Characteristics of phenotype and molecular type of Vibrio cholerae in Changping district of Beijing, 2013–2019

ObjectivesTo understand the characteristics of the phenotype and molecular type of Vibrio cholerae strains in Changping district of Beijing from 2013 to 2019.

MethodsThe conventional test was used for the detection of V. cholerae in suspected samples collected in Changping during this period. All V. cholerae O1 serotype Ogawa strains isolated were digested by two restrict enzyme (Not Ⅰ and SfiⅠ), and then analyzed with pulsed field gel electrophoresis. Nine virulence genes were detected by real-time PCR and PCR. The strains’ susceptibilities to 21 antibiotics were tested by minimal inhibitory concentration.

ResultsA total of 29 V. cholerae O1 serotype Ogawa strains (10 strains isolated from sporadic cases, 19 strains isolated from an outbreak) were isolated in Changping from 2013 to 2019. Among the 29 V. cholerae strains, three PFGE patterns (CP-01–03) were found with the similarity coefficient from 78.5% to 100%, and the CP-02 (27/29, 93.10%) was the predominant PFGE pattern. The gene toxR and hlyA were found in all the strains, but no ctxAB was found. The carriage rates of gene ompU, tcpA, tcpI, rtxC, zot and ace were 89.66%, 82.76%, 82.76%, 44.83%, 6.90% and 6.90%, respectively. Except cefazolin (0.00%) and streptomycin (3.45%), most V. cholerae strains were sensitive to the other 19 antibiotics (82.76%–100.00%).

ConclusionsAll the V. cholerae O1 serotype Ogawa strains isolated in Changping from 2013 to 2019 were non-toxigenic. Most V. cholerae O1 serotype Ogawa strains belonged to the same PFGE pattern. The carriage rates of gene toxR and hlyA were higher. The strains showed sensitivity to most antibiotics. Our data suggested that more attention should be paid to such strains and targeted measure are necessary in the future prevention and control to reduce cholera outbreak.