Treatment of Mycoplasma hominis Infection in the Vagina
For Mycoplasma hominis vaginal infection, the recommended first-line treatment is oral metronidazole 500 mg twice daily for 7 days. 1
Diagnosis
- M. hominis is often associated with bacterial vaginosis (BV) and is part of the altered vaginal flora that characterizes this condition 1
- Diagnosis is made through clinical criteria for BV (requiring 3 of 4 criteria: homogeneous discharge, clue cells, pH > 4.5, and positive whiff test) or through Gram stain 1
- Culture for M. hominis alone is not recommended as a diagnostic tool as it can be isolated from vaginal cultures in approximately 50% of women without symptoms 1
Treatment Algorithm
First-line Treatment
- Metronidazole 500 mg orally twice daily for 7 days 1
- This regimen has shown 95% cure rates for BV with associated M. hominis 1
- Patients should be advised to avoid alcohol during treatment and for 24 hours afterward 1
Alternative Regimens
- Metronidazole 2 g orally in a single dose (84% cure rate) 1
- Clindamycin cream 2%, one full applicator (5 g) intravaginally at bedtime for 7 days 1
- Metronidazole gel 0.75%, one full applicator (5 g) intravaginally, twice daily for 5 days 1
- Clindamycin 300 mg orally twice daily for 7 days 1
Special Considerations
Pregnancy
- Clindamycin vaginal cream is preferred during the first trimester of pregnancy due to contraindication of metronidazole 1
- During second and third trimesters, oral metronidazole can be used 1
Antibiotic Resistance
- Recent studies show increasing resistance of M. hominis to various antibiotics 2
- Tetracycline resistance is a significant concern, with studies showing that strains with MIC ≥16 μg/ml are more likely to persist after tetracycline therapy 3
- Doxycycline has shown good susceptibility rates (91%) for Ureaplasma and M. hominis in recent studies 4
Treatment Failure
- If symptoms persist after first-line therapy, consider testing for antimicrobial resistance 2
- Alternative options for resistant strains include:
Management of Sex Partners
- Routine treatment of sex partners is not recommended as it has not been shown to influence the woman's response to therapy or affect relapse/recurrence rates 1
Follow-Up
- Follow-up visits are not necessary if symptoms resolve 1
- Recurrence of BV with M. hominis is common, and alternative treatment regimens can be used for recurrent disease 1
Common Pitfalls
- Treating asymptomatic M. hominis colonization is not recommended, as the organism is a common commensal of the vagina 1
- Premature discontinuation of therapy can lead to treatment failure; patients should complete the full course even if symptoms improve
- Failure to advise patients about alcohol avoidance during metronidazole treatment can lead to disulfiram-like reactions 1
- Overlooking the possibility of tetracycline resistance when using doxycycline for treatment failures 3