环境水系分离嗜肺军团菌脉冲场凝胶电泳的分型研究

Typing of Legionella pneumophila strains isolated from environmental water systems using pulsed-field gel electrophoresis

目的初步揭示中国环境水系嗜肺军团菌分离株的脉冲场凝胶电泳(PFGE)分型特征。方法分别以SfiI和AscI为限制性内切酶,使用PFGE对菌株进行分型和聚类分析。结果单独使用SfiI、AscI和联合使用两种内切酶分别将78株嗜肺军团菌分为47、48和60个型别,分型得到的Simpson差异指数分别为0.9833、0.9817和0.9933;同一水系中分离的菌株既有带型相同或者相似者,又有带型差异较大者;相同型别的菌株可在同一水系中跨年份存在。结论PFGE对嗜肺军团菌具有很好的分辨率;多个克隆系的菌株可以在同一水系中共存,某些克隆系的菌株可以跨年份存在;环境水系中存在优势克隆系,这些优势克隆系应该在今后军团菌的监测中引起注意。

Objective To determine the pulsed-fieldgel electrophoresis （PFGE） patterns of Legionella pneumophila strains isolated from environmental water systems in China. Methods Typing and cluster analysis were performed using pulsed-field gel electrophoresis separately with two restriction enzymes, SfiI and AscI. Results When employing separately SfiI, AscI and combination of the two, PFGE identified 47, 48 and 60 types out of 78 strains of L. pneumophila, respectively, the Simpson difference indexes being 0. 9833, 0. 9817 and 0. 9933. Identical or similar banding patterns were noticed among the isolates from the same water system, though great difference in them was also seen. The presence of strains of identical type was evidenced in the same water system over years. Conclusion PFGE is a highly discriminatory for the subtyping of L. pneumophila. Coexistence of strains derived from multiple clones is evidenced in a same water system, those of certain clones present for years. Predominant clones, observed in environmental water systems, have aroused concerns for further surveillance work.