LAUSR

The ability of vancomycin-arginine (V-r) to extend the spectrum of activity of glycopeptides to Gram-negative bacteria was investigated. Its MIC toward Escherichia coli, including β-lactamase expressing Ambler classes A, B, and D, was 8 to 16 μg/ml. ABSTRACT The ability of vancomycin-arginine (V-r) to extend the spectrum of activity of glycopeptides to Gram-negative bacteria was investigated. Its MIC towards Escherichia coli, including β-lactamase expressing Ambler classes A, B, and D, was 8 to 16 μg/ml. Addition of 8 times the MIC of V-r to E. coli was acutely bactericidal and associated with a low frequency of resistance (<2.32 × 10−10). In vivo, V-r markedly reduced E. coli burden by >7 log10 CFU/g in a thigh muscle model. These data warrant further development of V-r in combatting E. coli, including resistant forms.