Explaining the Difference Between Mycoplasma genitalium and Mycoplasma hominis/Ureaplasma to Patients
Key Distinction: One is a True STI, the Others Are Usually Just Normal Bacteria
Mycoplasma genitalium is a sexually transmitted infection that causes real disease and requires testing and treatment when symptomatic, while Mycoplasma hominis and Ureaplasma species are commonly found in healthy people's genital tracts and usually do not need testing or treatment. 1, 2
Mycoplasma genitalium (M. gen)
What It Is
- M. genitalium is a true sexually transmitted pathogen that behaves similarly to chlamydia and gonorrhea 3, 4
- It causes 10-35% of non-chlamydial, non-gonococcal urethritis in men and is associated with cervicitis and pelvic inflammatory disease in 10-25% of women 5
- Transmission occurs through direct sexual contact with an infected partner 5
Symptoms That Matter
- In men: urethral discharge, burning with urination, and persistent urethritis that doesn't respond to standard treatment 5, 3
- In women: vaginal discharge, painful urination, pelvic pain, and pain with intercourse 5
- Asymptomatic infections are common but still represent true infection 5
When to Test
- Test when you have symptoms of urethritis or cervicitis 1
- Test when urethritis persists or returns after initial treatment for other STIs 1
- Testing requires nucleic acid amplification (NAAT) on urine or vaginal swab, ideally with resistance testing 1, 5
Treatment Approach
- First-line: Azithromycin 500 mg on day 1, then 250 mg on days 2-5 (85-95% cure rate for susceptible strains) 6, 5
- Second-line: Moxifloxacin 400 mg daily for 7 days for resistant infections 1, 5
- Doxycycline alone has only 30-40% cure rate and should not be relied upon 1, 5
Mycoplasma hominis and Ureaplasma species (M. hominis/Ureaplasma)
What They Are
- These are normal colonizers found in 40-80% of healthy sexually active people 2
- They are part of the normal genital flora and their presence does not automatically mean disease 2
- Finding them does not mean you have an STI that needs treatment 2
The Testing Problem
- Routine testing for M. hominis and Ureaplasma is NOT recommended in asymptomatic or symptomatic individuals 2
- Detecting these organisms leads to unnecessary antibiotic treatment that causes more harm than good 2
- Many commercial tests include these organisms, creating confusion and overtreatment 2
When They Might Matter (Rarely)
- M. hominis may be a cofactor in bacterial vaginosis, but treating the BV itself is what matters 7
- U. urealyticum might cause urethritis only when present in very high amounts, but this is uncommon 2
- Even when detected, treatment often doesn't help because they're usually just colonizers 2
Why Not to Test or Treat
- Testing and treating these organisms causes antimicrobial resistance in both these bacteria and other important pathogens 2
- The majority of people carrying these bacteria never develop disease 2
- There is no evidence that detecting and treating them does more good than harm 2
Clinical Algorithm for Your Provider
If You Have Urethritis or Cervicitis Symptoms:
- First, test for the real STIs: gonorrhea, chlamydia, and M. genitalium 2
- Do NOT test for M. hominis or Ureaplasma 2
- If standard treatment fails, then consider M. genitalium testing with resistance profiling 1
If You Have Vaginal Symptoms:
- Test for bacterial vaginosis first 2
- Test for gonorrhea, chlamydia, and trichomonas 2
- Do NOT test for M. hominis or Ureaplasma 2
Important Caveats
- Beware of multiplex PCR panels that automatically test for M. hominis and Ureaplasma—these create unnecessary anxiety and treatment 2
- If M. genitalium is detected, macrolide resistance testing should guide treatment choice 1, 5
- Sexual partners of patients with confirmed M. genitalium need evaluation and treatment 5
- Abstain from sexual activity for 7 days after single-dose therapy or until completion of multi-day regimens 6, 5