Synergistic interaction of miconazole and fluconazole at sub-MIC level on Candida albicans.

The in vitro combination effect of two azole antimycotics, miconazole and fluconazole, against Candida albicans was studied. When minimum (MIC) and sub-minimum (sub-MIC) inhibitory concentration and fractional inhibitory concentration (FIC) determinations were made, a synergistic interaction of the two agents at the concentration well below their individual MICs (at sub-MIC levels) was evidenced. The FIC index values ranged from 0.3 to 1.0 and the synergy was characterized by the potentiation of fluconazole activity with miconazole. The synergistic effect was also confirmed by a turbidometric method. On the other hand, such a synergistic effect against Candida krusei was not confirmed.