Legionella Culture of Environmental Water Samples Legionella DFA of Environmental Isolates Methodology: Direct Fluorescent Antibody Stain Standard reference procedures for Legionella culture and identification

Sample Reports   Legionella Culture DFA of Environmental Isolates

Significance:

• Legionnaires’ disease is an acute lobar pneumonia with multisystem manifestations

Legionnaires’ disease results from exposures to water sources containing the organism. Predisposing factors in a susceptible host include a compromised immune system, underlying disease, recent surgery, increased age, and heavy smoking.

It is important to be able to culture Legionella from environmental specimens. Analysis of water suspected of being contaminated with Legionella identifies potential sources of the disease. Commonly sampled sources include non-potable water from cooling towers, condensers, whirlpools, etc. and potable water from water distribution systems, water heaters and tanks, drinking fountains and ice machines.

Of the more than 48 species of Legionella, L. pneumophila is the species most commonly associated with disease. The organisms are nutritionally fastidious, nonsporeforming, aerobic, gram-negative, slender rods. Media containing cysteine, yeast extract, α-ketoglutarate, and iron (BCYE) are required for isolation of Legionella. Selective BCYE (medium containing antibiotics), is recommended for specimens likely to be contaminated with other bacteria.

Colonies gray-white to blue-green typically grow five days after incubation at 37ºC. Legionella species can be identified by immunofluorescent stains.

References:

• Fang GD, et al. Disease due to the Legionellaceae (other than Legionella pneumophila): historical, microbiological, clinical, and epidemiological review. Medicine 1989;68-116-132.
• Vickers RM, et al. Culture methodology for the isolation of Legionella pneumophila and other Legionellaceae from clinical and environmental specimens. Semin Respir Infect 1987;2:274.
• Zuravleff JJ, et al. Diagnosis of Legionnaires’ disease: an update of laboratory methods with new emphasis on isolation by culture. JAMA 1983; 250:1981.
• Stout JE, Rihs JD, Yu VL. Legionella. In “Manual of Clinical Microbiology”. Ed. Murray PR, Barron EJ, Jorgensen JH, Pfaller MA, Yolken RH. 2003. Am Soc Microbid. Washington, DC.

See also:

• Legionella Sample Collection Instructions
• Legionella Frequently Asked Questions
• Why SPL?