Prophylactic treatment of chronic bronchitis.

Exacerbations of chronic bronchitis may be caused by a variety of bacterial and viral agents. There is ample documentation of a role for Hemophilus influenza, Streptococcus pneumonia, Mycoplasma pneumoniae, influenza A and B viruses, and several other respiratory viruses in causing these exacerbations. Because of the lack of frequency of exacerbations (once every 20 to 78 weeks) and the wide range of pathogens, trials of prophylaxis with antibiotics have been difficult to conduct. Controlled trials conducted since the 1950s have shown mixed results, some demonstrating a reduction in the number of exacerbations and others failing to show efficacy. Of the antibiotics used, tetracycline seemed the most effective. Both the pneumococcal polysaccharide and killed influenza virus vaccines have been suggested for patients with chronic bronchitis. The antiviral drug amantadine has been recommended when vaccine cannot be used. This reviewer concludes that prophylactic antibiotics should be used in selected patients with one or more exacerbations yearly using a drug such as tetracycline. A one-time dose of pneumococcal vaccine and the annual use of killed influenza vaccine are also reasonable. During an influenza A epidemic, amantadine should be considered for unvaccinated patients. Future studies should study intermittent v chronic prophylaxis with cheap but appropriate antibiotics (chosen for their microbial spectrum), and should test newer antiviral vaccines and antiviral drugs as they become available.