In vitro fluconazole and nystatin susceptibility and clinical outcome in complicated vulvovaginal candidosis

To correlate fluconazole and nystatin susceptibility with clinical outcome for complicated vulvovaginal candidosis (VVC), 287 Candida isolates were collected from 283 patients with complicated VVC. In vitro fluconazole and nystatin susceptibility was tested using E-test or commercial agar diffusion method. The patients were treated with fluconazole or nystatin. The fluconazole-resistant and -susceptible dose-dependent (SDD) rates of Candida species were 0.8% (1/132) and 5.3% (7/132) respectively. The mycological cure rate at days 7-14 and days 30-35 in fluconazole SDD isolates was lower than that in fluconazole-susceptible isolates (42.9% vs. 88.7% and 28.6% vs. 76.6%, P < 0.05). The mycological cure rate at days 7-14 and days 30-35 in VVC caused by Candida albicans and non-albicans Candida species was 85.6% (219/256) vs. 88.9% (24/27) and 79.3% (203/256) vs. 81.5% (22/27), P > 0.05. All C. albicans and non-albicans Candida species were susceptible to nystatin in vitro. The mycological cure rate of the patients treated with nystatin at days 7-14 and days 30-35 in VVC was 85.4% (129/151) and 83.4% (126/151) respectively. We conclude that fluconazole resistance was rare and both C. albicans and non-albicans Candida species were susceptible to nystatin in vitro. The decrease in fluconazole susceptibility or a low concentration of fluconazole in the vagina was probably related to fluconazole therapeutic failure.