Pathogenomic Characterization of Multidrug-Resistant Escherichia coli Strains Carrying Wide Efflux-Associated and Virulence Genes from the Dairy Farm Environment in Xinjiang, China.

Background/

Objectives

Livestock species, particularly dairy animals, can serve as important reservoirs of E. coli, carrying antibiotic resistance and virulence genes under constant selective pressure and their spread in the environment. In this study, we performed the pathogenomic analysis of seven multidrug resistant (MDR) E. coli strains carrying efflux-associated and virulence genes from the dairy farm environment in Xinjiang Province, China.

Methods

First, we processed the samples using standard microbiological techniques followed by species identification with MALDI-TOF MS. Then, we performed whole genome sequencing (WGS) on the Illumina NovaSeq PE150 platform and conducted pathogenomic analysis using multiple bioinformatics tools.

Results

WGS analysis revealed that the E. coli strains harbored diverse antibiotic efflux-associated genes, including conferring resistance to fluoroquinolones, aminoglycosides, aminocoumarins, macrolides, peptides, phosphonic acid, nitroimidazole, tetracyclines, disinfectants/antiseptics, and multidrug resistance. The phylogenetic analysis classified seven E. coli strains into B1 (n = 4), C (n = 2), and F (n = 1) phylogroups. PathogenFinder predicted all E. coli strains as potential human pathogens belonging to distinct serotypes and carrying broad virulence genes (ranging from 12 to 27), including the Shiga toxin-producing gene (stx1, n = 1). However, we found that a few of the virulence genes were associated with prophages and genomic islands in the E. coli strains. Moreover, all E. coli strains carried a diverse bacterial secretion systems and biofilm-associated genes.

Conclusions

The present study highlights the need for large-scale genomic surveillance of antibiotic-resistant bacteria in dairy farm environments to identify AMR reservoir spillover and pathogenic risks to humans and design targeted interventions to further stop their spread under a One Health framework.