title: Chlamydia pneumoniae as a triggering infection in reactive arthritis.
abstract: OBJECTIVE
  To determine the role of Chlamydia pneumoniae as a triggering infection in reactive arthritis (ReA).
  
  
  METHODS
  Sixty patients with acute arthritis were screened for the evidence of triggering infections. In all patients, bacterial stool cultures, culture of Chlamydia trachomatis in urethra/cervix, and/or bacterial serology were studied. Chlamydia pneumoniae antibodies were measured by specific microimmunofluorescence test.
  
  
  RESULTS
  Thirty-five of 60 patients fulfilled the diagnostic criteria for ReA. Thirty-one patients had microbial/serological evidence of preceding infection due to Salmonella, Yersinia, Campylobacter or Chlamydia trachomatis, or they had enteritis or urethritis prior to arthritis. Four additional patients had high antibody titre for C. pneumoniae. Three of these four patients had preceding lower respiratory symptoms, and were positive for HLA-B27. The clinical picture of C. pneumoniae-positive ReA patients was similar to that of ReA patients with other definite aetiology.
  
  
  CONCLUSIONS
  Chlamydia pneumoniae is a triggering factor in approximately 10% of patients with acute ReA.
authors.affiliation: Department of Medicine, Helsinki University Central Hospital, Finland.
authors.forename: T
authors.initials: T
authors.lastname: Hannu
authors.forename: M
authors.initials: M
authors.lastname: Puolakkainen
authors.forename: M
authors.initials: M
authors.lastname: Leirisalo-Repo
mesh_terms: D000328:Adult; D000942:Antigens, Bacterial / Q000097:blood; D016918:Arthritis, Reactive / Q000276:immunology / Q000382:microbiology*; D002690:Chlamydia Infections / Q000150:complications* / Q000276:immunology; D016993:Chlamydophila pneumoniae; D005260:Female; D015796:HLA-B27 Antigen / Q000097:blood; D006801:Humans; D007070:Immunoglobulin A / Q000097:blood; D007074:Immunoglobulin G / Q000097:blood; D007075:Immunoglobulin M / Q000097:blood; D008297:Male; D008875:Middle Aged; D000091402:Prohibitins
chemical_list: D000942:Antigens, Bacterial; D015796:HLA-B27 Antigen; D007070:Immunoglobulin A; D007074:Immunoglobulin G; D007075:Immunoglobulin M; C000717331:PHB2 protein, human; D000091402:Prohibitins