Acute bronchitis

Acute bronchitis is an inflammation of the upper respiratory tract, usually following an acute respiratory infection. It is usually a viral infection, although sometimes a bacterial infection; pathogens are rarely identified. The most common symptoms of acute bronchitis are cough with or without sputum and/or fever. Patients with COPD may also have hemoptysis, burning chest pain, and hypoxemia.

The diagnosis is clinical and is made by exclusion. Acute bronchitis is treated supportively; antibiotics are needed only for patients with signs of bacterial infection (up to 10% of all cases of acute bronchitis). The prognosis is excellent in patients without lung disease, but in patients with COPD it may result in acute respiratory failure.

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Causes of acute bronchitis

Acute bronchitis is often a component of acute respiratory viral infections caused by:

• rhinoviruses,
• parainfluenza,
• influenza A or influenza B viruses,
• respiratory syncytial virus,
• coronavirus,
• respiratory adenoviruses.

Less common pathogens include Mycoplasma pneumoniae, Bordetella pertussis, and Chlamydia pneumoniae. Patients at risk include smokers and patients with COPD and other conditions that impair bronchial clearance mechanisms, such as cystic fibrosis or conditions that lead to bronchiectasis.

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Symptoms of acute bronchitis

Symptoms of acute bronchitis are a nonproductive or minimal but productive cough, accompanied by symptoms of acute respiratory viral infection or occurring after acute respiratory viral infection. The subjective sensation of dyspnea is a consequence of chest pain on breathing, not hypoxia, except in patients with underlying lung disease. Signs are often absent but may include scattered wheezing and whistling.

Sputum may be clear, purulent or blood-streaked. The characteristics of the sputum do not correspond to a specific etiology (i.e. viral or bacterial).

Diagnosis of acute bronchitis

The diagnosis of acute bronchitis is based on symptoms. Chest X-ray is required only if fever, shortness of breath, or other symptoms of acute bronchitis suggest pneumonia. Gram stain and sputum culture are not helpful.

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Treatment of acute bronchitis

Acute bronchitis in healthy people is a major reason for antibiotic abuse. Almost all patients require only symptomatic treatment for acute bronchitis, such as paracetamol and hydration. Antitussives should be used only to facilitate sleep. Patients with wheezing may benefit from inhaled beta-agonists (eg, salbutamol) or anticholinergics (eg, ipratropium bromide), but not more than 7 days. Oral antibiotics (eg, 7 days of amoxicillin 500 mg 3 times daily, oral doxycycline 100 mg twice daily, or trimethoprim-sulfamethoxazole 160/800 mg orally twice daily) are suggested to be useful in patients with COPD or other serious lung diseases if at least two of the following are present: severe cough, severe shortness of breath, increased amount and purulent character of sputum.

What is the prognosis for acute bronchitis?

Acute bronchitis has a favorable prognosis. Cough resolves within 2 weeks in 75% of patients. Patients with persistent cough should have a chest X-ray and be evaluated for pertussis (whooping cough) and noninfectious causes such as postnasal drainage, allergic rhinitis, and cough-variant asthma. In some patients, inhaled glucocorticoids given for a few days are effective if cough persists due to airway irritation.