The nucleoside reverse transcriptase inhibitors didanosine, lamivudine, stavudine and zidovudine show little effect on the virulence of Candida albicans in vitro

Nucleoside reverse transcriptase inhibitors (NRTIs) are used in the treatment of human immunodeficiency virus (HIV). Since the analogue 5-fluorouracil increases Candida albicans virulence in vitro, and zidovudine therapy is associated with enhanced C. albicans adherence and biofilm formation, we investigated the effects of commonly used NRTIs on the virulence of C. albicans isolated from 21 antiretroviral-naïve HIV/AIDS patients. The isolates were exposed to didanosine, lamivudine, stavudine and zidovudine at their expected patient serum peak levels and at one-half and two times these levels for 24 h and 72 h. Assays assessing changes in adherence, proliferation, biofilm formation and antifungal susceptibility were performed. No differences in these virulence characteristics of isolates exposed to NRTIs were noted in most cases. However, at 24 h and 72 h a significant increase in the rate of proliferation was observed in response to two-fold the peak concentration of lamivudine. The results suggest a limited effect of NRTIs on C. albicans virulence.