comparison of pcr based assay and cell culture in detection of urogenita l chlamydia trachomatis infection and determination of the inhibitory rate o f specimens under study

an amplification polymerase chain reaction (pcr) test for the direct detection of chlamydia trachomatis in urethral and endocervical swab specimens from symptomatic and asymptomatic women and men were compared to standard culture technique. during 6 months, 300 endocervical swab specimens from 205 asymptomatic women (64.4%) and 95 symptomatic women (31.6%), and 187 urethral swab specimens from 79 asymptomatic men (42.3%) and 108 symptomatic men (57.7%) attending the gynecology dept. and genitourinary clinic of royal victoria hospital, montreal, were collected. processed specimens were cultured in mccoy cells and pcr was performed in a tube containing primer for c. trachomatis and internal control (ic). pcr products were detected by colorimetric and hybridization assay. discrepant analysis for any specimens without unanimous results were performed by direct fluorescent antibody (dfa) or major outer membrane gene test (momp) with the 2sp medium sediment. in this study culture detected 13.1 % of asymptomatic and 33.6% of symptomatic infected women. by pcr, 16% of asymptomatic and 45.2% of symptomatic infected women exhibited positive results. by culture, 36.6% of asymptomatic and 45.3% of symptomatic men were positive, whereas 50.6% of asymptomatic and 51.8% of symptomatic men were positive by pcr. sensitivity and specificity of pcr for asymptomatic and symptomatic women were 82.5% and 99.3%, and 89.5% and 97.8% respectively. sensitivity and specificity of pcr for asymptomatic and symptomatic men were 93% and 100%, and 93.3% and 97.9% respectively. sensitivity and specificity of culture for asymptomatic and symptomatic women and men were 67.5% and 100%, 66.6% and 100%,67.4% and 81.6%, and 100% and 100% respectively. the overall sensitivity and specificity of pcr and culture were 90% and 98%, and 75.6% and 100%. the internal control revealed that 3.9% of specimens were inhibitory, but when an aliquot of 10 fold dilution of these specimens was retested, 73.6% of them were non-inhibitory. in this study pcr exhibited higher sensitivity than culture for detection of c. trachomatis in both endocervical and urethral swab specimens and can be recommended for use in the c1inical laboratory.