Objective:Todevelopasensitive,specificandsimplemethodfordetectionofextremelylownumbersofT.palliduminclinicalspecimens,asasignificantadditiontotheserologictestsforsyphilisdiagnosis.Methods:Double-tubenestedPCR(DN-PCR)andsingle-tubenestedPCR(SN-PCR)assayswereperformedtoamplifyspecificfragmentsoftheDNApolymeraseIgene(polA)ofT.pallidum.SensitivityandspecificityofthetwoPCRassaysweretested.EightysixwholebloodspecimensfrompersonswithsuspectedsyphilisweredetectedbythetwonestedPCRmethods.TheTPPAtestwasusedasacomparisonfordetectingsyphilisinserafromcorrespondingpatients.Results:OnlyspecificampliconscouldbeobtainedduringamplificationoftheT.pallidumpolAgeneandthedetectionlimitwasapproximately1organismwhenanalyzedongelbythetwoPCRmethods.Of86clinicalspecimens,62werepositivebyTPPA.Ofthese,54and51werepositivebytheDN-PCRandSN-PCR,respectively,whichdoesnotrepresentastatisticallysignificantdifferencebetweenthetwoPCRtests.Of24TPPA-negativespecimens,5werepositivebybothDN-PCRassayandSN-PCRassay.Conclusion:TheSN-polAPCRmethodisextremelysensitive,specificandeasytoperformfordetectinglownumbersofT.palliduminclinicalbloodspecimensasacomplementarytoserologyforsyphilisdiagnosis.
