Chronic cough is one of the most common complaints of the patients who visiting respiratory clinic. Controversy exists as to whether Chlamydial infection is associated with chronic cough. We evaluated the prevalence of the Chlamydia pneumoniae infection in patients with chronic cough using nested polymerase chain reaction (PCR).
Total 68 Patients who visited a referral hospital in Seoul Korea with complaints of cough lasting more than 3 weeks were enrolled from January to August 2005. These patients were verified that they were free from chest x-ray abnormalities, reversible airflow obstruction, reflux esophagitis, taking angiotensin converting enzyme inhibitor and other cough producing conditions. Methacholine bronchial provocation test, skin prick test for 33 common inhalant allergens, and induced sputum collection were done. Atopy was defined as positive results of any common inhalant allergens. Sputum eosinophilia was defined if eosinophil counts exceeded more than 3% of total sputum cells. Nested PCR tests were done to detect C. pneumoniae infection using induced sputum and peripheral blood mononuclear cells.
Among the total 68 patients, 19 patients (27.9%) were male. Mean age of the patients was 46.1 ± 13.5 years old. Mean duration of cough was 11.7 ± 27.6 months. Prevalence of atopy was 41.2%. The causes of the chronic cough were upper airway cough syndrome in 26.5%, eosinophilic bronchitis in 20.6%, cough variant asthma in 16.2%, post infectous cough in 2.9%, and idiopathic cough in 33.8%. C. pneumoniae was detected in one patient (1.5%) by PCR and this was ascertained by nucleotide sequencing. This patient was classified as idiopathic cough.
We concluded that the prevalence of C. pneumoniae infection in chronic cough is low. To confirm the significance of chlamydial infection in chronic cough, further studies are needed.
Chlamydial infection has a trivial role in chronic cough.
Jae-Young Lee, No Financial Disclosure Information; No Product/Research Disclosure Information