OBJECTIVETo analyze the characteristics of Sequence-based Typing (SBT) of the Serotype 1 Legionella pneumophila (Lp1) isolated from environmental water in China, and then create a preliminary database.

METHODSA total of 82 strains of Lp1 isolated from environmental water in 9 provinces of China between 2005 and 2008 were genotyped by SBT method and Pulsed-field Gel Electrophoresis (PFGE) method. The results of the two different typing methods were then compared by cluster analysis, adopting BioNumerics version 5.1 software.

RESULTSBy SBT method, the 82 strains of Lp1 were divided into 22 ST types, of which 17 new types and one new allele was discovered. The dominant type was ST-1 type, found in 8 provinces, accounting for 46.3% (38/82). ST-1, ST-150, ST-154, ST-159, ST-160 and ST-630 types were found in more than 2 isolated-sites; while more than 2 different ST types were found in 5 isolated-sites, as site B4, B5, B6, S3 and S8. In cluster analysis, 15 ST types were grouped into three complexes (ST-1 complex, ST-154 complex and ST-149 complex); and the other 7 ST types were not assigned complex. By PFGE method, 46 banding patterns were observed. As a result of the combination of the two methods, the 82 isolates strains could be divided into 54 molecular types, which showed a reliable accordance in the cluster analysis between the two methods.

CONCLUSIONThe SBT of the Lp1 in environmental water in China was unique. From the study, a preliminary SBT database was set up.