Nonpathogenic treponemes are a heterogenous group of treponemes found as commensals on the buccal and genital mucosa. They are also found on the surface of gastric and colonic epithelium in humans and animals. These include the following
Treponema species: Treponema denticola, Treponema macrodentium, Treponema oralis, Treponema socranski, and Treponema pectinovo-rum. T. denticola is an oral treponeme, which is easily cultivableon artificial medium. T. phagedenis is also known as Reiter’s and Kazan strain, and T. refringens is also known as Nichol’s strain.