Treatment of Bacterial Bronchitis
Critical Distinction: Acute vs. Chronic Bronchitis
For acute bacterial bronchitis in otherwise healthy adults, antibiotics should NOT be prescribed, as bacterial infection accounts for fewer than 10% of cases and routine antibiotic use provides minimal benefit (reducing cough by only half a day) while exposing patients to adverse effects. 1, 2
However, the treatment approach differs dramatically for chronic bronchitis exacerbations, where antibiotics are indicated in specific circumstances based on disease severity and clinical criteria.
Acute Bronchitis (Otherwise Healthy Adults)
When Antibiotics Are NOT Indicated
- Routine antibiotic therapy is not recommended regardless of cough duration, presence of purulent sputum, or patient expectations 1, 2
- Purulent sputum occurs in 89-95% of viral cases and does not indicate bacterial infection 2
- Respiratory viruses cause 89-95% of acute bronchitis cases 2
Exception: Confirmed or Suspected Pertussis
- Prescribe a macrolide antibiotic (erythromycin or azithromycin) for confirmed or suspected pertussis 2, 3
- Isolate patients for 5 days from start of treatment 2
- Early treatment within the first few weeks diminishes coughing paroxysms and prevents disease spread 2
When to Reconsider (Bacterial Superinfection)
If fever >38°C persists beyond 3 days, this strongly suggests bacterial superinfection rather than viral bronchitis and warrants antibiotic treatment 1, 2
- First-line: Amoxicillin-clavulanate for 5-8 days 2, 4
- Alternative: Second-generation cephalosporins or macrolides if amoxicillin-clavulanate is contraindicated 4
Chronic Bronchitis Exacerbations
Classification and Antibiotic Indications
The decision to use antibiotics depends on the stage of chronic bronchitis and presence of Anthonisen criteria (increased dyspnea, increased sputum volume, increased sputum purulence) 1:
Simple Chronic Bronchitis (FEV1 >80%)
- Immediate antibiotics NOT recommended, even if fever is present 1
- Reassess at 2-3 days: prescribe antibiotics only if fever >38°C persists beyond 3 days 1
Obstructive Chronic Bronchitis (FEV1 35-80%)
- Immediate antibiotics recommended only if ≥2 of 3 Anthonisen criteria are present 1, 5
- If <2 criteria present initially, reassess at 2-3 days and prescribe if fever >38°C persists beyond 3 days 1
Obstructive Chronic Bronchitis with Respiratory Insufficiency (FEV1 <35% or hypoxemia at rest)
- Immediate antibiotic therapy is recommended regardless of Anthonisen criteria 1
Antibiotic Selection for Chronic Bronchitis Exacerbations
Target Pathogens
Antibiotics must cover Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis 1, 4
First-Line Antibiotics (Infrequent Exacerbations, FEV1 ≥35%)
Amoxicillin remains the reference compound 1
- Amoxicillin 500 mg three times daily for 5-8 days 2
- Alternatives: First-generation cephalosporins, macrolides, pristinamycin, or doxycycline (particularly for beta-lactam allergy) 1
- Avoid cotrimoxazole due to inconsistent activity on pneumococci and poor benefit/risk ratio 1
Second-Line Antibiotics (Frequent Exacerbations ≥4/year OR FEV1 <35%)
Amoxicillin-clavulanate remains the reference antibiotic 1
Duration of Treatment
- Standard duration: 5-8 days for most bacterial bronchitis cases 2, 4
- 7-10 days for chronic bronchitis exacerbations with documented bacterial pathogens 1, 2
- Fever should resolve within 2-3 days after initiating antibiotics 2, 4
Critical Pitfalls to Avoid
- Do NOT prescribe antibiotics based on sputum color or purulence alone – this occurs in 89-95% of viral cases 2
- Do NOT prescribe antibiotics for cough duration alone – viral bronchitis cough typically lasts 10-14 days 2
- Do NOT assume bacterial infection before the 3-day fever threshold – most cases are viral 2
- Up to 25% of H. influenzae and 50-70% of M. catarrhalis produce β-lactamase, making simple aminopenicillins ineffective 2
- Always rule out pneumonia first by checking vital signs (heart rate >100, respiratory rate >24, temperature >38°C) and lung examination for focal findings 2
Monitoring and Reassessment
- Clinical reassessment should be performed 2-3 days after antibiotic initiation to evaluate treatment response 1, 2
- Reevaluate for other diagnoses (pneumonia, pertussis) if symptoms persist beyond 10-14 days 2
- Cough may persist longer than fever and should not be used as the sole indicator of treatment failure 4