Clinically relevant antibiotic resistance in Escherichia coli from black kites in southwestern Siberia: a genetic and phenotypic investigation

Genomic features, antimicrobial resistance and pathogenicity assessment of Escherichia coli serotype O177:H51 strain JS01 isolated from a diseased chicken

BACKGROUND

Avian colibacillosis, caused by avian pathogenic Escherichia coli (APEC), remains one of the most significant bacterial diseases threatening global poultry production and causing substantial economic losses. The dominant serotypes of APEC regional diversity, complicating prevention and control efforts. Given the pathogen's importance, this study focused on the microbiological identification of an E. coli strain (JS01) isolated from diseased chickens on a poultry farm in China. Further analyses were conducted to characterize its antimicrobial resistance (AMR) phenotype and pathogenicity. To elucidate its multi-drug resistance and pathogenic mechanisms, whole-genome sequencing (WGS) of JS01 was performed, followed by functional gene annotation, sequence typing, and serotype analysis. Additionally, the genetic evolutionary characteristics of JS01 were investigated through comparative genomics and phylogenetic tree analysis.

RESULTS

Strain JS01 was identified as an ST155 E. coli of O177:H51 serotype, exhibiting multi-drug resistant and strong virulence. WGS revealed that JS01's genome consists of one chromosome and three plasmids, comprising 4,670 coding DNA sequences with a total length 5,089,394 bp. The genome harbored 64 AMR genes and 177 virulence factor (VF) genes. The AMR genes were primarily associated with defense mechanisms conferring antibiotic resistance, while the VF genes were linked to adhesins, motility, and effector systems. Comparative genomic analysis indicated that JS01 is closely related to GCA_900636075.1, ASM1038v1 and ASM3229062v1, which were isolated from different hosts.

CONCLUSION

This study isolated and identified the O177: H51 serotype E. coli strain JS01 from chickens. The findings of this study provide valuable insights into the serotype distribution, antibiotic resistance patterns, and virulence characteristics of APEC isolates from diseased chickens in China. These results lay a foundation for future research to more accurately assess the impact of colibacillosis on the poultry industry and to develop targeted control strategies.

Molecular Characterization of Multidrug-Resistant Escherichia coli from Fecal Samples of Wild Animals

Antimicrobial resistance (AMR) surveillance in fecal Escherichia coli isolates from wildlife is crucial for monitoring the spread of this microorganism in the environment and for developing effective AMR control strategies. Wildlife can act as carriers of AMR bacteria and spread them to other wildlife, domestic animals, and humans; thus, they have public health implications. A total of 128 Escherichia coli isolates were obtained from 66 of 217 fecal samples obtained from different wild animals using media without antibiotic supplementation. Antibiograms were performed for 17 antibiotics to determine the phenotypic resistance profile in these isolates. Extended-spectrum β-lactamase (ESBL) production was tested using the double-disc synergy test, and 29 E. coli strains were selected for whole genome sequencing. In total, 22.1% of the wild animals tested carried multidrug-resistant E. coli isolates, and 0.93% (2/217) of these wild animals carried E. coli isolates with ESBL-encoding genes (blaCTX-M-65, blaCTX-M-55, and blaEC-1982). The E. coli isolates showed the highest resistance rates to ampicillin and were fully susceptible to amikacin, meropenem, ertapenem, and imipenem. Multiple resistance and virulence genes were detected, as well as different plasmids. The relatively high frequency of multidrug-resistant E. coli isolates in wildlife, with some of them being ESBL producers, raises some concern regarding the potential transmission of antibiotic-resistant bacteria among these animals. Gaining insights into antibiotic resistance patterns in wildlife can be vital in shaping conservation initiatives and developing effective strategies for responsible antibiotic use.

The faecal microbiome of the Australian silver gull contains phylogenetically diverse ExPEC, aEPEC and Escherichia coli carrying the transmissible locus of stress tolerance

Wildlife are implicated in the dissemination of antimicrobial resistance, but their roles as hosts for Escherichia coli that pose a threat to human and animal health is limited. Gulls (family Laridae) in particular, are known to carry diverse lineages of multiple-antibiotic resistant E. coli, including extra-intestinal pathogenic E. coli (ExPEC). Whole genome sequencing of 431 E. coli isolates from 69 healthy Australian silver gulls (Chroicocephalus novaehollandiae) sampled during the 2019 breeding season, and without antibiotic selection, was undertaken to assess carriage in an urban wildlife population. Phylogenetic analysis and genotyping resolved 123 sequence types (STs) representing most phylogroups, and identified diverse ExPEC, including an expansive phylogroup B2 cluster comprising 103 isolates (24 %; 31 STs). Analysis of the mobilome identified: i) widespread carriage of the Yersinia High Pathogenicity Island (HPI), a key ExPEC virulence determinant; ii) broad distribution of two novel phage elements, each carrying sitABCD and iii) carriage of the transmissible locus of stress tolerance (tLST), an element linked to sanitation resistance. Of the 169 HPI carrying isolates, 49 (48 %) represented diverse B2 isolates hosting FII-64 ColV-like plasmids that lacked iutABC and sitABC operons typical of ColV plasmids, but carried the serine protease autotransporter gene, sha. Diverse E. coli also carried archetypal ColV plasmids (52 isolates; 12 %). Clusters of closely related E. coli (<50 SNVs) from ST58, ST457 and ST746, sourced from healthy gulls, humans, and companion animals, were frequently identified. In summary, anthropogenically impacted gulls host an expansive E. coli population, including: i) putative ExPEC that carry ColV virulence gene cargo (101 isolates; 23.4 %) and HPI (169 isolates; 39 %); ii) atypical enteropathogenic E. coli (EPEC) (17 isolates; 3.9 %), and iii) E. coli that carry the tLST (20 isolates; 4.6 %). Gulls play an important role in the evolution and transmission of E. coli that impact human health.