<prompt> Reactive ahritis is caused by:StaphylococcusH. influenzaeN. gonorrhoeC. trachomatis  <response>: Ans. d C. trachomatis Ref CMDT 2014, p 825 Reactive ahritis formerly called Reiter syndrome is the clinical tetrad of uretheritis, conjunctivitis or uveitis, mucocutaneous lesions and aseptic ahritis. Most cases develop within days weeks after either a dysenteric infection or urogential infection. GI Urogenital Shigella Chlamydia trachomatus Salmonella Ureoplasma urealyticum Yersina Compylobacter Associated infection: Ahritis is most commonly assymetric, and frequently involves the large joints most commonly ankle and knee; Sacroiliatis and ankylosing spondylitis is observed in atleast 20 of patients; especially after frequent recurrences. 