ASSOCIATION OF VANCOMYCIN SERUM CONCENTRATIONS WITH OUTCOMES IN PATIENTS WITH GRAM-POSITIVE BACTEREMIA

We attempted to determine if an association exists between vancomycin serum concentrations resulting from traditional dosing regimens, and e fficacy and toxicity outcomes. We reviewed the medical charts of 273 c onsecutive patients prescribed 273 courses of vancomycin therapy for d ocumented, gram-positive bacteremia. Of the 273 courses of therapy, 45 and 31 patients met all criteria and were evaluated for toxicity and efficacy, respectively The duration of fever and abnormal white blood cell counts, length of hospital stay, overall mortality, serum creatin ine, and serum vancomycin concentrations were evaluated retrospectivel y No association between initial peak or trough levels with mortality was noted. However, patients were more likely to become afebrile withi n 72 hours if peak and trough concentrations were 20 mu g/ml or greate r and 10 mu g/ml or greater, respectively (p<0.01). Patients were also more likely to have their white blood cell count return to normal wit hin 72 hours if trough concentrations were 10 mu g/ml or above (p<0.01 ). No statistically significant correlation between nephrotoxicity and initial serum creatinine, days of hospital stay, or days of vancomyci n therapy were found. Serum concentrations of vancomycin, assessed bef ore the development of nephrotoxicity, were significantly higher in pa tients who became nephrotoxic. Mean (SD) trough concentrations were 23 .2 (2.5) mu g/ml and 10.2 (3.8) mu g/ml in nephrotoxic and nonnephroto xic patients, respectively. Our results suggest that the commonly acce pted therapeutic range for vancomycin trough concentrations (<10 mu g/ ml) may be too restrictive in patients receiving vancomycin therapy al one.