摘要
Objective: To develop a sensitive, specific and simple method for detection of extremely low numbers of T. pallidum in clinical specimens, as a significant addition to the serologic tests for syphilis diagnosis. Methods: Double-tube nested PCR(DN-PCR) and single-tube nested PCR(SN-PCR) assays were performed to amplify specific fragments of the DNA poly-merase I gene(polA) of T. pallidum. Sensitivity and specificity of the two PCR assays were tested. Eighty-six whole blood specimens from persons with suspected syphilis were detected by the two nested PCR methods. The TPPA test was used as a comparison for detecting syphilis in sera from corresponding patients. Results: Only specific amplicons could be obtained during amplification of the T. pallidum polA gene and the detection limit was approximately 1 organism when analyzed on gel by the two PCR methods. Of 86 clinical specimens, 62 were positive by TPPA. Of these, 54 and 51 were positive by the DN-PCR and SN-PCR, respectively, which does not represent a statistically significant difference between the two PCR tests. Of 24 TPPA-negative specimens, 5 were positive by both DN-PCR assay and SN-PCR assay. Conclusion: The SN- polA PCR method is extremely sensitive, specific and easy to perform for detecting low numbers of T. pallidum in clinical blood specimens as a complementary to serology for syphilis diagnosis.
目的建立一种检测临床标本中微量梅毒螺旋体(Tp)的简便、特异、敏感的方法,作为血清学方法的补充诊断梅毒。方法运用双管巢式PcR(SN-PCR)和单管巢式PCR(DN-PCR)扩增了Tp的DNA多聚酶Ⅰ基因(polA)的特异性片段,进行特异性和敏感性试验;用SN-PCR 和DN-PCR检测86份可疑梅毒的临床全血标本中TP polA,同时对相应血清标本用TPPA法检测。结果SN-PCR和DN-PCR polA PCR只在扩增Tp时有特异性产物,灵敏度均约为1个生物。检测86份临床标本,TPPA法阳性62份,DN PCR和SN-PCR PCR阳性数分别为54和 51,结果无显著性差异;TPPA法阴性24份,DN-PCR、SN-PCR阳性数均为5例,。结论SN-polA PCR具有高度敏感、特异、操作简便、不易污染等优点,适用于血液等标本中微量Tp的检测,是血清学方法诊断梅毒的有效补充。
