albicans isolates under planktonic conditions according to CLSI are given in Table 1. The biofilms of tested C. albicans isolates after 24, 48 or 72 h measured by XTT assay showed no significant difference in ODs (OD24 h: 1.048 ± 0.064; OD48 h: 0.985 ± 0.122; OD72 h: 1.12 ± 0.131, P > 0.05). The results of antifungal activities of amphotericin B, CAS and POS against C. albicans biofilms grown for 24, 48, and 72 are shown in Fig. 1 (% of XTT readings, mean ± standard error). By 24 h, CAS at 1–4 × MIC reduced the biofilm OD by ≥50% vs. the untreated control (P < 0.001). Significant reduction
in the biofilm OD was observed when the biofilms were incubated with amphotericin B at ≥4 × MIC (32.7% reduction, P = 0.002) and POS at ≥2 × MIC (16.5% reduction, P = 0.012). Amphotericin B achieved the reduction in the biofilm OD by 50% at high concentration of ≥32 × MIC (P < 0.001). By 48 h, all three antifungal agents achieved PLX4032 a significant Torin 1 chemical structure reduction in the biofilm OD: CAS at 1 × MIC by 25% reduction (P = 0.001), amphotericin B at 8 × MIC by 27% reduction (P = 0.03),
POS at 2 × MIC by 23% reduction (P = 0.04). However, no investigated antifungal agent reached ≥50% reduction in the biofilm OD. By 72 h, C. albicans biofilm exhibited similar susceptibility to amphotericin B and CAS as by 24 h. Caspofungin at 1 × MIC (P < 0.001) and amphotericin B at 4 × MIC (P < 0.001) reduced the biofilm OD by ≥50%. Posaconazole significantly decreased the biofilm OD at 1 × MIC by 32% (P = 0.001), but failed to reach ≥50% reduction in the biofilm OD. As shown in Fig. 2, no significant reduction in the colony counts of viable cells in biofilms after antifungal
treatment was observed (Fig. 2). The mean colony cell count determined in untreated C. albicans biofilm incubated for 24, 48 and 72 h was: 6 × 107 ±0.256 × 107; 8 × 107 ± 0.2 × 107; 9 × 107 ±0.3 × 107. Amphotericin B attained the maximum decrease in the colony count reaching one log unit at concentration of 128 × MIC against C. albicans biofilm grown for 24, 48 and 72 h. The management Reverse transcriptase of biofilm-associated implant infection requires both antimicrobial therapy and surgical intervention, preferentially with removal of the implant. However, if removal of the infected implant is not feasible, the therapy has to rely on fungal substances alone.18 The resistance of Candida biofilm to antifungal drugs is influenced by the maturation of biofilm due to consistent changes in the composition of biofilm matrix,19,20 metabolic activity11,21 and the rate of the drug diffusion through the biofilm.22In vitro data show that biofilm resistance to azoles is induced in the early stages of biofilm.11,23 On the other hand, reduced ergosterol in the cells membrane of Candida seems to be relevant for the inefficacy of amphotericin B against mature biofilm.24 However, the mechanism of echinocandin activity against biofilms formed by different Candida species remains unknown.