輸入水産食品におけるプラスミド伝播が推定されるセフェム系およびカルバペネム系プラスミド性薬剤耐性菌の汚染状況

Abstract

Food contamination with extended-spectrum beta-lactamase (ESBL)-producing bacteria is recognized as one of the public health concerns worldwide. Although fish and fishery products at retail in Japan have relied on the imported materials, no apparent evidences exist on the prevalence and property of genetic transfer in the ESBL-producing bacteria in those food specimens. This study aimed to investigate the prevalence of plasmid-mediated antibiotic-resistant bacteria in imported fishery products. Fifteen fishery products retailed in Japan, imported from Southeast and South Asia during January to March 2020, were examined to detect AmpC/ESBL-producing Escherichia coli, or antibiotic-resistant Vibrio spp. through culture in buffered peptone water (BPW) or alkaline peptone water (APW), followed by selective enrichment on CHROMagar ECC or CHROMagar Vibrio containing cefotaxime/meropenem. A total of 172 strains were finally isolated from 15 samples. 16S rRNA sequencing gene revealed the predominant distribution of Stenotrophomonas maltophilia and E. coli from CHROMagar ECC, and Enterococcus spp. and Vibrio spp. from CHROMagar Vibrio, respectively. Amongst, E. coli, Klebsiella pneumoniae, V. vulnificus, and V. parahaemolyticus were ESBL-producers and harboured CTX-M-15, 55, or 27. Aeromonas caviae and E. coli were AmpC β-lactamase-producers and harboured CMY-8 and CMY-2, respectively. One Enterobacter cloacae complex from one shrimp sample was resistant to meropenem and harboured NDM-1. A gene transfer assay revealed that all isolated ESBLs, except Vibrio spp. and carbapenemase-producing Enterobacter spp., transferred CTX-M or NDM-1 to E. coli ATCC25922 and BL21. Overall, our data indicated the frequent contamination of imported fishery materials with AmpC/ESBL and carbapenemase-producing bacteria, with possible transferability of CTX-M or NDM-1 genes to intestinal E. coli in humans.