Increased discrimination of Treponema pallidum strains by subtyping with a four-component system incorporating a mononucleotide tandem repeat in rspA.

A guanine mononucleotide repeat (MNR) in the rpsA (tp0279) gene was evaluated for improved strain discrimination using 72 Treponema pallidum-positive specimens. The tandem repeat combined with the enhanced CDC typing system (ECDCT) resulted in increased discrimination and should be useful for molecular epidemiologic studies on syphilis especially in outbreaks and among MSM.