From the Guidelines
The recommended first-line treatment for Legionella pneumonia is azithromycin 500mg IV or orally once daily for 7-10 days, or levofloxacin 750mg IV or orally once daily for 7-10 days, as these antibiotics can effectively penetrate cells where the bacteria reside. Legionella pneumonia, also known as Legionnaires' disease, is a severe form of pneumonia caused by Legionella bacteria, most commonly Legionella pneumophila. The diagnosis of Legionella pneumonia should be suspected in patients with pneumonia who have risk factors such as immunocompromise, recent travel, exposure to water cooling systems, or failure to respond to beta-lactam antibiotics 1.
Key Considerations
- The bacteria cannot be effectively treated with beta-lactams like penicillins or cephalosporins because these drugs cannot penetrate host cells where Legionella multiplies.
- Diagnosis is typically confirmed through urinary antigen testing, though this only detects L. pneumophila serogroup 1, or through specialized cultures 1.
- Prevention involves proper maintenance of water systems, particularly in healthcare facilities and hotels, to prevent bacterial growth.
- For severe cases, combination therapy with azithromycin plus rifampin 300mg twice daily may be considered, although the clinical benefit of rifampin combination therapy remains inconclusive based on currently available evidence 1.
Treatment Duration and Supportive Care
- The recommended total duration of antibiotics therapy for Legionella pneumonia is 7-10 days, but a longer antibiotic course of 21 days may be considered for immunosuppressed patients who are severely ill at presentation 1.
- Patients typically require hospitalization, supplemental oxygen, and supportive care including hydration and respiratory support.
- The treatment should be initiated as rapidly as is feasible, as delay in therapy is associated with an increased mortality rate 1.
Risk Factors and Prevention
- Risk factors for Legionella pneumonia include recent travel with an overnight stay outside of the home, exposure to spas, recent changes in domestic plumbing, renal or hepatic failure, diabetes, and systemic malignancy 1.
- Mortality rates are 5%–25% among immunocompetent hosts, and Legionella pneumonia should be suspected in patients with enigmatic pneumonia sufficiently severe to require care in the ICU, in the presence of an epidemic, or if there is failure to respond to a b-lactam 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 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
The diagnosis of Legionella pneumonia is typically made through culture and susceptibility testing. The treatment of Legionella pneumonia includes the use of antibiotics such as levofloxacin or azithromycin. Key points:
- Diagnosis: culture and susceptibility testing
- Treatment: antibiotics such as levofloxacin or azithromycin 2 3
From the Research
Diagnosis of Legionella Pneumonia
- The diagnosis of Legionella pneumonia is based mainly on the detection of Legionella pneumophila serogroup 1 antigen in urine 4
- Antigen-testing in urine by a rapid immunochromatographic test (ICT) is an easy to handle bedside test which provides a result within 15 minutes, with sensitivity and specificity reaching 80% and 100%, respectively 5
- New methodologies for detection tests have greater sensitivity and specificity, detect more species and serogroups of Legionella spp., and have the potential for use in epidemiological studies 4
Treatment of Legionella Pneumonia
- Erythromycin is the first-line treatment for Legionnaires' disease, with an intravenous dosage of 1g every 6 hours as initial therapy 6
- Clarithromycin is likely to become the preferred treatment once an intravenous preparation is available worldwide, and orally administered clarithromycin at the dosage of 500 mg every 12 hours may be recommended in developing countries 6
- Macrolides, doxycycline, fluoroquinolones, and ketolides are drugs with sufficient activity against Legionella spp. and are appropriate candidates for empirical initial antimicrobial treatment regimen of community-acquired pneumonia 5
- Fluoroquinolones, such as levofloxacin or moxifloxacin, or macrolides, such as azithromycin, are the recommended first-line therapy for Legionnaires' disease 4
- In severe Legionellosis, as well as in nosocomial legionellosis and immunosuppressed patients, intravenous fluoroquinolones are the first choice drugs, and azithromycin may be used as an alternative 5
- Quinolone/macrolide combinations, such as levofloxacin plus azithromycin, are the preferred therapy for legionellosis in immunocompromised patients 7