Is Enterococcus faecalis in the Vagina Abnormal?
Enterococcus faecalis in the vagina is abnormal and represents a pathological disruption of normal vaginal flora, most commonly associated with aerobic vaginitis (AV) or occurring as a consequence of antibiotic use.
Normal Vaginal Flora vs. Pathological States
The normal vaginal environment is dominated by H₂O₂-producing Lactobacillus species that maintain a pH of 3.8-4.2 1, 2, 3. When E. faecalis is present, it indicates a disruption of this protective ecosystem 4, 5.
Key Distinguishing Features:
- E. faecalis is found in only 17.33% of women who have not been treated with antibiotics, but in 44% of those who have used antibiotics 6
- The presence of E. faecalis typically elevates vaginal pH above 4.0, and often above 5.0, which is distinctly abnormal 4, 5
- E. faecalis is the most frequently isolated pathogen in aerobic vaginitis, accounting for approximately 31% of AV cases 4
Clinical Context: When E. faecalis Appears
Aerobic Vaginitis (Primary Pathological State)
E. faecalis is a causative agent of aerobic vaginitis, not a normal commensal organism of the vagina 4. AV is characterized by:
- Abnormal vaginal flora containing aerobic and intestinal pathogens 4
- Varying degrees of vaginal inflammation 4
- Frequency of 12-23.7% in symptomatic non-pregnant women 4
- Increased risk for sexually transmitted infections 4
Antibiotic-Associated Colonization
E. faecalis vaginal colonization increases significantly following antibiotic treatment 6, 7:
- Women treated for genital tract infections: 34.66% had E. faecalis 6
- Women treated for nonspecific colpitis: 52% had E. faecalis 6
- Women treated for extragenital infections: 45.33% had E. faecalis 6
Clinical Significance and Complications
Immediate Concerns
The presence of E. faecalis reduces the protective effect of lactobacilli and causes inflammation 4:
- Increases inflammatory markers (IL-6, IL-8, TNF) 4
- Changes vaginal pH to above 5.0 4
- Decreases vaginal defense mechanisms 4, 5
Long-Term Risks
E. faecalis in the vagina is associated with serious complications 4:
- Increased risk of HPV 16 infection 4
- Potential progression to cervical intraepithelial lesions (CIN) 4
- HPV 16 genes have been found in E. faecalis from cervical cancer biopsies 4
- Can colonize vaginal, cervical, and uterine tissue 7
Urinary Tract Infections
E. faecalis is the second most common cause of recurrent UTIs after E. coli, particularly in patients with risk factors for complicated UTIs 1.
Diagnostic Approach
pH Testing as Initial Screen
- Vaginal pH >4.0 is associated with E. faecalis in 52.78% of cases 5
- pH >4.0 with changed vaginal discharge color and positive amino odor test: 60.78% association with E. faecalis 5
- However, pH change alone cannot confirm E. faecalis presence—microbiological examination is necessary 5
Definitive Diagnosis
Microbiological culture of vaginal secretions is required for definitive diagnosis 5. The CDC guidelines note that culture is more sensitive than microscopic examination for detecting pathogens 1.
Treatment Considerations
There is no universally accepted clinical strategy for treating AV caused by E. faecalis 4. Most experts recommend:
- Combination therapy: antibacterial (antiseptic and antibiotic), hormonal, non-steroidal anti-inflammatory, and/or probiotics 4
- Topical antibiotic targeting the infectious agent 4
- Topical steroid to reduce inflammation 4
- Estrogen to treat atrophy 4
Antibiotic Sensitivity
E. faecalis shows minimal sensitivity to penicillin and streptomycin, but no resistance to vancomycin 6.
Critical Clinical Pitfalls
- Do not dismiss E. faecalis as normal vaginal flora—it represents pathological colonization requiring treatment 4, 6
- Do not rely on pH testing alone—always obtain microbiological confirmation 5
- Consider intensive treatment to prevent progression to precancerous cervical lesions, particularly in HPV-positive women 4
- Screen for E. faecalis after antibiotic treatment for any indication, as colonization risk increases significantly 6, 7