Clinical factors associated with fluconazole resistance in oral Candida from xerostomic head and neck cancer patients.

Post-radiation head and neck cancer (HNC) patients with xerostomia are predisposed to opportunistic oral candidiasis. While resistance to fluconazole, a first-line antifungal agent, is increasingly prevalent, it is not well-characterized among these patients. Thus, we aimed to evaluate fluconazole resistance and associated factors among Candida isolates from this population. Oral Candida isolates from xerostomic post-radiation HNC patients and healthy controls, with demographic, clinical, and biofilm-forming data, were obtained from previous studies. Fluconazole susceptibility was tested using E-test™ and interpreted according to CLSI-M60 guidelines. Data were analyzed using Chi-square test, Mann-Whitney-U test and multivariate regression with significance level at p < 0.05. Fluconazole resistance was observed in 8.8% of C.albicans and 16.7% of C.tropicalis isolates from HNC patients, but none from healthy controls, except for the intrinsically resistant C.krusei. The prevalence of fluconazole resistance was significantly higher in HNC group at both isolate and patient levels (p = 0.037 and 0.027, respectively). This association persisted after adjusted for potential confounders. Interestingly, fluconazole resistance was significantly associated with higher Candida load in cancer patients, while it was associated with lower biofilm formation in controls. Fluconazole resistance maybe more common in xerostomic post-radiation HNC patients, thus, cautions are warranted when prescribing fluconazole.