The Combined Effect of 5-Fluorocytosine and Amphotericin B in the Therapy of Murine Cryptococcosis

Summary 5-Fluorocytosine and amphotericin B were demonstrated to be at least additive in the therapy of murine cryptococcosis. The mechanism for this effect is not known. However, AmB seemed to inhibit the in vivo development of 5-FC resistance among C. neoformans in our model. These results raise the possibility that combined-drug therapy might reduce AmB toxicity and/or the appearance of 5-FC resistant cryptococci without compromising therapeutic efficacy in cryptococcal disease. We are greatly indebted to Dr. David W. Alling for constant and invaluable advice on the mathematical problems of experimental design and data analysis.