The Role of Amphotericin B Alone and in Combination with Different Antibiotics and Antifungals on Biofilms Produced by Candida Species

Abstract

Biofilm formation by Candida species is highly resistant to commonly used antifungal agents and is difficult to treat. Therefore, this study focused on effectiveness of combination therapy against Candida biofilms. The antimicrobial activities of amphotericin B (1 µg/ ml or 10 µg/ml) alone or in combination with various antibiotics (doxycycline (20 µg/ml), tigecycline (20 µg/ml), colistin (30 µg/ml), rifampicin (120 µg/ml), ciprofloxacin (20 µg/ml)) or antifungals (clotrimazole (2.5 µg/ml), anidulafungin (10 µg/ml), caspofungin (10 µg/ml), itraconazole (2.5 µg/ml) and fluconazole (10 µg/ml)) were investigated against fungal biofilms produced by C. albicans SC5314, C. tropicalis ATCC 750 and C. parapsilosis ATCC 22019. Fungal viability was monitored by culture (colony-forming unit (CFU). According to the results, rifampicin and ciprofloxacin enhanced the activity of amphotericin B (10 µg/ml). Among the antifungals, clotrimazole displayed the most significant effect in combination with amphotericin B (10 µg/ml), especially against C. parapsilosis biofilms. Consequently, combinations of amphotericin B and antibiotic or antifungal could be a promising option for the treatment of Candida biofilms.