A comparison of clinical outcomes between healthcare-associated infections due to community-associated methicillin-resistant Staphylococcus aureus strains and healthcare-associated methicillin-resistant S. aureus strains.

There are limited data examining whether outcomes of methicillin-resistant Staphylococcus aureus (MRSA) healthcare-associated infections (HAIs) are worse when caused by community-associated (CA) strains compared to HA strains. We reviewed all patients' charts at our institution from 1999 to 2009 that had MRSA first isolated only after 72 h of hospitalization (n=724). Of these, 384 patients had a MRSA-HAI according to CDC criteria. Treatment failure was similar in those infected with a phenotypically CA-MRSA strain compared to a phenotypically HA-MRSA strain (23% vs. 15%, P=0.10) as was 30-day mortality (16% vs. 19%, P=0.57). Independent risk factors associated with (P<0.05) treatment failure were higher Charlson Comorbidity Index, higher APACHE II score, and no anti-MRSA treatment. These factors were also associated with 30-day mortality, as were female gender, older age, MRSA bloodstream infection, MRSA pneumonia, and HIV. Our findings suggest that clinical and host factors, not MRSA strain type, predict treatment failure and death in hospitalized patients with MRSA-HAIs.