Syphilis

Treponema pallidum (TP) subspecies pallidum is an intracellular gram-negative spirochete bacterium that causes syphilis. Although mother-to-fetus transmission occurs during pregnancy or delivery, sexual transmission is the primary mode of transmission for syphilis. The primary cause of lesion formation is the immune system's reaction to T. pallidum. Antibodies directed against T. pallidum proteins are detected by treponemal assays. A positive treponemal antibody test result suggests that the patient has had syphilis in the past.