Culture (requires selective media) or PCR: detects multiple serotypes.
Antigen assay, direct fluorescent antibody, or serology detects L. pneumophila serotype 1 strains only (for review of diagnostics see Clin Microbiol Rev 28:95, 2015).
Classification
Gram negative bacilli
Legionella pneumophila (60-80% of cases)
Legionella (tatlockia) micdadei
Legionella wadsworthii
~40 species identified, most rarely associated with human disease
No proven benefit of Rifampin combination therapy (and drug interactions are a major issue in many patients) or combination of Azithromycin + fluoroquinolone
7-10 days of IV/po therapy depending on clinical response is appropriate for immunocompetent patients with legionella pneumonia.
14-21 days of therapy with IV/po therapy depending on clinical response is recommended for immunocompromised patients.
Duration of therapy not well defined, but prolonged therapy, up to 5 months, has been used
Comments
For endocarditis
Advise microbiology laboratory when considering the diagnosis of Legionella spp. endocarditis as it is possible to isolate the organism in blood culture media with special handling..
Infectious Diseases consultation recommended
Several Legionella spp have been reported as causes of endocarditis.
Most patients reported in the literature have undergone valve replacement in addition to medical therapy.
Treatment recommendations based on anecdotal case reports.