Comparative in vitro antifungal susceptibility activity of amphotericin B versus amphotericin B methyl ester against Candida albicans ocular isolates.

PURPOSE

To compare in vitro susceptibility of amphotericin B (AMB) and amphotericin B methyl ester (AME) (a more soluble and less toxic formulation of AMB) against Candida albicans isolates recovered from human cases of endophthalmitis.

METHODS

The in vitro susceptibility of AMB and AME was determined for C. albicans isolates recovered from endophthalmitis (N=10) and for C. albicans ATCC reference strain 90028 using the Clinical and Laboratory Standards Institute M27-A2 (NCCLS/CLSI) broth dilution method. All isolates were obtained from samples of vitreous humor of patients with suspected endophthalmitis within the last 5 years at the Bascom Palmer Eye Institute, University of Miami Miller School of Medicine (Miami, FL).

RESULTS

The minimal inhibitory concentrations (MICs) of AME were equal to or lower than values for AMB in 7 of the 10 isolates; range: AME (0.125-1 μg/mL) versus (0.5-1 μg/mL) for AMB. The MIC(90) value of both drugs was equal (1 μg/mL). Compared with AMB, the minimal fungicidal concentrations (MFCs) of AME were equal to or lower in 8 of 10 isolates; range: AME (0.125-2 μg/mL) versus AMB (0.25-4 μg/mL). MFC(90) values of AME (1 μg/mL) was slightly superior to AMB (2 μg/mL). The MIC of the quality control strain (ATCC(®) 90028) was within an acceptable range.

CONCLUSIONS

AME was equivalent to AMB in vitro against C. albicans. This formula may offer a slightly more efficient and less toxic formulation for the treatment of Candida endophthalmitis.