Escherichia coli from retail meats carry genes associated with uropathogenic Escherichia coli, but are weakly invasive in human bladder cell culture

Abstract

Aims: The aim of this study was to determine the uropathogenic potential of Escherichia coli isolated from retail meats.

Methods and results: Two hundred E. coli isolates recovered from retail meats, which were previously identified molecularly as extraintestinal pathogenic E. coli, were investigated for the presence of 21 uropathogenic E. coli (UPEC) virulence-associated genes. Twenty-three E. coli isolates were selected based on their serogroups and the number of virulence genes they contained, and further characterized using multilocus sequence typing, and by tissue culture assays for adherence to and invasion of T-24 human bladder cells and for their induction of interleukin (IL)-6 secretion. All virulence genes tested, except afa/dra and hlyD, were detected among the E. coli isolates. Multilocus sequence typing analysis of 23 selected isolates revealed that 17 isolates belonged to STs associated with human UPEC. Nearly all 23 isolates exhibited lower level of adherence and invasion compared to a clinical strain, UPEC CFT073.

Conclusions: These observations suggested that a small proportion of E. coli isolates from retail meats carry uropathogenic associated virulence genes and thus may serve as a reservoir of these genes to UPEC in the human intestine. Their virulence potential seemed limited as they were only weakly invasive in human bladder cell culture.

Significance and impact of the study: These findings support the hypothesis that retail meat E. coli may play a role in relation to urinary tract infection (UTI) and may be considered in development of a UTI prevention strategy.