Vibrios from the Norwegian marine environment : Characterization of associated antibiotic resistance and virulence genes

Abstract

A total of 116 Vibrio isolates comprising V. alginolyticus (n = 53), V. metschnikovii (n = 38), V. anguillarum (n = 21), V. antiquarius (n = 2), and V. fujianensis (n = 2) were obtained from seawater, fish, or bivalve molluscs from temperate Oceanic and Polar Oceanic area around Norway. Antibiotic sensitivity testing revealed resistance or reduced susceptibility to ampicillin (74%), oxolinic acid (33%), imipenem (21%), aztreonam (19%), and tobramycin (17%). Whole-genome sequence analysis of eighteen drug-resistant isolates revealed the presence of genes like β-lactamases, chloramphenicol-acetyltransferases, and genes conferring tetracycline and quinolone resistance. The strains also carried virulence genes like hly A, tlh, rtx A to D and ace A, E and F. The genes for cholerae toxin (ctx), thermostable direct hemolysin (tdh), or zonula occludens toxin (zot) were not detected in any of the isolates. The present study shows low prevalence of multidrug resistance and absence of virulence genes of high global concern among environmental vibrios in Norway. However, in the light of climate change, and projected rising sea surface temperatures, even in the cold temperate areas, there is a need for frequent monitoring of resistance and virulence in vibrios to be prepared for future public health challenges. This study investigated the occurrence of Vibrio spp. in water samples, fish and marine bivalves from the temperate Oceanic and Polar Oceanic areas around Norway. Five species, V. alginolyticus (n = 53), V. metschnikovii (n = 38), V. anguillarum (n = 21), V. antiquarius (n = 2) and V. fujianensis (n = 2) were isolated. We examined antimicrobial susceptibility, hemolytic activity and characterized antimicrobial resistance genes and virulence genes by whole genome sequencing. This study found low prevalence of multidrug resistance, and absence of virulence genes of high global concern.