First report of two foodborne Salmonella enterica subsp. enterica serovar Bovismorbificans isolates carrying a novel mega-plasmid harboring bla < sub > DHA-1 < /sub > and qnrB4 genes

In this study, we here report for the first time the isolation of two multi-drug resistant (MDR) S. Bovismorbificans strains co-harboring plasmid-encoded AmpC (pAmpC) β-lactamase gene (blaDHA-1) and qnrB gene, 16Sal017 isolated from a chicken meat sample and 16Sal018 from a grass carp fish sample, collected from retail markets in Guangzhou, China. The blaDHA-1 and qnrB genes in these two strains were both located on the same novel 217,773 bp IncHI2 plasmid belonged to ST2. The plasmid contained 16 additional acquired antimicrobial resistance genes encoding resistance to eight antibiotic classes and quaternary ammonium compound. Besides, 16Sal017 contained an additional 10,124 bp Col (pHAD28)-like plasmid harboring qnrS1. The blaDHA-1 and qnrB4 genes were located in an 18,198 bp region, sul1-qacEΔ1-ampR-blaDHA-1-pspABCDF-qnrB4-sapABC-IS91-sul1-qacEΔ1, which has been identified in various bacteria species, indicating the high transfer ability of blaDHA-1 and qnrB4 genes within this gene cluster. The IncHI2 plasmid was found to be transferable to Escherichia coli J53 by conjugation and resulted in the acquiring of multiple resistance in the transconjugants. Genome sequence comparisons by cgMLST and MAUVE alignment indicated 16Sal017 and 16Sal018 are highly similar and are not epidemiologically linked with strains from other sources and countries. Our findings suggest S. Bovismorbificans as a new host for conjugative mega-plasmid harboring blaDHA-1 and qnrB4 genes, and highlig...
Source: International Journal of Food Microbiology - Category: Food Science Authors: Source Type: research