Comparison of the antifungal effect of voriconazole and fluconazole on oral candidiasis before and during radiotherapy

Abstract

Background: Head‑and‑neck radiotherapy can change oral Candida species and cause candidiasis
resistance to common antifungals by making the changes to the oral cavity environment. Voriconazole
is a synthetic azole with extensive antifungal activity. The current study aimed at comparing the
antifungal activity of fluconazole and voriconazole on Candida species isolated from the oral cavity
of patients undergoing head‑and‑neck radiotherapy.
Materials and Methods: The present in vitro study was performed on samples isolated from
patients undergoing head‑and‑neck radiotherapy, before and during radiotherapy. After the
identification of the species, the antifungal effect of fluconazole and voriconazole was determined
by the microdilution method, and the minimum inhibitory concentration (MIC), the minimum
fungicidal concentration, and the antifungal susceptibility of the isolated strains were also measured.
The data were analyzed by the Chi‑squared and then two‑sided Fisher’s exact tests. P < 0.05 was
considered statistically significant.
Results: The study findings showed no significant difference in the susceptibility of Candida
albicans to voriconazole and fluconazole before and during radiotherapy. Before radiotherapy,
both voriconazole and fluconazole had similar effects on Candida tropicalis, but after radiotherapy,
voriconazole was less effective. However, both before and during radiotherapy, fluconazole had a
greater antifungal effect than voriconazole on Candida glabrata strains. The MICs of voriconazole
and fluconazole for both Candida parapsilosis and Candida krusei isolates were within the susceptible
or dose‑dependent range.
Conclusion: The current study results showed that voriconazole was not more effective than
fluconazole in the treatment of oral candidiasis in patients undergoing head‑and‑neck radiotherapy.
Key Words: Antifungal agents, candidiasis oral, fluconazole, head‑and‑neck neoplasms,
radiotherapy, voriconazole