What is the recommended treatment for Legionella?

From the Guidelines

The recommended treatment for Legionella infection is primarily with macrolide or fluoroquinolone antibiotics, with azithromycin or levofloxacin being the preferred first-line treatments. For most patients, azithromycin (500 mg daily for 7-10 days) or levofloxacin (750 mg daily for 7-10 days) are the preferred treatments, as supported by the most recent guidelines 1. The choice of antibiotic should be based on the severity of illness, the underlying health of the patient, and patient drug tolerance.

Key Considerations

• For severe cases requiring hospitalization, initial intravenous therapy may be necessary before transitioning to oral medication.
• Patients with immunocompromised status or severe disease may require longer treatment courses of 14-21 days.
• Doxycycline (100 mg twice daily) can be used as an alternative for patients who cannot tolerate macrolides or fluoroquinolones.
• Early treatment is crucial as it significantly reduces mortality rates, as emphasized in the guidelines for managing sepsis and septic shock 1.
• These antibiotics are effective because they can penetrate host cells where Legionella bacteria reside, as this pathogen is an intracellular organism that multiplies within alveolar macrophages.
• Supportive care including oxygen therapy, respiratory support, and management of complications is also essential, particularly for hospitalized patients.

Treatment Duration and Initiation

• The recommended total duration of antibiotics therapy for Legionella pneumonia is 7-10 days, with a longer course of 21 days considered for immunosuppressed patients who are severely ill at presentation 1.
• Treatment should begin promptly when Legionella is suspected, even before laboratory confirmation, as delayed therapy is associated with poorer outcomes, highlighting the importance of timely initiation of therapy 1.

From the FDA Drug Label

Levofloxacin tablets are indicated for the treatment of community-acquired pneumonia due to methicillin-susceptible Staphylococcus aureus, Streptococcus pneumoniae (including multi-drug-resistant Streptococcus pneumoniae [MDRSP]), Haemophilus influenzae, Haemophilus parainfluenzae, Klebsiella pneumoniae, Moraxella catarrhalis, Chlamydophila pneumoniae, Legionella pneumophila, or Mycoplasma pneumoniae [see Dosage and Administration (2.1) and Clinical Studies (14.2)]. Azithromycin for Injection, USP is indicated for the treatment of patients with infections caused by susceptible strains of the designated microorganisms in the conditions listed below... Community-acquired pneumonia due to Chlamydia pneumoniae, Haemophilus influenzae, Legionella pneumophila, Moraxella catarrhalis, Mycoplasma pneumoniae, Staphylococcus aureus, or Streptococcus pneumoniae in patients who require initial intravenous therapy The recommended treatments for Legionella are:

• Levofloxacin
• Azithromycin 2, 3, 3

From the Research

Recommended Treatment for Legionella

The recommended treatment for Legionella includes:

• Either a fluoroquinolone (levofloxacin or moxifloxacin) or a macrolide (azithromycin preferred) as first-line therapy 4, 5, 6
• Azithromycin or levofloxacin can be considered as first-line therapy for Legionnaires' disease 6
• Other antibiotics including tetracyclines, tigecycline, other fluoroquinolones and other macrolides (especially clarithromycin) are also effective 6
• Quinolone/macrolide combinations, eg, levofloxacin plus azithromycin, are preferred therapy for immunocompromised patients 5

Antibiotic Treatment Duration and Clinical Outcomes

• The duration of antibiotic therapy and its association with clinical outcomes is not well established 4
• Most published studies evaluating antibiotic treatment for Legionnaires' disease are observational and consequently susceptible to bias and confounding 4
• Well-designed studies are needed to assess the usefulness of diagnostic tests regarding clinical outcomes, as well as randomized trials comparing fluoroquinolones and macrolides or combination therapy that evaluate outcomes and adverse events 4

Treatment of Severe Legionnaires' Disease

• Severe Legionnaires' disease may require treatment with a quinolone, such as levofloxacin, which may be superior to macrolides in some cases 7
• A case study reported a patient with severe Legionella pneumonia who improved rapidly after switching from azithromycin to levofloxacin 7
• The optimal antibiotic choice for severe Legionnaires' disease in immunocompromised patients is not well established and requires further guidance from randomized controlled trials 7