Emphysematous pyelonephritis caused by Bacteroides fragilis.

A 50-year-old male presented with fever and anorexia of 2 days’ duration and a 3-week history of abdominal fullness. Two years earlier, he had left-sided acute pyelonephritis, incomplete duplicated ureters and a ureteral stone. The stone was removed. He also had hypertension, gout, and chronic renal failure with a serum creatinine 3.1mg/dl. Examination of the abdomen revealed a palpable mass with tenderness at the left upper quadrant. Investigations showed a white blood cell count of 21190 cells/mm, blood urea nitrogen 84mg/dl, serum creatinine 5.4mg/dl, and pyuria. The radiographs of the abdomen showed a huge retroperitoneal cavity filled with air and fluid (Figures 1 and 2). Emphysematous pyelonephritis (EPN) caused by ureteral stone obstruction was diagnosed. Percutaneous nephrostomy was performed immediately. Bacteriodes fragilis was isolated from the purulent fluid but not blood culture. Magnetic resonance imaging demonstrated hydronephrosis of the left lower pole kidney compressing the ureteropelvic junction of the upper pole (Figure 3). Due to difficulty in retrograde extraction of calculus, left heminephrectomy was attempted but failed. Subsequently, he had a left nephrectomy with serum creatinine 4.1mg/dl 6 months after operation. Discussion