Clinical and epidemiological factors associated with methicillin resistance in community-onset invasive Staphylococcus aureus infections: prospective multicenter cross-sectional study in Korea.

Abstract

Successful empirical therapy of Staphylococcus aureus infections requires the

ability to predict methicillin resistance. Our aim was to identify predictors of

methicillin resistance in community-onset (CO) invasive S. aureus infections.

Sixteen hospitals across Korea participated in this study from May to December

2012. We prospectively included cases of S. aureus infection in which S. aureus

was isolated from sterile clinical specimens </= 72 hours after hospitalization.

Clinical and epidemiological data were gathered and compared in

methicillin-resistant S. aureus (MRSA) and methicillin-susceptible S. aureus

(MSSA) cases. Community-associated (CA) infections were defined as in previous

studies. In total, there were 786 cases of community-onset S. aureus infection,

102 (13.0%) of which were CA-MRSA. In addition to known risk factors, exposure to

3rd generation cephalosporins in the past 6 months [odds ratio (OR), 1.922; 95%

confidence interval (CI), 1.176-3.142] and close contact with chronically ill

patients in the past month (OR, 2.647; 95% CI, 1.189-5.891) were independent risk

factors for MRSA infection. However, no clinical predictors of CA-MRSA were

identified. Methicillin resistance, CO infection, and appropriateness of

empirical antibiotics were not significantly related to 30-day mortality. MRSA

infection should be suspected in patients recently exposed to 3rd generation

cephalosporins or chronically-ill patients. There were no reliable predictors of

CA-MRSA infection, and mortality was not affected by methicillin resistance.