Introduction: Acute focal bacterial nephritis is an underdiagnosed condition. It clinically resembles acute pyelonephritis. If unrecognized and undertreated, it may progress into complications (kidney abscess and scars). Contrast-enhanced computed tomography (CT) reveals specific images of the disease and is considered the gold standard to make the diagnosis.
Case report: A 63-year-old male patient with solitary kidney presented with symptoms compatible with acute pyelonephritis. Kidney ultrasound was not conclusive. Because of persisting high-grade fever not resolving after 48 hours of antibiotics, a contrast-enhanced CT was then performed, and the diagnosis of acute focal bacterial nephritis was made. A repeat CT after three weeks of intravenous (IV) antibiotics showed marked improvement of the intrarenal lesions, and a fourth week of IV antibiotics was dispensed.
Conclusion: Diagnosing acute focal bacterial nephritis is important (particularly in a patient with solitary kidney). This will dictate the therapy duration. Unlike acute pyelonephritis, acute focal bacterial nephritis requires at least three weeks duration of antibiotics to avoid progress into further complications.