Background : Chlamydia trachomatis is one of the most frequent causes of sexually transmitted diseases. The nested PCR has been proven to be more sensitive and specific than the conventional microbiological assay for the detection of C. trachomatis from clinical samples. We have successfully detected C. trachomatis from clinical samples of cervical scrapings using the nested PCR for the endogenous plasmid.
Methods : This study included 200 patients with pelvic inflammatory disease attending the Hanyang University Hospital. The inoculated monolayer was stained with C. trachomatis specific monoclonal antibody (HYM 1-1, home made) and fluorescein isothiocyanate labeled antimouse immunoglobulin. The DNA of the sample was purified by Instagene. The nested PCR was performed with Chlamydia ampi-test and for the specimens with discrepant results confirmatory PCR assay was performed, which amplifies a major outer membrane protein (MOMP) gene.
Results : A specimen was considered as true positive if it was positive in cell culture assay. The nested PCR-positive specimens were considered to be true positive if they could be verified by MOMP gene-PCR, otherwise, they were considered to be false negative.
Eight out of 200 specimens were nested PCR-positive and culture-positive, and 188 specimens were negative by both tests. There were 4 discrepant tests(culture negative and nested PCR positive). Two of them could be confirmed as positive by MOMP gene PCR. For other two samples, the positive nested PCR result could not be confirmed by MOMP gene PCR, and they were reported as false positive. Altogether, 10(5%) of the patients had chlamydial infection by definition. The sensitivity and specificity of the cell culture was 66% and 100%, and the nested PCR was 100% and 99%, respectively.
Conclusion : The nested PCR would be clearly superior to the cell culture method if problems due to contamination could be eliminated.
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