In-vitro Interactions between Fluconazole and Diphenyl Diselenide against Various Candida Species

In the immunocompromised population, Candida species are the most aetiologic agents causing severe nosocomial fungal infections. Candida species, irrespective of being commensals in the human microbiome, are the fourth most prevalent source of potentially fatal yeast infections. Monotherapy is frequently employed to treat invasive fungal infections, but sometimes, patients do not favor the monotherapy treatment regime. It may be because of the reduced susceptibility of the pathogen toward traditional antimycotic drugs. Antimycotic drug combination therapy could be a better choice in such specific circumstances. In our study, we evaluated the interactions of fluconazole with diphenyl diselenide. The antimycotic susceptibilities of Candida species for fluconazole and diphenyl diselenide were determined by broth microdilution assay, and the in-vitro interactions of fluconazole with diphenyl diselenide were studied by using disc diffusion assay and chequerboard assay. The nature of the interactions was assessed by calculating the fractional inhibitory concentration index (FICI). The interactions were also analyzed by the response surface approach. The minimum inhibitory concentrations (MICs) for fluconazole and diphenyl diselenide as determined by the broth microdilution assay against Candida species were 4 μg/ml-512 μg/ml and 1 μg/ml-32 μg/ml, respectively. The FICI values varied from 0.375 to 2. Our finding demonstrated that there is no antagonism interaction between fluconazole and diphenyl diselenide in Candida species. Thus, this innovative combination should be explored in the future.