AN EXPERIMENTAL-MODEL OF ASCENDING PYELONEPHRITIS DUE TO CANDIDA-ALBICANS IN RATS

We developed a new experimental model of ascending Candida pyelonephri tis in female rats with leukopenia and vesicoureteral reflux. Rats wer e treated transperitoneally with cyclophosphamide (200 mg/kg) to induc e leukopenia 3 days before and transurethrally with diluted acetic aci d solution to induce vesicoureteral reflux 1 day before inoculation of Candida albicans strain, ATCC 10259 (containing 10(7) cells). Microsc opy revealed acute pyelonephritis in which Candida cells invaded from the fornix and/or papilla into the medulla within 3 days after inocula tion. Between 7 and 28 days after inoculation, chronic pyelonephritis reached the cortex. The incidence of pyelonephritis increased graduall y and was approximately 80% after 7 days. Candida colony counts of bla dder urine specimens obtained by direct puncture were significantly gr eater in rats with pyelonephritis extending into the parenchyma than i n those with pyelonephritis located along the pelvis (p < 0.01). These results suggest that this rat model shows the characteristic feature of ascending pyelonephritis due to C. albicans and that the severity o f Candida pyelonephritis can be estimated from Candida counts of bladd er urine.