A study on the pathogenic characteristics and traceability of Vibrio cholera strains circulated in Hubei province in 2012

Abstract

Objective Toinvestigate the pathogenic characteristics of Vibrio cholera strains isola- ted from Hubei province in 2012, and to identify the source of infection by analyzing their genetic correla- tions. Methods The biochemical identification, toxin gene detection and drug susceptibility test were car- ried out to analyze a total of 35 Vibrio cholera strains isolated from three epidemic areas. Comparison of ge- nomic DNA fingerprints and cluster analysis among isolates of Vibrio cholera was conducted by using pulsed- field gel electrophoresis （PFGE）. Results All of the 35 strains were Vibrio cholera O139, of which 71.42% were toxic strains. The drug resistance rates of Vibrio cholera strains to tetracycline, cotrimoxazole and rifampincin were 57.14%, 88.57% and 80.00%, respectively. Analysis of genomic DNA fingerprints of the isolates showed highly similar with similarity values ranging from 80% -100%. Most of the strains iso- lated from the same epidemic area fell into the same one cluster with 100% homology in genome Only a strain isolated from turtle in Jingzhou area was belong to a different cluster. Conclusion The Vibrio cholera 0139 strains were the dominant strains causing the outbreaks of cholera in Hubei province in 2012. Most of them were toxigenic strains. A large majority of the strains had developed resistance to tetracycline, eotri- moxazole and rifampincin, but all strains showed high susceptibility to ceftriaxone and imipenem. Vibrio cholera strains isolated from the same epidemic area were mainly belonged to the same one cluster, sugges- ting the same source of infection. However, the strains varied among different epidemic area. Follow-up in- vestigations of three outbreaks of cholera in this study were all associated with food infection. Therefore, more attention should be paid to food sanitation and safety measurement. Although a non-toxigenic strain iso- lated from turtle was not associated with the epidemic of cholera, surveillance for seafood and aquatic prod- ucts would still be necessary. Key words: Vibrio cholera; Toxin gene; Drug resistance rate; Pulse field gel electrophoresis