Risk factors for community-associatedStaphylococcus aureusinfections: results from parallel studies including methicillin-resistant and methicillin-sensitiveS. aureuscompared to uninfected controls

Abstract

SUMMARYDespite the increasing burden of community-associated methicillin-resistantStaphylococcus aureus(CA-MRSA) infections, the risk factors are not well understood. We conducted a hypothesis-generating study using three parallel case-control studies to identify risk factors for CA-MRSA and community-associated methicillin-susceptibleS. aureus(CA-MSSA) infections. In the multivariate model, antimicrobial use in the 1–6 months prior to culture was associated with CA-MRSA infection compared to CA-MSSA [adjusted odds ratio (aOR) 1·7,P=0·07] cases. Antimicrobial use 1–6 months prior to culture (aOR 1·8,P=0·04), history of boils (aOR 1·6,P=0·03), and having a household member who was a smoker (aOR 1·3,P=0·05) were associated with CA-MRSA compared to uninfected community controls. The finding of an increased risk of CA-MRSA infection associated with prior antimicrobial use highlights the importance of careful antimicrobial stewardship.