Nephrotoxicity of vancomycin in infective endocarditis: a retrospective analysis

Introduction

Infective endocarditis (IE) is a life-threatening condition requiring prompt and effective antimicrobial therapy. Vancomycin is one of the most often used antibiotic drugs to treat IE. However, nephrotoxicity is a concern given the relevant morbidity associated with it, requiring regular dose adjustments.

Purpose

To assess the association between vancomycin treatment and acute kidney injury (AKI) in patients with IE.

Methods

Retrospective study of 30 patients admitted for IE and treated with vancomycin in a Cardiology Department, over a 5-year period. Baseline characteristics, laboratory results, vancomycin dosages and trough levels were obtained. Vancomycin levels ≥21 µg/mL were categorized as supratherapeutic. Timely vancomycin dose adjustment was defined as appropriate dose modifications accordingly to drug monitoring results within 24 hours. AKI was diagnosed according to the KDIGO criteria. Statistical analysis included Chi-square and Mann-Whitney U.

Results

Mean age of 70 ± 12 years; 66.7% were male. Chronic kidney disease (CKD) was present in 30% (n=9) and mean admission creatinine was 1.35 mg/dL. In-hospital mortality was 23.3% (n=7). AKI occurred in 50% (n=15) of patients. Only 33.3% (n=10) of patients had timely vancomycin dose adjustments and 50% had supratherapeutic vancomycin levels on the first measurement. Patients without timely vancomycin dose adjustments (87.5% vs. 10%, χ² = 15.143, p < 0.001), atrial fibrillation (76.9% vs. 29.4%; χ² = 6.652, p = 0.01), treated with diuretics (75% vs. 35.7%; χ² = 4.013, p = 0.045) and with supratherapeutic vancomycin trough levels at the third measurement (91.7% vs. 20.0%; χ² = 8.731, p = 0.001) had a significantly higher prevalence of AKI.

Additionally, vancomycin levels at the second and third measurements were significantly higher in patients with AKI (32 µg/mL vs. 20 µg/mL, p = 0.037; 30 µg/mL vs. 18 µg/mL, p = 0.019, respectively). Discharge creatinine levels remained increased in the AKI group (2.17 mg/dL vs. 1.39 mg/dL, p = 0.029).

Additionally, patients with AKI had a significantly longer duration of vancomycin therapy (40 vs. 9 days, p = 0.003). While gentamicin use showed a near-significant trend (p = 0.065), no significant associations were observed for previous CKD (p = 0.7), HF (0.251), DM (p=1) or concomitant radiocontrast use (p = 0.396).

In-hospital mortality was 23.3%, and it was not significantly higher in those who developed AKI (p=0.390).

Conclusion

In patients with IE treated with vancomycin, we observed a higher incidence of AKI than typically reported in the general inpatient population. However, this did not contribute to additional in-hospital mortality. Our findings emphasize the importance of close vancomycin monitoring and timely adjustments to prevent AKI. Future studies should explore alternative monitoring strategies and interventions to minimize nephrotoxicity.