Polymerase Chain Reaction Assay With Urine Specimens in the Diagnosis of Acute Chlamydia trachomatis Infection in Women

OBJECTIVE The purpose of this study was to evaluate the benefits achievable by Amplicor polymerase chain reaction (PCR) (F. Hoffmann-LaRoche Ltd., Basel, Switzerland) with urine specimens in addition to PACE 2 (Gen-Probe, Inc., San Diego, California) assay with cervical swab specimens in the diagnosis of Chlamydia trachomatis in women. METHODS Cervical and urine specimens from 286 women were tested for C. trachomatis by PACE 2 and Amplicor PCR, respectively. All urine specimens were analyzed undiluted and diluted 1:10 to detect and eliminate possible PCR inhibition. A confirmatory PCR assay using major outer membrane protein-based primers (MOMP-PCR) was used on urine specimens that were positive by PCR from women who were negative by PACE 2 with cervical swab specimens. RESULTS Of the endocervical specimens, 26 were positive by the PACE 2 assay. The PCR with urine was positive in 21 of these patients. When the urine specimens were analyzed diluted 1:10, 4 of the 5 PCR-negative specimens from PACE 2-positive patients turned positive by the PCR. Additionally, 4 urine specimens from PACE 2-negative women were positive by the PCR with urine, and 3 of them could be confirmed by MOMP-PCR. Altogether, 29 women were found to be positive for C. trachomatis by either of the two assays. CONCLUSIONS By using the PCR with urine specimens, an 11% increase in sensitivity could be achieved in addition to that obtained by PACE 2 assay with cervical swab specimens. In the present material, however, the increased sensitivity was reversed by the presence of PCR inhibitors in 14% of the female urine specimens. Amplicor PCR with urine specimens can undoubtedly be recommended for the diagnosis of chlamydial infections in women. However, constant monitoring of the PCR inhibition seems highly advisable to obtain full benefit of the sensitivity of the PCR.