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

Abstract

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.