To investigate the situation of multi-drug resistant(MDR)of V.parahaemolyticus from aquatic food sources and the transmission mechanism of MDR mediated by plasmids,in this study,a total of 300 aquatic food samples including Pneumatophorus japonicus,Litopenaeus vannamei and Crassostrea gigas were collected,and V.parahaemolyticus was isolated and identified by traditional culture method,PCR,Gram staining,biochemical identification and sequencing verification.PCR was used to analyze the two virulence genes of thermostable direct hemolysin(tdh)and TDH related hemolysin(trh)carried by the V.parahaemolyticus isolates,and Kirby-Bauer disk diffusion method was employed to detect the isolates to 19 types of drugs in 9 categories and analyze the multi-drug resistance of the isolates.The plasmid elimination test,plasmid extraction and typing test and plasmid conjugation transfer test were fulfilled to examine the plasmid-mediated transmission of antimicrobial resistance(AMR)of MDR V.parahaemolyticus isolates.The results showed that 95 strains of V.parahaemolyticus were isolated and identified from 300 aquatic food samples,the isolation rate was 31.7％(95/300),and the virulence genes of tdh and trh were not detected.The antimicrobial susceptibility testing revealed that the MDR rate of V.parahaemolyticus isolates was 30.5％(29/95)and the most isolates resistance to ampicillin and rifampicin.Plasmid elimination test of 29 MDR isolates showed that antimicrobial resistance phenotype of 15 isolates disappeared completely or partially.Plasmids of the 15 isolates were extracted and typed,of which 13 isolates carried IncF type of plasmid.Conjugation transfer test of 10 isolates carrying plasmids with ampicillin resistance showed that all plasmids had ability of conjugation transfer and the antimicrobial resistance was stable.In conclusion,the V.parahaemolyticus isolated from aquatic food in this study were all devoid of the tdh and trh virulence genes,hence exhibiting low pathogenicity.However,the rate of multi-drug resistance was relatively high,with a 51.7％(15/29)plasmid-mediated resistance rate among multi-drug resistant strains.The horizontal transmission of the antimicrobial resistance,likely facilitated by plasmids as carriers,may be predominantly driven by IncF-type plasmids.This study lays a certain theoretical foundation for regulating aquaculture medication and blocking the spread of AMR microorganisms in aquatic food sources.
NETL
NSTL
万方数据
