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Legionnaires' disease bacterium isolated in 1947

J E McDade, D J Brenner, F M Bozeman

    Annals of Internal Medicine
    |April 1, 1979
    PubMed

    Insights

    Serologic, cultural, and DNA studies confirm the Legionnaires

    Area of Science:

    • Microbiology
    • Infectious Diseases
    • Bacteriology

    Background:

    • Legionnaires' disease (LD) is a severe pneumonia caused by Legionella bacteria.
    • An unidentified bacterial agent was isolated in 1947, prior to the recognition of LD.

    Purpose of the Study:

    • To determine the taxonomic relationship between the Legionnaires' disease bacterium and an unclassified agent from 1947.
    • To compare cultural and serologic characteristics and DNA relatedness.

    Main Methods:

    • Comparative growth studies on various culture media.
    • Serological testing using convalescent sera from LD patients and experimentally infected guinea pigs.
    • DNA extraction, thermal denaturation for guanine-cytosine content determination, and DNA hybridization.

    Main Results:

    • Both the LD bacterium and the 1947 isolate exhibited identical growth requirements and limitations.
    • Both agents showed positive reactions with LD patient and experimental animal sera.
    • DNA analysis revealed 39% guanine-plus-cytosine content and high DNA relatedness between the isolates.

    Conclusions:

    • The Legionnaires' disease bacterium and the 1947 unclassified agent are the same species.
    • This finding clarifies the historical context of Legionnaires' disease agent discovery.
    • The LD bacterium is also antigenically related to an organism isolated in 1959.

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