Reactive arthritis is an aseptic arthritis that develops after an infection elsewhere in the body. The triad of arthritis, urethritis, and conjunctivitis -Reiter's syndrome - is one distinct variety of reactive arthritis.

Many micro-organisms may induce reactive arthritis, and new agents are continuously being added to the list, suggesting a pathogenic mechanism that is not antigen specific. The condition is associated most commonly with urogenital or enteric infections with Chlamydia trachomatis, Yersinia enterocolitica, salmonella, shigella, and campylobacter.1, 2 Less common or more recently identified agents include Clostridium difficile, Vibrio parahaemolyticus, Borrelia burgdorferi, Chl pneumoniae, and ureaplasma. A type of reactive arthritis not associated with HLA-B27 may occur after infections with ß haemolytic streptococci and neisseria. In about one quarter of all cases the triggering organism remains unknown.1

Between 60% and 90% of patients with postvenereal or postenteric reactive arthritis are positive for HLA-B27.1, 2 The arthritis usually develops within four weeks of the primary infection; it is typically oligoarticular and asymmetric. Painful joints …