Mycoplasma hominis is a species of bacteria in the genus Mycoplasma. M. hominis has the ability to penetrate the interior of human cells. Along with ureaplasmas, mycoplasmas are the smallest free-living organisms known. They have no cell wall and therefore do not Gram stain. M. hominis is associated with pelvic inflammatory disease and bacterial vaginosis. It is also associated with male infertility. This species causes a sexually transmitted disease. Growth of "fried egg" colonies on glucose agar medium within 24–48 hours is a characteristic of Mycoplasma hominis.