Molecular approaches for the diagnosis of syphilis

Is a molecular diagnostic method needed for the laboratory diagnosis of syphilis? The answer is that in several instances a sensitive and specific method for the direct demonstration of T. pallidum would be beneficial. To date, the clearest progress has been made in the area of GUD and congenital diagnosis. The multiplex PCR method promises to be useful in GUD. It may be particularly useful in large scale epidemiological studies of GUD. For diagnostic purposes, its use will likely be limited to larger centers seeing sufficient numbers of patients. Congenital syphilis diagnostics could certainly use a tool that would help distinguish truly infected from noninfected asymptomatic infants born to seropositive mothers. IgM serologies are useful tools in symptomatic infants but their role, and that of PCR, in asymptomatics is not clear at this time. Certainly, prospective studies with adequate follow-up of infants to clearly document infection are needed to resolve this. Finally, neurosyphilis patients would also benefit from a sensitive and specific test to identify the presence of T. pallidum in the CSF and monitor effective therapy. To date, the experience with PCR is not consistent and additional investigations are needed. The use of molecular diagnostics in syphilis is not as well established as it is for other STDs. However, there is a need and it is hoped that work in this area will continue.