中国O1群El Tor霍乱弧菌产毒株表型多态性研究

Phenotypic diversity of toxigenic Vibrio cholerae O1 El Tor strains identified in China

目的：了解近50年中国不同地区分离的O1群El Tor型霍乱弧菌产毒株的生物表型特征变化。方法采用多粘菌素B敏感试验、第Ⅳ组霍乱噬菌体裂解试验、VP试验和溶血实验进行表型特征分析。结果生物型表型特征分析表明133株菌具有典型的El Tor生物型表型特征，其余251株菌呈现不典型的El Tor生物型表型特征；综合ctxB、rstR基因型和生物型表型特征分析，385株检测菌株中64株为典型El Tor生物型菌株，21株菌有典型的El Tor生物型表型特征但携带古典型ctxB基因，杂合型特征菌有280株，根据ctxB、rstR和表型特征的不同组合可再分为45个杂合型。结论中国O1群El Tor霍乱弧菌菌株呈现明显的表型多态性，传统的表型分型特征不能有效区分古典生物型和El Tor生物型菌株。

Objective To understand the phenotypic diversity of toxigenic Vibrio cholerae O1 El Tor strains isolated from different provinces in China during the last 50 years. Methods Traditional biotyping testings including susceptibility to polymyxin B,sensitivity to groupⅣphage, Voges-Proskauer test and haemolysis of sheep erythrocytes were conducted. Results Data from Biotype-specific phenotype analysis revealed that only 133 isolates carryed the typical El Tor phenotypes while the other 251 isolates displayed atypical El Tor phenotypes. Combined with ctxB, rstR genotypes and phenotypic characteristics,64 isolates were identified as typical El Tor biotype,21 were El Tor variants that showing the typical El Tor biotype-specific phenotype but with ctxBclas . 280 isolates were defined as the hybrid groups with traits of both classical and El Tor biotypes that could be further classified into 45 groups,based on the combination of genotypes of ctxB,rstR and phenotypic characteristics. Conclusion Toxigenic Vibrio cholerae O1 El Tor strains that isolated from different provinces in China displayed high phenotypic diversity. The traditional biotype traits could not be used to correctly distinguish the two different biotypes.