Background: The prevalence and role of Chlamydia pneumoniae in chronic obstructive pulmonary disease (COPD) remain unclear, and molecular methods of detection may help clarify this relationship.
Methods: Consecutive clinically stable patients with smoking-related COPD attending a tertiary care outpatient clinic were enrolled in this cross-sectional study. Peripheral blood mononuclear cells were obtained from 100 patients, and induced sputum was obtained in 62 patients. C. pneumoniae DNA was detected in blood or sputum by nested polymerase chain reaction (PCR).
Results: Patients had mean age (standard deviation) of 65.8 (10.7) years, mean forced expiratory volume in one second (SD) of 1.34 (0.61) L, and 61 (61.0%) were male. C. pneumoniae nucleic acids were detected in 27 (27.0%) patients. Among 62 patients with both blood and sputum available, blood specimens were superior to induced sputum for detection of C. pneumoniae DNA (21 versus 7 detected, P=0.003). Current smoking (odds ratio [OR]=2.6, 95 % confidence interval [CI]: 1.1, 6.6, P=0.04), season (November to April) (OR=3.6, 95% CI: 1.4, 9.2, P=0.007), and chronic sputum production (OR=6.4, 95% CI: 1.8, 23.2, P=0.005) were associated with detection of C. pneumoniae DNA.
Conclusions: C. pneumoniae DNA prevalence was higher among current smokers, and during winter/spring months. Prospective molecular studies are needed to examine the role of C. pneumoniae detection in COPD disease symptoms and progression.