Significance

Legionnaires’ disease is an acute lobar pneumonia with multi-system 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.

The organisms are nutritionally fastidious, non-sporeforming, 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 37º C.

The most common disease-causing member of the Legionellaceae family is Legionella pneumophila. This member has 15 named serogroups, all of which we can detect. Approximately half of the more than 58 named species of Legionella have been implicated in human disease. The methods and reagents used by Special Pathogens Laboratory can detect the primary disease-causing species and serogroups of Legionella. These methods include primary culture followed by latex agglutination and fluorescent antibody staining methods. If these classical identification methods are indeterminate, molecular sequencing methods can be used for further identification to the species level. This technology would identify any member of the family for which a nucleotide sequence is in GenBank.

The list of Legionella species implicated in disease and tested for using SPL methods and reagents:

  • L. pneumophila (serogroups 1–15)
  • L. dumoffii
  • L. micdadei
  • L. bozemanii (serogroup 1)
  • L. longbeachae (serogroups 1, 2)
  • L. jordanis L. feeleii (serogroup 1)
  • L. gormanii
  • L. wadsworthii
  • L. hackeliae
  • L. maceachernii
  • L. oakridgensis
  • L. cherrii
  • L. sainthelensi
  • L. anisa
  • L. parisiensis
  • L. spiritensis
  • L. jamestownensis
  • L. steigerwaltii
  • L. rubrilucens
  • L. erythra

Test Method 

SPL modified ISO standards:

  • 1173: 2017. Water Quality: Enumeration of Legionella

Turn around time  

7 to 10 days

Test code  

101

Sample Transport

Overnight delivery is suggested. Please see Legionella Sampling and Shipping or consult with the laboratory for sample transport requirements.