A case of emphysematous pyelonephritis induced by Citrobacter freundii infection.

A 79-year-old female with diabetes mellitus had general fatigue, a high fever and vomiting. A CT revealed acute emphysematous pyelonephritis (EPN). A nephrectomy was performed on the 2(nd) hospital day. The results of the blood culture showed the presence of Citrobacter freundii infection. The patient's post-operative course was uneventful. This case is the second reported case of EPN induced by Citrobacter freundii. Bacteremia induced by Citrobacter freundii infection typically results in a high mortality rate. In this case, the early diagnosis of the EPN using CT and immediate medical treatment, including urgent elective nephrectomy, were key to the favorable outcome.

INTRODUCTION

Emphysematous pyelonephritis (EPN) is a rare disease. A history of diabetes mellitus and female gender are common predisposing factors.[123] In comparison with simple pyelonephritis, EPN is an acute severe necrotizing infection of the renal parenchyma, and is a life-threatening condition, with a mortality rate of up to 21%.[2] Among the reported cases of EPN, there has been the only one report of the disease induced by Citrobacter freundii infection.[4]

CASE REPORT

A 79-year-old female with diabetes mellitus and hypertension had general fatigue, high fever and vomiting, was transferred to our hospital. She was experiencing a state of systemic inflammatory response syndrome and had lower abdominal tenderness. A computed tomography (CT) scan for detection of the septic focus suggested acute emphysematous pyelonephritis (EPN) [Figure 1]. She was treated conservatively, however, her condition did not improve, so an urgent right nephrectomy was performed on the 2nd hospital day. The results of the blood and urine culture showed the presence of Citrobacter freundii infection. The patient's post-operative course was uneventful and discharged on foot.

Figure 1

The abdominal CT scan on arrival. It indicates an air density (arrow) area in the right renal swelling parenchyma with dirty fat signs, suggesting acute emphysematous pyelonephritis

This case is the second reported case of EPN induced by C. freundii.[4] Bacteremia induced by C. freundii infection typically results in a high mortality rate. In this case, early diagnosis of EPN using CT and immediate medical treatment, including urgent elective nephrectomy, was key to the favorable outcome.