Is Azithromycin (a macrolide antibiotic) effective for treating pneumonia?

From the Guidelines

Azithromycin is a recommended antibiotic option for treating community-acquired pneumonia, particularly for outpatient treatment in previously healthy individuals without risk factors for drug-resistant Streptococcus pneumoniae (DRSP) infection. The Infectious Diseases Society of America/American Thoracic Society consensus guidelines recommend a macrolide, such as azithromycin, as a strong option for outpatient treatment in this patient population 1.

Key Considerations

• Azithromycin is effective against common pneumonia-causing pathogens, including Streptococcus pneumoniae, Haemophilus influenzae, Mycoplasma pneumoniae, and Legionella species.
• For patients with comorbidities or risk factors for DRSP infection, combination therapy with a beta-lactam antibiotic, such as ceftriaxone or amoxicillin-clavulanate, is recommended 1.
• A more recent study from 2020 suggests that the same range of pathogens should be considered in patients with COVID-19-related pneumonia, and recommends a beta-lactam plus a macrolide, such as azithromycin, as a combination therapy for low-risk inpatients 1.
• Another study from 2019 found that azithromycin had a good eradication rate of Chlamydia pneumoniae, with an eradication rate of about 80% with a 5-day course 1.

Treatment Recommendations

• Azithromycin is typically prescribed at a dose of 500mg on the first day, followed by 250mg daily for 4 additional days (5 days total) 1.
• For hospitalized patients with more severe pneumonia, azithromycin may be given intravenously at 500mg daily until improvement allows switching to oral therapy.
• Patients should complete the full course of treatment, even if symptoms improve quickly, and monitor for side effects, including gastrointestinal disturbances, QT prolongation, or allergic reactions.

From the FDA Drug Label

Azithromycin Tablets, USP are indicated for the treatment of patients with mild to moderate infections (pneumonia: see WARNINGS) caused by susceptible strains of the designated microorganisms in the specific conditions listed below Community-acquired pneumonia due to Chlamydophila pneumoniae, Haemophilus influenzae, Mycoplasma pneumoniae or Streptococcus pneumoniae in patients appropriate for oral therapy Azithromycin should not be used in patients with pneumonia who are judged to be inappropriate for oral therapy because of moderate to severe illness or risk factors such as any of the following: patients with cystic fibrosis, patients with nosocomially acquired infections, patients with known or suspected bacteremia, patients requiring hospitalization, elderly or debilitated patients, or patients with significant underlying health problems that may compromise their ability to respond to their illness (including immunodeficiency or functional asplenia) In the treatment of pneumonia, azithromycin has only been shown to be safe and effective in the treatment of community-acquired pneumonia due to Chlamydia pneumoniae, Haemophilus influenzae, Mycoplasma pneumoniae or Streptococcus pneumoniae in patients appropriate for oral therapy

Key Points:

• Azithromycin is indicated for the treatment of community-acquired pneumonia due to certain microorganisms in patients appropriate for oral therapy.
• It should not be used in patients with pneumonia who are judged to be inappropriate for oral therapy due to moderate to severe illness or certain risk factors.
• The drug has only been shown to be safe and effective in the treatment of community-acquired pneumonia due to specific microorganisms in patients appropriate for oral therapy 2, 2.

Clinical Decision: Azithromycin can be used to treat pneumonia in patients with mild to moderate community-acquired pneumonia due to susceptible strains of certain microorganisms, but it is not recommended for patients with moderate to severe illness or certain risk factors.

From the Research

Efficacy of Azithromycin for Pneumonia

• Azithromycin has been shown to be effective in the treatment of community-acquired pneumonia (CAP) in several studies 3, 4, 5, 6, 7.
• A study published in 2005 found that a single 2.0-g dose of azithromycin microspheres was as effective and well tolerated as a 7-day course of extended-release clarithromycin in the treatment of adults with mild-to-moderate CAP 3.
• Another study published in 2014 found that azithromycin infusion was effective in patients with mild or moderate CAP, with an efficacy rate of 88.5% 4.
• A study published in 2000 found that intravenous azithromycin followed by oral azithromycin was effective in hospitalized patients with CAP, with a clinical cure rate of 77% 5.
• A study published in 2009 found that a 3-day course of azithromycin was effective in adults with mild to moderately severe CAP, including those with macrolide-resistant Streptococcus pneumoniae infection 6.
• A study published in 2003 found that azithromycin monotherapy was effective in patients hospitalized with mild-to-moderate community-acquired pneumonia, with a shorter length of stay compared to other treatment regimens 7.

Safety and Tolerability

• Azithromycin has been shown to be well tolerated in several studies, with a low incidence of adverse events 3, 4, 5, 6, 7.
• The most common adverse events reported with azithromycin were gastrointestinal in nature, such as diarrhea and nausea 3, 4, 6.
• A study published in 2005 found that the incidence of treatment-related adverse events was 26.3% with azithromycin microspheres and 24.6% with extended-release clarithromycin 3.
• A study published in 2014 found that 19 patients (20 cases) out of 62 patients reported possible adverse effects of azithromycin, but all of these adverse effects were mild and resolved soon after cessation of azithromycin 4.

Clinical Response

• The clinical response to azithromycin has been shown to be high in several studies, with clinical cure rates ranging from 77% to 94.7% 3, 4, 5, 6, 7.
• A study published in 2005 found that the clinical cure rate at the test-of-cure visit was 92.6% for azithromycin microspheres and 94.7% for extended-release clarithromycin 3.
• A study published in 2014 found that the efficacy of azithromycin in patients with mild CAP was 85.2% and in patients with moderate CAP was 91.2% 4.
• A study published in 2000 found that the clinical cure rate was 77% for azithromycin and 74% for the comparator regimen 5.