What is the most likely cause of recurrent white, curdy vaginal discharge with labial irritation in a 21‑year‑old woman?

Recurrent Vulvovaginal Candidiasis (VVC)

This is almost certainly recurrent vulvovaginal candidiasis (VVC), a fungal infection caused by Candida albicans in approximately 90% of cases, characterized by white, thick, curd-like discharge with vulvar itching and labial irritation. 1

Clinical Presentation

The combination of recurrent white discharge with labial skin irritation strongly suggests VVC based on the following characteristic features:

• White, thick, "cottage cheese" or curd-like vaginal discharge is the hallmark finding 1, 2
• Intense vulvar pruritus (itching) is the most specific symptom for VVC 1, 2
• Labial irritation, erythema, edema, and excoriation result from the inflammatory response 1
• Vaginal pH remains normal (≤4.5), which distinguishes VVC from bacterial vaginosis or trichomoniasis 1, 3, 2

Diagnostic Confirmation Required

Do not treat empirically without confirming the diagnosis, especially in recurrent cases, because symptoms are nonspecific and misdiagnosis is common. 1, 4

Essential diagnostic steps include:

• Measure vaginal pH with narrow-range pH paper; pH ≤4.5 supports VVC 3, 2
• Perform wet mount microscopy with 10% KOH to visualize yeast cells or pseudohyphae (sensitivity 50-70%) 1, 2
• Obtain vaginal culture for Candida species identification if wet mount is negative or symptoms persist after treatment 1, 4
• Species identification is critical in recurrent cases because 10-20% of recurrent VVC is caused by non-albicans species (especially C. glabrata) that are azole-resistant 2, 4

Classification: Recurrent vs. Chronic VVC

Since this patient has recurrent episodes, classify the severity to guide treatment duration:

• Recurrent VVC (RVVC) is defined as ≥4 symptomatic episodes within 12 months 1, 5
• Chronic VVC (CVVC) describes women with continuous or near-continuous symptoms 5, 6
• Complicated VVC includes recurrent disease, severe symptoms, non-albicans species, or immunocompromised hosts 1

Treatment Algorithm

For Acute Episodes (Initial Treatment)

Use extended-duration therapy for recurrent cases, not single-dose regimens:

• Topical azole therapy for 7-14 days is first-line 1, 2:
  • Clotrimazole 1% cream 5g intravaginally daily for 7-14 days 1, 2
  • Miconazole 2% cream 5g intravaginally daily for 7 days 1, 2
  • Terconazole 0.4% cream 5g intravaginally daily for 7 days 1, 2

OR

• Oral fluconazole 150mg every 72 hours for 3 doses (total of 3 doses over 1 week) 1

For Recurrent VVC (Maintenance Therapy)

After achieving initial cure with 10-14 days of induction therapy, maintenance suppression is essential to prevent recurrence:

• Fluconazole 150mg orally once weekly for 6 months is the most convenient and well-tolerated regimen, achieving symptom control in >90% of patients 1, 2
• Alternative maintenance regimens if fluconazole is not feasible 1:
  • Clotrimazole 500mg vaginal suppository once weekly for 6 months
  • Clotrimazole 200mg twice weekly for 6 months

Critical caveat: After stopping maintenance therapy, expect a 40-50% recurrence rate, so counsel the patient accordingly and plan for long-term follow-up. 1

Special Considerations and Pitfalls

Host Factors to Evaluate

Screen for predisposing conditions that classify the case as complicated VVC and require extended therapy: 1, 2

• Uncontrolled diabetes mellitus
• Immunosuppression or HIV infection (though treatment regimens remain identical) 1
• Pregnancy (use only 7-day topical azoles, never oral fluconazole due to teratogenicity risk) 1, 2
• Recent antibiotic use
• Obesity 7

Non-Albicans Species Resistance

If symptoms persist despite appropriate azole therapy, suspect C. glabrata or other non-albicans species: 1, 2, 4

• C. glabrata accounts for 10-20% of recurrent cases and shows reduced azole susceptibility 2, 4
• Boric acid 600mg vaginal suppositories daily for 14 days is effective for azole-resistant C. glabrata 1
• Alternative: topical 17% flucytosine cream ± 3% amphotericin B cream for 14 days (requires compounding) 1

Partner Treatment

Do not routinely treat sexual partners because VVC is not sexually transmitted and partner therapy does not reduce recurrence rates 2

Treat the partner only if he has symptomatic balanitis (erythema and pruritus of the glans) with topical antifungal 2

Common Diagnostic Errors to Avoid

• Never treat based solely on symptoms or patient self-diagnosis; 10-20% of women harbor asymptomatic Candida colonization that does not require treatment 2
• Do not recommend over-the-counter self-medication unless the patient has a prior confirmed VVC diagnosis with identical recurrent symptoms 2
• Always consider coexisting sexually transmitted infections and test for N. gonorrhoeae and C. trachomatis when clinically indicated 3, 2
• Recognize that metronidazole treatment for bacterial vaginosis can precipitate VVC in 12.5-30% of patients, so consider concurrent antifungal therapy if both conditions are present 2

Follow-Up Strategy

• Instruct the patient to return only if symptoms persist after therapy or recur within 2 months 2
• After completing 6 months of maintenance therapy, monitor closely because 40-50% will experience recurrence 1
• If recurrence continues despite optimal therapy, obtain repeat culture with antifungal susceptibility testing to identify resistant species 2, 4