Legionella Infection Treatment & Management

Updated: Nov 13, 2018
  • Author: Mobeen H Rathore, MD, CPE, FAAP, FIDSA; Chief Editor: Russell W Steele, MD  more...
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Medical Care

For Legionnaires disease (LD), a high level of suspicion and prompt initiation of adequate antimicrobial therapy are critical to improve clinical outcomes. [33] In contrast, for Pontiac fever, treatment is symptomatic, and no antimicrobial therapy is recommended.

Therapy effective in patients with legionellosis should be considered for initial empirical treatment for severe community-acquired pneumonia (CAP) and for specific patients with nosocomial pneumonia. Support therapy in patients with shock and respiratory failure is administered as needed.

  • Situations suggesting Legionella disease

    • Gram stains of respiratory samples revealing many polymorphonuclear leukocytes with few or no organisms

    • Hyponatremia

    • Pneumonia with prominent extrapulmonary manifestations (eg, diarrhea, confusion, other neurologic symptoms)

    • Failure to respond to administration of beta-lactams, aminoglycoside antibiotics, or both

  • Antimicrobial therapy for Legionella disease

    • Specific therapy includes antibiotics capable of achieving high intracellular concentrations (eg, macrolides, quinolones, ketolides, tetracyclines, rifampin). The reported rank order of in vitro and intracellular activity against L pneumophila is quinolones, then ketolides, and then macrolides [34] . Beta-lactams and aminoglycosides have activity against Legionella species in vitro but are not clinically effective.

    • No prospective randomized studies have been performed regarding antibiotic effectiveness in patients with Legionella disease. Recommendations are based on retrospective reviews and experimental (laboratory and animal) studies.

    • Azithromycin is the drug of choice for children with suspected or confirmed Legionella disease. [1] With rare exceptions, the initial course should be intravenously administered. After a good clinical response is observed, it can be switched to the oral route. In patients with severe disease or who appear to be unresponsive to monotherapy, the addition of rifampin is recommended.

    • Certain fluoroquinolones (eg, levofloxacin, moxifloxacin) are effective and are recommended for adults with severe disease. [35] Because macrolides may interfere with drugs metabolized by cytochrome P450 (CYP) 3A4 isoenzyme (eg, cyclosporine), the quinolones mentioned above are suitable alternatives to treat Legionnaires disease in patients taking cyclosporine or other CYP3A4 substrates. An older fluoroquinolone, ciprofloxacin, does inhibit CYP3A4. Although the US Food and Drug Administration (FDA) has not approved fluoroquinolones for persons younger than 18 years (because of concerns about arthropathy in studies of juvenile animals), they have been successfully used to treat children with Legionnaires disease [3, 36, 13] and may be used in children in special circumstances.

    • Other alternatives include doxycycline or trimethoprim (TMP) and sulfamethoxazole (SMZ).

    • The recommended duration of therapy is 5-10 days if azithromycin is used. If other drugs are used, the duration should be 2-3 weeks. For patients with severe disease or immunocompromise, prolonged courses may be required.


Surgical Care

See the list below:

  • Surgical drainage of pulmonary or extrapulmonary disease may be necessary.



See the list below:

  • Infectious disease specialist

  • Critical care specialist

  • Pulmonologist

  • Health-department officials: Confirmed cases of Legionnaires disease should be reported to local health-department officials. Legionellosis is a notifiable disease in the United States.