Acute bronchitis is a very common condition, particularly in the cold and flu season. In general, it is one of the most common conditions people see their doctors for. An individual with acute bronchitis will present to their physician because of a persistent cough, usually lasting for one to three weeks. The cough is often productive, meaning sputum and mucous is coughed up. These individuals are often convinced they have a bacterial infection requiring antibiotics. However, acute bronchitis is actually one of the most common causes of antibiotic misuse.
The nagging, congested cough of acute bronchitis is almost always caused by a virus, not bacteria. Antibiotics will do nothing to clear a viral infection. However, around 70 percent of patients with acute bronchitis who seek medical treatment from a physician are given a prescription for antibiotics. The patient then spends money, time and energy on taking a useless medication with risk of side effects. By prescribing an antibiotic for acute bronchitis, the physician is also contributing to the development of widespread antibiotic resistance.
It is important for a physician to be able to distinguish acute bronchitis from other causes of productive cough that may actually benefit from antibiotics. Acute bronchitis is most often a viral infection of the upper airways. Implicated viruses include including influenza A and B, parainfluenza, coronavirus (types 1-3), rhinovirus, respiratory syncytial virus (RSV), and human metapneumovirus. Rarely, acute bronchitis is caused by an organism that requires antibiotic treatment including Mycoplasma pneumoniae, Chlamydia pneumoniae, or Bordatella pertussis.
Mycoplasma should be suspected in young adults with a persistent cough that is accompanied by sore throat, constitutional symptoms such as fatigue and decreased appetite, and head congestion. However, studies of adults with acute cough lasting for more than five days show that Mycoplasma pneumoniae is the causative microbe in fewer than 1 percent of cases.
The clinical features of acute bronchitis caused by Chlamydia pneumoniae include sore throat, laryngitis, and bronchitis. In particular, hoarseness and a low grade fever, although uncommon, are suggestive findings of C. pneumoniae. This form of acute bronchitis caused only 5% of cases in a group of college students studied.
B. pertussis and B. parapertussis cause whooping cough. Pertussis only accounts for about 1 percent of cases of acute bronchitis in the United States. Most adults and the vast majority of children have been immunized against Pertussis. However, individuals who have been only partially immunized may have an atypical presentation of whooping cough that presents similarly to viral bronchitis.
Acute bronchitis is common and frequently misdiagnosed as a bacterial infection of one form or another. Patients and physicians can prevent the misuse of antibiotics by understanding the signs and symptoms of acute viral bronchitis and when bacterial causes of bronchitis should be suspected.
Reference: Acute Bronchitis in Adults. UpToDate Online. http://www.uptodate.com.