Brady MF, Sundareshan V.
2021 Jul 10. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 Jan–. PMID: 28613558. (Book)
Excerpt
- Legionnaires’ disease is caused by Legionella pneumophila. Pontiac fever refers to a benign, self-limited, acute febrile illness which is linked serologically to L pneumophila.
- L pneumophila causes pneumonia and should be considered as a pathogen in any patient with atypical pneumonia.
- The Legionella bacterium was first identified in 1976 in Philadelphia. Contamination of the water in the air conditioning system was suspected. Patients developed symptoms ranging from flu-like symptoms to multisystem organ failure. Of the 182 infected, 29 died.
- Legionnaires’ disease describes infections caused by the Legionellaceae family.
- The Legionella bacterium is a small, aerobic, waterborne, gram-negative, unencapsulated bacillus that is nonmotile and oxidase and catalase positive.
- Legionella bacterium is a fastidious organism and will not grow anaerobically on a standard media. Buffered charcoal yeast extract agar is the medium of choice for isolation.
- The Legionellaceae consists of more than 42 species. L. pneumophila is the most common species, and it causes 90% of the cases of legionellosis, followed by L. micdadei, L. bozemanii, L. dumoffii, and L. longbeachae.
- Fifteen serogroups of L. pneumophila have been identified, with serogroups 1, 4, and 6 identified as the causes of human disease. Serogroup 1 is thought to be responsible for 80% of the reported cases.