Chlamydia pneumoniae--a new causative agent of reactive arthritis and undifferentiated oligoarthritis. J Braun, S Laitko, J Treharne, U Eggens, P Wu, A Distler, and J Sieper Department of Medicine, Klinikum Steglitz, Free University of Berlin, Germany.   This article has been cited by other articles in PMC. link
  AbstractOBJECTIVE--To examine whether reactive arthritis (ReA) known to occur after a urogenital infection with Chlamydia trachomatis can also follow an infection with Chlamydia pneumoniae, a recently described species of Chlamydiae that is a common cause of respiratory tract infectionsⁱ. METHODS--Specific antibodies (microimmunofluorescence test) and lymphocyte proliferation to C trachomatis and C pneumoniae in paired samples of peripheral blood and synovial fluid were investigated in 70 patients with either reactive arthritis (ReA) or undifferentiated oligoarthritis (UOA). RESULTS--Five patients with acute ReA after an infection with C pneumoniae are reported. Three had a symptomatic preceding upper respiratory tract infection and two had no such symptoms. In all patients a C pneumoniae-specific lymphocyte proliferation in synovial fluid and a high specific antibody titre suggesting an acute infection was found. CONCLUSION--C pneumoniae needs to be considered a new important cause of reactive arthritis.