Megalocytic Interstitial Nephritis Following Acute Pyelonephritis with Escherichia coli Bacteremia: A Case Report

Megalocytic interstitial nephritis is a rare form of kidney disease caused by chronic inflammation. We report a case of megalocytic interstitial nephritis occurring in a 45-yrold woman who presented with oliguric acute kidney injury and acute pyelonephritis accompanied by Escherichia coli bacteremia. Her renal function was not recovered despite adequate duration of susceptible antibiotic treatment, accompanied by negative conversion of bacteremia and bacteriuria. Kidney biopsy revealed an infiltration of numerous histiocytes without Michaelis-Gutmann bodies. The patient's renal function was markedly improved after short-term treatment with high-dose steroid. Graphical Abstract Keywords: Acute Kidney Injury, Megalocytic Interstitial Nephritis, Interstitial Nephritis INTRODUCTION Megalocytic interstitial nephritis is a rare form of chronic renal inflammatory disease associated with defect in intracellular destruction of invading foreign organisms by macrophages (1). These unusual inflammatory disorders are often associated with chronic urinary tract infection by Gram-negative bacteria (2). Although the pathogeneses of these diseases are unclear, macrophage bactericidal dysfunction has been presumed as a possible pathogenic mechanism (3). We report an extraordinary case of a 45-yr-old woman who had oliguric acute kidney injury (AKI) and acute pyelonephritis with Escherichia coli (E. coli) bacteremia, accompanied by megalocytic interstitial nephritis.