National Center for Biotechnology Information NCBI NLM MEDLINE humans pubmed abstract nih national institutes of health national library of medicine research support u.s. gov't adult adolescent aged middle aged Child Infant P.H.S. preschool risk factors Incidence anti-bacterial agents / therapeutic use community-acquired infections / epidemiology community-acquired infections / microbiology methicillin resistance* population surveillance staphylococcal infections / microbiology georgia / epidemiology staphylococcal infections / epidemiology* staphylococcus aureus* / drug effects drainage african continental ancestry group european continental ancestry group staphylococcal infections / therapy minnesota / epidemiology baltimore / epidemiology community-acquired infections / therapy pmid:15814879 doi:10.1056/nejmoa043252 scott k fridkin jeffrey c hageman active bacterial core surveillance program of the emerging infections program network endemic diseases / statistics & numerical data staphylococcus aureus* / isolation & purification