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Volume 23, Number 11—November 2017
Etymologia

Etymologia: Legionella pneumophila

Ronnie HenryComments to Author 

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Legionella pneumophila [leʺjə-nelʹə nooʺmo-filʹə]

In the summer of 1976, as the United States was celebrating the bicentennial of the Declaration of Independence, a mysterious acute respiratory illness developed in attendees at an American Legion convention in Philadelphia shortly after the attendees returned from the convention. In total, 182 Legionnaires became ill, and 29 died.

Researchers in the Leprosy and Rickettsia Branch at Centers for Disease Control (CDC), headed by Charles C. Shepard, observed that guinea pigs became ill after being inoculated with lung tissues from patients who died. A few gram-negative bacilli were seen in guinea pig tissues, but these were believed to be normal flora or contaminants. The bacteria could not at first be isolated in embryonated eggs because the standard procedure for isolating rickettsiae at the time was to include penicillin and streptomycin to prevent contamination.

Figure 1

Thumbnail of Joseph McDade, CDC scientist who discovered the cause of Legionnaires’ disease.

Figure 1. Joseph McDade, CDC scientist who discovered the cause of Legionnaires’ disease.

Figure 2

Thumbnail of Lung cells with intra-alveolar exudate containing macrophages and polymorphonuclear leukocytes after infection with Legionella pneumophila, the causative agent of Legionnaires’ disease. Photos: McDade, R.E. Bates/CDC; photomicrograph, F.W. Chandler/CDC.

Figure 2. Lung cells with intra-alveolar exudate containing macrophages and polymorphonuclear leukocytes after infection with Legionella pneumophila, the causative agent of Legionnaires’ disease. Photos: McDade, R.E. Bates/CDC; photomicrograph, F.W. Chandler/CDC.

Returning to work after Christmas 1976, CDC microbiologist Joseph McDade (Figure 1) was bothered by these unexplained findings. He again attempted to grow the bacteria in embryonated eggs, this time without antibiotics, and successfully isolated a large inoculum of pure culture that could be grown on agar. These bacteria were determined to be the etiologic organism of Legionnaires’ disease and were eventually named Legionella (for the Legionnaires) pneumophila (Greek pneumon [lung] + philos [loving]) (Figure 2).

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References

  1. McDade  JE, Shepard  CC, Fraser  DW, Tsai  TR, Redus  MA, Dowdle  WR. Legionnaires’ disease: isolation of a bacterium and demonstration of its role in other respiratory disease. N Engl J Med. 1977;297:1197203. DOIPubMed
  2. Winn  WC Jr. Legionnaires disease: historical perspective. Clin Microbiol Rev. 1988;1:6081. DOIPubMed

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Cite This Article

DOI: 10.3201/eid2311.et2311

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Table of Contents – Volume 23, Number 11—November 2017

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Ronnie Henry, Centers for Disease Control and Prevention, 1600 Clifton Rd NE, Mailstop E03, Atlanta, GA 30329-4027, USA

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Page created: October 16, 2017
Page updated: October 16, 2017
Page reviewed: October 16, 2017
The conclusions, findings, and opinions expressed by authors contributing to this journal do not necessarily reflect the official position of the U.S. Department of Health and Human Services, the Public Health Service, the Centers for Disease Control and Prevention, or the authors' affiliated institutions. Use of trade names is for identification only and does not imply endorsement by any of the groups named above.
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