TY - JOUR
T1 - Reduced Antifungal Susceptibility of Vulvovaginal Candida Species at Normal Vaginal pH Levels
T2 - Clinical Implications
AU - Spitzer, Mark
AU - Wiederhold, Nathan
N1 - Publisher Copyright:
© Lippincott Williams & Wilkins.
PY - 2018/4/1
Y1 - 2018/4/1
N2 - Objective The aims of the study were to assess for differences in antifungal in vitro potency at pH 7 and pH 4 and to discuss any potential clinical implications of that difference. Materials and Methods A retrospective analysis of 217 first positive yeast cultures from 217 patients. Yeast isolates underwent antifungal susceptibility testing, with minimum inhibitory concentrations (MICs) (microgram per milliliter) measured at pH 7 and pH 4 for fluconazole, itraconazole, miconazole, clotrimazole, terconazole, and nystatin. Only the first isolates collected from each patient were included in the analysis. Results Yeast first isolates included 173 Candida albicans, 15 Candida glabrata, and 29 isolates from 8 other species. Geometric mean (GM) MIC values for all antifungals were significantly higher when tested at pH 4 (p <.001 for all comparisons). For C. albicans, the largest GM MIC differences were observed for terconazole (0.17 pH 7 vs 6.17 pH 4) and clotrimazole (0.04 vs 0.24). For terconazole, 97.7% of the isolates had a MIC of 1 or less at pH 7 but 83.2% had a MIC of 4 or higher at pH 4. For C. glabrata, terconazole (GM MIC = 0.26 pH 7 vs >64 pH 4), clotrimazole (0.13 vs 6.96), miconazole (0.06 vs 0.76), and fluconazole (3.17 vs 26.6) were most affected. All C. glabrata isolates had a MIC of 1 or less for terconazole at pH 7 and one had a MIC of 8 at pH 4, whereas all the rest were highly resistant (MIC > 64). Conclusions Antifungals have reduced in vitro potency when tested at lower pH. Candida glabrata is more affected than C. albicans. The impact may be greatest for the antifungal terconazole and against C. glabrata isolates.
AB - Objective The aims of the study were to assess for differences in antifungal in vitro potency at pH 7 and pH 4 and to discuss any potential clinical implications of that difference. Materials and Methods A retrospective analysis of 217 first positive yeast cultures from 217 patients. Yeast isolates underwent antifungal susceptibility testing, with minimum inhibitory concentrations (MICs) (microgram per milliliter) measured at pH 7 and pH 4 for fluconazole, itraconazole, miconazole, clotrimazole, terconazole, and nystatin. Only the first isolates collected from each patient were included in the analysis. Results Yeast first isolates included 173 Candida albicans, 15 Candida glabrata, and 29 isolates from 8 other species. Geometric mean (GM) MIC values for all antifungals were significantly higher when tested at pH 4 (p <.001 for all comparisons). For C. albicans, the largest GM MIC differences were observed for terconazole (0.17 pH 7 vs 6.17 pH 4) and clotrimazole (0.04 vs 0.24). For terconazole, 97.7% of the isolates had a MIC of 1 or less at pH 7 but 83.2% had a MIC of 4 or higher at pH 4. For C. glabrata, terconazole (GM MIC = 0.26 pH 7 vs >64 pH 4), clotrimazole (0.13 vs 6.96), miconazole (0.06 vs 0.76), and fluconazole (3.17 vs 26.6) were most affected. All C. glabrata isolates had a MIC of 1 or less for terconazole at pH 7 and one had a MIC of 8 at pH 4, whereas all the rest were highly resistant (MIC > 64). Conclusions Antifungals have reduced in vitro potency when tested at lower pH. Candida glabrata is more affected than C. albicans. The impact may be greatest for the antifungal terconazole and against C. glabrata isolates.
KW - C. albicans
KW - C. glabrata
KW - Candida
KW - antifungal susceptibility
KW - terconazole
KW - vaginal pH
KW - vaginitis
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U2 - 10.1097/LGT.0000000000000383
DO - 10.1097/LGT.0000000000000383
M3 - Article
C2 - 29474241
AN - SCOPUS:85044329573
SN - 1089-2591
VL - 22
SP - 152
EP - 158
JO - Journal of Lower Genital Tract Disease
JF - Journal of Lower Genital Tract Disease
IS - 2
ER -