A frequently diagnosed infection in children and adults, acute bronchitis is typically a viral respiratory infection with lower tract symptoms, such as cough, phlegm, hoarseness, or wheezing. This syndrome should be distinguished from acute exacerbations in patients with chronic bronchitis, who are more vulnerable, who might be colonized with different bacterial flora in the respiratory tract, and who might require more aggressive treatment. In acute bronchitis in otherwise healthy patients, viral causes predominate. RSV and rhinovi-rus are common causative organisms even during influenza season.
Treatment of acute bronchitis in otherwise healthy patients should be primarily supportive because the condition is largely self-limited. Patients with underlying pulmonary disease, or even smokers, may have a higher rate of pulmonary complications (e.g., secondary pneumonia) or exacerbation of COPD. Options for symptomatic treatment include air humidifiers, cough suppressants, and antipyretic analgesics. Although p-agonists are sometimes prescribed, there is no evidence for a treatment benefit in the absence of measurable airway obstruction.
Antibiotic use is controversial. Because the most frequent cause is viral, bronchitis has often been overtreated with antibiotics, which would be a preventable source of antibiotic resistance. However, in patients with a productive cough persisting beyond 10 to 14 days, treatment with antibiotics may be indicated to treat bacterial co-infection, especially in smokers or in patients with underlying pulmonary disease. In a study of community-acquired acute bronchitis in France, polymerase chain reaction (PCR) testing revealed that 4.1% of patients were infected with Chlamydia pneumoniae and 2.3% with Mycoplasma pneumoniae (Gaillat et al., 2005).
A systematic review of RCTs comparing antibiotic therapy with placebo in the treatment of acute bronchitis or acute productive cough without underlying cause found a significant benefit for the antibiotic therapy, as measured by days of illness, persistent cough, and abnormal lung findings on examination (Smucny et al., 2004). An increase in adverse effects in the antibiotic-treated group compared with the placebo group outweighed many of these benefits, however, and caution in using antibiotics unnecessarily to prevent the spread of antibiotic-resistant bacteria is still valid at the population level. The specific choice of antibiotic seems to have little impact, despite known patterns of bacterial resistance in most communities. A systematic review of controlled trials that compared azithromycin to amoxicillin or amoxicillin-clavulanic acid in patients with clinical evidence of acute bronchitis, pneumonia, and acute exacerbation of chronic bronchitis found no significant advantage for using the macrolide antibiotic (Panpanich et al., 2004).
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