M. hominis is a common inhabitant of the genitourinary tract. Although some strains growon ordinary blood agar as nonhemolytic pinpoint colonies, the organism is best detected on Mycoplasma agar, on which it grows rapidly. M. hominis and Ureaplasma can be differen-tiated by demonstrating arginine breakdown by the former and urease activity by the latter. At least seven antigenic variants of M. hominis have been described. To date, the major clinical condition associated with M. hominis infection is postabortal or postpartum fever. Mycoplasma hominis is isolated from the blood of about 10% of women with this condi-tion. Occasional infections of the central nervous system or joints also have been de-scribed, primarily in patients with antibody deficiency syndromes or premature infants.
The diseases appear to be self-limiting, although antibiotic therapy may decrease the duration of fever and hospitalization. Serologic studies and animal experiments have also indicated that pelvic inflammatory disease syndromes in women may be associated with M. hominis infection of the fallopian tubes. The organism is sensitive to tetracycline. Incontrast to U. urealyticum and M. pneumoniae, M. hominis is resistant to erythromycin.