A case of emphysematous pyelonephritis in an older man with poorly controlled type 2 diabetes mellitus.

Emphysematous pyelonephritis (EPN) is a necrotizing bacterial infection characterized by gas retention and a poor prognosis. We present the case of a 75-year-old man who was diagnosed early with EPN and received multidisciplinary treatment. He had poorly controlled type 2 diabetes mellitus (DM) and chronic kidney disease (CKD), and was treated with oral hypoglycemic drugs, including a sodium-glucose co-transporter-2 inhibitor. He experienced the onset of back pain in the midsection of his back, tenderness in the costovertebral angle, and a high fever (> 39 °C), accompanied by tachycardia, hypotension, and tachypnea. The patient was diagnosed with pyelonephritis and septic shock. Immediate measures encompassing empirical antibiotic therapy, administration of noradrenaline, blood glucose regulation, and urethral catheterization were implemented. However, due to the persistent fever (> 38 °C) and lack of improvement in his condition, abdominal computed tomography (CT) was repeated on the fourth day. This revealed the presence of gas around the right kidney parenchyma, leading to a diagnosis of EPN that had evolved from acute pyelonephritis. Subsequently, percutaneous drainage of the right kidney parenchyma was performed. Subsequently, multidisciplinary treatment was continued, and his condition gradually improved. Clinicians should evaluate abdominal CT when acute pyelonephritis does not improve within a few days of antibiotic therapy. Disease progression from acute pyelonephritis to EPN should be considered in patients with DM and CKD.