Use of a peptide based enzyme immunoassay in diagnosis of Chlamydia trachomatis triggered reactive arthritis

Objective. To assess the presence of circulating IgA and IgG antibodies to Chlamydia trachomatis in sera of patients with reactive arthritis (ReA) and other arthritides. Methods. A peptide based enzyme immunoassay (EIA) was used to study 132 pat ients divided into 5 groups: C. trachomatis triggered ReA, uroarthritis, en teroarthritis, oligoarthritis, and rheumatoid arthritis (RA). Followup sera were available from 19 patients. Results. An increased prevalence of C. trachomatis antibodies was observed in patients with ReA triggered by C. trachomatis; 18/23 (78%) had IgA and 1 9/23 (83%) had IgG antibodies. In patient groups with uroarthritis (n = 12) , enteroarthritis (n = 56), oligoarthritis (n = 16), and RA (n = 25), C. tr achomatis IgA/IgG antibodies were detected in 58%/75%, 27%/21%, 25%/31%, an d 20%/32% of patients, respectively. Both the IgA and IgG antibodies were p ositive in 74%, 50%, 16%, 25%, and 12% of the patients with C. trachomatis triggered ReA, uroarthritis, enteroarthritis, oligoarthritis, and RA. respe ctively. Based on positivity of both isotypes the sensitivity of the assay was 74% and specificity 84%. In the followup sera, an association between c irculating C. trachomatis-specific antibody concentrations and clinical dis ease outcome of the arthritis was seen in patients with culture-positive C. trachomatis triggered ReA. Conclusion. C. trachomatis species-specific peptide EIA correlates well wit h conventional diagnosis of primary C. trachomatis infection in patients wi th ReA. This assay may be a valuable contribution to the diagnosis of C. tr achomatis triggered ReA.