Abstract: ObjectiveTo analyze the drug susceptibility and molecular features of Vibrio cholerae O1 and O139 from cholera cases and outer environment in Guangdong province. MethodsVibrio cholerae O1 and O139 strains were isolated from cholera cases samples and outer environmental samples (Pearl River water and seafood) from 2006 to 2007. The serotype, toxic gene carrying and molecular typing of the Vibrio cholerae strains from different samples were studied by serological and molecular biological methods, and the drug susceptibility test for these strains was conducted. ResultsA total of 170 strains of Vibrio cholerae were isolated from the samples of different sources, of these strains, 37 were from cholera cases and 133 were from outer environment (37 from seafood, and 96 from Pearl River water). The predominated serotype of Vibrio cholerae from two sources was Inaba of serogroup O1. Most strains from cholera cases were toxin-producing with the ctxA toxic gene carrying rate (83.8%) which was significantly higher than the strains from outer environment (4.5%).The drug susceptibility test indicated that the drug resistant rates of toxin-producing strains from cholera cases to nalidixic acid and trimethoprim+sulfamethoxazole (78.8%, 78.8%) were higher than non-toxin producing strains from outer environment (50.6%, 13.9%, P0.05). The drug resistant rate of the strains isolated from outer environment to doxycycline (17.7%) was higher than the strains isolated from cholera cases (0%，P0.05). The drug resistant rate of O139 strains to ampicillin (70%) was higher than Inaba and Ogawa strains (8.9%，0%，P0.01). PFGE cluster analysis indicated that the high genetic diversity existed among the toxin-producing strains of O139, epidemic strains of O1 and other O1/O139 strains. ConclusionThe sources of O1 and O139 strains were complex and diverse in Guangdong province, which could be a great challenge to the prevention and control of cholera. Close attention should be paid on the variation of serotype of Vibrio cholerae