Risk of nephrotoxicity with combination vancomycin-aminoglycoside antibiotic therapy.

One hundred five patients receiving concurrent aminoglycoside and vancomycin therapy of at least 5 days' duration were retrospectively reviewed for development of nephrotoxicity. All had their vancomycin and aminoglycoside serum concentrations controlled by a clinical pharmacokinetics service. Nephrotoxicity occurred in 28 (27%) of the patients. Twenty-two of the 28 had other factors that are known to contribute to renal failure (amphotericin B therapy, sepsis, liver disease, obstructive uropathy, pancreatitis, anesthesia). The remaining six developed nephrotoxicity without other known contributing factors. Logistic regression analysis revealed associations between nephrotoxicity and age, sex, aminoglycoside trough and vancomycin peak and trough serum concentrations, length of aminoglycoside and vancomycin therapy, concurrent amphotericin B therapy, liver disease, neutropenia, and peritonitis (p less than 0.05). In addition to factors previously reported, this study found that neutropenia and peritonitis are associated with an increased risk of nephrotoxicity. Patients with one or more risk factors warrant close monitoring of renal function as well as vancomycin and aminoglycoside serum concentrations.