Preferential emergence of reduced vancomycin susceptibility in health care-associated methicillin-resistant Staphylococcus aureus isolates during continuous-infusion vancomycin therapy in an in vitro dynamic model.

Bacterial killing and the development of reduced vancomycin susceptibility during continuous-infusion vancomycin (CIV) therapy were dependent on the area under the concentration-time curve over 24 h divided by the MIC (ƒAUC(24)/MIC), with values of ≥ 240 (equivalent total serum AUC(24)/MICs of ≥ 480) being bactericidal and suppressing emerging resistance in methicillin-resistant Staphylococcus aureus (MRSA). Also, vancomycin therapy was less likely to be bactericidal and 4.4 times more likely to lead to reduced vancomycin susceptibility in health care-associated MRSA than in community-associated MRSA.