Is therapy with fluconazole (Fluconazole) and boric acid appropriate for treating Candida glabrata infection in the presence of other Candida species?

Treatment of Candida glabrata Infection with Mixed Candida Species

For vulvovaginal candidiasis with C. glabrata in the presence of other Candida species, boric acid vaginal suppositories (600 mg daily for 14 days) are the recommended first-line treatment, as fluconazole is frequently ineffective against C. glabrata. 1

Understanding C. glabrata and Treatment Challenges

C. glabrata presents unique treatment challenges:

• C. glabrata is intrinsically less susceptible to fluconazole and other azoles 1, 2
• FDA drug information specifically notes that many C. glabrata isolates are only "intermediately susceptible" to fluconazole 2
• C. glabrata resistance often involves upregulation of CDR genes, resulting in resistance to multiple azoles 2

Treatment Algorithm for Mixed Candida Infections Including C. glabrata

First-Line Treatment:

• Boric acid vaginal suppositories: 600 mg daily for 14 days 1
  • Achieves 63.6-78% mycological cure rate for C. glabrata 3, 4
  • Effective against both C. glabrata and other Candida species 5
  • Strong recommendation despite low-quality evidence 1

Alternative Options (if boric acid fails):

1. Nystatin intravaginal suppositories: 100,000 units daily for 14 days 1
2. Topical 17% flucytosine cream alone or combined with 3% AmB cream daily for 14 days 1
   • Achieves 90% success in women who failed boric acid and azole therapy 6

Why Not Fluconazole First?

• Fluconazole achieves only 28.6-33.3% mycological cure for C. glabrata 3
• C. glabrata should be considered resistant to fluconazole 1, 2
• Treatment of C. glabrata with azoles, including voriconazole, is frequently unsuccessful 1

Advantages of Boric Acid for Mixed Infections

1. Broad-spectrum activity: Effective against multiple Candida species, including both C. albicans and non-albicans species 5, 4
2. Anti-biofilm properties: Unlike fluconazole, boric acid inhibits hyphal formation and reduces biofilm formation 5
3. Less resistance development: Population-level variation for resistance is narrower for boric acid than fluconazole 5

Important Clinical Considerations

• Diagnosis confirmation: Before treatment, confirm diagnosis with wet mount preparation using saline and 10% potassium hydroxide to demonstrate yeast/hyphae and normal pH (4.0-4.5) 1
• Compounding requirement: Boric acid vaginal suppositories must be compounded by a pharmacist for specific patient use 1
• Follow-up: Approximately 30-40% of patients may experience recurrence after treatment completion 7
• Safety: Local side effects are uncommon with boric acid regimens 6

For Recurrent Infections

If recurrence occurs after successful treatment:

• Consider maintenance therapy with nystatin vaginal suppositories (100,000 units daily) 1
• For recurring vulvovaginal candidiasis: 10-14 days of induction therapy followed by fluconazole 150 mg weekly for 6 months (if the infection becomes susceptible to fluconazole) 1

The presence of C. glabrata among other Candida species requires prioritizing treatment strategies effective against this more resistant organism, making boric acid the optimal first choice.