Characteristics of phenotype and molecular type of Vibrio cholerae O1 in Beijing, 2018

ObjectiveTo understand the characteristics of the phenotype and molecular type of Vibrio cholerae O1 in Beijing in 2018.

MethodsThe strains of V. cholerae were isolated from cholera cases and external environments. Serotyping was performed for the strains with routine identification methods, and V. cholerae toxin gene were detected by using real-time PCR. The sensitivities of the strains to 21 kinds of antibiotics was conducted with micro-broth dilution method. Pulsed field gel electrophoresis (PFGE) with Xba Ⅰ and Not Ⅰ restriction enzymes was performed for the molecular typing of V. cholerae O1 strains.

ResultsIn 29 V. cholerae O1 strains isolated, the proportions of non-toxin producing Ogawa strains, non-toxin producing Inaba strains and toxin producing Ogawa strains were 62.07% (18/29), 24.14% (7/29) and 13.79% (4/29) respectively. The resistance rate of the strains to cefazolin was highest (82.76%), all the strains were sensitivity to meropenem (100.00%). Twenty eight strains were drug resistant with 9 drug resistance types, the highest was resistant to 13 antibiotics; there were 13 resistance categories to 11 classes of antibiotics, the highest was resistant to 7 classes of antibiotics. Results from PFGE indicated that the 29 V. cholerae strains were classified into 16 molecular types.

ConclusionV. cholerae O1 was mainly non-toxic in Beijing, and multi drug resistance of V. cholerae O1was severe. The results of PFGE molecular typing suggested that the attention should be paid to food safety, especially to strengthen the monitoring of aquatic products.