Antifungal susceptibility of genital yeast isolates, Auckland, 2016-2025

Our aim was to record current susceptibility results of genital yeast isolates and to compare the results to the previous report covering the period 2001-2015.

Genital yeast isolates had their antifungal susceptibility determined by disc diffusion or minimum inhibitory concentration following standard methods. Sequential isolates from the same person had their initial and last susceptibility results compared.

Disc testing was performed on 1,307 initial isolates; 17 (1.3%) were from males. The most frequent isolates were Candida albicans (64%), Nakaseomyces glabratus complex (17%) and Candida parapsilosis complex (7%). While 94% of isolates were susceptible to clotrimazole, susceptibility for other azoles ranged from 62% to 84%. All isolates were susceptible to nystatin. Isolates non-susceptible to one topical azole were often resistant to all azoles tested. For fluconazole, itraconazole and miconazole fewer isolates were susceptible than in the previous time period. The susceptibility to clotrimazole did not change. One hundred and eight women had sequential isolates, range 2-5, collected 1 week to 75 months apart, median 6 months. Four pairs (4%) had a change from susceptible to resistant, all for miconazole, suggesting increased resistance. All latter isolates were susceptible to at least two other azoles and nystatin.

There appears to have been an increase in antifungal resistance to several topical agents used for genital yeast infections. However, in a previously susceptible isolate, treatment failure seldom indicates a change to antifungal resistance. Women with recurrent vulvovaginal yeast infection can be reasonably treated empirically while identification and susceptibility results are awaited.