Escherichia coli-induced emphysematous pyelonephritis in a diabetic patient with polycystic kidney disease

Emphysematous pyelonephritis is a rare, necrotizing infection of the kidney and the perirenal space resulting in the formation of gas in both structures and associated with a high mortality rate. In 90% of cases it affects one kidney only; in the remaining 10% with bilateral emphysematous pyelonephritis aggressive surgical intervention may be required. Women are much more frequently affected than men, with diabetes mellitus (in 70-90% of cases) and urinary tract obstruction being common predisposing conditions. The pathogenesis of the disease is linked to four main factors: the presence of gasforming bacteria; hyperglycemia; inadequate tissue perfusion; and reduced immune response. Lactose-fermenting bacteria such as Escherichia coli and Klebsiella pneumoniae are the most common infectious agents. We report a case of unilateral emphysematous pyelonephritis due to a ruptured cyst infected by E. coli in a diabetic patient with polycystic kidney disease. The resulting septic shock necessitated an emergency right nephrectomy.