Are Mycoplasma hominis and Ureaplasma parvum STDs?
Mycoplasma hominis and Ureaplasma parvum are not considered classic sexually transmitted diseases, but rather sexually-associated organisms that colonize the urogenital tract and are transmitted through sexual contact without necessarily causing disease. 1
Key Distinction from True STDs
M. hominis and U. parvum are part of the altered vaginal flora in bacterial vaginosis (BV) rather than primary sexually transmitted pathogens like gonorrhea or chlamydia. 1
Multiple CDC guidelines from 1993-2006 consistently state that BV is associated with sexual activity but is not considered exclusively an STD, and these organisms are components of the BV flora. 1
Women who have never been sexually active are rarely affected by BV, indicating sexual transmission plays a role, but the organisms themselves don't behave like classic STDs. 1
Treatment of male sex partners has not been found beneficial in preventing recurrence, which is fundamentally different from true STDs where partner treatment is essential. 1
Clinical Significance and Testing Recommendations
Routine testing for M. hominis and U. parvum is not recommended in asymptomatic or symptomatic men and women, according to the European STI Guidelines Editorial Board position statement. 2
Asymptomatic carriage is extremely common (40-80% in some populations), and the majority of colonized individuals never develop disease. 2
Recent high-quality evidence from 2021 demonstrates that M. hominis is only associated with symptoms when BV is present, and shows no association with symptoms in women without BV. 3
U. parvum specifically shows no association with genital symptoms or clinical signs in nonpregnant women, even after adjusting for other infections. 3
Contrast with Mycoplasma genitalium
M. genitalium is distinctly different and is recognized as a true emerging STI requiring partner notification and treatment. 4
The 2025 European Urology guidelines confirm that U. urealyticum and M. hominis strains are associated with male infertility, but U. parvum is not. 1
Critical Clinical Pitfalls
The widespread use of multiplex PCR panels that include these organisms has led to overdiagnosis and overtreatment, creating unnecessary antimicrobial resistance and economic burden. 2
Detection does not equal disease - finding these organisms in asymptomatic individuals or even symptomatic patients does not automatically warrant treatment. 2
If M. hominis is detected in symptomatic women, evaluate and treat for BV first rather than treating the organism in isolation. 3, 2
In men with urethritis symptoms, exclude N. gonorrhoeae, C. trachomatis, M. genitalium, and T. vaginalis before considering U. urealyticum as a cause. 2