Detection of Ureaplasma urealyticum by PCR and biovar determination by liquid hybridization

An assay which combines the direct detection of Ureaplasma urealyticum with biovar determination was developed and applied to 618 urogenital specimens. U. urealyticum was detected by inhibitor-controlled PCR. A 429-bp fragment of the urease gene was amplified. The amplicons were labelled with digoxigenin during PCR. Biovar determination was performed by liquid hybridization with biotin-labelled biovar-specific probes, and the hybrids were detected with peroxidase-conjugated sheep anti-digoxigenin immunoglobulin G Fab fragments. Results of PCR and culture for 453 urogenital specimens from women and 105 urethral specimens from men could be compared. Among the specimens from women, 63% were PCR positive as well as culture positive, 0.9% were positive only by PCR, and 4% were positive only by culture. Among the specimens from men, 15% were PCR positive as well as culture positive, 1% were positive only by PCR, and 9% were positive only by culture. By using culture as the reference method, the PCR had a sensitivity of 94% and a specificity of 98% when applied to specimens from women and a sensitivity of 64% and a specificity of 99% when applied to specimens from men. Overall, 80% of the PCR-positive specimens contained biovar 1,13.5% contained biovar 2, and 6.5% contained both biovars.