Disulfiram reverses fluconazole-resistance mediated by Cdr1 in Candida albicans and interferes with biofilm formation

The incidence of Candida albicans infections has risen markedly, particularly among immunocompromised individuals and cancer patients undergoing chemotherapy. Fluconazole is commonly used as a first-line treatment for C. albicans infections; however, increasing clinical resistance poses a significant therapeutic challenge. As a result, developing new strategies to enhance the management of C. albicans infections has become critical. This study aims to assess the prevalence of azole's resistance among clinical C. albicans isolates in Egypt and to evaluate disulfiram/fluconazole combination against fluconazole resistant isolates. A total of 64 C. albicans clinical isolates were tested for fluconazole susceptibility using disc diffusion method and broth microdilution method (alone and in combination with disulfiram). The combination of fluconazole and disulfiram was further assessed using checkerboard method. The expression levels of resistance determinants were analyzed using RT-PCR. Molecular docking was used for further analysis. Sixteen isolates (25%) were resistant to fluconazole. Combination with subinhibitory concentration of disulfiram reduced the minimum inhibitory concentration (MIC) of fluconazole in resistant isolates (2-128 fold). Checkerboard assay revealed that fluconazole/disulfiram combination was mostly synergistic. In fluconazole-resistant isolates, Cdr1 was overexpressed, whereas disulfiram (at subinhibitory concentration) has triggered its downregulation. Docking studies showed that disulfiram may compete with ATP for binding and may disrupt fluconazole's interaction with Cdr1. Additionally, disulfiram exhibited a potent anti-biofilm activity against the tested C. albicans isolates. Fluconazole/disulfiram combination appears to be a promising approach for overcoming fluconazole resistance in C. albicans. Further studies are needed to validate this finding and explore its clinical potential. KEY POINTS: • Fluconazole/disulfiram combination is a promising approach to overcome fluconazole resistance in C. albicans • Disulfiram triggered downregulation of Cdr1 expression in fluconazole-resistant C. albicans. • Disulfiram competes with ATP for Cdr1 binding, disrupting fluconazole-Cdr1 interaction.