5-Fluorocytosine in the treatment of experimental candidiasis in immunosuppressed mice.

A model infection with Candida albicans was established in mice. The animals were pretreated for 1 week with azathioprine, given dexamethasone, and then infected intravenously with Candida. Mortality for the group given Candida infection alone was 20%, 38% when azathioprine was added, and 50% when dexamethasone and azathioprine were given with infection. The titers of Candida in most mice were 10(6) per gram of kidney. The rest of the mice were killed at 30 days. At this time, 16% had no evidence of Candida in the kidneys, but 40% of the mice had titers of 10(6) or more. Mice treated with 5-fluorocytosine had a mortality of less than 4% in 30 days. Five percent of the treated mice killed at 30 days had titers of Candida of 10(6). Therefore, 5-fluorocytosine increases survival in the presence of continued therapy with azathioprine with or without pretreatment with dexamethasone. The survival is associated with decreased titers of Candida in the kidneys.