Acute Focal Bacterial Nephritis: Two Cases and Review of the Literature

RATIONALE: Acute focal bacterial nephritis (AFBN) has mainly been reported in pediatrics. It may be an underdiagnosed condition in adults because it resembles acute pyelonephritis (APN) in its clinical presentation. PRESENTING CONCERNS OF THE PATIENTS: Two young women (25 and 27 years old, respectively) presented with complaints compatible with a diagnosis of APN. However in both, fever was of high grade, persistent for several days in spite of antibiotic administration, and there was demonstrated worsening of the inflammatory biomarkers. A contrast-enhanced computed tomography (CECT) led to the diagnosis in both cases. DIAGNOSES: Contrast-enhanced computed tomography reveals the most sensitive and specific images of AFBN. This includes wedge-shaped lesions with decreased enhancement, which may be focal or multifocal. INTERVENTIONS (INCLUDING PREVENTION AND LIFESTYLE): Antibiotic therapy for at least 3 weeks. OUTCOMES: Resolution of AFBN was obtained after 3 weeks of antibiotics. LESSONS LEARNED: Our 2 cases illustrate the importance of CECT imaging to confirm the diagnosis of AFBN. Interstitial bacterial inflammation may have a worse prognosis if not diagnosed early and efficiently treated. Unlike APN, the management of AFBN requires at least 3 weeks of antibiotics to prevent the development of renal scarring and renal abscess.