Determining Susceptibility in Candida Vaginal Isolates

Area of Science:

• Medical Mycology
• Clinical Microbiology
• Pharmacology

Background:

• * Increasing demand for antifungal drug susceptibility testing (AST) for *Candida albicans* in women with refractory or recurrent vulvovaginal candidiasis.
• * Fluconazole resistance in *Candida albicans* is a growing clinical concern.
• * Azole antifungal drug activity is reduced at the acidic pH commonly found in vaginal infections.

Purpose of the Study:

• * To evaluate the impact of different pH levels on the accuracy of antifungal drug susceptibility testing for *Candida albicans*.
• * To determine the optimal pH for AST to detect clinically relevant fluconazole resistance in vaginal isolates.

Main Methods:

• * Antifungal drug susceptibility testing (AST) performed on *Candida albicans* vaginal isolates.
• * Comparative testing at standard pH 7.0 and acidic pH 4.5.
• * Evaluation of fluconazole activity across different pH conditions.

Main Results:

• * Standard pH 7.0 testing likely underestimates azole resistance in *Candida albicans* vaginal isolates.
• * Testing at pH 4.5 identifies a greater number of clinically relevant azole-resistant isolates.
• * Fluconazole resistance in *Candida albicans* is more prevalent at acidic vaginal pH.

Conclusions:

• * Antifungal drug susceptibility testing for *Candida albicans* vaginitis should be conducted at pH 4.5.
• * Performing AST at pH 4.5 improves the detection of fluconazole-resistant *Candida albicans*.
• * This adjustment is crucial for guiding effective treatment of refractory or recurrent candidiasis.