Etiological study of non-O1/O139 Vibrio cholerae infection cases
Objechve To investigate the homology,virulence and drug resistance of non-O1/O139 Vibrio cholerae isolated from an epidemic in Shanghai in 2023,and conduct traceability investigation and genetic analysis.Methods In September 2023,3 diarrhea cases suspected to be infected with Vibrio cholerae and 7 environmental samples were collected from Xuhui District of Shanghai,and the bacteria were isolated by blood plate culture medium,biochemical and serological identification,Real-time PCR method was used to detect the virulence genes of Vibrio cholerae,broth dilution drug susceptibility test was conducted for the isolated strains,whole genome sequencing was performed by using the second-generation sequencing platform,to predict virulence genes and drug resistance genes.Results A total of 10 strains of non-O1/O139 Vibrio cholerae were isolated from 10 samples,carrying virulence genes such as hlyA,rtx and T6SS.cgSNP showed that there were at least 8 947 nucleotide sites differences among the strains,and cgMLST showed that all the 10 strains were not clusters.The multiple drug resistance rate of 10 strains was 80％,the sensitivity rate to azithromycin,chloramphenicol,gentamicin,tetracycline,amikacin and norfloxacin were all 100％,the resistance rate to cefazolin,imipenem,meropenem and ciprofloxacin were 80％,60％,50％and 50％,respectively.A total of 24 drug resistance genes were detected positive in 10 strains.Quinolone resistance gene(Qnr)and polymyxin resistance gene(Alm)were detected positive in all strains.Conclusion The 10 strains of non-O1/O139 Vibrio cholerae isolated from this epidemic showed biological diversity,the distribution of virulence genes,drug resistance genes and drug resistance phenotypes were different.
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