Genome sequence of Vibrio anguillarum isolates carrying a novel class A fi-lactamase VAN-1: do migratory fish transport novel resistance factors?

Objectives: The aim of the study was to understand the genetic basis of resistance of five fi-lactam resis -tant Vibrio anguillarum isolates obtained from the gut content of Atlantic mackerel (Scomber scomberus), using whole genome sequencing and to characterize a novel fi-lactamase (VAN-1) from these isolates. Method: Antibiotic sensitivity pattern was determined using SensititreTM plates and whole genome se-quencing was carried out using Illumina MiSeq-based sequencing. The blaVAN-1 gene was synthesized and expressed in Escherichia coli Top10 cells. Results: Five isolates obtained (out of 73) from the gut content of Atlantic mackerel were identified as Vibrio anguillarum. Whole genome assemblies ranged from 3.894 to 3.906 million bases in length with an average of 50 contigs. A novel fi-lactamase blaVAN-1, sharing 77.7% nucleotide identity with a known mobile fi-lactamase from Vibrio species was detected. The blaVAN-1 gene in these isolates is flanked by a truncated IS5 family transposase on one end and a hypothetical protein and outer membrane protein followed by another IS5 family transposase on the other end, suggesting its potential for mobility. The blaVAN-1 gene was absent in V. anguillarum type strain (ATCC 14181) and V. anguillarum isolates from bivalves and sea water in Norway. VAN-1 conferred ampicillin resistance when expressed in E. coli , thus confirming the functionality of this gene. Conclusions: Our study highlights the importance of the marine environment as a reservoir of new an-tibiotic resistance genes. Our results suggest that migratory fish may transport novel antibiotic resistance determinants over long distances. (c) 2022 The Author(s). Published by Elsevier Ltd on behalf of International Society for Antimicrobial Chemotherapy. This is an open access article under the CC BY license ( http://creativecommons.org/licenses/by/4.0/ )

Automated summary

The aim of this study was to understand the genetic basis of resistance to fi-lactam antibiotics in Vibrio anguillarum isolates obtained from Atlantic mackerel, and to identify a novel fi-lactamase (VAN-1) from these isolates using whole genome sequencing. The results showed that a novel fi-lactamase gene blaVAN-1, which shares nucleotide identity with a known mobile fi-lactamase from Vibrio species, was detected in the isolates. The study highlights the importance of the marine environment as a reservoir of new antibiotic resistance genes and suggests the potential for long-distance transport of antibiotic resistance determinants by migratory fish.