Vancomycin-associated acute interstitial nephritis in a patient with infective endocarditis.

Vancomycin, a bacterial cell wall inhibitor, can cause nephrotoxicity, typically presenting as acute tubular necrosis (ATN) but, in rare cases, can lead to acute interstitial nephritis (AIN). Risk factors include high doses, prolonged use, other nephrotoxic drugs and pre-existing kidney impairment. This case describes a man in his 70s with multiple comorbidities who developed AIN after 9 days of vancomycin therapy for a methicillin-resistant Staphylococcus aureus infection from infective endocarditis. His serum creatinine rose from 1.2 to 5.5 mg/dL, correlating with a supratherapeutic vancomycin level (40 mcg/mL). Despite stopping vancomycin, his renal function continued to worsen, leading to a diagnosis of AIN confirmed by renal biopsy. Despite high-dose corticosteroids, haemodialysis was required to stabilise renal function, emphasising the importance of early monitoring of vancomycin levels to mitigate nephrotoxicity risks.