Cough is typically worse at night or with exercise; lasts >2 weeks in 50% and 4 weeks in 25% of patients; may be associated with bronchospasm and/or excessive mucus production.
Diagnosis is primarily clinical. Other causes for acute cough such as pneumonia, asthma, or postnasal drip should be ruled out if suspected.
Treatment is aimed at symptom reduction until infection is resolved and bronchial damage repaired. Antibiotics are not recommended in the majority of patients.
Complications are rare; the primary complication is a postbronchitis syndrome, which can produce a cough lasting several months.
Acute bronchitis is defined as a self-limiting lower respiratory tract infection, to distinguish this condition from common colds and other upper respiratory ailments. Bronchitis refers specifically to infections causing inflammation in the bronchial airways, whereas pneumonia denotes infection in the lung parenchyma resulting in consolidation of the affected segment or lobe.
Although there is no universally accepted definition for acute bronchitis, the criteria proposed by MacFarlane offer a practical approach: (a) an acute illness of <21 days; (b) cough as the predominant symptom; (c) at least 1 other lower respiratory tract symptom, such as sputum production, wheezing, chest pain; (d) no alternative explanation for the symptoms.
[1]
MacFarlane J, Holmes W, Gard P, et al. Prospective study of the incidence, aetiology and outcome of adult lower respiratory tract illness in the community. Thorax. 2001;56:109-114.
http://www.ncbi.nlm.nih.gov/pubmed/11209098?tool=bestpractice.com
While the MacFarlane criteria state that the symptoms usually last <3 weeks, other studies have shown that cough may linger for >30 days in about a quarter of patients with acute bronchitis.
[2]
Williamson HA Jr. Pulmonary function tests in acute bronchitis: evidence for reversible airway obstruction. J Fam Pract. 1987;25:251-256.
http://www.ncbi.nlm.nih.gov/pubmed/3625141?tool=bestpractice.com
Consequently, acute bronchitis can still be present in patients with coughs lasting >1 month.
This topic focuses on acute bronchitis in adults.