广东省霍乱病例与环境来源霍乱弧菌的耐药性和分子分型研究

Study of drug resistance and molecular typing of Vibrio cholerae from cholera cases and outer environment in Guangdong province

目的比较分析广东省霍乱病例及环境来源O1/O139群霍乱弧菌抗生素敏感性和分子分型特征。方法选取2006-2007年广东省霍乱病例及相关来源、环境(珠江水体和海水产品)来源的O1/O139群霍乱弧菌。采用血清学、药物敏感性试验和分子生物学方法,研究不同来源的霍乱弧菌在菌型分布、药物敏感性、毒素基因携带以及分子分型方面的异同。结果2006-2007年,广东省共分离各类来源O1/O139群霍乱弧菌170株。其中,病例及相关来源菌株37株,环境来源菌株133株(海水产品来源37株、珠江水体96株)。两种来源菌株的菌型构成均以O1群E l Tor稻叶型为主;病例及相关来源菌株以产毒株为主,ctxA毒素基因携带率(83.8%)显著高于环境菌株(4.5%);药物敏感性试验显示,以产毒株为主的病例及相关来源菌株对萘啶酸和复方新诺明的耐药率(78.8%,78.8%)高于以非产毒株为主的环境来源菌株(50.6%,13.9%,P<0.05)。环境来源菌株对多西环素的耐药率(17.7%)高于病例及相关来源菌株(0%,P<0.05)。O139群菌株对氨苄西林的耐药率(70%)高于稻叶型和小川型菌株(8.9%,0%,P<0.01)。脉冲场凝胶电泳(PFGE)聚类分析显示,O139群霍乱弧菌产毒株之间,O1群霍乱弧菌流行株之间以及其他的O1/O139群霍乱弧菌之间,PFGE型别表现为明显的遗传多样性。结论广东省O1/O139群霍乱弧菌来源复杂多样,霍乱防控形势严峻,需要密切注意菌株型别变异情况及菌株变异趋势。

Objective To analyze the drug susceptibility and molecular features of Vibrio cholerae O1 and O139 from cholera cases and outer environment in Guangdong province. Methods Vibrio 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. Results A 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 ctx.4 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%, P 〈0.05）. 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%, P〈0.05）. The drug resistant rate of O139 strains to ampicillin （70%） was higher than Inaba and Ogawa strains （8.9% ,0%, P 〈 0. 01 ）. PFGE cluster analysis indicated that the high genetic diversity existed among the toxinproducing strains of O139, epidemic strains of O1 and other O1/O139 strains. Conclusion The 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.