Treponema pallidum is a parasitic spirochaete bacterium. There are different kinds of Treponema pallidum, which cause diseases like syphilis, bejel, pinta and yaws.

The most common disease caused by Treponema pallidum is syphilis, a serious sexually transmitted infection.

Syphilis is treated and cured by taking antibiotics. Usually, the first treatment used is penicillin. Antibiotic resistance has developed to a number of agents. Ceftriaxone, a third-generation cephalosporin antibiotic, may be as effective as penicillin-based treatment.

Pennicilin is still effective, but "the potential of this spirochete to develop additional antibiotic resistance could seriously compromise syphilis treatment and control".