OBJECTIVE--To study the clinical characteristics of respiratory tract illness caused by Chlamydia pneumoniae.
Design: -Prospective clinical, bacteriologic, and serologic study. Secondarily, a matched comparison of patients with and without evidence of C pneumoniae infection (serologic titers greater than or equal to 1:64 and less than 1:16, respectively).
Setting: --Four primary care (family practice) clinics in Madison, Wis, and nearby towns.
Patients: --The study included 365 white males and females (mean age, 34.2 years).
Main outcome measures: --Association of acute C pneumoniae infection with signs and symptoms of respiratory illness and the relationship of C pneumoniae antibody titer with wheezing at the time of enrollment in the study, and with the diagnosis of asthmatic bronchitis.
Results: --Nine (47%) of 19 patients with acute C pneumoniae infection had bronchospasm during respiratory illness, and there was a strong quantitative association of C pneumoniae titer with wheezing at the time of enrollment in the study (P = .01). In the matched study, C pneumoniae antibody was significantly associated with asthmatic bronchitis after, but not before, respiratory illness (odds ratio, 7.2; 95% confidence interval, 2.2 to 23.4). Four infected patients had newly diagnosed asthma after illness, and four others had exacerbation of previously diagnosed asthma. There was no serologic evidence of coexisting Mycoplasma pneumoniae, Chlamydia trachomatis, or respiratory viral infection in 96% of patients with asthmatic bronchitis and asthma.
Conclusions: --Some C pneumoniae antibody titers, although not diagnostic of chlamydial infection by present criteria, probably represent acute reinfection or ongoing chronic infection. Repeated or prolonged exposure to C pneumoniae may have a causal association with wheezing, asthmatic bronchitis, and asthma.