Acute Bronchitis Management

Diagnosis and Etiology

• Acute bronchitis is characterized by self-limited inflammation of the large airways, cough lasting up to 6 weeks, and viral etiology in >90% of cases, with clinical features including inconstant fever, retrosternal burning sensation, and normal auscultation or diffuse bronchial rales 1, 2
• Over 90% of acute bronchitis cases have a nonbacterial cause, primarily viral, with only Bordetella pertussis, Mycoplasma pneumoniae, and Chlamydia pneumoniae established as nonbacterial causes (accounting for only 5-10% of cases) 1
• Streptococcus pneumoniae, Haemophilus influenzae, or Moraxella catarrhalis are not typically associated with acute bronchitis in adults without underlying lung disease 1

Antibiotic Use

• The American College of Physicians recommends against the use of antibiotics for the treatment of acute bronchitis in immunocompetent adults, due to limited evidence of benefit and potential harm 3, 4, 1, 2
• Systematic reviews of randomized controlled trials have found limited evidence to support antibiotic use for acute bronchitis, with randomized, placebo-controlled trials consistently failing to support a role for antibiotic treatment 3, 1
• Antibiotics should only be considered if the bronchitis worsens significantly, a complicating bacterial infection is strongly suspected, or the patient has developed pneumonia (confirmed by chest X-ray) 4

Symptomatic Relief

• Patients may benefit from cough suppressants (dextromethorphan or codeine), expectorants (guaifenesin), first-generation antihistamines (diphenhydramine), decongestants (phenylephrine), and β-agonists (only for patients with underlying asthma or COPD) 3, 5, 2

Complications and Special Considerations

• Pneumonia is unlikely in the absence of tachycardia (heart rate >100 beats/min), tachypnea (respiratory rate >24 breaths/min), fever (oral temperature >38°C), and abnormal findings on chest examination (rales, egophony, or tactile fremitus) 3
• Purulent sputum (yellow or green) does not signify bacterial infection; it is due to inflammatory cells or sloughed mucosal epithelial cells 3
• For suspected pneumococcal pneumonia, the first choice is amoxicillin 3g/day orally, with a duration of 14 days, while for suspected atypical pathogens, the first choice is oral macrolides (e.g., azithromycin) 2, 6
• Macrolide antibiotics, such as azithromycin, are effective against atypical pathogens (Mycoplasma, Chlamydia) and have advantages including short course, once-daily dosing, and better tolerated gastrointestinal profile 6
• Beta-lactam/beta-lactamase inhibitor combinations, such as amoxicillin-clavulanate, are effective against beta-lactamase producing organisms and have advantages including better coverage for H. influenzae and M. catarrhalis, but should not be used without justification 2, 7

Treatment Principles