Study on the effect of fluoxetine against Candida albicans, alone or combined with fluconazole

Objective To evaluate the inhibitory activity of fluoxetine alone and in combination with fluconazole on Candida albicans. Methods This study used standard strains of Candida albicans, clinical isolates of Candida albicans, and drug-resistant strains of Candida albicans for experiments to prepare the planktonic and biofilm states of Candida albicans, respectively. The effect of fluoxetine on Candida albicans was detected by XTT reduction method. Pharmacodynamic properties of fluoxetine against Candida albicans biofilm were determined by improved time-kill test. The morphological changes of fluoxetine on Candida albicans biofilm were observed by scanning electron microscopy, and the synergistic effect of fluoxetine combined with fluconazole on Candida albicans biofilms was detected by the checkerboard dilution method. Results Fluoxetine had inhibitory effects on three types of Candida albicans biofilms. The minimum drug concentration that inhibited 50% activity (SMIC50) of biofilms of standard strains of Candida albicans and drug-resistant strains was 32 μg/mL; the SMIC50 of clinical strains of Candida albicans biofilm was 64 μg/mL. Time-kill test displayed that the biofilm activity of three types of Candida albicans significantly decreased compared to the control group at the fluoxetine concentration of 1×SMIC50 and 2×SMIC50. Scanning electron microscopy observation showed that compared with the control group, the number of fungal hyphae in the biofilm of Candida albicans treated with fluoxetine decreased and their morphology wrinkled. The checkerboard microdilution method showed that the combination of fluoxetine and fluconazole exhibited a synergistic effect on the standard strain of Candida albicans bioflim, while showing no or antagonistic effects on the other two strains. Conclusion Fluoxetine alone has inhibitory effects on biofilms of different types of Candida albicans and has a synergistic inhibitory effect on biofilms of standard strains of Candida albicans combined with fluconazole.