Evaluation of Amphotericin B and Micafungin Combination Against Clinical Isolates of Aspergillus Species

Abstract

We aimed to evaluate the efficacy of a combination of amphotericin B (AMB) and micafungin (MCFG) against 25 clinical isolates of Aspergillus species in vitro. We examined fungal growth in the presence of these drugs using a checkerboard method with the tetrazolium salt: 2,3-bis (2- methoxy-4-nitro-5-sulphophenyl)-2H-tetrazolium-5-carboxyanilide inner salt (XTT) to determine the efficacy of an AMB/MCFG combination in inhibition of filamentous fungal growth, evaluated based on 50% reduction of metabolic activity.

The fractional inhibitory concentration index showed that the drugs synergistically inhibited 36% of the isolates. Activity was judged as indifferent for 64% isolates; antagonistic interaction was not detected. The AMB/MCFG combination was more effective than AMB alone when sub-inhibitory concentrations of AMB were used.

This report demonstrates the efficacy of AMB/MCFG combination for inhibiting the growth of Aspergillus species in vitro, warranting the extension of such studies to animal models.

Keywords:

• Aspergillus species
• combination effect
• amphotericin B
• micafungin
• XTT
• opportunistic infection
• immunosuppression