Potential triggering infections of reactive arthritis

Objectives: The aim of the study was to investigate possible triggering infections causing reactive arthritis (ReA) of urogenital origin. Methods: One hundred and twenty ReA patients, 85 control group patients with other arthritides (61 with rheumatoid arthritis, 13 with osteoarthritis, and 11 with microcrystal arthritis), and 52 healthy persons were tested for urogenital tract inflammation and several infectious agents. Ligase chain reaction was used for detection of Chlamydia trachomatis (CT). Genital mycoplasmas Ureaplasma urealyticum (Uu) and Mycoplasma hominis (Mh) were tested using the Mycoplasma Duo Test (MDT). Only titres greater than 10(4) CCU/mL were accepted as pathogenecity threshold levels for Uu. Results: Inflammation of the urogenital tract (most frequently urethritis in men and cervicitis in women) was found in 95% of patients with acute ReA. Possible causative pathogens were identified in 58% of ReA patients. CT was found in 29%, Uu in 21%, and Mh in 8% of patients with ReA. While CT and Uu were found more often in HLA-B27-positive than in HLA-B27-negative patients, this was statistically proved only for CT. In ReA males Uu was found four times more frequently than in men with other arthritides. Conclusions: In active ReA of urogenital origin, inflammation of the urogenital tract is found in the majority of patients. Although CT is the main microorganism associated with urethritis in men and cervicitis in women, mycoplasmas, especially Uu, may be possible aetiological factors for ReA.