Vancomycin-Resistant Staphylococcus aureus - Delaware, 2015.

Vancomycin-resistant Staphylococcus aureus (VRSA) is a rare, multidrug-resistant bacterium of public health concern that emerged in the United States in 2002. VRSA (S. aureus with vancomycin minimum inhibitory concentration [MIC] ≥16 μg/mL) arises when vancomycin resistance genes (e.g., the vanA operon, which codes for enzymes that result in modification or elimination of the vancomycin binding site) from vancomycin-resistant enterococci (VRE) are transferred to S. aureus (1). To date, all VRSA strains have arisen from methicillin-resistant S. aureus (MRSA). The fourteenth VRSA isolate (VRSA 14) identified in the United States was reported to CDC in February 2015.