Molecular diagnostic of syphilis.

Syphilis is a sexually transmitted infection caused by Treponema pallidum subsp. pallidum with an increasing incidence in Spain and in the rest of the world. Diagnosis is based mainly on serology, since direct diagnosis by dark field microscopy presents difficulties that limit its widespread use. Molecular biology techniques can be a useful tool for diagnosis in primary and secondary syphilis, although not all types of samples show the same behaviour. These techniques are also useful for the diagnosis of congenital syphilis. They are not recommended, however, for neurosyphilis, due to the low sensitivity of polymerase chain reaction in cerebrospinal fluid. These techniques have been used to study the controversial origin of syphilis, and, through the enhanced Centers for Disease Control method, to perform typing, which helps to elucidate the epidemiology of this infection. Finally, molecular techniques can detect mutations related to macrolide resistance, which are present in a very high percentage of infections.