An article on the possible link between vancomycin trough concentrations and nephrotoxicity appears in a recent issue of Clinical Infectious Diseases (2009;49:507-14) . The article describes a retrospective study of 166 patients treated at Albany Medical Center Hospital in Albany, New York between January 2005 and December 2006. The study found that patients in the ICU, those with a weight of >/= 101 kg, and those with prolonged exposure to elevated vancomycin troughs (> 20mg/L) were associated with a greater risk for developing nephrotoxicity. The authors conclude that the vancomycin trough value was the parameter that best described this risk of toxicity. Based on this information, it appears that successful treatment of serious methicillin-resistant S.aureus infections with higher minimum inhibitory concentrations (MIC) may place patients at a greater risk for developing nephrotoxicity. The findings in the article are significant as recent guidelines recommend higher vancomycin trough concentrations for complicated S.aureus infections.
Although interesting and possibly informative, the information contained in the study is based on a small observational study in a single facility. The findings cannot necessarily be extrapolated to any significant degree to other patient populations and further studies are necessary to confirm the results on a larger scale. For now it appears that aggressive vancomycin therapy in addition to cautious monitoring of renal function and patient status is prudent when trough levels are approaching 20mg/L.