Intracellular Loss of Potassium in Candida albicans After Exposure to Polyene Antifungal Antibiotics

Eleven antifungal antibiotics, representing three broad macrolide classes, were studied in Candida albicans for their effect on growth and on the fate of intracellular K. Marked differences were observed among these antibiotics between their growth-inhibitory activities and their adverse effects on the integrity of the cellular membrane as evidenced by loss of K. Antibiotics most active in inhibiting growth of C. albicans were amphotericin B, trichomycin, candidin, candicidin (all heptaenes), and nystatin (a tetraene). In addition to those antibiotics, filipin and fungichromin also caused rapid leakage of K from yeast cells. Interestingly, fungichromin was the least active of the 11 antibiotics in inhibiting growth. Concentrations of rimocidin 10 times as great as those required for growth inhibition caused only a slight loss in intracellular K after 60 min.