[Direct detection of Treponema pallidum in diagnosis of syphilis]

Available methods for direct diagnosis of syphilis are summarized with emphasis being on those promising for routine use. Direct detection of the causative agent T. pallidum is limited since the agent is not able to synthesize enzyme cofactors, fatty acids and nucleotides de novo, is completely dependent on its host and thus culture on synthetic media is not feasible. Direct diagnosis of syphilis is based on rabbit infectivity testing (RIT), dark field or fluorescent microscopy and recently also on molecular biological methods used with increasing frequency in routine practice. Suitability and usability of different methods for direct detection of T. pallidum at different stages of syphilis are explained. Except for molecular biological methods, most of detection techniques can only be used at the primary and secondary stages or in early congenital syphilis. Major PCR methods for diagnosis of syphilis are presented. Not all of them are suitable for use in routine practice owing to differences in their sensitivity and design. The polA PCR method appears to be the most promising in this regard.