ESBLs‐producing Escherichia coli from sheep‐origin: Genome‐wide virulence genes identification and in vivo virulence assessment in mice and Galleria mellonella

Abstract

The worldwide spread of pathogenic Escherichia coli, together with the multidrug resistant linked with extended‐spectrum β‐lactamases (blaCTX‐M, blaTEM and blaOXA), not only affect the health of animals and humans but also bring huge economic losses to animal husbandry. Despite the high levels of virulence present in many extended‐spectrum beta‐lactamases (ESBLs)‐producing E. coli isolates, however, few studies have comprehensively assessed the pathogenicity of ESBLs‐producing E. coli isolates. Thus, the aim of the present study was to investigate the presence of virulence genes in third‐generation cephalosporin–resistant E. coli and to assess their pathogenicity and zoonotic potential. Previously, we identified 67 ESBLs‐producing E. coli strains from sheep anal swabs in northwest China. In this study, we genotypically and phenotypically characterized isolates of E. coli that produce ESBLs. According to the VirulenceFinder and virulence factors database, all ESBLs‐producing E. coli strains harboured a wide range of virulence genes. The ColV plasmid‐related genes (hlyF, ompT, iss, iutA and cvaC) were present in 52 (77.6%) ESBLs‐producing E. coli isolates. Surprisingly, quite a number of extraintestinal pathogenic E. coli virulence‐related genes were detected in 62 (92.5%) of 67 isolates. A total of 33 serotypes and 37 sequence types (STs) were found in 67 ESBLs‐producing isolates. ST10 is the most prevalent ST, which is represented by five strains. The cluster analysis showed that CC10 and CC23 were the common clonal complexes (CCs). Predominant serotypes were O8 (10%) and O9 (9%) followed by 6% each of O89, O101 and O185. Most sheep‐origin ESBLs‐producing E. coli held the highly pathogenic to human and displayed moderate‐to‐vigorous‐intensity motor capacity. The ESBLs‐producing E. coli isolates with numerous virulence‐related genes were able to cause multiple infectious diseases in animal models (mice, neonatal rats and Galleria mellonella). To our knowledge, this study represents an important first step for a comprehensive characterization of pathogenicity and zoonotic potential of sheep‐origin ESBLs‐producing E. coli isolates. These findings may be of significant value for the identification of pathogenicity and zoonotic potential risks associated with sheep‐origin ESBLs‐producing E. coli.