Culture requires special media which is not commonly available.
Urinary antigen detects L. pneumophila serogroup 1. While most infections (~84%) are from serogroup 1 not all cases of Legionella will be detected by urinary antigen.
Test | Sensitivity (%) | Specificity (%) |
---|---|---|
Culture | 20-80 | 100 |
Urinary antigen (L. pneumophila serogroup 1) | 70-100 | 95-100 |
PCR | 95-99 | >99 |
Direct Fluorescent Antibody (DFA) | 25-75 | >95 |
Paired serology | 80-90 | >99 |
Aerobic small gram negative bacillus.
Reservoir is water. Aerosolization by cooling towers, spas, shower heads, etc.
Occurs in outbreaks.
Person-to-person transmission not documented.
Pneumonia (Legionnaires disease)
Pontiac fever (Self-limited febrile illness)
Extrapulmonary infections rare, but include endocarditis
Risk factors include: