Chlamydia pneumoniae and exacerbations of asthma in adults

Background: Chlamydia pneumoniae is a frequent causative agent of acute respiratory disease and has been recently reported as a possible cause of asthma. Objective: We assessed the prevalence of C. pneumoniae infections in adult patients with acute exacerbations of asthma. Methods: One hundred sixty-eight adult patients with acute exacerbations of asthma and 108 control subjects matched for age, sex, and smoking status were studied. Nasopharyngeal swab specimens were obtained from all subjects and analyzed by isolation in cell culture and polymerase chain reaction (PCR) test for C. pneumoniae. Serum samples were also obtained and tested for C. pneumoniae-specific antibodies by the microimmunofluorescence test. Results: C. pneumoniae was isolated from two (1.2%) asthma patients and none from controls and detected by PCR from nine (5.4%) cases and one (0.9%) control. Both culture positive specimens were also positive in PCR. Further, serologic evidence of acute C. pneumoniae infection was present in 15 (8.9%) of asthma patients and in three (2.8%) of controls (P = .048). The prevalence of C. pneumoniae-specific IgG and IgA was significantly higher in asthma cases than in controls (IgG greater than or equal to 1:16: 85.1% versus 67.6%, P = .001; IgA greater than or equal to 1:16: 47.6% versus 16.7%, P < .001). Mean titer of Ige and IgA was also significantly greater in asthma cases than in controls (IgG: 38.8 versus 18.1, P = .0001; IgA: 17.2 versus 6.1, P = .0001). Conclusions: Our data suggest that C. pneumoniae infection may trigger acute exacerbations of adult asthma.