Legionella sp.

by Henry Chambers last updated Aug 23, 2023 09:13 AM © Antimicrobial Therapy, Inc.
Legionella sp.

Clinical Setting

  • Community or hospital-acquired pneumonia, extrapulmonary infections occur but are rare.
  • Risk factors: chronic lung disease, smoking, and solid organ transplant.
  • See also, Legionella pneumonia, Legionella endocarditis.


  • 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).


  • Gram negative bacilli
  • Legionella pneumophila (60-80% of cases)
  • Legionella (tatlockia)   micdadei
  • Legionella wadsworthii
  • ~40 species identified, most rarely associated with human disease

Primary Regimens

Alternative Regimens

Antimicrobial Stewardship

  • Duration of therapy.
    • 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.