Antimicrobial efficacy of sophorolipid: addressing Candida albicans biofilm formation and antimicrobial resistance

Antimicrobial resistance poses a critical global health threat, necessitating innovative strategies to combat drug-resistant pathogens. Candida albicans, a common fungal pathogen, increasingly resists conventional antifungals. This study explores the potential of sophorolipid (SL) and clinical antifungal drug combinations to counteract resistance and influence pathogen-drug interactions in C. albicans. Sophorolipids derived from yeast extract-containing media (SLs-Y) and soybean meal media (SLs-S) demonstrated notable antibiofilm activity, with BIC50 values of 1024 mg/L against preformed biofilms and 512 mg/L against young biofilms, respectively. The combination of crude SLs with four antifungals—fluconazole, ketoconazole, itraconazole, and amphotericin B—yielded promising results, particularly with itraconazole and amphotericin B, warranting further investigation with purified SLs.
Remarkably, combining itraconazole with purified SLs achieved an four-fold enhancement in antibiofilm activity compared to individual treatments, reducing the BIC50 to 2 mg/L with SLs-Y at 256 mg/L. This combination also reduced metabolic activity by 50% at 2 mg/L with SLs-Y. Similarly, amphotericin B exhibited synergistic effects with SLs-Y, achieving significant antibiofilm activity and metabolic reduction at 0.5 mg/L. These findings underscore the potential of SL-antifungal combinations in developing more effective antifungal therapies. By leveraging the synergistic effects of SLs and clinical antifungals, this approach offers a promising solution to overcome resistance mechanisms and enhance treatment outcomes for C. albicans infections.