Chlamydia pneumoniae infection in acute exacerbations of COPD

Chlamydia pneumoniae, strain TWAR, is a frequent causative agent of acute respiratory disease. We assessed the incidence and prevalence of Chlamydia pneumoniae infections in COPD. We studied, from January 1990 to May 1991, 142 out-patients with acute purulent exacerbations of chronic obstructive pulmonary disease (COPD) and 114 healthy control subjects. Oropharyngeal swab specimens were collected at each exacerbation and analysed using a high definition monoclonal indirect fluorescent antibody test for Chlamydia pneumoniae identification. Immunoglobulins G and M (IgG and IgM) fractions of antibodies to Chlamydia pneumoniae were studied by microimmunofluorescence test. Prevalence of specific IgG was 63% in COPD, and 46% in controls (Chi-squared test p = 0.007). Moreover, mean titre of IgG was significantly higher in COPD than in controls. Five patients were positive for specific IgM (≥ = 1:16), and one had a fourfold increase of IgG titre; four of these patients had been treated with ciprofloxacin 1 g · day^-1 for 10 days, and two with erythromycin, 3 g · day^-1 for 14 days, with remission of signs and symptoms of exacerbation. Chlamydia pneumoniae identification was always negative. Our data suggest that Chlamydia pneumoniae infection is a rather frequent event in COPD, since at least 4% of exacerbations may be associated with it.