Vaginal Flora Status of Ureaplasma urealyticum and Lactobacillus iners
Lactobacillus iners is part of normal vaginal flora but provides less protection than other Lactobacillus species, while Ureaplasma urealyticum is a commensal organism commonly found in healthy women but can act as an opportunistic pathogen under certain conditions.
Lactobacillus iners: A Normal but Less Protective Commensal
Prevalence and Classification
- L. iners is one of the most frequently isolated Lactobacillus species from healthy human vaginas, alongside L. crispatus, L. gasseri, and L. jensenii 1
- In reproductive-age women, there is typically a predominance of one or more Lactobacillus species, with L. iners being among the most common 2
Clinical Significance and Limitations
- L. iners becomes the dominant species following standard metronidazole treatment for bacterial vaginosis, which likely contributes to the high recurrence rates (50-80% within one year) 3
- While L. iners can maintain acidic vaginal pH similar to more protective species like L. crispatus, vaginal pH testing alone cannot distinguish between these communities 3
- The selection of L. crispatus over L. iners for probiotic development reflects that natural predominance does not equal protective capacity 3
Ureaplasma urealyticum: A Common Commensal with Pathogenic Potential
Colonization Rates in Healthy Women
- U. urealyticum may be found in the vagina/cervix of 40-80% of sexually mature women 4
- In a longitudinal study of healthy women, U. urealyticum was isolated intermittently in 40% of women with bacterial vaginosis, 25% with candida, and 50% with normal microscopy 5
Pathogenic Role
- U. urealyticum is recognized as a potential etiologic agent in pelvic inflammatory disease (PID), though it is not classified among the primary sexually transmitted organisms like N. gonorrhoeae and C. trachomatis 6
- The organism exists as part of the vaginal flora but can cause disease under certain circumstances, particularly when ascending to the upper genital tract 6
Clinical Implications
Interpretation of Positive Findings
- Finding U. urealyticum on a single occasion in asymptomatic women may not be clinically significant, as it can be part of normal intermittent colonization 5
- Treatment is indicated when U. urealyticum is associated with clinical syndromes such as PID or when symptoms are present 7, 8
Treatment Considerations When Indicated
- Doxycycline 100 mg orally twice daily for 7 days is the first-line treatment when U. urealyticum infection requires therapy 7, 8
- Azithromycin 1 g orally in a single dose is an alternative, particularly when compliance concerns exist 7, 8
- Sexual partners should be evaluated and treated, with abstinence from sexual intercourse for 7 days after single-dose therapy or until completion of a 7-day regimen 7, 8
Common Pitfalls to Avoid
- Do not automatically treat asymptomatic colonization with U. urealyticum, as it may represent normal flora rather than infection 5
- Do not assume that L. iners-dominated flora provides the same protection as L. crispatus-dominated flora, despite both maintaining acidic pH 3
- Symptoms correlate poorly with microbiological findings, so clinical context is essential for interpretation 5