Ultraviolet Light Disinfection of Hospital Water for Preventing NosocomialLegionellaInfection: A 13-Year Follow-Up

Abstract

AbstractBackground and Objective:CDC has estimated that 23% ofLegionellainfections are nosocomial. When a new hospital was being constructed and a substantial increase in transplantation was anticipated, an ultraviolet light apparatus was installed in the water main of the new building because 27% of water samples from taps in the old hospital containedLegionella.This study reports the rate of nosocomialLegionellainfection and water contamination since opening the new hospital.Methods:Charts of all patients with positiveLegionellacultures, direct immunofluorescent antibody (DFA), or urine antigen between April 1989 and November 2001 were reviewed. Frequencies of DFAs and urine antigens were obtained from the laboratory.Results:None of the 930 cultures of hospital water have been positive since moving into the new building. Fifty-three (0.02%) of 219,521 patients had a positiveLegionellatest; 41 had pneumonia (40 community acquired). One definiteL. pneumophilapneumonia confirmed by culture and DFA in August 1994 was nosocomial (0.0005%) by dates. This patient was transferred after prolonged hospitalization in another country, was transplanted 11 days after admission, and developed symptoms 5 days after liver transplant. However, tap water from the patient's room did not growLegionella.Seventeen (2.5%) of 670 urine antigens were positive forLegionella(none nosocomial). Thirty-three (1.2%) of 2,671 DFAs were positive, including 7 patients (21%) without evidence of pneumonia and 6 (18%) who had an alternative diagnosis.Conclusion:Ultraviolet light usage was associated with negative water cultures and lack of clearly documented nosocomialLegionellainfection for 13 years at this hospital.