What is the appropriate first‑line and second‑line treatment for oral and vaginal candidiasis and associated lesions in a 15‑week pregnant woman with negative STD (sexually transmitted disease) and STI (sexually transmitted infection) testing and a history of effective prior antifungal therapy?

Treatment of Thrush and Sores in a 15-Week Pregnant Woman

For vaginal candidiasis at 15 weeks gestation, prescribe a 7-day course of topical azole therapy—specifically clotrimazole 1% cream 5g intravaginally daily or miconazole 2% cream 5g intravaginally daily—and avoid all oral antifungal agents including fluconazole, which is contraindicated throughout pregnancy due to teratogenic risks. 1

First-Line Treatment for Vaginal Candidiasis in Pregnancy

Topical azole antifungals are the only safe and effective option during pregnancy, with 7-day regimens achieving 80–90% cure rates. 1

Recommended Regimens (choose one):

• Clotrimazole 1% cream 5g intravaginally daily for 7–14 days 1
• Clotrimazole 100mg vaginal tablet once daily for 7 days 1
• Miconazole 2% cream 5g intravaginally daily for 7 days 1
• Terconazole 0.4% cream 5g intravaginally daily for 7 days 1

Seven-day courses are significantly more effective than shorter 3–4 day regimens in pregnancy (OR 11.7,95% CI 4.21–29.15), making them the standard duration. 2

Critical Contraindication: Oral Fluconazole

Oral fluconazole must be strictly avoided at any dose throughout pregnancy, particularly in the first trimester, due to documented associations with spontaneous abortion, craniofacial defects (craniosynostosis), cardiac malformations, and skeletal abnormalities. 1

The CDC explicitly states that only intravaginal topical azole agents are safe for use during pregnancy; systemic azoles are contraindicated. 1, 3

Addressing the "Sores"

For oral thrush (if the "sores" are oral candidiasis), prescribe nystatin oral suspension 400,000–600,000 units (4–6 mL) swish-and-swallow four times daily for 7–14 days, as systemic azoles remain contraindicated. 4

If the lesions are vulvar rather than oral, they may represent severe vulvovaginal candidiasis with associated vulvar erythema and edema, which still requires the same 7–14 day topical azole regimen. 1

Critical pitfall: If the sores are painful ulcers rather than candidal lesions, reconsider the diagnosis despite negative STI testing—herpes simplex virus, aphthous ulcers, or contact dermatitis may present similarly and require different management. 5

Diagnostic Confirmation Before Treatment

Confirm the diagnosis by measuring vaginal pH (should be ≤4.5 for candidiasis) and performing wet-mount microscopy with 10% KOH to visualize yeast or pseudohyphae, which are present in 50–70% of true VVC cases. 5

Typical symptoms include vulvar pruritus, thick white "cottage-cheese" discharge, vulvar burning, and absence of malodor; these findings strongly favor VVC over bacterial vaginosis or trichomoniasis. 1, 5

If symptoms persist after completing the 7-day course, obtain vaginal cultures to identify non-albicans Candida species (e.g., C. glabrata), which account for 10–20% of refractory cases and require alternative therapy. 6

Treatment Efficacy and Follow-Up

Topical azole therapy achieves symptom relief and negative cultures in 80–90% of pregnant patients after completing the prescribed course. 1

Instruct the patient to return only if symptoms persist after therapy or recur within 2 months; routine follow-up is unnecessary if symptoms resolve. 1

For severe vulvovaginitis with extensive erythema and edema, extend the topical azole regimen to 10–14 days rather than the standard 7 days. 1, 6

Partner Management

Routine treatment of the patient's partner is not indicated because vulvovaginal candidiasis is not sexually transmitted, and partner therapy does not reduce recurrence rates. 1, 3

Exception: If the partner has symptomatic balanitis (erythema and pruritus of the glans), treat him with topical antifungal cream (e.g., clotrimazole 1% twice daily for 7 days) to relieve his symptoms. 1, 3

Common Pitfalls to Avoid

Never prescribe oral fluconazole during pregnancy, even as a single 150mg dose—this is the most critical error to avoid, as the teratogenic risk is well-documented. 1

Do not use short-course (1–3 day) topical regimens in pregnancy; they have significantly lower efficacy than 7-day courses and lead to treatment failure. 2, 1

Avoid treating asymptomatic Candida colonization detected on routine examination; 10–20% of pregnant women harbor Candida without infection, and treatment is indicated only when symptoms are present. 1, 5

Oil-based vaginal creams and suppositories may weaken latex condoms and diaphragms; counsel the patient to use alternative contraception during treatment if needed. 6

Recurrent Infection Considerations

If the patient experiences recurrent episodes (≥3 per year), extend each treatment course to 10–14 days and investigate predisposing factors such as uncontrolled diabetes or immunosuppression. 6, 7

Maintenance suppressive therapy with weekly fluconazole is effective in non-pregnant women but is contraindicated during pregnancy; instead, treat each symptomatic episode individually with 7-day topical azole courses. 7