tested to have mec A and mec C genes. AMR genes encoding ESBL [blaTEM in 21, blaSHV in 45 and blaCTX-M in 11] was tested positive in 77 E. coli isolates. Among, Salmonella isolates 44/45 were screened to have AMR genes [tet in 13, sul3 & sul4 in 20 and qnrA in 11]. Antibiotic sensitivity test confirmed the antimicrobial resistance. Isolation of pathogens of public health importance and demonstration of genetic elements conferring antimicrobial resistance in the synanthropic rodents confirms that they act as reservoirs and appropriate sentinels to monitor AMR spillover in the environment.

Occurrence and characteristics of extended-spectrum-β-lactamase producing Escherichia coli (blaTEM-128) isolated from Mus musculus captured from a veterinary clinic and houses in Tunis, Tunisia

Antimicrobial resistance in Enterobacteriaceae is a public health problem. Rodents, can be a potential vector for transmission of multidrug resistant bacteria between animals, humans, and environment. The aim of our study was to assess the level of Enterobacteriaceae present in the intestines of rats collected from different locations in Tunisia, then to determine their antimicrobial susceptibility profiles, to screen extended spectrum β-lactamases-producing strains and determine the molecular mechanism of β-lactams resistance. Between July 2017 and June 2018, 55 strains of Enterobacteriaceae were isolated from 71 rats captured in various locations in Tunisia. Antibiotic susceptibility testing was performed using the disc diffusion method. Genes encoding ESBL and mcr genes were investigated by RT-PCR, standard PCR and sequencing when these genes were found. Fifty-five strains of Enterobacteriaceae were identified. The overall prevalence of ESBL production found in our study was 12.7 % (7/55) of which two E. coli strains were DDST positive, one isolated from a house-caught rat and one from the veterinary clinic and harbored the bla_TEM-128 gene. In addition, the other five strains were DDST negative and harbored the bla_TEM gene, including three strains isolated from collective restaurant (n = 2: bla_TEM-163; n = 1: bla_TEM-1), one strain isolated from the veterinary clinic (bla_TEM-82), and one strain isolated from a house (bla_TEM-128). The results of our study suggest that rodents may play a role in the spread of antimicrobial resistant E. coli, highlighting the need to protect the environment and monitor antimicrobial resistant bacteria in rodents to prevent their spread to other wildlife and humans.

High Prevalence of Beta-Lactam-Resistant Escherichia coli in South Australian Grey-Headed Flying Fox Pups (Pteropus poliocephalus)

The emergence of antimicrobial-resistant Escherichia coli in wildlife is concerning-especially resistance to clinically important beta-lactam antibiotics. Wildlife in closer proximity to humans, including in captivity and in rescue/rehabilitation centres, typically have a higher prevalence of antimicrobial-resistant E. coli compared to their free-living counterparts. Each year, several thousand Australian fruit bat pups, including the grey-headed flying fox (GHFF; Pteropus poliocephalus), require rescuing and are taken into care by wildlife rescue and rehabilitation groups. To determine the prevalence of beta-lactam-resistant E. coli in rescued GHFF pups from South Australia, faecal samples were collected from 53 pups in care. A combination of selective culture, PCR, antimicrobial susceptibility testing, whole-genome sequencing, and phylogenetic analysis was used to identify and genetically characterise beta-lactam-resistant E. coli isolates. The prevalence of amoxicillin-, amoxicillin-plus-clavulanic-acid-, and cephalosporin-resistant E. coli in the 53 pups was 77.4% (n = 41), 24.5% (n = 13), and 11.3% (n = 6), respectively. GHFF beta-lactam-resistant E. coli also carried resistance genes to aminoglycosides, trimethoprim plus sulphonamide, and tetracyclines in 37.7% (n = 20), 35.8% (n = 19), and 26.4% (n = 14) of the 53 GHFF pups, respectively, and 50.9% (n = 27) of pups carried multidrug-resistant E. coli. Twelve E. coli strain types were identified from the 53 pups, with six strains having extraintestinal pathogenic traits, indicating that they have the potential to cause blood, lung, or wound infections in GHFFs. Two lineages-E. coli ST963 and ST58 O8:H25-were associated with human extraintestinal infections. Phylogenetic analyses determined that all 12 strains were lineages associated with humans and/or domestic animals. This study demonstrates high transmission of anthropogenic-associated beta-lactam-resistant E. coli to GHFF pups entering care. Importantly, we identified potential health risks to GHFF pups and zoonotic risks for their carers, highlighting the need for improved antibiotic stewardship and biosafety measures for GHFF pups entering care.

Characterization of beta-lactam-resistant Escherichia coli from Australian fruit bats indicates anthropogenic origins

Antimicrobial-resistant Escherichia coli, particularly those resistant to critically important antimicrobials, are increasingly reported in wildlife. The dissemination of antimicrobial-resistant bacteria to wildlife indicates the far-reaching impact of selective pressures imposed by humans on bacteria through misuse of antimicrobials. The grey-headed flying fox (GHFF; Pteropus poliocephalus), a fruit bat endemic to eastern Australia, commonly inhabits urban environments and encounters human microbial pollution. To determine if GHFF have acquired human-associated bacteria, faecal samples from wild GHFF (n=287) and captive GHFF undergoing rehabilitation following illness or injury (n=31) were cultured to detect beta-lactam-resistant E. coli. Antimicrobial susceptibility testing, PCR and whole genome sequencing were used to determine phenotypic and genotypic antimicrobial resistance profiles, strain type and virulence factor profiles. Overall, 3.8 % of GHFF carried amoxicillin-resistant E. coli (wild 3.5 % and captive 6.5 %), with 38.5 % of the 13 GHFF E. coli isolates exhibiting multidrug resistance. Carbapenem (blaNDM-5) and fluoroquinolone resistance were detected in one E. coli isolate, and two isolates were resistant to third-generation cephalosporins (blaCTX-M-27 and ampC). Resistance to tetracycline and trimethoprim plus sulfamethoxazole were detected in 69.2% and 30.8 % of isolates respectively. Class 1 integrons, a genetic determinant of resistance, were detected in 38.5 % of isolates. Nine of the GHFF isolates (69.2 %) harboured extraintestinal virulence factors. Phylogenetic analysis placed the 13 GHFF isolates in lineages associated with humans and/or domestic animals. Three isolates were human-associated extraintestinal pathogenic E. coli (ST10 O89:H9, ST73 and ST394) and seven isolates belonged to lineages associated with extraintestinal disease in both humans and domestic animals (ST88, ST117, ST131, ST155 complex, ST398 and ST1850). This study provides evidence of anthropogenic multidrug-resistant and pathogenic E. coli transmission to wildlife, further demonstrating the necessity for incorporating wildlife surveillance within the One Health approach to managing antimicrobial resistance.

Association between the blaCTX-M-14-harboring Escherichia coli Isolated from Weasels and Domestic Animals Reared on a University Campus

Antimicrobial-resistant (AMR) bacteria affect human and animal health worldwide. Here, CTX-M-14-producing Escherichia coli isolates were isolated from Siberian weasels (Mustela sibirica) that were captured on a veterinary campus. To clarify the source of bacteria in the weasels, we examined the domestic animals reared in seven facilities on the campus. Extended-spectrum β-lactamase (ESBL)-producing E. coli were isolated on deoxycholate hydrogen sulfide lactose agar, containing cephalexin (50 μg/mL) or cefotaxime (2 μg/mL), and were characterized with antimicrobial susceptibility testing, pulsed-field gel electrophoresis (PFGE), replicon typing, and β-lactamase typing analyses. Next-generation sequencing of the ESBL-encoding plasmids was also performed. CTX-M-14 producers isolated from both domestic animals and weasels were classified into six clusters with seven PFGE profiles. The PFGE and antimicrobial resistance profiles were characterized by the animal facility. All CTX-M-14 plasmids belonged to the IncI1 type with a similar size (98.9-99.3 kb), except for one plasmid that was 105.5 kb in length. The unweighted pair group method with arithmetic mean (UPGMA) revealed that the CTX-M-14 plasmid in the weasel isolates might have the same origin as the CTX-M-14 plasmid in the domestic animals. Our findings shed further light on the association of antimicrobial resistance between wild and domestic animals.

Antimicrobial resistance in Escherichia coli isolates from frugivorous (Eidolon helvum) and insectivorous (Nycteris hispida) bats in Southeast Nigeria, with detection of CTX-M-15 producing isolates

Thirty-five Escherichia coli isolates obtained from the liver, spleen and intestines of 180 frugivorous and insectivorous bats were investigated for antimicrobial resistance phenotypes/genotypes, prevalence of Extended-Spectrum beta-lactamase (ESBL) production, virulence gene detection and molecular typing. Eight (22.9 %) of the isolates were multidrug resistant (MDR). Two isolates were cefotaxime-resistant, ESBL-producers and harbored the bla_CTX-M-15 gene; they belonged to ST10184-D and ST2178-B1 lineages. tet(A) gene was detected in all tetracycline-resistant isolates while int1 (n = 8) and bla_TEM (n = 7) genes were also found. Thirty-three of the E. coli isolates were assigned to seven phylogenetic groups, with B1 (45.7 %) being predominant. Three isolates were enteropathogenic E. coli (EPEC) pathovars, containing the eae gene (with the variants gamma and iota), and lacking stx1/stx2 genes. Bats in Nigeria are possible reservoirs of potentially pathogenic MDR E. coli isolates which may be important in the ecology of antimicrobial resistance at the human-livestock-wildlife-environment interfaces. The study reinforces the importance of including wildlife in national antimicrobial resistance monitoring programmes.

Detection and characterization of Enterobacteriaceae family members carried by commensal Rattus norvegicus from Tehran, Iran

Wild rats are known to carry different microorganisms and are considered a reservoir of zoonotic pathogens worldwide. The urban rats were collected from five districts of Tehran and Gram-negative bacteria (GNB) were isolated from fecal samples and were identified using classical biochemical tests. The antibiotic susceptibility patterns of isolated bacteria were determined by Kirby-Bauer disk diffusion method, the results of which were interpreted in line with CLSI guideline. The frequency of antibiotic-resistant genes was identified using multiplex-PCR. Moreover, PCR method was used to identify the frequency of Escherichia coli O157:H7 and main categories of diarrheagenic E. coli including EPEC, ETEC, EIEC, EAEC, and STEC pathotypes. A total of 100 Rattus norvegicus were trapped and fecal samples were collected. Overall, 72 fecal samples were positive for GNB. E. coli (n = 46/72) had the highest frequency among the isolated GNB. Among E. coli isolates, the highest and lowest resistance rates belonged to ampicillin (56.5%) and ceftriaxone (0%), respectively. Klebsiella spp. was 100% resistant to imipenem, and streptomycin (0%) was the most effective antimicrobial agent on Klebsiella spp. Among surveyed genes, bla_TEM (95.8%) and bla_aadA-1 (58.3%) had the highest frequency, while bla_KPC, and bla_CMY-2 were not detected among Enterobacteriaceae. Herein, O157: H7 serotype was not detected and aEPEC (87%) was the most common pathotype detected. Results suggested that rodents might be a reservoir of antimicrobial-resistant pathogens and rodent control along with implementation of surveillance programs should be considered as a critical priority for urban health.

Antimicrobial resistance and gene regulation in Enteroaggregative Escherichia coli from Egyptian children with diarrhoea: Similarities and differences

Enteroaggregative Escherichia coli (EAEC) is a common diarrhoeagenic human pathogen, isolated from patients in both developing and industrialized countries, that is becoming increasingly resistant to many frontline antibiotics. In this study, we screened 50 E. coli strains from children presenting with diarrhea at the outpatients clinic of Assiut University Children’s Hospital, Egypt. We show that all of these isolates were resistant to multiple classes of antibiotics and identified two as being typical EAEC strains. Using whole genome sequencing, we determined that both isolates carried, amongst others, bla_CTX-M and bla_TEM antibiotic resistance genes, as well as many classical EAEC virulence determinants, including the transcriptional regulator, AggR. We demonstrate that the expression of these virulence determinants is dependent on AggR, including aar, which encodes for a repressor of AggR, Aar. Since biofilm formation is the hallmark of EAEC infection, we examined the effect of Aar overexpression on both biofilm formation and AggR-dependent gene expression. We show that whilst Aar has a minimal effect on AggR-dependent transcription it is able to completely disrupt biofilm formation, suggesting that Aar affects these two processes differently. Taken together, our results suggest a model for the induction of virulence gene expression in EAEC that may explain the ubiquity of EAEC in both sick and healthy individuals.

A metagenomic glimpse into the gut of wild and domestic animals: Quantification of antimicrobial resistance and more

Antimicrobial resistance (AMR) in bacteria is a complex subject, why one need to look at this phenomenon from a wider and holistic perspective. The extensive use of the same antimicrobial classes in human and veterinary medicine as well as horticulture is one of the main drivers for the AMR selection. Here, we applied shotgun metagenomics to investigate the AMR epidemiology in several animal species including farm animals, which are often exposed to antimicrobial treatment opposed to an unique set of wild animals that seems not to be subjected to antimicrobial pressure. The comparison of the domestic and wild animals allowed to investigate the possible anthropogenic impact on AMR spread. Inclusion of animals with different feeding behaviors (carnivores, omnivores) enabled to further assess which AMR genes that thrives within the food chain. We tested fecal samples not only of intensively produced chickens, turkeys, and pigs, but also of wild animals such as wild boars, red foxes, and rodents. A multi-directional approach mapping obtained sequences to several databases provided insight into the occurrence of the different AMR genes. The method applied enabled also analysis of other factors that may influence AMR of intestinal microbiome such as diet. Our findings confirmed higher levels of AMR in farm animals than in wildlife. The results also revealed the potential of wildlife in the AMR dissemination. Particularly in red foxes, we found evidence of several AMR genes conferring resistance to critically important antimicrobials like quinolones and cephalosporins. In contrast, the lowest abundance of AMR was observed in rodents originating from natural environment with presumed limited exposure to antimicrobials. Shotgun metagenomics enabled us to demonstrate that discrepancies between AMR profiles found in the intestinal microbiome of various animals probably resulted from the different antimicrobial exposure, habitats, and behavior of the tested animal species.

Occurrence and Antimicrobial Resistance Traits of Escherichia coli from Wild Birds and Rodents in Singapore

Antimicrobial resistance (AMR) in Escherichia coli (E. coli) poses a public health concern worldwide. Wild birds and rodents, due to their mobility, are potential vehicles for transmission of AMR bacteria to humans. Ninety-six wild birds’ faecal samples and 135 rodents’ droppings samples were collected and analysed in 2017. Forty-six E. coli isolates from wild birds and rodents were subjected to AMR phenotypic and genotypic characterisation. The proportion of E. coli isolates resistant to at least one of the antimicrobials tested from wild birds (80.8%) was significantly higher than that of isolates from rodents (40.0%). The proportion of E. coli isolates resistant to each antimicrobial class for wild birds was 3.8% to 73.1% and that for rodents was 5.0% to 35.0%. Six out of 26 E. coli isolates from wild birds (23.1%) and two out of 20 (10.0%) isolates from rodents were multi-drug resistant (MDR) strains. These MDR E. coli isolates were detected with various antimicrobial resistance genes such as bla_TEM-1B and qnrS1 and could be considered as part of the environmental resistome. Findings in this study suggested that wild birds and rodents could play a role in disseminating antimicrobial resistant E. coli, and this underscores the necessity of environment management and close monitoring on AMR bacteria in wild birds and rodents to prevent spreading of resistant organisms to other wildlife animals and humans.

Urban brown rats (Rattus norvegicus) as possible source of multidrug-resistant Enterobacteriaceae and meticillin-resistant Staphylococcus spp., Vienna, Austria, 2016 and 2017

Background

Brown rats (Rattus norvegicus) are an important wildlife species in cities, where they live in close proximity to humans. However, few studies have investigated their role as reservoir of antimicrobial-resistant bacteria.

Aim

We intended to determine whether urban rats at two highly frequented sites in Vienna, Austria, carry extended-spectrum β-lactamase-producing Enterobacteriaceae, fluoroquinolone-resistant Enterobacteriaceae and meticillin-resistant (MR) Staphylococcus spp. (MRS).

Methods

We surveyed the presence of antimicrobial resistance in 62 urban brown rats captured in 2016 and 2017 in Vienna, Austria. Intestinal and nasopharyngeal samples were cultured on selective media. We characterised the isolates and their antimicrobial properties using microbiological and genetic methods including disk diffusion, microarray analysis, sequencing, and detection and characterisation of plasmids.

Results

Eight multidrug-resistant Escherichia coli and two extensively drug-resistant New Delhi metallo-β-lactamases-1 (NDM-1)-producing Enterobacter xiangfangensis ST114 (En. cloacae complex) were isolated from nine of 62 rats. Nine Enterobacteriaceae isolates harboured the bla_CTX-M gene and one carried a plasmid-encoded ampC gene (bla_CMY-2). Forty-four MRS were isolated from 37 rats; they belonged to seven different staphylococcal species: S. fleurettii, S. sciuri, S. aureus, S. pseudintermedius, S. epidermidis, S. haemolyticus (all mecA-positive) and mecC-positive S. xylosus.

Conclusion

Our findings suggest that brown rats in cities are a potential source of multidrug-resistant bacteria, including carbapenem-resistant En. xiangfangensis ST114. Considering the increasing worldwide urbanisation, rodent control remains an important priority for health in modern cities.

A survey of extended-spectrum beta-lactamase-producing Enterobacteriaceae in urban wetlands in southwestern Nigeria as a step towards generating prevalence maps of antimicrobial resistance

In many countries, emission of insufficiently treated wastewater into water bodies appears to be an important factor in spreading clinically relevant antimicrobial resistant bacteria. In this study, we looked for the presence of Enterobacteriaceae strains with resistance to 3rd generation cephalosporin antibiotics in four urban wetlands in southwestern Nigeria by isolation, whole genome sequencing and qPCR enumeration of marker genes. Genome analysis of multi-drug resistant and potentially pathogenic Escherichia coli isolates (members of the widely distributed ST10 complex) revealed the presence of the extended spectrum beta-lactamase gene blaCTX-M-15 on self-transmissible IncF plasmids. The gene was also present together with a blaTEM-1B gene on self-transmissible IncH plasmids in multi-drug resistant Enterobacter cloacae isolates. A Citrobacter freundii isolate carried blaTEM-1B on an IncR-type plasmid without discernable conjugation apparatus. All strains were isolated from a wetland for which previous qPCR enumeration of marker genes, in particular the ratio of intI1 to 16S rRNA gene copy numbers, had indicated a strong anthropogenic impact. Consistent with the isolation origin, qPCR analysis in this study showed that the blaCTX-M gene was present at an abundance of 1x10-4 relative to bacterial 16S rRNA gene copy numbers. The results indicate that contamination of these urban aquatic ecosystems with clinically relevant antibiotic resistant bacteria is substantial in some areas. Measures should therefore be put in place to mitigate the propagation of clinically relevant antimicrobial resistance within the Nigerian aquatic ecosystems.

Wild owls colonized by international clones of extended-spectrum β-lactamase (CTX-M)-producing Escherichia coli and Salmonella Infantis in the Southern Cone of America

Extended-spectrum β-lactamases (ESBLs)-producing Enterobacteriaceae have been classified as critical priority pathogens by the World Health Organization (WHO). We have conducted a microbiological and genomic surveillance study, in order to investigate the occurrence and features of antibiotic-resistant bacteria in wild birds admitted to a wildlife rescue and rehabilitation centre in Chile. This study reports for the first time the occurrence of highly virulent ESBL-producing Escherichia coli and Salmonella enterica serovar Infantis in wild owls inhabiting the Southern Cone of America. Genomic analysis revealed a wide resistome (for antibiotics, heavy metals and disinfectants) among international lineages of E. coli belonging to ST345 and ST2705, and S. Infantis ST32, producing CTX-M-8 or CTX-M-65 ESBLs. On the other hand, wide virulome was associated with a highly virulent behaviour in the Galleria mellonella infection model. Worryingly, all these lineages have been previously reported in humans, supporting that wide resistome and virulome could be contributing to rapid adaptation and dissemination of these clones at the human-animal-environment interface. In summary, wild owls can constitute environmental reservoirs of international clones of ESBL (CTX-M)-producing E. coli and S. Infantis carrying a wide resistome and virulome, in the Southern Cone of America, with potential risks to human, animal and environmental health.