Acute exacerbations of asthma in adults: Role of Chlamydia pneumoniae infection

Respiratory infections precipitate wheezing in many asthmatic patients and may be involved in the aetiopathogenesis of asthma. Several studies have demonstrated that viral infections may provoke asthma. Bacterial infections seem to play a minor role. However, Chlamydia pneumoniae has been recently reported as a possible cause of asthma The aim of the present study was to evaluate the role of C. pneumoniae infection in acute exacerbations of asthma in adults. Seventy four adult out-patients with a diagnosis of acute exacerbation of asthma were studied. Acute and convalescent (23 weeks) serological determination of antibodies to cytomegalovirus, respiratory syncytial virus, adenovirus, influenza A and B, parainfluenza 1 and 3. Mycoplasma pneumoniae and Legionella pneumophila were performed by means of immunofluorescence tests. C. pneumoniae specific antibodies were detected by two microimmunofluorescence tests using a specific antigen (TW-183) and a kit with three chlamydial antigens. Pharyngeal swab specimens were also obtained for C. pneumoniae identification. Samples for bacterial culture were obtained in patients with productive cough (15 out of 74 patients). Fifteen patients (20%) presented seroconversion to at least one of the studied pathogens. Seven were found to be infected by virus, six by C. pneumoniae alone, and one by M. pneumoniae. One more patient showed seroconversion to C. pneumoniae and cytomegalovirus. In one out of 15 patients with productive cough, sputum culture yielded H. influenzae 10 ⁵ colony forming units (cfu)·ml ^-(')1.. In conclusion, viruses were involved in about 9% of asthma attacks, while acute infection with intracellular bacteria was detected in 11% of cases. Notably, most of the latter (7 out of 8 cases) were due to C. pneumoniae infection. Further studies are needed in order to elucidate whether C. pneumoniae plays a role only as precipitant of asthma symptoms or is actually one of the causes of asthma.