Treponema denticola infection is not a cause of false positive Treponema pallidum serology

It has been supposed for years that parodontal disease can be a cause of false positive results in syphilis serology, but so far there are not any definitive data that can support this hypothesis. In this study we tested 250 serum samples obtained from blood donors; all of them were negative when routinaly screened for antibodies against Treponema pallidum. Then, all these samples were tested by immunoenzymatic (ELISA) and Western Blot (WB) assays to investigate reactivities against T. denticola. 13 samples showed a strong positivity when tested by both methods. When tested by WB against T. pallidum no sample met the positivity criteria. Nevertheless, bands with molecolar weights of about 30-35 KDa (endoflagellar core antigens) were recognized. All the 13 subjects serologically T. denticola positive underwent oral clinical and radiological observation; all of them showed a very poor parodontal situation (CPSS>103). 11 crevicular fluid samples out of the total of 13 patients showed to be T. denticola positive by Real Time PCR carried out using a LightCycler system. In this study we demonstrated that the presence of T. denticola in the crevicular fluid samples obtained from patients with a severe periodontal situation and/or a positive serology against T. denticola is not a cause of false positive results in syphilis serology.