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Legionnaires' disease bacterium isolated in 1947.
Annals of Internal Medicine
|April 1, 1979
Summary
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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