中国2000-2008年间甲型副伤寒沙门菌脉冲场凝胶电泳和多位点序列分析

目的 分析我国2000-2008年间甲型副伤寒沙门菌流行株的分子分型及病原进化上的特征.方法 应用以Spe Ⅰ为限制性内切酶的脉冲场凝胶电泳(pulsed-field gel electrophoresis,PFGE)方法 和基于9个管家基因位点(aroC、thrA、hisD、purE、sucA、dnaN、hemD、adk和purA)的多位点序列分析(multilocus sequence typing,MLST)分型方法 ,对我国2000-2008年间分离自10个地区的118株甲型副伤寒沙门菌流行株进行分析.结果 应用PFGE方法 将118株甲型副伤寒沙门菌分为32个型,其中包含5株以上的优势PFGE带型有5种.而应用MLST方法 ,所有菌株只分出了2个序列分型(sequence type,ST),各菌株的管家基因序列高度保守,呈现高度克隆化.结论 中国2000-2008年间甲型副伤寒沙门菌菌株应用MLST这种分型方法 很难区分,MLST不适于甲型副伤寒沙门菌的暴发调查和流行病学监测.目前中国的甲型副伤寒是由高度克隆化的菌株引起全国范围的扩散 流行.随着年份的变迁,也积累了散在的变异.

Multilocus sequence typing and pulsed-field gel electrophoresis analysis of Salmonella Paratyphi A isolates from 2000 to 2008, China

Objective To analyze molecular and evolution characteristics of Salmonella Paratyphi A isolates from 2000 to 2008, China. Methods Using pulsed-field gel electrophoresis (PFGE) method with Spe Ⅰ restriction enzyme, and multilocus sequence typing (MLST) method based on housekeeping genes (aroC, thrA, hisD, purE, sucA, dnaN, hemD, adk, and purA), the genomic variations of 118 Salmonella Paratyphi A isolates from 10 regions during 2000 to 2008 were analyzed. Results Using PFGE method, 118 Salmonella Paratyphi A isolates were clustered into 32 PFGE patterns, and 5 patterns were predominant (5 isolates or above). However,only 2 MLST types were identified for all isolates with MLST method. Among all Salmonella Paratyphi A isolates, the sequences of housekeeping genes were highly conservative and showed a high degree of cloning. Conclusion For Chinese epidemic Salmonella Paratyphi A isolates during 2000 - 2008, MLST method showed low discrimination power and the MLST method should not be applied to outbreak and epidemiological surveillance of Salmonella Paratyphi A. Currently, nationwide paratyphoid fever epidemics is caused by highly clonal isolates in China. As the time changes, these isolates also accumulate sporadic mutations.