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Nosocomial Legionnaires' disease caused by aerosolized tap water from respiratory devices
Abstract:
Five cases of nosocomial Legionnaires' disease which occurred over a five-month period were retrospectively investigated. Chart review showed that during the two- to 10-day incubation period before the onset of illness, all of the patients inhaled aerosolized tap water from jet nebulizers (four patients) or from a portable room humidifier (one patient), and all received high dosages of corticosteroids or adrenocorticotropic hormone. Exposure to both factors was highly significant (P less than 0.000001) when compared with the rate of exposure in 69 control patients. Environmental cultures yielded Legionella pneumophila from tap water and from reservoirs of tap water-filled respiratory devices. The yield was highest from hot tap water, in which the free chlorine level was less than 0.05 parts per million. Thus, Legionnaires' disease may be caused by contaminated aerosols from respiratory devices, and the use of contaminated tap water in such devices represents a previously unrecognized hazard to which corticosteroid-treated patients should not be exposed.
Insights
Nosocomial Legionnaires
Area of Science:
- Infectious Diseases
- Environmental Health
- Respiratory Medicine
Background:
- Legionnaires' disease is a severe pneumonia.
- Nosocomial outbreaks pose significant public health risks.
- Immunocompromised patients are particularly vulnerable.
Purpose of the Study:
- To investigate the cause of a cluster of nosocomial Legionnaires' disease cases.
- To identify risk factors associated with disease acquisition in hospitalized patients.
- To evaluate the role of respiratory devices and water systems in disease transmission.
Main Methods:
- Retrospective case-control study of five patients with nosocomial Legionnaires' disease.
- Chart review to identify patient exposures and clinical characteristics.
- Environmental sampling of respiratory devices and water sources for Legionella pneumophila.
- Statistical analysis to compare exposure rates between cases and controls.
Main Results:
- All five patients inhaled aerosolized tap water from respiratory devices (jet nebulizers or humidifiers).
- All patients received high-dose corticosteroids or adrenocorticotropic hormone.
- Exposure to both factors was highly statistically significant (P < 0.000001).
- Legionella pneumophila was isolated from tap water and device reservoirs, especially in low-chlorine hot water.
Conclusions:
- Contaminated aerosols from respiratory devices using tap water are a significant cause of nosocomial Legionnaires' disease.
- Immunosuppression (corticosteroids) combined with exposure to contaminated aerosols is a critical risk factor.
- Maintaining adequate chlorine levels in hospital water systems and using sterile water in respiratory devices are crucial preventive measures.