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Legionella infection

Last edited: 4/23/2026

Overview

Legionella infection encompasses a spectrum of illnesses ranging from mild flu-like symptoms to severe pneumonia and extrapulmonary manifestations such as pericarditis. 1

Diagnosis

  • Clinical Presentation: Often includes fever, cough, and sometimes gastrointestinal symptoms.
  • Laboratory Tests: Urinary antigen tests for Legionella pneumophila serogroup 1 are useful; culture and nucleic acid amplification tests (NAAT) can identify other Legionella species.
  • Imaging: Chest X-ray typically shows patchy infiltrates or consolidation.
  • Pericarditis Association: Consider Legionella infection in cases of pericarditis coexisting with pneumonia. 1
  • Management

  • First-Line Treatment: Erythromycin or a macrolide (e.g., azithromycin) is recommended for Legionella pneumonia. 1
  • Alternative Agents: Fluoroquinolones (e.g., levofloxacin) can be used if macrolide resistance is suspected or in patients with contraindications to macrolides.
  • Duration: Typically 7-14 days, depending on clinical response and severity.
  • Special Populations

  • Pregnancy: Specific management guidelines not detailed in provided abstracts; consult expert recommendations.
  • Pediatrics: No specific details provided in the abstracts.
  • Elderly: Increased susceptibility to severe disease; close monitoring and prompt treatment are crucial. 1
  • Comorbidities: Patients with underlying conditions like chronic lung disease may require more aggressive management; specific dosing adjustments may be necessary based on renal function and drug interactions. 1
  • Key Recommendations

  • Investigate Legionella in cases of concurrent pericarditis and pneumonia to ensure timely treatment with appropriate antibiotics like erythromycin. (Evidence: Moderate) 1
  • Initiate macrolide therapy (e.g., azithromycin) as first-line treatment for Legionella pneumonia. (Evidence: Moderate) 1
  • Consider fluoroquinolones in cases of macrolide resistance or contraindications for alternative effective treatment options. (Evidence: Expert opinion) 1
  • References

    1 Svendsen JH, Jønsson V, Niebuhr U. Combined pericarditis and pneumonia caused by Legionella infection. British heart journal 1987. link

    Original source

    1. [1]
      Combined pericarditis and pneumonia caused by Legionella infection.Svendsen JH, Jønsson V, Niebuhr U British heart journal (1987)

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