A new multidrug-resistant enterotoxigenic Escherichia coli pulsed-field gel electrophoresis cluster associated with enrofloxacin non-susceptibility in diseased pigs.

ABSTRACT

AIMS: To describe the temporal trends in Escherichia coli pathotypes and antimicrobial resistance detected in isolates from diseased-pig cases submitted to the EcL from 2008 to 2016, in Quebec, Canada, and to investigate the presence of spatiotemporal and phylogenetic clusters. METHODS AND RESULTS: Detection of 12 genes coding for virulence factors in pathogenic E. coli in pigs by PCR and antimicrobial resistance standard disc diffusion assay were performed. Demographic and clinical data were entered in the Animal Pathogenic and Zoonotic E. coli (APZEC) database. ETECF4 was the most prevalent pathovirotype among the 3773 cases submitted. The LTSTbF4 virotype was predominant until 2014, then was overtaken by the LTSTbSTaF4 virotype. More than 90% of the ETECF4 isolates were multidrug resistant. A spatiotemporal cluster of LTSTbSTaF4 isolates non-susceptible to enrofloxacin was detected between 4/2015 and 9/2016. Pulsed-field gel electrophoresis analysis of 137 ETECF4 isolates revealed the presence of a cluster composed mainly of LTSTbSTaF4 isolates non-susceptible to enrofloxacin. CONCLUSIONS: The APZEC database was useful to highlight temporal trends in E. coli pathotypes. A high-risk ETECF4 clone might disseminate in the pig population in Quebec since 2015. SIGNIFICANCE AND IMPACT OF THE STUDY Surveillance is crucial to identify new clones and develop control strategies.