石家庄市集中空调冷却塔水中嗜肺军团菌的基因序列分型研究

Sequence -based typing research for Legionella pneumophila isolated from the air -conditioning cooling towers in Shijiazhuang

目的采用基因序列分型方法(sequence-based typing,SBT)研究石家庄市集中空调冷却塔水中军团菌基因特征。方法将石家庄市集中空调冷却塔水中分离出的35株Lp1血清型嗜肺军团菌提取基因组DNA,选取嗜肺军团菌7个管家基因flaA、pilE、asd、mip、mompS、proA、neuA进行PCR扩增,将扩增产物纯化后测序。测序结果上传欧盟军团菌感染工作组(EWGLI)数据库进行比对,得到基因型别(sequence type,ST),对结果进行基因序列分型和系统进化分析。结果 35株Lp1血清型嗜肺军团菌共分为4个ST型,其中1株由于neuA基因不能被扩增而未分型;1株为新的ST型,已获EWGLI分配序号(ST1021);其余为ST1型32株,ST345型1株。结论石家庄市集中空调冷却塔水中嗜肺军团菌分离株的流行以ST1型为主,ST345型和ST1021型为特有型别。SBT分型可以作为研究嗜肺军团菌进化关系的重要手段之一。

Objective To evaluate the gene characteristics of Legionella pneumophila isolated from the water samples of air-conditioning cooling towers in public places of Shijiazhuang, Hebei by sequence-based typing （SBT）. Methods Genomic DNA was extracted from 35 strains of Lp 1 from the water samples of cooling towers in Shijiazhuang. Seven kinds of housekeeping genes including flaA, pilE, asd, mip, mompS, proA, neuA of Legionella pneumophila were amplified by PCR. Amplified products were purified and sequenced and the results were compared with the database of EWGLI,and the genotype （sequence type, ST） was get, typing and analyzing of the phylogenetic were conducted. Results A total of 35 strains of serotype Lpl LegioneUa pneumophila were divided into four ST types,one was not typed due to absence of neuA gene, one was new ST type, and was newly assigned （ST1021） by EWGLI, the remaining was 32 strains of ST1, one strain of ST345. MEGA4.0 software was used to establish the phylogenetic tree. Conclusion The dominant ST type is STI, while ST345 and ST1021 are unique type of Legionella pneumophila isolated from the water samples of air-conditioning cooling tower in Shijiazhuang. SBT typing can be used as one of the important means to study Legionella pneumophila evolutionary relationships.