What treatment options are available for a patient with resistant vaginal thrush (candidiasis) that persists despite antifungal treatment?

Treatment Options for Resistant Vaginal Thrush (Candidiasis)

For resistant vaginal thrush that persists despite conventional antifungal treatment, boric acid vaginal suppositories (600mg daily for 14 days) are recommended as an effective treatment option, especially for non-albicans Candida species. 1

Diagnosis Confirmation

• Before initiating treatment for resistant thrush, confirm diagnosis with wet mount preparation using saline and 10% potassium hydroxide to demonstrate presence of yeast or hyphae 1
• Vaginal cultures should be obtained to identify non-albicans species, particularly Candida glabrata, which is found in 10-20% of patients with recurrent vulvovaginal candidiasis (RVVC) 1
• Normal vaginal pH (<4.5) is typically associated with vulvovaginal candidiasis 2

Treatment Algorithm for Resistant Vaginal Thrush

Step 1: Identify the Type of Resistant Infection

• Non-albicans Candida species (especially C. glabrata)

  • Conventional antimycotic therapies are less effective against these species 1
  • Longer duration (7-14 days) with a non-fluconazole azole drug is recommended as first-line therapy 1
  • If recurrence occurs, boric acid 600mg in a gelatin capsule administered vaginally once daily for 2 weeks is recommended 1
  • This boric acid regimen has clinical and mycologic eradication rates of approximately 70% 1

• Azole-resistant C. albicans

  • Extremely rare but can occur 1
  • Topical boric acid (600mg daily for 14 days) may be successful 1
  • Alternative options include topical 17% flucytosine cream alone or in combination with 3% AmB cream administered daily for 14 days (must be compounded by a pharmacy) 1

Step 2: For Recurrent Vulvovaginal Candidiasis (RVVC)

• Defined as ≥4 episodes of symptomatic VVC within 1 year 1
• Usually caused by azole-susceptible C. albicans 1
• After controlling contributing factors (e.g., diabetes):
  • Induction therapy with 10-14 days of topical or oral azole 1
  • Followed by suppressive regimen for at least 6 months 1
  • Most convenient regimen: weekly oral fluconazole 150mg, which achieves control in >90% of patients 1

Evidence for Boric Acid Effectiveness

• Boric acid has shown comparable efficacy to fluconazole in some studies, with cure rates of 46.7% vs 37.3% respectively 3
• Particularly effective for non-albicans Candida species that are resistant to conventional azole treatments 4
• Mycologic cure rates with boric acid vary from 40% to 100% across studies 4
• Considered a safe, alternative, economic option when conventional treatment fails due to non-albicans Candida or azole-resistant strains 4

Vaginal Probiotics as Adjunctive Therapy

• Lactobacillus recolonization (via yogurt or capsules) shows promise for treatment of yeast vaginitis with little potential for harm 5
• Probiotics with appropriate lactobacillus strains have shown encouraging initial results and warrant further investigation 6

Safety Considerations and Side Effects

• Boric acid may cause vaginal burning sensation (<10% of cases), water discharge during treatment, and vaginal erythema 4
• Boric acid should be avoided during pregnancy 7
• Oral azoles (fluconazole, itraconazole) should not be administered during pregnancy according to manufacturers 6
• For pregnant women with vulvovaginal candidiasis, only topical azole therapies should be used 2

Follow-Up Recommendations

• Patients should be instructed to return for follow-up visits if symptoms persist or recur within 2 months of onset of initial symptoms 1
• After cessation of maintenance therapy for RVVC, a 40-50% recurrence rate can be anticipated 1
• For persistent non-albicans VVC, a maintenance regimen of 100,000 units of nystatin delivered daily via vaginal suppositories has been successful 1