Pyelonephritis was studied after an intravenous injection of Candida albicans, Staphylococcus aureus, or enterococcus in alloxan-diabetic rats and in waterdiuresing or non-diuresing nondiabetic rats. The renal microbial populations of C. albicans or S. aureus were found to be >10i colony-forming units per g for up to 42 days in diabetic rats, whereas the kidneys tended to become sterile in nondiabetic rats. No significant difference was found in the course of enterococcal pyelonephritis in

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... tic versus control rats. The difference in the 50% infective dose for each microorganism between diabetic and control rats was c1 logwo. Neither duration of diabetes nor weight loss contributed to the greater and more sustained renal populations of C. albicans and S. aureus in diabetic rats. The inflammatory reaction in kidneys infected with S. aureus or C. albicans was greater in diabetic rats. Fungus balls associated with ureteral obstruction and gross multiple renal abscesses occurred in diabetic, but not in nondiabetic, rats infected with Candida. Growth of C. albicans and S. aureus in vitro in urine from diabetic rats was significantly greater than it was in urine from control rats. Addition of water or glucose to the urine of non-diuresing, nondiabetic rats significantly increased in vitro growth of S. aureus and C. albicans. These studies demonstrate greater severity of infection in the diabetic kidney due to S. aureus and C. albicans, which can be partially explained by decreased inhibitory activity of urine for these organisms in diabetic rats. 116:778-781.