Aim and Background: Legionnaires’ disease is caused by inhalation of contaminated aerosols with Legionella from a variety of water sources. The aim of this study was to characterize the rate of contamination of environmental and hospital water sources by legionella spp in Ahvaz by using standard culture method and polymerase chain reaction (PCR).

Materials and methods:A total of 100 water samples were collected from environmental and hospital sources in Ahvaz. After decontamination with Hcl-Kcl treatment, samples were centrifuged and inoculated on to buffered charcoal yeast extract agar (BCYE) and MWY media. In order to confirm bacterial colonies as legionella, DNA was extracted and 16S rRNA was amplified using PCR.

Results:Out of 100 samples, 15% were positive for Legionella by culture method. Among positive cultures 8% and 7% were obtained from hospital and environmental water sample, respectively. By PCR all the positive cultures had 16s rRNA and confirmed as Legionella Spp.

Conclusion:According to the study results, despite of using purification water 15% of water samples were contaminated with Legionella spp. In order to control and prevent spread of Legionella spp, disinfection of water sources is necessary.