ESBL-Producing Escherichia coli Carrying CTX-M Genes Circulating among Livestock, Dogs, and Wild Mammals in Small-Scale Farms of Central Chile

Stray Dogs (Mongrels) Are Potent Reservoir of Drug-Resistant Pathogens: A Study in Peri-Urban Areas of Kolkata, India

This study depicts the drug-resistance and phylogenomic characteristics of 365 Escherichia coli (EC) and 76 Klebsiella pneumoniae (KP) isolated from stray dogs (293) in and around Kolkata, India. Initial screening found 59 isolates, including 48 E. coli and 11 KP multidrug resistant, which included 33 extended-spectrum β-lactamase, 41 AmpC β-lactamase and 18 metallo-β-lactamase producers carrying blaNDM-1 (11) and blaNDM-5 (7) genes. Majority of them had the resistant genes such as blaCTX-M (33), blaTEM (18), blaSHV (4), blaOXA (17), blaFOX (2), blaDHA (2), blaCITM (15), blaCMY-2 (13), blaGES (2) and blaVEB (2), qnrS (15), qnrB (3), aac-6'-Ib-cr (14), tetA (26), tetB (14), sul-1 (25), armA (2) and rmtB (6), in addition to adherence genes such as csgA (33), fimA (27), fliC (13), sdiA (33), rcsA (38), and rpoS (39). They also carried plasmid of diverse replicon types of which IncFIA and FIB were the most frequent. Phylogrouping categorized most of the MDR E. coli in phylogroup A (20), B1 (14), and B2 (6). Enterobacteriaceae repetitive intergenic consensus-polymerase chain reaction (ERIC-PCR) showed genetic diversity of multidrug resistant isolates irrespective of their origin, resistance, and virulence types, differentiating the EC in five clades (A-E) and KP in four clades (A-D). As these stray dogs, which had no history or scope of previous antimicrobial therapy, were found to have contracted potential antimicrobial resistance pathogens, the role of environment in spread of such pathogens and further possibility of human infections cannot be ruled out.

Genomic epidemiology of third-generation cephalosporin-resistant Escherichia coli from Argentinian pig and dairy farms reveals animal-specific patterns of co-resistance and resistance mechanisms

Control measures are being introduced globally to reduce the prevalence of antibiotic resistance (ABR) in bacteria on farms. However, little is known about the current prevalence and molecular ecology of ABR in bacterial species with the potential to be key opportunistic human pathogens, such as Escherichia coli, on South American farms. Working with 30 dairy cattle farms and 40 pig farms across two provinces in central-eastern Argentina, we report a comprehensive genomic analysis of third-generation cephalosporin-resistant (3GC-R) E. coli, which were recovered from 34.8% (cattle) and 47.8% (pigs) of samples from fecally contaminated sites. Phylogenetic analysis revealed substantial diversity suggestive of long-term horizontal and vertical transmission of 3GC-R mechanisms. CTX-M-15 and CTX-M-2 were more often produced by isolates from dairy farms, while CTX-M-8 and CMY-2 and co-carriage of amoxicillin/clavulanate resistance and florfenicol resistance were more common in isolates from pig farms. This suggests different selective pressures for antibiotic use in these two animal types. We identified the β-lactamase gene blaROB, which has previously only been reported in the family Pasteurellaceae, in 3GC-R E. coli. blaROB was found alongside a novel florfenicol resistance gene, ydhC, also mobilized from a pig pathogen as part of a new composite transposon. As the first comprehensive genomic survey of 3GC-R E. coli in Argentina, these data set a baseline from which to measure the effects of interventions aimed at reducing on-farm ABR and provide an opportunity to investigate the zoonotic transmission of resistant bacteria in this region.

IMPORTANCE

Little is known about the ecology of critically important antibiotic resistance among bacteria with the potential to be opportunistic human pathogens (e.g., Escherichia coli) on South American farms. By studying 70 pig and dairy cattle farms in central-eastern Argentina, we identified that third-generation cephalosporin resistance (3GC-R) in E. coli was mediated by mechanisms seen more often in certain species and that 3GC-R pig E. coli were more likely to be co-resistant to florfenicol and amoxicillin/clavulanate. This suggests that on-farm antibiotic usage is key to selecting the types of E. coli present on these farms. 3GC-R E. coli and 3GC-R plasmids were diverse, suggestive of long-term circulation in this region. We identified the de novo mobilization of the resistance gene blaROB from pig pathogens into E. coli on a novel mobile genetic element, which shows the importance of surveying poorly studied regions for antibiotic resistance that might impact human health.

A preliminary report on critical antimicrobial resistance in Escherichia coli, Enterococcus faecalis, and Enterococcus faecium strains isolated from healthy dogs in Chile during 2021-2022

Antimicrobial Resistance (AMR) represents one of the main current threats to global public health; where production animals, companion animals, humans, and the environment play a significant role in its dissemination. However, little attention has been given to companion animals as reservoirs and disseminators of relevant antimicrobial resistant bacteria, especially in South American countries such as Chile. For this reason, this research aimed to estimate the prevalence of AMR to different critical antibiotics at a screening level in commensal bacteria such as E. coli and Enterococcus spp., isolated from healthy pet dogs in the Metropolitan Region of Chile, studying their geographical distribution and evaluating associations of phenotypic resistance to different antibiotics. Thus, in E. coli we detected AMR to all critical drugs assessed, including 34.1% to amoxicillin, 20.1% to colistin, 15.7% to enrofloxacin, and 9.2% to cefotaxime. On the other hand, AMR prevalence in E. faecalis was 8.1% for ampicillin and 3.4% for vancomycin; while for E. faecium the AMR prevalence was 19.1% for ampicillin and 10.2% for vancomycin. Additionally, significant differences in prevalence of the different possible AMR were detected according to their geographical distribution, suggesting the existence of various risk factors and stressing the need to establish mitigation measures specific to the differences identified.

Molecular detection of extended-spectrum β-lactamase-producing Escherichia coli from bat caves on Lombok Island

Background

The discovery of antibiotic-resistant Enterobacteriaceae bacteria in wild animals is an indication of their potential for wildlife as a reservoir. Bats are natural reservoir hosts and a source of infection for several microorganisms and have the potential to become vectors for the spread of zoonotic diseases.

Aim

A study was conducted based on these characteristics to identify and detect the blaTEM gene in Eschericia coli isolated from bat excrements in Tanjung Ringgit Cave, East Lombok.

Methods

Bat fecal samples were firstly inoculated onto eosin methylene blue agar media. Recovered bacterial isolates were further characterized using standard microbiological techniques. Antimicrobial susceptibility testing was done using the Kirby-Bauer disc diffusion method. blaTEM gene detection was carried out using polymerase chain reaction (PCR).

Results

Out of the 150 bat fecal samples obtained from Tanjung Ringgit cave, Lombok Island, Indonesia, 56 (37%) were positive for E. coli. Eight (8) out of the 56 E. coli isolates that underwent antimicrobial susceptibility testing using the disc diffusion method were confirmed to be multidrug-resistant as they exhibited resistance to at least three different classes of antibiotics. Out of the eight (8) multidrug resistance E. coli isolates recovered from fecal samples of bats, 2 (two) harbored the blaTEM gene.

Conclusion

The discovery of the blaTEM gene in bat fecal samples indicates the potential for wild animals, especially bats, to spread ESBL resistance genes to the environment and to humans.

Genomic insights into ESBL-producing Escherichia coli isolated from non-human primates in the Peruvian Amazon

Introduction

Extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae are on the WHO priority pathogens list because they are associated with high mortality, health-care burden, and antimicrobial resistance (AMR), a serious problem that threatens global public health and should be addressed through the One Health approach. Non-human primates (NHP) have a high risk of acquiring these antibiotic-resistant bacteria due to their close phylogenetic relationship with humans and increased anthropogenic activities in their natural environments. This study aimed to detect and analyze the genomes of ESBL-producing Escherichia coli (ESBL-producing E. coli) in NHP from the Peruvian Amazon.

Materials and methods

We collected a total of 119 fecal samples from semi-captive Saguinus labiatus, Saguinus mystax, and Saimiri boliviensis, and captive Ateles chamek, Cebus unicolor, Lagothrix lagothricha, and Sapajus apella in the Loreto and Ucayali regions, respectively. Subsequently, we isolated and identified E. coli strains by microbiological methods, detected ESBL-producing E. coli through antimicrobial susceptibility tests following CLSI guidelines, and analyzed their genomes using previously described genomic methods.

Results

We detected that 7.07% (7/99) of E. coli strains: 5.45% (3/55) from Loreto and 9.09% (4/44) from Ucayali, expressed ESBL phenotype. Genomic analysis revealed the presence of high-risk pandemic clones, such as ST10 and ST117, carrying a broad resistome to relevant antibiotics, including three blaCTX-M variants: blaCTX-M-15, blaCTX-M-55, and blaCTX-M-65. Phylogenomic analysis confirmed the clonal relatedness of high-risk lineages circulating at the human-NHP interface. Additionally, two ESBL-producing E. coli strains were identified as EPEC (eae) and ExPEC according to their virulence profiles, and one more presented a hypermucoviscous phenotype.

Discussion

We report the detection and genomic analysis of seven ESBL-producing E. coli strains carrying broad resistome and virulence factors in NHP from two regions of the Peruvian Amazon. Some of these strains are closely related to high-risk pandemic lineages previously reported in humans and domestic animals, highlighting the negative impact of anthropogenic activities on Amazonian wildlife. To our knowledge, this is the first documentation of ESBL-producing E. coli in NHP from the Amazon, underscoring the importance of adopting the One Health approach to AMR surveillance and minimizing the potential transmission risk of antibiotic-resistant bacteria at the human-NHP interface.

IS26 drives the dissemination of bla CTX-M genes in an Ecuadorian community

IMPORTANCE

The horizontal gene transfer events are the major contributors to the current spread of CTX-M-encoding genes, the most common extended-spectrum β-lactamase (ESBL), and many clinically crucial antimicrobial resistance (AMR) genes. This study presents evidence of the critical role of IS26 transposable element for the mobility of bla CTX-M gene among Escherichia coli isolates from children and domestic animals in the community. We suggest that the nucleotide sequences of IS26-bla CTX-M could be used to study bla CTX-M transmission between humans, domestic animals, and the environment, because understanding of the dissemination patterns of AMR genes is critical to implement effective measures to slow down the dissemination of these clinically important genes.

Rats as sources of multidrug-resistant Enterobacteriaceae in animal production environments

Rattus norvegicus and Rattus rattus are commensal pest rodents, considered reservoirs and vectors of zoonotic pathogens. In livestock farms, the wide use of antimicrobials and their release into the environment lead to high long-term residual concentrations, which may in turn lead to the occurrence of antimicrobial resistance (AMR). Farm environments serve as AMR sources, resulting in the transmission of antimicrobial-resistant bacteria and their AMR genes of livestock origin into wildlife. This study aimed to analyse the profile of enterobacteria carrying AMR determinants in rats captured in livestock farms to determine their potential vectors as for the spread of AMR. To this end, 56 rats (52 R. norvegicus and 4 R. rattus) were live-trapped on 11 farms (pig, dairy, poultry and mixed farms) located in central Argentina, from spring 2016 to autumn 2017. From 50 of the R. norvegicus individuals and three of the R. rattus individuals found in 10 of the farms, we isolated 53 Escherichia coli and five Salmonella strains. Susceptibility to antimicrobials, genotypic profiles, minimal inhibitory concentration of colistin and the presence of mcr-1 and genes encoding extended-spectrum β-lactamase (ESBL) were determined. Of the 58 isolates not susceptible to different antimicrobial classes, 28 of the E. coli strains and two of the Salmonella strains were defined as multi-drug resistant (MDR). S. Westhampton and S. Newport recovered were not susceptible to ampicillin or all the cephems tested. One of the E. coli obtained showed resistance to colistin and harboured the mcr-1 gene, demonstrated by PCR and conjugation. In two ESBL-producing Salmonella isolated from rats, CTX-M-2 genes were responsible for the observed resistance to third-generation cephalosporins. The MDR E. coli isolates showed several different resistance patterns (23), although some of them were the same in different individuals and different farms, with six resistance patterns, evidencing the dispersion of strains. These findings suggest that rats play a role in the dissemination of AMR determinants between animal, humans and environmental reservoirs.

Detection of antimicrobial-resistant Enterobacterales in insectivorous bats from Chile

Enterobacterales of clinical importance for humans and domestic animals are now commonly detected among wildlife worldwide. However, few studies have investigated their prevalence among bats, particularly in bat species living near humans. In this study, we assessed the occurrence of Extended-spectrum beta-lactamase-producing (ESBL) and carbapenemase-resistant (CR) Enterobacterales in rectal swabs of bats submitted to the Chilean national rabies surveillance program from 2021 to 2022. From the 307 swabs screened, 47 (15%) harboured cefotaxime-resistant Enterobacterales. Bats carrying these bacteria originated from 9 out of the 14 Chilean regions. Most positive samples were obtained from Tadarida brasiliensis (n = 42), but also Lasiurus varius, L. cinereus and Histiotus macrotus. No Enterobacterales were resistant to imipenem. All ESBL-Enterobacterales were confirmed as Rahnella aquatilis by MALDI-TOF. No other ESBL or CR Enterobacterales were detected. To our knowledge, this is the first screening of antibiotic-resistant bacteria in wild bats of Chile, showing the bat faecal carriage of R. aquatilis naturally resistant to cephalosporins, but also including acquired resistance to important antibiotics for public health such as amoxicillin with clavulanic acid. Our results suggest unknown selective pressures on R. aquatilis, but low or no carriage of ESBL or CR Escherichia coli and Klebsiella spp. Future studies should assess the zoonotic and environmental implications of R. aquatilis, which are likely present in the guano left by bats roosting in human infrastructures.

Multiple clonal transmissions of clinically relevant extended-spectrum beta-lactamase-producing Escherichia coli among livestock, dogs, and wildlife in Chile

OBJECTIVES

Extended-spectrum beta-lactamase-producing Escherichia coli (ESBL-E. coli) are a main cause of human deaths associated with antimicrobial resistance (AMR). Despite hundreds of reports of the faecal carriage of ESBL-E. coli in domestic and wild animals, the dynamics of its circulation remains poorly understood.

METHODS

We used whole genome sequencing of 19 ESBL-E. coli previously isolated in the same local setting from dogs, livestock, and a wild rodent in Central Chile to assess potential cross-species transmission of ESBL-E. coli.

RESULTS

Isolates harboured a large number of AMR (n = 95) and virulence (n = 45) genes, plasmids replicons (n = 24), and E. coli sequence types including top extraintestinal pathogenic E. coli ST410, ST58, ST88, and ST617. Almost identical clones (<50 single nucleotide polymorphisms difference, same antibiotic and heavy metal resistance genes, virulence genes, and plasmids) were found in faeces of dogs, cattle, or sheep from the same farm, and in a dog and a wild rodent living in proximity.

CONCLUSIONS

To our knowledge, this is the first report of multiple clonal cross-species transmission of ESBL-E. coli in domestic and potentially wild animals of Latin America. Our results suggest that relatively rare spread of AMR across animal species can still occur by both clonal and plasmid dissemination. Our study highlights the need for establishing preventive measures to limit the circulation of these bacteria among animals in agricultural settings, particularly given the highly pathogenic profile of several E. coli strains detected in these animals.

Phenotypic and genotypic antimicrobial resistance in Escherichia coli strains isolated from household dogs in Chile

Introduction

Antimicrobial resistance (AMR) is a major threat to animal and public health worldwide; consequently, several AMR surveillances programs have been implemented internationally in both human and veterinary medicine, including indicator bacteria such as Escherichia coli. However, companion animals are not typically included in these surveillance programs. Nevertheless, there have been reports of increasing levels of antimicrobial resistance in E. coli strains isolated from dogs worldwide. In Chile, there is limited information available on AMR in E. coli isolated from companion animals, which prevents the establishment of objective prevention and control measures.

Methods

For this reason, the aim of this study was to characterize the phenotypic and genotypic AMR of E. coli strains isolated from healthy household dogs in Chile. For this purpose, a multi-stage sampling was carried out in the Metropolitan Region of Chile, obtaining samples from 600 healthy dogs. These samples were processed using traditional bacteriology and molecular techniques to isolate E. coli strains. We assessed the minimal inhibitory concentration of 17 antimicrobials and conducted a search of six antimicrobial resistance genes, as well as class 1 and 2 integrons, in the isolated strains.

Results

Two-hundred and twenty-four strains of E. coli were recovered, and 96.9% (n = 217) showed resistance to at least one drug and only 3.1% (n = 7) were susceptible to all analyzed antimicrobials. Most strains were resistant to cefalexin (91.5%, n = 205, 1st-generation cephalosporin), followed by ampicillin (68.3%, n = 153) and cefpodoxime (31.3%, n = 70, 3rd-generation cephalosporin). Moreover, 24.1% (n = 54) tested positive for extended-spectrum-β-lactamases and 34.4% (n = 77) were multidrug resistant. As for the AMR genes, the most detected was qnrB (28.1%, n = 63), followed by blaCTX-M (22.3%, n = 50), and blaTEM-1 (19.6%, n = 44). Additionally, 16.1% (n = 36) harbored class 1 integrons. Our study shows that E. coli strains isolated from healthy household dogs exhibit resistance to several relevant drugs and also antimicrobial resistance genes considered critical for human health. These results can be used as a starting point for the prevention and control of antimicrobial resistance from companion animals. This background should be considered when formulating future resistance surveillance programs or control plans in which companion animals must be included.

Longitudinal study of ESBL/AmpC-producing Enterobacterales strains sharing between cohabiting healthy companion animals and humans in Portugal and in the United Kingdom

Extended-spectrum beta-lactamase (ESBL)- and plasmid-mediated cephalosporinase (AmpC)-producing Enterobacterales (ESBL/AmpC-E) are an increasing healthcare problem in both human and veterinary medicine. The aim of this study was to investigate the possible sharing of ESBL/AmpC-E strains between healthy companion animals and humans of the same household in Portugal (PT) and the United Kingdom (UK). In a prospective longitudinal study, between 2018 and 2020, faecal samples were collected from healthy dogs (n=90), cats (n=20) and their cohabiting humans (n=119) belonging to 41 PT and 44 UK households. Samples were screened for the presence of ESBL/AmpC-E and carbapenemase-producing bacteria. Clonal relatedness between animal and human strains was established by using REP-PCR fingerprinting method, followed by whole-genome sequencing (WGS) of selected strains. ESBL/AmpC-E strains were detected in companion animals (PT=12.7%, n=8/63; UK=8.5%, n=4/47) and humans (PT=20.7%, n=12/58; UK=6.6%, n=4/61) in at least one timepoint. REP-PCR identified paired multidrug-resistant ESBL/AmpC-producing Escherichia coli strains from companion animals and owners in two Portuguese households (4.8%) and one UK household (2.3%). WGS analysis of nine E. coli strains from these three households confirmed that interhost sharing occurred only between the two animal-human pairs from Portugal. Three shared strains were identified: one CTX-M-15-producing E. coli strain in a cat-human pair (O15-H33-ST93) and two CTX-M-15- and CTX-M-55/CMY-2-producing E. coli strains, in a dog-human pair (O8:H9-ST410 and O11:H25-ST457, respectively) at different timepoints. These E. coli clonal lineages are human pandemic, highlighting the role of companion animals living in close contact with humans in the dissemination and persistence of antimicrobial resistance in the household environment.

Investigating One Health risks for human colonisation with extended spectrum β-lactamase-producing Escherichia coli and Klebsiella pneumoniae in Malawian households: a longitudinal cohort study

BACKGROUND

Low-income countries have high morbidity and mortality from drug-resistant infections, especially from enteric bacteria such as Escherichia coli. In these settings, sanitation infrastructure is of variable and often inadequate quality, creating risks of extended-spectrum β-lactamase (ESBL)-producing Enterobacterales transmission. We aimed to describe the prevalence, distribution, and risks of ESBL-producing Enterobacterales colonisation in sub-Saharan Africa using a One Health approach.

METHODS

Between April 29, 2019, and Dec 3, 2020, we recruited 300 households in Malawi for this longitudinal cohort study: 100 each in urban, peri-urban, and rural settings. All households underwent a baseline visit and 195 were selected for longitudinal follow-up, comprising up to three additional visits over a 6 month period. Data on human health, antibiotic usage, health-seeking behaviours, structural and behavioural environmental health practices, and animal husbandry were captured alongside human, animal, and environmental samples. Microbiological processing determined the presence of ESBL-producing E coli and Klebsiella pneumoniae, and hierarchical logistic regression was performed to evaluate the risks of human ESBL-producing Enterobacterales colonisation.

FINDINGS

A paucity of environmental health infrastructure and materials for safe sanitation was identified across all sites. A total of 11 975 samples were cultured, and ESBL-producing Enterobacterales were isolated from 1190 (41·8%) of 2845 samples of human stool, 290 (29·8%) of 973 samples of animal stool, 339 (66·2%) of 512 samples of river water, and 138 (46·0%) of 300 samples of drain water. Multivariable models illustrated that human ESBL-producing E coli colonisation was associated with the wet season (adjusted odds ratio 1·66, 95% credible interval 1·38-2·00), living in urban areas (2·01, 1·26-3·24), advanced age (1·14, 1·05-1·25), and living in households where animals were observed interacting with food (1·62, 1·17-2·28) or kept inside (1·58, 1·00-2·43). Human ESBL-producing K pneumoniae colonisation was associated with the wet season (2·12, 1·63-2·76).

INTERPRETATION

There are extremely high levels of ESBL-producing Enterobacterales colonisation in humans and animals and extensive contamination of the wider environment in southern Malawi. Urbanisation and seasonality are key risks for ESBL-producing Enterobacterales colonisation, probably reflecting environmental drivers. Without adequate efforts to improve environmental health, ESBL-producing Enterobacterales transmission is likely to persist in this setting.

FUNDING

Medical Research Council, National Institute for Health and Care Research, and Wellcome Trust.

TRANSLATION

For the Chichewa translation of the abstract see Supplementary Materials section.

Extended-Spectrum β-Lactamase-Producing Escherichia coli Isolated from Food-Producing Animals in Tamaulipas, Mexico

Extended-spectrum β-lactamase (ESBL)-producing E. coli has become an important global problem for the public health sector. This study aims to investigate the E. coli antimicrobial resistance profile among living food-producing animals in Tamaulipas, Mexico. A total of 200 fecal samples were collected from bovines, pigs, chickens and sheep. A total of 5.0% of the strains were phenotypically confirmed as ESBL producers. A high percentage of phenotypic antimicrobial resistance was observed against gentamicin (93.3%), tetracycline (86.6%) and streptomycin (83.3%). The gentamicin-resistant strains showed MDR, distributed among 27 resistance patterns to different antimicrobials. The antimicrobial resistance gene tet(A) was detected in 73.3% of isolates, aadA1 in 60.0% and sul2 in 43.3% of strains. The bla_CTX-M gene was found in 23.3% of strains. The virulence gene hlyA was detected in 43.3% of isolates; stx1 and stx2 were not detected in any strain. The phylotyping indicated that the isolates belonged to groups A (33.3%), B1 (16.6%), B2 (40.0%) and D (10.0%). These results show that food-producing animals might be a reservoir of ESBL-producing bacteria and may play a role in their spread.

Multidrug-Resistant ESBL-Producing E. coli in Clinical Samples from the UK

Globally, cephalosporin therapy failure is a serious problem for infection control. One causative agent of cephalosporin-resistant infections is multidrug-resistant (MDR) E. coli producing extended-spectrum β-lactamases (ESBLs) and/or plasmid-encoded AmpC (pAmpC) β-lactamases. We evaluated the occurrence of ESBL/pAmpC genetic determinants in phenotypically MDR E. coli isolated from clinical samples of blood, faeces, ear effusion, urine and sputum from a UK hospital. Phenotypic resistance profiling for 18 antibiotics (from seven classes) showed that 32/35 isolates were MDR, with resistance to 4-16 of the tested antibiotics. Of the isolates, 97.1% showed resistance to ampicillin, 71.4% showed resistance to co-amoxiclav, cefotaxime, ceftazidime and ceftiofur, and 68.5% showed resistance to cefquinome. bla_CTX-M, bla_TEM and bla_OXA-1 genes were detected in 23, 13 and 12 strains, respectively, and Intl1 was detected in 17 isolates. The most common subtypes among the definite sequence types were CTX-M-15 (40%) and TEM-1 (75%). No E. coli isolates carried pAmpC genes. Significant correlations were seen between CTX-M carriage and cefotaxime, ceftiofur, aztreonam, ceftazidime and cefquinome resistance; between bla_CTX-M, bla_TEM and bla_OXA-1 carriage and ciprofloxacin resistance; and between Intl1 carriage and trimethoprim/sulfamethoxazole resistance. Thus, MDR phenotypes may be conferred by a relatively small number of genes. The level and pattern of antibiotic resistance highlight the need for better antibiotic therapy guidelines, including reduced use and improved surveillance.

Genetic Diversity and New Sequence Types of Escherichia coli Coharboring β-Lactamases and PMQR Genes Isolated from Domestic Dogs in Central Panama

Background: β-lactamase-producing Escherichia coli are a widely distributed source of antimicrobial resistance for animals and humans. Little is known about the susceptibility profile and genetic characteristics of E. coli strains isolated from domestic dogs in Latin America. Methods: We report on a cross-sectional study that evaluated E. coli strains isolated from fecal samples of domestic dogs in central Panama. The extended-spectrum β-lactamase (ESBL), AmpC genes, and plasmid-mediated quinolone resistance were investigated. Molecular typing using Pasteur’s multilocus sequence typing (MLST) was conducted. Results: A total of 40 E. coli isolates were obtained, of which 80% (32/40) were resistant to at least one of the antibiotics tested, while 20% (8/40) were sensitive to all antibiotics analyzed in this study (p < 0.001). Forty percent of the strains were resistant to three or more antibiotics. The most common resistance was to tetracycline (45%) and ampicillin (30%) while 2.5% showed an ESBL phenotype. Antibiotic resistance genes were detected for one β-lactamase (blaTEM-1) and two plasmid-mediated quinolone resistance (PMQR) enzymes (qnrS and qnrB). In addition, mutations in the chromosomal AmpC gene were observed at positions −35, −28, −18, −1, and +58. Fourteen different sequence types (STs) were identified; the most frequent were ST399 and ST425 (12% each). ST3 and ST88, which have been previously identified in human clinical isolates, were also evidenced. Three new STs were found for the first time: ST1015, ST1016 (carrier of the blaTEM-1 gene), and ST1017 (carrier of the blaTEM-1, qnrS, and qnrB genes). Conclusions: In the intestinal strains of E. coli isolated from domestic dogs, there was a high frequency of resistance to antibiotics. The presence of genes from plasmids and chromosomal mutations that conferred antibiotic resistance, the identification of isolates previously reported in humans, and the genetic diversity of STs (including three that were newly identified) confirmed the determinants of resistance to antibiotics in the domestic dogs from central Panama.

Evaluation of Retail Meat as a Source of ESBL Escherichia coli in Tamaulipas, Mexico

In recent decades, the appearance of a group of strains resistant to most β-lactam antibiotics, called extended-spectrum β-lactamases (ESBLs), has greatly impacted the public health sector. The present work aimed to identify the prevalence of ESBL-producing Escherichia coli strains in retail meat from northeast Tamaulipas. A total of 228 meat samples were obtained from 76 different stores. A prevalence of E. coli ESBL of 6.5% (15/228) was detected. All (15/15) of the ESBL strains were multiresistant. Altogether, 40% (6/15) of the strains showed the presence of class 1 integrons. The isolates identified with bla_CTX-M (20%) also showed co-resistance with the tet (A and B), str (A and B), and sul (2 and 3) genes. A total of 20% of the strains belonged to the B2 and D phylogroups, which are considered pathogenic groups. None of the ESBL-positive strains contained any of the virulence gene factors tested. The presence of ESBL-producing E. coli strains in meat indicates a potential risk to the consumer. Although most of these strains were classified as commensals, they were found to serve as reservoirs of multiresistance to antimicrobials and, therefore, are potential routes of dispersion of this resistance to other bacteria.

Can Stray Cats Be Reservoirs of Antimicrobial Resistance?

The emergence and spread of antimicrobial resistance (AMR) is a global problem that requires a One Health approach. Despite several studies have reported the role of companion animals as reservoirs of AMR, limited information is available regarding the role of cats in the circulation of AMR. In this study, we evaluated the phenotypic and genotypic profile of 75 Escherichia coli isolated from rectal swabs and fecal samples of 75 stray cats (living in solitary or in a colony) sampled in Palermo (Sicily, Italy), to determine whether these animals may participate in the spread of AMR. Susceptibility to 8 antibiotics was tested using Minimum Inhibitory Concentration assays, while the presence of the common antibiotic resistance genes blaTEM, blaCTX-M, tet(A), and tet(B) was investigated by PCR. From the 75 E. coli isolates analyzed, 43% were resistant to at least one of the eight antibiotics tested, with 31% of the isolates resistant to ampicillin, 23% to cefotaxime, 21% to tetracycline, 20% to cefazolin, and 17% to amoxicillin/clavulanic acid. Most isolates harbored the blaTEM gene (29%), followed by blaCTX-M (23%), tet(A) (21%), and tet(B) (20%). Our results confirm the fecal carriage of antibiotic-resistant E. coli and clinically relevant resistance genes in stray cats. This study highlights the potential role of stray cats in the spread of AMR in urban environments, emphasising the need to better understand their role in AMR circulation when planning strategies to combat it.

Characterization of Extended-Spectrum β-Lactamase-Producing Escherichia coli Isolates That Cause Diarrhea in Sheep in Northwest China

Development of extended-spectrum-β-lactamase (ESBL)-producing Escherichia coli is one the greatest threats faced by mankind. Among animals, chickens, pigs, and cattle are reservoirs of these pathogens worldwide. Nevertheless, there is a knowledge gap on ESBL-producing E. coli from small ruminants (i.e., sheep and goats) in China. The aim of this study was to identify and characterize the resistance profiles, resistomes, and sequence features of 67 ESBL-producing E. coli isolates from sheep in northwest China. The findings showed that blaCTX-M and blaTEM were the most prevalent. Interestingly, we found that the resistance gene mcr-1 was widespread in sheep merely from Shaanxi areas, accounting for 19.2% (5/26). The highly prevalent serotypes and FumC-FimH (CH) typing isolates were O8 and C4H32, respectively. High-risk E. coli clones, such as sequence type 10 (ST10), ST23, ST44, and ST58, were also found in China's sheep population. A total of 67 ESBL-producing isolates were divided into five phylogenetic groups, namely, B1 (n = 47, 70.1%), B2 (n = 1, 1.5%), C (n = 14, 20.9%), E (n = 1, 1.5%), and F (n = 1, 1.5%), with the phylogenetic groups for 3 isolates (4.5%) remaining unknown. Moreover, ESBL-producing E. coli isolates were also characterized by the abundance and diversity of biocide/metal resistance genes and insert sequences. We found that in ESBL-producing E. coli isolates, there were two different types of isolates, those containing ESBL genes or not, which led to large discrepancies between resistance phenotypes and resistomes. In summary, our study provides a comprehensive overview of resistance profiles and genome sequence features in ESBL-producing E. coli and highlights the possible role of sheep as antibiotic resistance gene disseminators into humans. IMPORTANCE Antimicrobial resistance (AMR), especially the simultaneous resistance to several antibiotics (multidrug resistance [MDR]), is one of the greatest threats to global public health in the 21st century. Among animals, chickens, pigs, and cattle are reservoirs of these pathogens worldwide. Nevertheless, there is a knowledge gap on ESBL-producing E. coli from small ruminants in China. This study is the largest and most comprehensive analysis of ESBL-producing E. coli isolates from sheep, including antibiotic resistance profiles, phylogenetic groups, serotypes, multilocus sequence types (MLST), insert sequences (IS), antibiotic resistance genes, disinfectant resistance genes, and heavy metal resistance genes. We recommend extending the surveillance of AMR of sheep-origin E. coli to prevent future public health risks.

Campylobacter jejuni and Other Emerging Campylobacteraceae in Retail Beef Liver - An Underestimated Potential Source?

Bovine by-products, such as liver, could be an underestimated source of Campylobacter jejuni. Therefore, our aims were to evaluate the occurrence of C. jejuni and other Campylobacteraceae in retail beef liver and characterize their antibiotic resistance (ciprofloxacin, tetracycline, erythromycin, and gentamicin) and potential genetic relationship by flagellin gene Restriction Fragment Length Polymorphism (flaA-RFLP) and Multilocus Sequence Typing (MLST) with clinical strains. Seventy-six out of 206 samples (36.9%) were positive for Campylobacter and related organisms. Arcobacter butzleri was the most frequently isolated species (21.8%), followed by C. jejuni (9.7%), C. fetus (7.8%) and C. coli (1%). The C. jejuni strains showed resistance to tetracycline (17.2%) or ciprofloxacin (6.9%), with only one strain resistant to both antibiotics. Meanwhile, 8.3% of ciprofloxacin resistance was observed in C. fetus. The other species showed no resistance. Most of the clonal complexes (CC) in which the C. jejuni genotypes were grouped (CC-21, 42, 48 and 52), coincided with genotypes of clinical strains previously reported in Chile. As such, this study provides evidence that beef liver could be an underestimated route for resistant C. jejuni to humans. Further studies should assess whether this food could play a role in the transmission of other emerging Campylobacteraceae such as those reported here.

Humans and Hoofed Livestock Are the Main Sources of Fecal Contamination of Rivers Used for Crop Irrigation: A Microbial Source Tracking Approach

Freshwater bodies receive waste, feces, and fecal microorganisms from agricultural, urban, and natural activities. In this study, the probable sources of fecal contamination were determined. Also, antibiotic resistant bacteria (ARB) were detected in the two main rivers of central Chile. Surface water samples were collected from 12 sampling sites in the Maipo (n = 8) and Maule Rivers (n = 4) every 3 months, from August 2017 until April 2019. To determine the fecal contamination level, fecal coliforms were quantified using the most probable number (MPN) method and the source of fecal contamination was determined by Microbial Source Tracking (MST) using the Cryptosporidium and Giardia genotyping method. Separately, to determine if antimicrobial resistance bacteria (AMB) were present in the rivers, Escherichia coli and environmental bacteria were isolated, and the antibiotic susceptibility profile was determined. Fecal coliform levels in the Maule and Maipo Rivers ranged between 1 and 130 MPN/100-ml, and 2 and 30,000 MPN/100-ml, respectively. Based on the MST results using Cryptosporidium and Giardia host-specific species, human, cattle, birds, and/or dogs hosts were the probable sources of fecal contamination in both rivers, with human and cattle host-specific species being more frequently detected. Conditional tree analysis indicated that coliform levels were significantly associated with the river system (Maipo versus Maule), land use, and season. Fecal coliform levels were significantly (p < 0.006) higher at urban and agricultural sites than at sites immediately downstream of treatment centers, livestock areas, or natural areas. Three out of eight (37.5%) E. coli isolates presented a multidrug-resistance (MDR) phenotype. Similarly, 6.6% (117/1768) and 5.1% (44/863) of environmental isolates, in Maipo and Maule River showed and MDR phenotype. Efforts to reduce fecal discharge into these rivers should thus focus on agriculture and urban land uses as these areas were contributing the most and more frequently to fecal contamination into the rivers, while human and cattle fecal discharges were identified as the most likely source of this fecal contamination by the MST approach. This information can be used to design better mitigation strategies, thereby reducing the burden of waterborne diseases and AMR in Central Chile.

Possible Acquisition of ESBL-mediated Antimicrobial Resistance by Farmers from Aquatic Reservoir used for Bathing and Cleaning of Water Buffalos (Bubalus bubalis) with Intestinal Carriage of ESBL Producing Escherichia coli

Little information is available on the risk of human subjects for acquisition of antimicrobial resistance (AMR) from aquatic environment other than those treated with antimicrobials for aquaculture. Carriage of extended-spectrum beta-lactamase (ESBL) and carbapenemase categories of AMR by enteric bacteria in livestock have been frequently reported. Dissemination of these categories of AMR to the environment thus poses a threat for their transmission to farmers engaged in livestock care posing a severe public health hazard. A study on the prevalence of ESBL- and carbapenemase-mediated AMR among Escherichia coli isolated from earth pond environment used for bathing and cleaning of buffalos (Bubalus bubalis) and from human subjects engaged in such activity revealed isolation rate of ESBL positivity to be higher in human subjects engaged in washing and bathing of buffalos (37.5%) compared to those without engagement in such activities (20.7%) with CTX-M type ESBL, a group of class A ESBL, as the predominant molecular type (97.4%). While no carbapenemase positivity could be detected among E. coli isolated from pond environment or buffalos, small percentage of carbapenemase could be detected among the E. coli isolated from human subjects although the risk was not higher than those not associated with bathing and cleaning of buffalos. Bathing and cleaning of buffalos could potentially facilitate transmission of ESBL resistance from livestock to human subjects in pond environment.

Identification of extended-spectrum beta-lactamase (CTX-M)-producing Klebsiella pneumoniae belonging to ST37, ST290, and ST2640 in captive giant pandas

Background

Extended-spectrum β-lactamases (ESBL)-producing strains of Klebsiella pneumoniae remain a worldwide, critical clinical concern. However, limited information was available concerning ESBL-producing Klebsiella pneumoniae in giant pandas. The objective of this study was to characterize ESBL-producing Klebsiella pneumoniae isolates from captive giant pandas. A total of 211 Klebsiella pneumoniae isolates were collected from 108 giant pandas housed at the Chengdu Research Base of Giant Panda Breeding (CRBGP), China. Samples were screened for the ESBL-producing phenotype via the double-disk synergy test.

Result

A total of three (1.42%, n = 3/211) ESBL-producing Klebsiella pneumoniae strains were identified, and characterization of ESBL-producing Klebsiella pneumoniae isolates were studied by the detection of ESBL genes and mobile genetic elements (MGEs), evaluation of antimicrobial susceptibility and detection of associated resistance genes. Clonal analysis was performed by multi-locus sequencing type (MLST). Among the three ESBL-producing isolates, different ESBL-encoding genes, including bla_CTX-M, and bla_TEM, were detected. These three isolates were found to carry MGEs genes (i.e., IS903 and tnpU) and antimicrobial resistance genes (i.e., aac(6')-Ib, aac(6')-I, qnrA, and qnrB). Furthermore, it was found that the three isolates were not hypermucoviscosity, resistant to at least 13 antibiotics and belonged to different ST types (ST37, ST290, and ST2640).

Conclusion

Effective surveillance and strict infection control strategies should be implemented to prevent outbreaks of ESBL-producing Klebsiella pneumoniae in giant pandas.

Effect of Intramuscularly Administered Oxytetracycline or Enrofloxacin on Vancomycin-Resistant Enterococci, Extended Spectrum Beta-Lactamase- and Carbapenemase-Producing Enterobacteriaceae in Pigs

Simple Summary

Nowadays, there is great concern about the prevalence of multidrug resistant bacteria in food-producing animals since they are potential sources of transmission to humans. The aim of this work was to evaluate the effect of two antibiotics (oxytetracycline and enrofloxacin) treatments in pigs on resistant bacteria that are considered a threat to public health. This study highlights that the use of oxytetracycline or enrofloxacin in food-producing animals could select resistant bacteria in pig faeces. Special care should be taken to avoid faecal contamination of carcasses during slaughter.

Abstract

Nowadays, there is a great concern about the prevalence of multidrug resistant Enterococcus spp. and Enterobacteriaceae in food-producing animals. The aim of this work was to evaluate the effect of oxytetracycline or enrofloxacin treatment on vancomycin-resistant enterococci (VRE), extended spectrum β-lactamase (ESBL) and carbapenemase-producing Enterobacteriaceae in pigs. A total of 26 piglets were received and distributed in three groups. Group 1 was treated with enrofloxacin (N = 12), group 2 with oxytetracycline (N = 10) and group 3 did not receive any treatment (control group) (N = 4). A higher number of vancomycin-resistant E. faecium were recovered compared to E. faecalis. In the pigs treated with enrofloxacin, vancomycin resistant E. faecium was found in a higher percentage of animals than in the control group. ESBL-producing E. coli was not detected in rectal samples from control animals. However, it was detected in 17–20% of animals treated with oxytetracycline on days 6 to 17 and in 17–50% of the animals treated with enrofloxacin. Carbapenemase-producing E. coli was isolated in animals treated with oxytetracycline, but not in animals treated with enrofloxacin or in the control group. This study highlights that the use of oxytetracycline or enrofloxacin in food-producing animals could select ESBL and carbapenemase-producing E. coli. Further studies shall be needed to validate the results obtained, considering a more robust and extended experimental design.

First Global Report of Plasmid-Mediated mcr-1 and Extended-Spectrum Beta-Lactamase-Producing Escherichia coli from Sheep in Portugal

Resistances to extended-spectrum cephalosporins (ESC) and colistin are One Health issues since genes encoding these resistances can be transmitted between all sectors of the One Health concept, i.e., human, animal, and the environment. Among food-producing animals, sheep farming has long been overlooked. To fill in this knowledge gap, we looked for ESC- and colistin resistance in 21 faecal samples collected from sheep in one farm in the south of Portugal. ESC-resistant isolates were selected on MacConkey agar plates supplemented with cefotaxime. Susceptibility testing was performed by the disk-diffusion method according to CLSI, while colistin MIC was determined by broth microdilution. ESC- and colistin-resistance genes were identified by PCR, and the clonality of all isolates was assessed by XbaI-PFGE. The replicon content was determined by PCR according to the PCR-based replicon typing (PBRT) scheme. Sixty-two non-duplicate ESC-resistant E. coli isolates were identified, which all presented an extended-spectrum beta-lactamase (ESBL) phenotype, mostly due to the presence of CTX-M genes. One CTX-M-1-producing E. coli was concomitantly colistin-resistant and presented the plasmid-mediated mcr-1 gene. Nearly all isolates showed associated resistances to non-beta-lactam antibiotics, which could act as co-selectors, even in the absence of beta-lactam use. The results showed a high proportion of ESBL-producing E. coli in sheep faeces. Their dissemination was very dynamic, with the spread of successful clones between animals, but also a large diversity of clones and plasmids, sometimes residing in the same animal. This study highlights the need for global surveillance in all food-producing sectors, in order to avoid the dissemination of genes conferring resistance to last-resort antibiotics in human medicine.

Extended-Spectrum-β-Lactamase- and AmpC-Producing Escherichia coli in Domestic Dogs: Spread, Characterisation and Associated Risk Factors

In veterinary medicine, the issue of antimicrobial resistance was mainly addressed in food-producing animals (although companion animals also deserve attention). Indeed, these species may be reservoir of resistant microorganisms, such as extended-spectrum β-lactamase and AmpC (ESBL/AmpC)-producing bacteria. Dogs in particular may transmit them to close-contact humans. Overall 266 faecal samples of healthy dogs were microbiologically and molecularly analyzed to investigate ESBL/AmpC-producing Escherichia coli and the effects of host and environmental factors on their spread. A prevalence of 25.9% of ESBL/AmpC-producing E. coli, supported by bla_CTX-M (79.7%), bla_TEM (47.8%), bla_CMY (13%), and bla_SHV (5.8%) gene detection, emerged. Dogs frequenting extra-urban environments showed significantly higher odds of being positive to ESBL/AmpC E. coli (30.2%) compared to urban dogs (16.7%) identifying the environment as a risk factor. About 88.4% of isolates were resistant to cephalosporins, 8.7% to cephalosporins and carbapenems, and 2.9% to cephalosporins, carbapenems, and penicillins. ESBL/AmpC-producing E. coli expressing bla_CMY were significantly more resistant to cefoxitin, cefotaxime/clavulanic acid and ceftazidime/clavulanic acid, highlighting its negative effects. Our results suggest the role of domestic dogs as a maintenance host of ESBL/AmpC-producing E. coli leading to a constant health monitoring. The recorded resistances to carbapenems implies attention and further investigations.

Isolation of Ciprofloxacin and Ceftazidime-Resistant Enterobacterales From Vegetables and River Water Is Strongly Associated With the Season and the Sample Type

The dissemination of antibiotic-resistant bacteria (ARB) from water used for crop irrigation to vegetables is poorly studied. During a year, five farmer markets in a city in Central Chile were visited, and 478 vegetable samples (parsleys, corianders, celeries, lettuces, chards, and beets) were collected. Simultaneously, 32 water samples were collected from two rivers which are used to irrigate the vegetables produced in the area. Resistant Enterobacterales were isolated and identified. Colistin resistance gene mcr-1 and extended spectrum β-lactamases (ESBL) were molecularly detected. The association of environmental factors was evaluated, with the outcomes being the presence of Enterobacterales resistant to four antibiotic families and the presence of multidrug resistance (MDR) phenotypes. Parsley, coriander, and celery showed the highest prevalence of resistant Enterobacterales (41.9% for ciprofloxacin and 18.5% for ceftazidime). A total of 155 isolates were obtained, including Escherichia coli (n=109), Citrobacter sp. (n=20), Enterobacter cloacae complex (n=8), Klebsiella pneumoniae (n=8), and Klebsiella aerogenes (n=1). Resistance to ampicillin (63.2%) and ciprofloxacin (74.2%) was most frequently found; 34.5% of the isolates showed resistance to third-generation cephalosporins, and the MDR phenotype represented 51.6% of the isolates. In two E. coli isolates (1.29%), the gene mcr-1 was found and ESBL genes were found in 23/62 isolates (37%), with bla_CTX-M being the most frequently found in 20 isolates (32%). Resistant Enterobacterales isolated during the rainy season were less likely to be MDR as compared to the dry season. Understanding environmental associations represent the first step toward an improved understanding of the public health impact of ARB in vegetables and water.

Antimicrobial Resistance Genes and Diversity of Clones among Faecal ESBL-Producing Escherichia coli Isolated from Healthy and Sick Dogs Living in Portugal

The purpose of this study was to analyse the prevalence and genetic characteristics of ESBL and acquired-AmpC (qAmpC)-producing Escherichia coli isolates from healthy and sick dogs in Portugal. Three hundred and sixty-one faecal samples from sick and healthy dogs were seeded on MacConkey agar supplemented with cefotaxime (2 µg/mL) for cefotaxime-resistant (CTX^R) E. coli recovery. Antimicrobial susceptibility testing for 15 antibiotics was performed and the ESBL-phenotype of the E. coli isolates was screened. Detection of antimicrobial resistance and virulence genes, and molecular typing of the isolates (phylogroups, multilocus-sequence-typing, and specific-ST131) were performed by PCR (and sequencing when required). CTX^RE. coli isolates were obtained in 51/361 faecal samples analysed (14.1%), originating from 36/234 sick dogs and 15/127 healthy dogs. Forty-seven ESBL-producing E. coli isolates were recovered from 32 sick (13.7%) and 15 healthy animals (11.8%). Different variants of bla_CTX-M genes were detected among 45/47 ESBL-producers: bla_CTX-M-15 (n = 26), bla_CTX-M-1 (n = 10), bla_CTX-M-32 (n = 3), bla_CTX-M-55 (n = 3), bla_CTX-M-14 (n = 2), and bla_CTX-M-variant (n = 1); one ESBL-positive isolate co-produced CTX-M-15 and CMY-2 enzymes. Moreover, two additional CTX^R ESBL-negative E. coli isolates were CMY-2-producers (qAmpC). Ten different sequence types were identified (ST/phylogenetic-group/β-lactamase): ST131/B2/CTX-M-15, ST617/A/CTX-M-55, ST3078/B1/CTX-M-32, ST542/A/CTX-M-14, ST57/D/CTX-M-1, ST12/B2/CTX-M-15, ST6448/B1/CTX-M-15 + CMY-2, ST5766/A/CTX-M-32, ST115/D/CMY-2 and a new-ST/D/CMY-2. Five variants of CTX-M enzymes (CTX-M-15 and CTX-M-1 predominant) and eight different clonal complexes were detected from canine ESBL-producing E. coli isolates. Although at a lower rate, CMY-2 β-lactamase was also found. Dogs remain frequent carriers of ESBL and/or qAmpC-producing E. coli with a potential zoonotic role.

Antimicrobial resistance in wildlife and in the built environment in a wildlife rehabilitation center

Injured and orphaned wildlife are often brought to Wildlife Rehabilitation Centers (WRC) to be cared for by professionals to ultimately be released back to their natural habitats. In these centers, animals may spend months and frequently receive prolonged antibiotic therapy. Therefore, WRC may play a role in the emergence and dissemination of antimicrobial resistance (AMR). The goal of this study was to investigate the presence and antibiotic resistance profiles of Gram-negative bacteria with reduced susceptibility to cephalosporins in both the wildlife admitted to a WRC and in the WRC built environment in Chile. A cross-sectional study was conducted sampling animals undergoing rehabilitation (n = 64) and the WRC environment (n = 160). Isolated bacterial species were identified with MALDI-TOF, and antimicrobial susceptibility determined using the disk diffusion method. Enterobacteriaceae and Pseudomonadaceae were the dominant bacterial families among the environmental (n = 78) and animal (n = 31) isolates. For Enterobacteriaceae, isolates of the most abundant species (E. coli) were classified into 20 antibiotic resistance profiles, with eight of those isolates being resistant to more than nine antibiotics, including imipenem. Isolates of the Pseudomonadaceae family identified 11 isolates with resistance to antibiotics such as carbapenems and quinolones. Even though a cluster analysis based on antibiotic resistance patterns did not show a clear overlap between environmental and animal isolates, it is important to highlight the identification of isolates resistant to carbapenems, which is very relevant from a public health perspective. Further, numerous antibiotic resistance profiles were observed in different bacterial species, indicating not only environmental contamination with a wide diversity of bacteria, but also a wide diversity of resistant bacteria in animals at the WRC. The approach taken by sampling animals and their hospital environment can be useful in understanding AMR dynamics in wildlife rehabilitation settings, as well as the potential dissemination of AMR into the natural environment.

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The wildlife center was contaminated with wide diversity of resistant bacteria.

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There was wide diversity of resistant bacteria in wildlife at the center.

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Resistant isolates to carbapenems were present, which has public health relevance.

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No clear overlap between wildlife and the center antibiotic resistance patterns.

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Wildlife rehabilitation should be considered in antimicrobial resistance dynamics.

The Role of Gulls as Reservoirs of Antibiotic Resistance in Aquatic Environments: A Scoping Review

The role of wildlife with long-range dispersal such as gulls in the global dissemination of antimicrobial resistance (AMR) across natural and anthropogenic aquatic environments remains poorly understood. Antibiotic-resistant bacteria have been detected in resident and migratory gulls worldwide for more than a decade, suggesting gulls as either sentinels of AMR pollution from anthropogenic sources or independent reservoirs that could maintain and disperse AMR across aquatic environments. However, confirming either of these roles remains challenging and incomplete. In this review, we present current knowledge on the geographic regions where AMR has been detected in gulls, the molecular characterization of resistance genes, and the evidence supporting the capacity of gulls to disperse AMR across regions or countries. We identify several limitations of current research to assess the role of gulls in the spread of AMR including most studies not identifying the source of AMR, few studies comparing bacteria isolated in gulls with other wild or domestic species, and almost no study performing longitudinal sampling over a large period of time to assess the maintenance and dispersion of AMR by gulls within and across regions. We suggest future research required to confirm the role of gulls in the global dispersion of AMR including the standardization of sampling protocols, longitudinal sampling using advanced satellite tracking, and whole-genome sequencing typing. Finally, we discuss the public health implications of the spread of AMR by gulls and potential solutions to limit its spread in aquatic environments.