Detection of Legionella spp. in Water Samples taken from Cooling Tower and Water Holding Systems in a Hospital in Metro Manila

Dianne Melody A. De Roxas and Adelwisa R. Ortega

Department of Medical Microbiology, College of Public Health,
University of the Philippines Manila


Background. Hospitals present ideal locations for transmission of Legionnaires' disease, a pneumonia-like disease caused by Legionella spp. In these settings, hospitalized patients may be exposed to aerosols generated by cooling towers, respiratory therapy equipment, showers and faucets, that facilitate transmission of the bacterium.

Objective. The study aimed to determine the presence of Legionella spp. in water samples take from the cooling tower and water holding systems of a hospital in Metro Manila.

Methods. A total of 12 water samples were collected: 6 samples from the cooling tower, 4 from two cisterns and 2 from the water tank. The samples were concentrated, acid-treated, gram-stained and cultured. Biochemical tests were done for identification of Legionella spp.

Results. Legionella spp. was detected in 2 (16.67%) out of 12 samples, both of them from the pre-condenser sampling site of the hospital's cooling tower.

Conclusion. The study documents the presence of Legionella spp. in the cooling tower, a potential source of infectiious aerosols that can be disseminated in the hospital and affect hospitalized patients.

Key Words: Legionella spp., cooling tower Buffered Charcoal Yeast Extract (BCYE) agar