Increasing rate of non-Candida albicans yeasts and fluconazole resistance in yeast isolates from women with recurrent vulvovaginal candidiasis in Leeds, United Kingdom.

Objectives: Azoles have been the mainstay of recurrent vulvovaginal candidiasis (RVVC) for many years. Because of a recent anecdotal increase in non-Candida albicans yeasts (NCAY) and azole-resistant C. albicans cases, their prevalence was calculated from cultures for yeasts in women with complicated/RVVC over 3 years.

Methods: Retrospective data search of vaginal cultures from adult women in Leeds, UK between April 2018 and March 2021 was conducted. Samples with clinical details of complicated/RVVC had full yeast identification and antifungal susceptibility performed. Differences in prevalence between 12-month periods were determined using χ² tests.

Results: Over the 3 years, cultures were performed on 5461 vaginal samples from women with clinical information indicating they had complicated/RVVC, RVVC, with 1828 (33.5%) growing yeasts.Over 85% of yeasts each year were C. albicans, however the proportion declined yearly with an increase in NCAY species. Nakaseomyces glabrata was the most frequent NCAY species isolated, increasing from 2.8% in 2018-19 to 6.8% in 2020-21. Total NCAY species increased from 6.0% in 2018-19 to 12.6% in 2020-21. Fluconazole-sensitive dose-dependant (SDD) and resistant isolates increased from 3.5% in 2018-19 to 7.7% in 2019-20 and 9.6% in 2020-21. Most resistance was in C. albicans and the majority of cases were seen in primary care. Most fluconazole non-sensitive isolates were either SDD or resistant to itraconazole (77% and 23%, respectively) and were intermediate or resistant to voriconazole (36.4% and 60%, respectively).

Conclusion: There was a significant increase in the prevalence of NCAY and fluconazole-resistant C. albicans in complicated/RVVC cultures over these 3 years. Successful treatment of such cases can be very challenging. The exact reasons for this increase remain unclear but it follows a policy change that encouraged a clinical diagnosis and empirical treatment of vulvovaginal candidiasis, rather than fungal culture, in primary care.