Pulsed field gel electrophoresis typing of Legionella pneumophila in cooling water and condensed water from centralized air conditioning system in Huizhou

Objective To understand the genetic characteristics of Legionella pneumophila isolated from cooling water and condensed water of centralized air conditioning system in the public places of Huizhou, Guangdong province, and establish local L. pneumophila pulsed-field gel electrophoresis (PFGE) typing database. Methods By using PFGE, 35 strains of L. pneumophila isolated from cooling water and condensed water of centralized air conditioning system in the public places of Huizhou from 2012 to 2016 were tested for their fingerprints, and cluster analysis was performed with BioNumerics 6.6 software. Results The 35 strains of L. pneumophila were divided into 29 PFGE types, with the similarity ranging from 21.70% to 100.00%. Each type contained 1-3 strains, and there were 5 groups of strains sharing same type, no predominant PFGE type were found. The strains belonged to the same PFGE type were collected from the same place. There were more than two kinds of different PFGE types in the strains isolated from the same place. Same PFGE type were detected in the strains isolated from cooling water and condensed water collected at same place; The strains belonged to same serotype had different PFGE patterns, indicating that PFGE patterns differed among the strains. Conclusion The strains of L. pneumophila isolated from cooling tower water and condensed water of centralized air conditioning system in the public places of Huizhou showed genetic diversity.