Definition
Uncomplicated Acute Bronchitis
- A self-limiting acute lower respiratory tract infection (LRTI) characterized by the sudden onset of cough with or without sputum production, in an otherwise healthy individual
- Diagnosis is based on clinical findings
Pathogenesis
- An inflammatory response to infections of the bronchial epithelium of the large airways of the lungs
- Begins with mucosal injury, epithelial cell damage and release of proinflammatory mediators
- Transient airflow obstruction and bronchial hyper-responsiveness
- Purulence can result from either bacterial or viral infection
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Viral
- The most common cause (90% of cases) of bronchial inflammation in otherwise healthy adults presenting with acute bronchitis
- Influenza A and B, parainfluenza 3 and respiratory syncytial virus (RSV) produce primarily lower respiratory tract disease
- Coronavirus, adenovirus and rhinoviruses more commonly produce upper respiratory tract symptoms
Non-viral
- Mycoplasma pneumoniae, Chlamydia pneumoniae, Bordetella pertussis (5-10% of cases)
- B pertussis most likely to cause prolonged cough
- Environmental cough triggers (eg dust, dander, toxic fume inhalation)
Signs and Symptoms
Lower Respiratory Tract Infection (LRTI)
- Cough and/or increase in sputum production
- Breathlessness/wheeze
- Sweats and/or sore throat
- Increase in temperature
Clinical Presentation of Uncomplicated Acute Bronchitis
- Predominant symptom: Cough with or without sputum production that persists for <3 weeks
- The cough generally lasts 7-10 days but occasionally persists for >1 month
- Influenza (flu) virus typically causes a non-productive cough
- If cough persists for >3 weeks, consider investigation of other diagnoses (eg tuberculosis in endemic areas)
- Sputum may be clear, white, yellow, green or even tinged with blood
- Green/yellow (purulent) sputum production is indicative of an inflammatory reaction that can result from either viral or bacterial infection
- Cough may be accompanied by clinical features that suggest an acute respiratory tract infection (eg sore throat, rhinorrhea, hoarseness)
- Patient may also present with retrosternal chest pain on coughing, dyspnea, wheezing, fever, fatigue or night cough