What respiratory conditions is Azithromycin (Zithromax) used to treat?

Azithromycin Indications for Respiratory Conditions

Azithromycin is indicated for acute bacterial respiratory infections including community-acquired pneumonia, acute bacterial sinusitis, acute exacerbations of chronic bronchitis, and pharyngitis/tonsillitis, and for long-term prophylaxis in bronchiectasis patients with three or more exacerbations per year. 1, 2

FDA-Approved Acute Respiratory Infections

Community-Acquired Pneumonia (CAP)

• Azithromycin is FDA-approved for mild to moderate CAP caused by Chlamydophila pneumoniae, Haemophilus influenzae, Mycoplasma pneumoniae, or Streptococcus pneumoniae in patients appropriate for oral therapy. 1
• It should NOT be used in patients with moderate to severe illness, cystic fibrosis, nosocomial infections, known/suspected bacteremia, hospitalized patients, elderly/debilitated patients, or those with immunodeficiency or functional asplenia. 1
• Recommended as first-line therapy for outpatients without cardiopulmonary disease or risk factors for drug-resistant S. pneumoniae. 3

Acute Bacterial Exacerbations of Chronic Obstructive Pulmonary Disease (AECOPD)

• FDA-approved for AECOPD caused by Haemophilus influenzae, Moraxella catarrhalis, or Streptococcus pneumoniae. 1
• Appropriate when at least two of the Anthonisen triad criteria are present (increased dyspnea, sputum volume, or sputum purulence). 3

Acute Bacterial Sinusitis

• FDA-approved for acute bacterial sinusitis caused by H. influenzae, M. catarrhalis, or S. pneumoniae. 1
• Appropriate for subacute purulent maxillary sinusitis, especially after symptomatic treatment failure, with typical 5-day duration. 3

Pharyngitis/Tonsillitis

• FDA-approved for pharyngitis/tonsillitis caused by Streptococcus pyogenes as an alternative to first-line therapy in patients who cannot use penicillin. 1
• Penicillin remains the drug of choice for S. pyogenes infection and rheumatic fever prophylaxis. 1
• Susceptibility testing should be performed as some strains are resistant to azithromycin. 1

Long-Term Prophylactic Use in Chronic Respiratory Conditions

Bronchiectasis

• Long-term azithromycin (250mg three times weekly) is strongly recommended for adults with bronchiectasis experiencing three or more exacerbations per year. 2, 4
• This reduces exacerbation frequency by approximately 50% (rate ratio 0.50,95% CI 0.35-0.70). 2
• For patients with chronic Pseudomonas aeruginosa infection, azithromycin is recommended when inhaled antibiotics are contraindicated, not tolerated, or not feasible. 2, 4
• For non-Pseudomonas infected bronchiectasis, macrolides are suggested as first-line long-term antibiotic therapy. 2, 4
• Minimum treatment duration of 6-12 months is needed to assess efficacy, with regular reassessment every 6 months. 2, 4

Chronic Obstructive Pulmonary Disease (COPD)

• Long-term azithromycin (250mg daily for 12 months) significantly reduces exacerbation rates in COPD patients (RR=0.83,95% CI 0.72-0.95). 4
• May be considered for exacerbation prevention in former smokers ≥65 years with moderate to very severe airflow obstruction on optimized regimens. 3

Pediatric Bronchiectasis

• Long-term macrolide antibiotics are strongly recommended for children/adolescents with bronchiectasis and recurrent exacerbations (more than one hospitalized or three or more non-hospitalized exacerbations in the previous 12 months). 2
• Treatment should be for at least 6 months with regular reassessment. 2

Critical Pre-Treatment Requirements for Long-Term Therapy

Cardiac Screening

• ECG must be performed before initiating long-term therapy; azithromycin is contraindicated if QTc >450ms for men or >470ms for women. 2, 4, 3
• Repeat ECG 1 month after starting treatment to check for new QTc prolongation. 2
• Avoid in patients with history of heart disease, low serum potassium, slow pulse rate, family history of sudden death, or concurrent use of QT-prolonging drugs. 2, 3

Microbiological Assessment

• Sputum culture should be performed before starting long-term therapy to screen for non-tuberculous mycobacterial (NTM) infections. 2, 4
• Macrolide monotherapy must be avoided if NTM is identified. 2
• Monitor sputum culture and sensitivity regularly during treatment, though in vitro resistance may not affect clinical efficacy. 2

Monitoring During Treatment

• Liver function tests should be checked 1 month after starting treatment and then every 6 months. 2
• Assess efficacy at 6 and 12 months using objective measures (exacerbation rate, CAT score, quality of life); stop treatment if no benefit. 2

Important Contraindications and Cautions

• Do NOT prescribe azithromycin for acute uncomplicated bronchitis, viral upper respiratory tract infections, common cold, or congestive rhinosinusitis. 3
• Macrolide-resistant S. pneumoniae prevalence is 25-50%, limiting effectiveness in some pneumonia cases. 3
• Gastrointestinal side effects are dose-related; if they occur at 500mg three times weekly, reduce to 250mg three times weekly if clinical benefit has been demonstrated. 2
• Long-term antibiotic choice should only be initiated by respiratory specialists after optimizing airway clearance and treating modifiable underlying causes. 2