Antifungal synergism. A proposed dosage for corneal storage medium

Fungal infections from eye bank-preserved corneas have led us to search for antifungal agents that will eliminate yeast and mold in McCarey-Kaufman (MK) medium and concurrently be nontoxic. Amphotericin B, natamycin, nystatin, and clotrimazole were tested in synergistic combinations in vitro against nine yeast and six mold specimens. For average yeast and mold concentrations of 3.4 X 10(4) and 1.36 X 10(4) colony-forming units (CFUs)/mL at 5 degrees C, and 3.36 X 10(4) and 2.3 X 10(3) CFUs/mL at 37 degrees C, respectively, a synergistic combination of all four drugs at one twelfth the minimal fungicidal concentrations proved fungicidal. This synergistic combination did not alter donor human corneal morphology under specular microscopy, nor did it inhibit rabbit corneal endothelial cell division preserved and propagated in antifungal supplemented MK medium. The synergistic drug mixture did prove to be fungicidal when the endothelial cells were challenged with fungal inoculum.