title: Serology of Chlamydia pneumoniae in patients with chronic cough.
abstract: OBJECTIVE
  Chronic cough is one of the more common respiratory symptoms. Controversy exists as to whether Chlamydia infection is associated with chronic cough. As such, the association of chronic cough with serological evidence of Chlamydia pneumoniae (C. P) infection and a systemic inflammatory marker was assessed.
  
  
  METHODS
  Thirty-seven patients who visited Kangwon National University Hospital for chronic cough between September 2003 and August 2004 and 37 age-matched healthy controls were evaluated for C. P. antibodies and C-reactive protein. Chronic infection was defined as an IgG or IgA titre between 1:64 and 1:512, and acute infection was defined as IgM=1:16 or IgG titre of=1:512 or IgA=1:512. A nasopharyngeal swab was evaluated for C. P. DNA using the polymerase chain reaction.
  
  
  RESULTS
  The median duration of cough was 3 months (1-240). Nineteen patients (49%) and 19 controls had titres consistent with chronic infection, and the titre difference was not significant (P=0.592). Nine patients and two controls had titres consistent with acute infection (24.3% vs. 5.4%). Acute infection was significantly more prevalent in the patients with chronic cough (P=0.023). There was no difference in the C-reactive protein value (0.13 vs. 0.14, P=0.84). Three patients were positive for C. P. DNA.
  
  
  CONCLUSIONS
  Acute Chlamydia infection was more prevalent in patients with chronic cough, whereas chronic Chlamydia infection was not. There was no elevation of a systemic inflammatory marker in patients with chronic cough.
authors.affiliation: Department of Internal Medicine, College of Medicine, Kangwon National University Hospital, Chunchon, Kangwon-Do, Korea. pulmo2@knuh.or.kr
authors.forename: Woo Jin
authors.initials: WJ
authors.lastname: Kim
authors.forename: Hui Young
authors.initials: HY
authors.lastname: Lee
authors.forename: Mi Eun
authors.initials: ME
authors.lastname: Lee
authors.forename: Seung-Joon
authors.initials: SJ
authors.lastname: Lee
mesh_terms: D000328:Adult; D000368:Aged; D000907:Antibodies, Bacterial / Q000097:blood* / Q000276:immunology; D015415:Biomarkers / Q000097:blood; D002097:C-Reactive Protein / Q000032:analysis; D016022:Case-Control Studies; D023521:Chlamydophila Infections / Q000097:blood* / Q000150:complications / Q000175:diagnosis; D016993:Chlamydophila pneumoniae / Q000235:genetics / Q000276:immunology*; D002908:Chronic Disease; D003371:Cough / Q000097:blood* / Q000209:etiology / Q000276:immunology; D004269:DNA, Bacterial / Q000235:genetics; D005260:Female; D006801:Humans; D007070:Immunoglobulin A / Q000032:analysis; D007074:Immunoglobulin G / Q000032:analysis; D008297:Male; D008875:Middle Aged; D018410:Pneumonia, Bacterial / Q000097:blood* / Q000150:complications / Q000175:diagnosis; D015995:Prevalence
chemical_list: D000907:Antibodies, Bacterial; D015415:Biomarkers; D004269:DNA, Bacterial; D007070:Immunoglobulin A; D007074:Immunoglobulin G; D002097:C-Reactive Protein