What are the diagnostic criteria and treatment options for a vaginal yeast infection?

Diagnostic Criteria and Treatment for Vaginal Yeast Infection

Diagnostic Criteria

Diagnose vulvovaginal candidiasis when a woman presents with symptoms of vaginitis AND either microscopy demonstrates yeasts/pseudohyphae OR culture/testing is positive for yeast species, with vaginal pH ≤4.5. 1

Clinical Presentation

• Typical symptoms include pruritus (itching), vaginal discharge (thick, white, "curd-like"), vaginal soreness, vulvar burning, dyspareunia, and external dysuria 1
• Physical findings include vulvar edema, erythema, excoriation, fissures, and vaginal/vulvar erythema 1
• None of these symptoms are specific for vulvovaginal candidiasis and can result from other infectious or noninfectious causes 1

Laboratory Confirmation Required

• Vaginal pH ≤4.5 is characteristic of candidiasis (distinguishes from bacterial vaginosis and trichomoniasis which have pH >4.5) 1
• Wet mount with 10% KOH improves visualization of yeasts and pseudohyphae by disrupting cellular material 1
• Microscopy sensitivity is only 50-70%, so culture should be obtained if wet mount is negative but clinical suspicion remains high 1, 2
• Do NOT treat asymptomatic colonization: 10-20% of women normally harbor Candida species without symptoms 1

Classification for Treatment Selection

• Uncomplicated VVC (90% of cases): mild-to-moderate, sporadic, nonrecurrent disease in normal host with C. albicans 1
• Complicated VVC (10% of cases): severe or recurrent disease (≥4 episodes/year), non-albicans species, or abnormal host (diabetes, immunosuppression, pregnancy) 1

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Treatment Options

For Uncomplicated Vulvovaginal Candidiasis

Single-dose oral fluconazole 150 mg is equally effective as topical azoles and achieves >90% response rates. 1

First-Line Options (Choose One):

• Oral fluconazole 150 mg single dose 1, 3
• Topical azole agents (all equally effective, no superior agent): 1
  • Clotrimazole 1% cream 5g intravaginally for 7-14 days 1
  • Clotrimazole 500 mg vaginal tablet, single application 1
  • Miconazole 2% cream 5g intravaginally for 7 days 1
  • Terconazole 0.8% cream 5g intravaginally for 3 days 1

Important: Topical azoles are more effective than nystatin and achieve 80-90% symptom relief and negative cultures 1

For Complicated Vulvovaginal Candidiasis

Complicated cases require extended therapy: topical agents for 7-14 days OR fluconazole 150 mg every 72 hours for 3 doses. 1

Treatment Algorithm:

1. For severe symptoms or recurrent disease: Use 7-14 day topical azole regimen OR fluconazole 150 mg every 72 hours × 3 doses 1
2. For C. glabrata infection (often azole-resistant): 1
   • First option: Boric acid 600 mg intravaginal gelatin capsules daily for 14 days 1
   • Second option: Nystatin 100,000-unit vaginal suppositories daily for 14 days 1
   • Third option: Topical 17% flucytosine cream ± 3% amphotericin B cream daily for 14 days (must be compounded) 1

For Recurrent Vulvovaginal Candidiasis (≥4 Episodes/Year)

Treat with 10-14 days induction therapy followed by fluconazole 150 mg weekly for 6 months. 1

Maintenance Protocol:

• Induction phase: Topical azole for 10-14 days OR oral fluconazole for 10-14 days 1
• Maintenance phase: Fluconazole 150 mg once weekly for 6 months achieves control in >90% of patients 1
• Expected relapse: 40-50% recurrence rate after stopping maintenance therapy 1

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Special Populations

Pregnancy

• Use only topical azole agents (oral fluconazole is not recommended during pregnancy) 1
• Topical azoles are safe and effective throughout pregnancy 1

HIV-Infected Patients

• Treat identically to HIV-negative patients with same regimens and expected response rates 1

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Over-the-Counter Self-Treatment

OTC preparations (clotrimazole, miconazole) should only be used by women previously diagnosed with VVC who have recurrent identical symptoms. 1

When to Seek Medical Care:

• First-time symptoms (must be professionally diagnosed first) 1, 4
• Symptoms persist after OTC treatment 1
• Symptoms recur within 2 months 1
• Presence of fever, chills, abdominal/back pain, or foul-smelling discharge (suggests STD or other serious condition) 4

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Common Pitfalls

• Do not diagnose by symptoms alone: Physical examination findings are nonspecific (LR range 2.1-8.4 for inflammatory signs), and microscopy is essential 5
• Do not treat asymptomatic positive cultures: This represents normal colonization, not infection 1
• Do not assume all vaginal symptoms are yeast: Bacterial vaginosis (40-50% of cases) and trichomoniasis (15-20%) are more common causes of vaginitis than candidiasis (20-25%) 6
• Obtain culture if microscopy is negative but clinical suspicion remains, as wet mount sensitivity is only 50-70% 1, 2
• Consider non-albicans species if treatment fails, particularly C. glabrata which is often azole-resistant 1, 2