Antimicrobial Drug Use and Resistant Staphylococcus Aureus in a Network of Academic Medical Center Hospitals.

Hospitalized patients can become infected with a variety of microorganisms, but infections caused by Staphylococcus aureus (i.e., "staph" infections) are particularly common. The main strategy to reduce the number of patients infected with Staph. aureus is to decrease cross-transmission from one patient to another. In addition, increasing evidence suggests that improvements in antimicrobial drug use--promoted by hospital Antimicrobial Stewardship programs (ASPs) -- may also favorably impact rates of Staph. aureus infections. While many Staphylococcal strains remain susceptible to an old drug called methicillin (methicillin-susceptible Staph aureus, or MSSA), many Staph. aureus are methicillin-resistant (MRSA). The drug of choice for MRSA has historically been vancomycin, and vancomycin is now the most commonly prescribed antibiotic in US teaching hospitals. Vancomycin-resistant Staph. aureus (VRSA) is still uncommon, but some Staph. aureus are developing "low level" resistance to vancomycin. These strains are often called S. aureus with MIC "creep" to vancomycin (SA-MICcreep), and Staphylococcus aureus with Heterogeneous Resistance to Vancomycin (hVISA), but the epidemiology, clinical significance and risk factors for these organisms are not well described. We will survey UHC participating hospitals to learn more about these organisms, the drug and ASP related risk factors, and whether hospitals are trying to identify these organisms.