The role of infection in asthma.

The possible role of bacterial, viral and fungal infections in the development, exacerbation and treatment of asthma are discussed. Although bacterial allergy has in the past been advocated as an important etiologic factor for asthma, the evidence is inconclusive. Hyposensitization with bacterial antigens is no longer an accepted treatment. Bacterial infection of the nasal sinuses and bronchi may exacerbate an asthmatic attack and in some cases patients benefit from antibiotic therapy. However, bacterial infections in asthma and allergic rhinitis do not always require treatment and if treated this is not sufficient alone to reverse symptoms. Opinions vary as to the importance of viral infections. There is evidence that the immunologic consequences of intrabronchial infection with Aspergillus fumigatus may cause exacerbations of asthma.