Respiratory Symptoms, Asthma, Atopy and Chlamydia pneumoniae IgG Antibodies in a General Population Sample of Young Adults

Abstract

Background: This study was designed to test the association of Chlamydia pneumoniae infection with respiratory symptoms and atopy.

Methods: A general population sample of 369 young adults (aged 20-44 years) completed a questionnaire on respiratory symptoms and underwent skin prick testing. C pneumoniae IgG and IgM serum titers were measured by micro-immunofluorescence. Prior infection was defined by titers of IgG ≥ 1:32, acute infection by titers of IgG ≥ :512 and/or IgM ≥ 1:16.

Results: The prevalence of cough and phlegm was higher in subjects with (19.0%) than in those without (11.4%) prior C. pneumoniae infection (p = 0.01). A similar difference was found for wheezing (14.3% vs 8.0%; p = 0.05), whereas the percentage of asthmatics was equally distributed between seropositive and seronegative subjects. IgG titers ≥ 1:128 were found more frequently in atopic subjects (p = 0.04). After adjusting for any confounding factors, cough and phlegm (but not wheezing) were found significantly associated with C. pneumoniae positivity, both for 1 : 32 (OR 1.80; 95% CI: 1.01-3.36; p = 0.05) and for 1 : 128 titers (OR 2.31; 95% CI: 1.20-4.42; p = 0.01). A significant association was also found for atopy, for titers ≥ 1 : 128 (OR 1.73; 95% CI: 1.01-3.20, p = 0.05). Acute infection was not associated with respiratory symptoms or asthma.

Conclusion: We conclude that C. pneumoniae infection is associated with cough and phlegm and may have a role in the pathogenesis of chronic respiratory diseases. Moreover, our results indicate a relationship between atopy and C. pneumoniae infection.