What antibiotics are recommended for treating bronchitis?

Antibiotics for Bronchitis

Antibiotics should NOT be routinely prescribed for acute bronchitis in otherwise healthy adults, as this is predominantly a viral illness and antibiotic treatment does not meaningfully alter the clinical course. 1

When Antibiotics Are NOT Indicated

For uncomplicated acute bronchitis in healthy adults, antibiotics provide no clinically significant benefit and should be avoided. 1

• Acute bronchitis is viral in the vast majority of cases, caused by influenza, parainfluenza, respiratory syncytial virus, coronavirus, adenovirus, and rhinoviruses 1
• Only 5-10% of cases are caused by non-viral pathogens (Bordetella pertussis, Mycoplasma pneumoniae, Chlamydophila pneumoniae) 1
• Randomized controlled trials consistently show antibiotics reduce cough duration by only 0.5 days while increasing adverse effects (nausea, vomiting, rash) by 20% 1, 2
• The FDA removed uncomplicated acute bronchitis as an indication for antibiotic therapy in 1998 1

Critical Distinction: Rule Out Pneumonia First

Before diagnosing acute bronchitis, pneumonia must be excluded, as management differs entirely. 1

• In healthy adults under 70 years, pneumonia is unlikely if ALL of the following are absent: heart rate >100 bpm, respiratory rate >24 breaths/min, fever >38°C, and abnormal chest examination findings (rales, egophony, fremitus) 1
• Purulent or green/yellow sputum does NOT indicate bacterial infection—this reflects inflammatory cells, not bacteria 1, 3

Specific Exceptions Where Antibiotics ARE Indicated

1. Confirmed or Suspected Pertussis (Whooping Cough)

Patients with confirmed or probable pertussis should receive a macrolide antibiotic immediately and be isolated for 5 days. 1

• Erythromycin is the treatment of choice (or trimethoprim-sulfamethoxazole if macrolides cannot be given) 1
• Early treatment within the first few weeks diminishes coughing paroxysms and prevents disease spread 1
• Treatment beyond this period is unlikely to benefit the patient but still prevents transmission 1

2. Chronic Obstructive Pulmonary Disease (COPD) Exacerbations

Antibiotics are indicated in COPD patients when at least 2 of 3 Anthonisen criteria are present: increased sputum volume, increased sputum purulence, increased dyspnea. 3, 4

First-Line Antibiotics for COPD Exacerbations:

• Amoxicillin is the first-line choice for patients with FEV1 ≥35% and infrequent exacerbations 3, 4
• First-generation cephalosporins are acceptable alternatives 3
• For penicillin allergy: macrolides (azithromycin), doxycycline, or pristinamycin 3

Second-Line Antibiotics for COPD Exacerbations:

• Amoxicillin-clavulanate is the reference second-line therapy 3
• Second-generation cephalosporins (cefuroxime-axetil) or third-generation (cefpodoxime-proxetil, cefotiam-hexetil) 3
• Fluoroquinolones active against pneumococci (levofloxacin, moxifloxacin) for treatment failures or severe disease 3, 5

Severe COPD (FEV1 <35%):

Immediate antibiotic therapy is recommended during all exacerbations in patients with chronic respiratory insufficiency. 3, 4

3. Fever Persisting Beyond 3 Days

If fever >38°C persists for more than 3 days, this suggests bacterial superinfection or pneumonia rather than simple viral bronchitis. 3

• This clinical scenario warrants reconsideration of the diagnosis and possible antibiotic initiation 3
• Chest radiography should be considered to exclude pneumonia 1

Target Pathogens When Antibiotics Are Used

When antibiotics are indicated (COPD exacerbations, suspected bacterial superinfection), coverage should include: 3

• Streptococcus pneumoniae
• Haemophilus influenzae
• Moraxella catarrhalis

Antibiotics to AVOID

Do NOT use the following antibiotics as they provide inadequate coverage or have unfavorable risk-benefit profiles: 3

• Fluoroquinolones inactive against pneumococci (ciprofloxacin, ofloxacin)
• Cefixime (inadequate pneumococcal coverage)
• Cotrimoxazole/trimethoprim-sulfamethoxazole (inconsistent pneumococcal activity, poor benefit/risk ratio)

Common Pitfalls to Avoid

• Do not assume purulent sputum indicates bacterial infection—this is inflammatory debris, not bacteria 1, 3
• Do not prescribe antibiotics to meet patient expectations—take time to explain the viral etiology and lack of antibiotic benefit 1
• Do not confuse acute bronchitis with COPD exacerbations—the latter requires antibiotics when Anthonisen criteria are met 3, 4
• Do not use azithromycin for simple acute bronchitis—one study showed significantly more adverse events than placebo with no benefit 1, 6
• Do not forget to assess for pertussis in the appropriate epidemiologic context—this is the one bacterial cause requiring treatment 1

Duration of Treatment When Antibiotics Are Used

For COPD exacerbations requiring antibiotics, treat for at least 7 days. 4

• Fever should resolve within 2-3 days of starting appropriate antibiotics 4
• Clinical reassessment should occur at 5-7 days 4