Relationship of bacterial and viral infections to exacerbations of asthma.

Abstract

Asthmatic patients (51) were followed for up to 18 mo. During this time 111 exacerbations of wheeze were recorded. Involvement by pathogenic respiratory bacteria and viruses was investigated directly by culture and indirectly by antibody [Ab] studies. Proof of infection was found in only 12 (10.8%) of the 111 exacerbations. Only 8 patients provided sputum samples. Potential bacterial pathogens [Haemophilus influenzae, Streptococcus pneumoniae and Staphylococcus aureus] were found in 4. Viruses [rhinovirus, coxsackie B virus, influenza A, influenza B and adenovirus] were isolated in 4 of 27 exacerbation specimens; significant rises in specific viral Ab titers occurred in 3. Six patients developed precipitating Ab to respiratory bacteria, but only 1 in relation to an exacerbation. The great majority of exacerbations of asthma in these patients were not due to respiratory tract infection.