EVALUATION OF ELISA TO DETECT CHLAMYDIA-TRACHOMATIS ANTIGEN IN URINE SAMPLES FROM ARTHRITIS PATIENTS

Objective: To determine whether examination of urine samples using ELI SA allows the detection of asymptomatic C. trachomatis infection in ar thritis patients. Methods: The in vitro sensitivity of IDEIA(R) Chlamy dia ELISA to detect C. trachomatis in urine samples was determined by the investigation of serial dilutions of chlamydial elementary bodies. In a clinical study, urine samples from 402 consecutive arthritis pat ients (182 men and 220 women) in a tertiary care rheumatology clinic w ere examined for asymptomatic chlamydial infection by ELISA and the re sults were compared to culture and direct immunofluorescence assay (DF A, MicroTrak(R)) of urogenital swabs. Results: The in vitro sensitivit y of ELISA for detecting purified elementary bodies of C. trachomatis serovar K in urine was 60 infection forming units. Twenty-three of 402 arthritis patients (6%) had asymptomatic chlamydial infection as show n by DFA and culture from urogenital smears. The ELISA method identifi ed only 3 of 17 swab-positive patients among 271 patients when urine s pecimens were collected during the clinical visit, while the assay det ected all 6 swab-positive patients among 131 patients when first-voide d early morning urine specimens were used (p < 0.001). Conclusion: It is mandatory to examine only first voided early morning urine samples if ELISA is used instead of DFA or culture form urogenital swabs to de tect asymptomatic chlamydial infection in arthritis patients.