Comparison of culture and fluorescence PCR methods for Legionella pneumophila detection in central air conditioning systems

Objective To compare traditional culture and real-time TaqMan-based polymerase chain reaction(PCR) methods for the detection of Legionella pneumophila in central air conditioning system.Methods Nine stores,hotels,hospitals and offices were randomly selected for the study.Specimens were collected from the cooling water,the biofilm and the silt of central air conditioning systems.Legionella was tested by traditional culture,and was verified with real-time TaqMan-based PCR.Results Eighteen samples of water-cooled central air-conditioning systems were tested and four(22.2%) strains of Legionella pneumophila were isolated.The detection rates of Legionella pneumophila were 22.2%,25% and 20% respectively for the specimens collected from the cooling water,the biofilm and the silt.The method of real-time TaqMan-based PCR detected bacterial in 9(50%) specimens.The detection rates of Legionella pneumophila were 44.4%,50% and 60% respectively for the specimens collected from the cooling water,the biofilm and the silt.Conclusion Legionella pneumophila was existed in the central air conditioning systems in Jinhua city.The Legionella pneumophila detection rate was higher by real-time TaqMan-based PCR than by traditional culture.