Genomic Analysis and Virulence Features of Vibrio cholerae Non-O1/Non-O139 Harbouring CARB-Type β-Lactamases From Freshwater Bodies, Argentina

Abstract

Vibrio cholerae is a globally distributed, free-living bacterium in aquatic ecosystems. While non-O1/non-O139 serogroups typically do not produce cholera toxin, they have the potential to cause diarrhoea. These strains may act as reservoirs of antibiotic resistance in rivers, lakes and oceans. Understanding their genetic resistance and virulence can shed light on their role in spreading antimicrobial resistance and their pathogenicity. In this study, we characterised 60 V. cholerae non-O1/non-O139 strains from 16 freshwater bodies located throughout the Province of Córdoba, Argentina. We found none of the strains carried cholera toxin and identified ampicillin resistance as the most prevalent phenotype. Whole genome sequencing revealed that all ampicillin-resistant strains (n = 10) carried CARB β-lactamases, leading to the identification of new CARB variants (CARB-59 to CARB-62) likely associated with the V. cholerae superintegron. Two strains were notably related and exhibited enhanced virulence due to an unusual genetic arrangement of the VPI-1 pathogenicity island, encoding both the toxin co-regulated pilus and a type VI secretion system cluster subclass i5, commonly found in non-cholera Vibrio species. These findings provide significant insights into the genetic diversity and virulent potential of ampicillin-resistant environmental V. cholerae non-O1/non-O139 and enhance our understanding of the evolution of CARB β-lactamases within the species.