Vancomycin nephrotoxicity: Vancomycin tubular casts with characteristic electron microscopic findings

Area of Science:

• Nephrology
• Pathology
• Pharmacology

Background:

• Diabetes mellitus is a leading cause of chronic kidney disease.
• Vancomycin is a critical antibiotic for treating Gram-positive bacterial infections.
• Acute kidney injury (AKI) is a potential complication of vancomycin therapy.

Observation:

• A 46-year-old male with diabetes developed AKI and oliguria post-vancomycin initiation for a foot infection.
• Renal biopsy showed advanced diabetic nephropathy and acute vancomycin nephrotoxicity.
• Distinctive tubular casts with vancomycin and uromodulin coprecipitation were observed.

Findings:

• Microscopic examination revealed acute tubulointerstitial injury and characteristic hyaline and vancomycin-uromodulin casts.
• Immunostaining confirmed vancomycin and uromodulin coprecipitation within tubular casts.
• Electron microscopy demonstrated concentric vancomycin casts within a uromodulin matrix, supporting diabetic nephropathy and vancomycin toxicity.

Implications:

• Vancomycin-induced tubular injury may be characterized by unique uromodulin-vancomycin casts.
• Early detection and management, including vancomycin cessation and steroid therapy, can lead to renal function recovery.
• This case highlights the importance of monitoring renal function in diabetic patients receiving vancomycin.