Detection of Treponema pallidum by semi-nested PCR in the cerebrospinal fluid of asymptomatic HIV-infected patients with latent syphilis.

ABSTRACT

BACKGROUND: Neurosyphilis diagnosis is frequently dependent upon the results of serological tests and cerebrospinal fluid abnormalities, but the reliability of findings in patients with HIV-1 infection has been questioned, especially in asymptomatic patients with latent syphilis. In this study, we present the data on the presence of T. pallidum DNA in CSF from asymptomatic HIV-infected patients with the diagnosis of syphilis. METHODS: CSF and serum samples were collected from 12 HIV-infected patients attending a tertiary care clinic located in southern Brazil, during the period 2012 to 2013. RESULTS: In CSF samples from five of 12 patients (40%), we detected T. pallidum DNA. Unexpectedly, in these patients, the CSF cell count, protein and glucose levels were normal. In addition, none of these 5 CSF samples presented a positive VDRL reaction. Serum VDRL titers were similar between patients with positive and negative CSF T. pallidum DNA. Most patients with detectable T. pallidum DNA presented low serum VDRL titers. A higher serum VDRL titer of 164 was observed in only one patient. CONCLUSIONS: Our results have shown that asymptomatic HIV-infected patients with evidence of latent syphilis and normal CSF might present detectable T. pallidum DNA in the CSF. The detection of T. pallidum DNA by our seminested PCR provides additional information beyond conventional CSF analysis for the diagnosis of neurosyphilis. The detection of T. pallidum DNA in CSF despite normal CSF findings in HIV-infected patients could also provide a different therapeutic approach including the use of intravenous aqueous crystalline penicillin.