What is a suitable antibiotic for a patient with acute bronchitis and an allergy to azithromycin (Zithromax)?

Acute Bronchitis Treatment with Azithromycin Allergy

For acute uncomplicated bronchitis, antibiotics should not be prescribed at all—regardless of azithromycin allergy—because 89-95% of cases are viral and antibiotics provide no clinical benefit while causing significant adverse effects. 1, 2

Critical First Step: Rule Out Pneumonia

Before diagnosing acute bronchitis, you must exclude pneumonia by checking for:

• Heart rate >100 beats/min
• Respiratory rate >24 breaths/min
• Oral temperature >38°C (100.4°F)
• Abnormal chest examination findings (rales, egophony, tactile fremitus) 1, 2

If ANY of these are present, obtain chest radiography and treat as pneumonia, not bronchitis. 1, 2

Why Antibiotics Don't Work in Acute Bronchitis

• Respiratory viruses cause 89-95% of acute bronchitis cases 1, 2
• Antibiotics reduce cough duration by only 0.5 days (12 hours) 1
• Antibiotics significantly increase adverse events (RR 1.20; 95% CI 1.05-1.36) 1
• Purulent sputum occurs in 89-95% of viral cases and does NOT indicate bacterial infection 1, 2
• Cough duration does NOT indicate bacterial infection—viral bronchitis cough typically lasts 10-14 days 1, 2

Appropriate Management of Uncomplicated Acute Bronchitis

Patient education is the cornerstone of management:

• Inform patients that cough typically lasts 10-14 days after the visit, even without antibiotics, and may persist up to 3 weeks 1, 2
• Explain that antibiotics expose them to adverse effects while contributing to antibiotic resistance without providing benefit 1
• Patient satisfaction depends more on physician-patient communication than whether an antibiotic is prescribed 3, 1

Symptomatic treatment options:

• Codeine or dextromethorphan may provide modest effects on severity and duration of cough, particularly when dry cough is bothersome and disturbs sleep 3, 1
• β2-agonist bronchodilators (albuterol) should only be used in select adult patients with wheezing accompanying the cough 3, 1
• Elimination of environmental cough triggers and vaporized air treatments are reasonable low-risk measures 3, 1

Exception: Pertussis (Whooping Cough)

If pertussis is confirmed or suspected, prescribe an alternative macrolide:

• Erythromycin is the recommended alternative macrolide for pertussis 1
• Patients should be isolated for 5 days from the start of treatment 1
• Early treatment within the first few weeks diminishes coughing paroxysms and prevents disease spread 1

When to Reassess

Instruct patients to return if:

• Fever persists >3 days (suggests bacterial superinfection or pneumonia) 1, 2
• Cough persists >3 weeks (consider other diagnoses: asthma, COPD, pertussis, gastroesophageal reflux) 1
• Symptoms worsen rather than gradually improve 1

Special Populations: Chronic Bronchitis/COPD Exacerbations

These guidelines do NOT apply to patients with:

• Chronic bronchitis or COPD exacerbations
• Immunocompromised state
• Cardiac failure
• Insulin-dependent diabetes
• Age >75 years with significant comorbidities 1

For acute bacterial exacerbation of chronic bronchitis (ABECB) with azithromycin allergy, alternative antibiotics include:

First-Line Alternatives:

• Doxycycline 100 mg twice daily for 7-10 days for moderate-severity exacerbations 1
• Amoxicillin 500 mg three times daily for 5-8 days (if no beta-lactam allergy and beta-lactamase negative organisms) 1

Second-Line Alternatives:

• Amoxicillin/clavulanate 625 mg three times daily for 14 days for severe exacerbations or beta-lactamase producing organisms 1
• Levofloxacin (respiratory fluoroquinolone) for high-risk patients or frequent exacerbations 1, 4

Alternative Macrolide Options (if only azithromycin allergy, not class allergy):

• Erythromycin as an alternative macrolide 3
• Clarithromycin 500 mg twice daily for 7-14 days achieves 90-97% clinical cure rates in ABECB 1

Critical Pitfalls to Avoid

• Don't prescribe antibiotics based on colored sputum—this is the most common reason for inappropriate antibiotic prescribing in viral bronchitis 2
• Don't assume bacterial infection before the 3-day fever threshold—most cases are viral 1
• Don't use purulent sputum color as an indication for antibiotics—it occurs in 89-95% of viral cases 1, 2
• Approximately one-third of patients diagnosed with "recurrent acute bronchitis" actually have undiagnosed asthma or COPD—consider these diagnoses in recurrent cases 1