Ureaplasma is a group of tiny bacteria commonly found in the urogenital tracts of both men and women. They are part of the normal genital flora but can cause infection under certain conditions. Ureaplasma species, particularly Ureaplasma urealyticum and Ureaplasma parvum, are associated with conditions such as urethritis, pelvic inflammatory disease (PID), and infertility. While they can be sexually transmitted, they are not always classified strictly as STIs.