Wednesday, July 02, 2008
Legionnaires Disease
from Paul H. Edelstein in Legionella: Molecular Microbiology
The history of Legionnaires' disease began at least 33 years before the 1976 Philadelphia epidemic, when Legionella micdadei was isolated from human blood. Multiple isolations of several different Legionella spp. were made prior to 1976, and it was known by 1968 that tetracycline therapy prevented deaths in L. pneumophila-infected chicken embryos. The 1976 epidemic provided the scientific focus and resources necessary to determine that L. pneumophila caused epidemic pneumonia and to show that epidemics of Legionnaires' disease had occurred worldwide many years before 1976. Despite a surfeit of available resources and expertise, the effort to isolate the etiologic agent succeeded solely on the basis of one person's determination to solve a scientific problem and his willingness to reexamine his assumptions about prior laboratory results. Pontiac fever, a disease of unknown etiology, is a self-limiting and short duration febrile illness that has been associated with exposure to L. pneumophila. Because of non-specific clinical findings that overlap with other diseases, accurate diagnosis of Pontiac fever in non-outbreak settings is impossible. Legionnaires' disease can be diagnosed specifically through specialized laboratory tests, but not by clinical findings alone. This is because the clinical findings of Legionnaires' disease overlap with those of other more common causes of community acquired pneumonia. Antimicrobial therapy of Legionnaires' disease requires the use of drugs that are active against intracellular Legionellaspp., such as tetracyclines, macrolides, azalides and antibacterial quinolones.
Further reading: Legionella: Molecular Microbiology
The history of Legionnaires' disease began at least 33 years before the 1976 Philadelphia epidemic, when Legionella micdadei was isolated from human blood. Multiple isolations of several different Legionella spp. were made prior to 1976, and it was known by 1968 that tetracycline therapy prevented deaths in L. pneumophila-infected chicken embryos. The 1976 epidemic provided the scientific focus and resources necessary to determine that L. pneumophila caused epidemic pneumonia and to show that epidemics of Legionnaires' disease had occurred worldwide many years before 1976. Despite a surfeit of available resources and expertise, the effort to isolate the etiologic agent succeeded solely on the basis of one person's determination to solve a scientific problem and his willingness to reexamine his assumptions about prior laboratory results. Pontiac fever, a disease of unknown etiology, is a self-limiting and short duration febrile illness that has been associated with exposure to L. pneumophila. Because of non-specific clinical findings that overlap with other diseases, accurate diagnosis of Pontiac fever in non-outbreak settings is impossible. Legionnaires' disease can be diagnosed specifically through specialized laboratory tests, but not by clinical findings alone. This is because the clinical findings of Legionnaires' disease overlap with those of other more common causes of community acquired pneumonia. Antimicrobial therapy of Legionnaires' disease requires the use of drugs that are active against intracellular Legionellaspp., such as tetracyclines, macrolides, azalides and antibacterial quinolones.
Further reading: Legionella: Molecular Microbiology
Labels: bacteriology, bacterium, legionella
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