Whole-genome sequencing of strains of Vibrio spp. from China reveals different genetic contexts of blaCTX-M-14 among diverse lineages

Objectives: To investigate the prevalence and genetic contexts of the bla(CTM-M-14) gene harboured by foodbome isolates of Vibrio spp. in China. Methods: A total of 1856 Vibrio spp. isolates collected from raw meat and shrimp samples in Guangdong Province of China were screened for bla(CTM-M-14) by PCR. The bla(CTM-M-14)-positive isolates were characterized by MIC, PFGE, MLST, conjugation, S1-PFGE and Southern blotting and WGS using Illumina and Nanopore platforms. Results: A total of 35 (1.9%) Vibrio isolates were positive for bla(CTM-M-14), including 33 Vibrio parahaemolyticus strains and two Vibrio alginolyticus strains. MLST showed that most of the bla(CTX-M-14)-bearing isolates could be assigned into two major STs, with ST163 being more prevalent (n = 23), followed by ST180 (n = 6). Whole-genome analysis of these 35 isolates revealed that the bla(CTM-M-14) gene was associated with ISEcp1 in the upstream region, of which 32 bla(CTM-M-14) genes were located in the same loci of chromosome I, 1 bla(CTM-M-14) gene was located in a novel chromosomal integrative conjugative element (ICE) belonging to the SXT/R391 family and 2 bla(CTM-M-14), genes were located in the same type of plasmid, which belonged to the IncP-1 group. Conjugation experiments showed that only the plasmid-borne bla(CTM-M-14) gene could be transferred to the recipient strain Escherichia coli J53. Conclusions: The emergence of the noveL ICE and IncP-1 plasmids has contributed to the variable genetic contexts of bla(CTX-M-)(14) among strains of Vibrio spp. and facilitated the horizontal transfer of such genes between Vibrio spp. and other zoonotic pathogens, resulting in a rapid increase in the prevalence of bla(CTM-M-14)-bearing bacterial pathogens worldwide.

Automated summary

This study investigated the prevalence and genetic contexts of the bla(CTX-M-14) gene in foodborne Vibrio isolates in China. The results showed that this gene was widely distributed in Vibrio species and could be transferred horizontally between strains, contributing to the rapid increase in prevalence of bla(CTX-M-14)-bearing bacterial pathogens worldwide.