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Nosocomial outbreak of Legionnaires' disease: molecular epidemiology and disease control measures

J M Johnston, R H Latham, F A Meier

    Infection Control : IC
    |February 1, 1987
    PubMed

    Insights

    Molecular techniques identified a single cooling tower as the source of a Legionnaires' disease outbreak. Chlorination successfully eradicated the bacteria from the cooling tower and hospital water system.

    Area of Science:

    • Infectious Diseases
    • Environmental Microbiology
    • Molecular Epidemiology

    Background:

    • Nosocomial Legionnaires' disease outbreaks pose significant risks in healthcare settings.
    • Identifying the source of Legionella pneumophila is crucial for effective outbreak control.
    • Molecular subtyping is essential for linking environmental sources to patient infections.

    Purpose of the Study:

    • To investigate the source and epidemiology of a nosocomial Legionnaires' disease outbreak.
    • To determine the effectiveness of chlorination in controlling Legionella pneumophila.
    • To evaluate decontamination strategies for hospital water systems.

    Main Methods:

    • Utilized molecular laboratory techniques, including plasmid profiling and monoclonal antibody reactions, for bacterial strain characterization.
    • Collected and analyzed patient isolates and water samples from cooling towers and potable water systems.
    • Employed epidemiological analysis to correlate cases with environmental exposures.

    Main Results:

    • All patient isolates were identified as Legionella pneumophila serogroup 1 with identical molecular profiles.
    • A single cooling tower was identified as the likely source, matching the patient isolate subtype.
    • Chlorination of the cooling tower eradicated the epidemic strain, and superchlorination decontaminated the potable water system.

    Conclusions:

    • Molecular subtyping definitively linked the Legionnaires' disease outbreak to a specific cooling tower.
    • Chlorination proved effective in controlling the outbreak strain in cooling towers and potable water.
    • Superchlorination of hospital water systems offers a simple and cost-effective method for Legionella eradication.

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