我国婴儿配方粉来源的克罗诺杆菌脉冲场凝胶电泳分子分型和多位点序列分型研究

Study on pulsed field gel electrophoresis and multilocus sequence typing of Cronobacter isolated from powdered infant formula

目的探讨我国婴儿配方粉污染克罗诺杆菌的主要分子分型特征,分析不同地区间菌株亲缘相关性,为我国克罗诺杆菌引起的疾病溯源提供技术支撑。方法采用脉冲场凝胶电泳(PFGE)和多位点序列分型(MLST)两种方法,对全国19个省/自治区/直辖市婴儿配方粉来源的49株克罗诺杆菌进行分型研究。结果 49株克罗诺杆菌PFGE分型得到38个带型,未发现有明显的优势分型和聚集现象。MLST共获得15个已知序列型(ST型)和2个新ST型,ST4、ST1和ST64为优势型别,分别占菌株总数的20.4%(10/49)、18.4%(9/49)、10.2%(5/49)。PFGE型和MLST型结果分析表明,具有相同PFGE型的菌株也有相同的MLST型,而相同MLST型却不一定具有较高的亲缘关系。结论我国婴儿配方粉来源的克罗诺杆菌图谱具有高多态性和离散性,据此预测我国婴儿配方粉污染克罗诺杆菌导致婴儿患病以散发为主,出现多人患病的暴发事件几率较低。

Objective To investigate the majority molecular typing characteristics of Cronobacter contamination in powdered infant formula（ PIF）,analyze the genetic correlation of strains from different provinces,and provide technical support to track diseases of Cronobacter infection in China. Methods Pulsed field gel electrophoresis（ PFGE） and multilocus sequence typing（ MLST） were used to analysis 49 strains isolated from PIF from 19 provinces in China. Results Totally 49 strains of Cronobacter were divided into 38 clusters,no obvious dominant cluster and aggregation were found. There were 15 ST types and 2 new ST types in 49 strains,ST4,ST1 and ST64 were the dominant types,accounted for 20. 4%（ 10/49）,18. 4%（ 9/49）,10. 2%（ 5/49）,respectively. The result of PFGE and MLST showed that strains with the same PFGE type also had the same MLST type,however,the same MLST type was not necessarily related. Conclusion Cronobacter isolated from PIF in China showed highly polymorphism and discreteness,it could predict that the infant infected by Cronobacter contamination in PIF in China was mainly sporadic,the incidence of outbreak of multiple people was low.