多位点序列分型和脉冲场凝胶电泳在肠炎沙门菌分子分型的比较

目的 比较多位点序列分型技术和脉冲场凝胶电泳（PFGE）技术在肠炎沙门菌菌株间分型的分辨率。方法 分别建立肠炎沙门菌的6个管家基因thrA、pure、sucA、aroC、hemD、dnaN和一个特异性的DNA标记Sdf Ⅰ的多位点序列分型技术，及以寡切点的XbaⅠ、SpeⅠ作为限制性内切酶的PFGE方法，并应用上述方法对食品中的分离株进行分型，比较两种方法的分辨率。结果 PFGE可以将50株肠炎沙门菌分为11个型。并且通过双酶系统的双重PFGE分型，还可以将PFGE型别再精细划分为亚型；MLST则揭示了在同一血清型内部，各菌株之间的管家基因碱基序列高度保守，而在沙门菌不同血清型的核苷酸序列之间，则分别存在不同数量的碱基差异。即MLST方法只能用于血清型之间，不能在血清型内部进行分型研究。结论 与MLST比较，PFGE方法在肠炎沙门菌的分型方面显示了比较高的分辨率。

Comparison of mnltilocas sequence typing system and pulsed-field gel electrophoresis in typing of Salmonella enteritidis

OBJECTIVE: To compare the discriminatory ability between multilocus sequence typing system (MLST) and pulsed-field gel electrophoresis (PFGE). METHODS: Salmonella enteritidis strains, isolated from food in China were identified by MLST, under PCR products of thrA, purE, sucA, aroC, hemD, dnaN and Sdf I. The same set of strains was typed by PFGE using Xba I, Spe I as the restriction enzyme in order to compare the discriminatory power of the methods. RESULTS: Data from MLST revealed the lack of diversity among the strains of the same serotype and the number of variable nucleotide sites per locus ranged from 1 to 23 between Salmonella typhi LT2 and other serotypes of Salmonella. However, 50 Salmonella enteritidis strains were identified as 11 patterns and more sub-patterns by PFGE. CONCLUSION: In strain typing, PFGE was the highly discriminatory method comparing to the MLST system.