What is the diagnosis and treatment for a suspected vaginal yeast infection?

Diagnosis and Treatment of Vaginal Yeast Infection

Diagnostic Approach

For suspected vaginal yeast infection, obtain a vaginal swab or vaginal secretions for microscopy and culture to confirm the diagnosis before initiating treatment, as clinical symptoms alone are nonspecific and lead to misdiagnosis in over half of cases. 1

Specimen Collection and Processing

• Collect vaginal secretions or a vaginal swab from the affected area for optimal diagnostic yield 1
• Vaginal secretions spread directly onto a microscopy slide are superior to swabs for microscopic examination 1
• The vaginal pH should be normal (≤4.5) in vulvovaginal candidiasis 1

Microscopic Examination

• Prepare wet mount preparations using both saline and 10% potassium hydroxide (KOH) 1
• KOH disrupts cellular material and improves visualization of yeast and pseudohyphae 1
• Look for budding yeast cells or pseudohyphae, though their presence alone doesn't confirm infection as 10-20% of asymptomatic women harbor Candida 1
• Important caveat: Not all Candida species form pseudohyphae (e.g., C. glabrata shows only yeast cells), and microscopy has poor sensitivity of only 57-61% 1

Culture

• Culture on fungal selective media using semi-quantitative techniques is essential and remains the gold standard 1
• Culture is 100% sensitive but only 82% specific, as it may detect colonization rather than infection 1
• Species identification should be performed in recurrent/complicated cases and patients with prior azole exposure 1

Molecular Testing

• PCR testing for Candida group (C. albicans, C. dubliniensis, C. parapsilosis, C. tropicalis) demonstrates superior performance with 90.9% sensitivity and 94.1% specificity compared to microscopy 1
• PCR provides higher sensitivity (90.7% vs 57.5%) and specificity (93.6% vs 89.4%) than clinical diagnosis alone 1
• However, only FDA-approved PCR tests should be used, as some commercially available tests lack proper validation 1

Treatment Recommendations

Uncomplicated Vulvovaginal Candidiasis

For uncomplicated vaginal yeast infection, treat with either a single 150 mg oral dose of fluconazole OR a short course (1-7 days) of topical azole therapy, both achieving >90% cure rates. 1

First-Line Options (Choose One):

Oral therapy:

• Fluconazole 150 mg as a single oral dose 1, 2

Topical intravaginal therapy (over-the-counter):

• Clotrimazole 1% cream 5g daily for 7-14 days 1
• Clotrimazole 2% cream 5g daily for 3 days 1
• Miconazole 2% cream 5g daily for 7 days 1
• Miconazole 4% cream 5g daily for 3 days 1
• Miconazole 1200 mg vaginal suppository as a single dose 1, 3
• Tioconazole 6.5% ointment 5g as a single application 1

Topical intravaginal therapy (prescription):

• Terconazole 0.4% cream 5g daily for 7 days 1
• Terconazole 0.8% cream 5g daily for 3 days 1
• Butoconazole 2% cream 5g as a single application (bioadhesive formulation) 1

Complicated Vulvovaginal Candidiasis

For complicated infection (severe symptoms, recurrent disease, non-albicans species, immunocompromised host), extend treatment to 7-14 days with topical azoles OR fluconazole 150 mg every 72 hours for 3 doses. 1

• Topical azole therapy for 7-14 days is preferred for complicated cases 1
• Alternative: Fluconazole 150 mg every 72 hours for a total of 3 doses 1

C. glabrata Infections

C. glabrata vulvovaginal candidiasis requires non-azole therapy due to frequent azole resistance. 1

• First option: Nystatin 100,000-unit vaginal suppository daily for 14 days 1
• Second option: Boric acid 600 mg in gelatin capsules intravaginally daily for 14 days (requires compounding) 1
• Third option: Topical 17% flucytosine cream alone or combined with 3% amphotericin B cream daily for 14 days (requires compounding) 1

Recurrent Vulvovaginal Candidiasis (≥4 Episodes/Year)

For recurrent vulvovaginal candidiasis, provide 10-14 days of induction therapy followed by fluconazole 150 mg weekly for 6 months as maintenance suppression. 1

• Induction: Topical azole for 10-14 days OR oral fluconazole for 10-14 days 1
• Maintenance: Fluconazole 150 mg orally once weekly for 6 months 1
• This regimen is supported by high-quality evidence 1

Antifungal Susceptibility Testing

• Perform susceptibility testing for isolates from patients who fail treatment, have recurrent infections, or harbor non-albicans species 1
• Use reference methods or validated commercial techniques 1
• Testing is particularly important for C. glabrata and other species with known reduced azole susceptibility 1

Critical Clinical Considerations

When NOT to Self-Treat

• First episode of vaginal symptoms (requires physician diagnosis) 3
• Presence of fever, chills, lower abdominal/back pain, or foul-smelling discharge (suggests STD or other serious infection) 3
• Multiple sex partners or new sex partner (requires STD screening) 3
• Pregnancy (requires physician management) 3

Treatment During Menstruation

• Treatment can be continued during menstrual periods 3
• Avoid tampons during treatment as they may remove medication; use sanitary pads instead 3

Important Warnings

• Oil-based vaginal creams and suppositories may damage latex condoms and diaphragms 1, 3
• Avoid alcohol during metronidazole therapy if bacterial vaginosis is being treated concurrently 1
• Complete the full treatment course even if symptoms improve to prevent treatment failure 4

Mixed Infections

• Be alert for concurrent bacterial vaginosis, which occurs in 34% of patients with recurrent bacterial vaginosis 5
• Mixed infections require treatment of both conditions simultaneously for optimal results 5
• The lack of symptom specificity mandates laboratory confirmation rather than empirical treatment 5