Obstructive Pyelonephritis With Enterococcal Bacteremia Despite Unremarkable Urinalysis

Obstructive pyelonephritis can be diagnostically challenging when urinary findings are unremarkable. <i>Enterococcus faecalis</i> is a well-known cause of complicated urinary tract infections and bacteremia; however, its clinical presentation may be atypical in patients with obstruction. A 73-year-old man presented with fever and left flank pain. Urinalysis and urinary sediment examination on admission were normal, and a urine culture was not obtained during the initial evaluation. Two sets of blood cultures yielded <i>E. faecalis</i>. Non-contrast computed tomography revealed a 12-mm left ureteral stone with hydronephrosis, leading to a diagnosis of obstructive pyelonephritis. Ureteral stenting was promptly performed, and empirical cefmetazole therapy was initiated. Despite adequate urinary drainage, fever persisted. <i>E. faecalis</i> was also isolated from renal pelvic urine obtained at the time of stent placement. Based on the clinical course and antimicrobial susceptibility results, therapy was switched to oral amoxicillin/clavulanate, resulting in rapid defervescence. Renal function improved markedly, and the patient recovered without septic shock or disseminated intravascular coagulation. This case highlights the importance of considering obstructive pyelonephritis despite negative urinalysis findings and reassessing antimicrobial therapy when fever persists after urinary drainage.