Vancomycin and Oxacillin Synergy for Methicillin-Resistant Staphylococci

An increase in oxacillin activity was observed against methicillin-resistant coagulase-negative staphylococci (MRCNS) and methicillin-resistant Staphylococcus aureus (MRSA) in the presence of a sub-MIC of vancomycin. Vancomycin and oxacillin were synergistic against 14 of 21 strains of MRCNS and MRSA. A pattern of enhanced killing was also supported by time-kill studies. These results suggest that combinations of sub-MICs of vancomycin and oxacillin may have therapeutic benefits against methicillin-resistant staphylococci.