The high prevalence of Legionella pneumophila contamination in hospital potable water systems in Taiwan: implications for hospital infection control in Asia.

Background: The major sources of Legionnaires' disease (LD) are the potable water systems of large buildings including hospitals, nursing homes, and hotels. Culturing the hospital water system for Legionella allows a preventive approach for hospital-acquired LD. However, hospital-acquired LD is rarely reported in Taiwan, and environmental cultures of Legionella in hospital water systems in Taiwan have never been systematically performed.

Objective: The objective of this study was to determine if Legionella is present in hospital water systems in Taiwan. Water quality analysis was also performed to determine if geographic differences in water quality result in different Legionella positivity rates.

Method: The water systems of 16 hospitals throughout Taiwan were tested for Legionella by culture. Standardized culture procedures were followed.

Results: Legionella pneumophila was isolated from 63% (10/16) of the hospital water systems; 19% (3/16) of the hospitals had an L. pneumophila positive rate greater than 30%. L. pneumophila serogroups 1 and 6 (strains that are most responsible for Legionella infections) were isolated from 80% (8/10) and 60% (6/10), respectively, of the hospitals that yielded L. pneumophila in their water distribution systems.

Conclusion: As was shown in epidemiological studies in the USA and Spain, hospital-acquired legionellosis may be prevalent but underdiagnosed in Taiwan.