MRSA感染的患病率在美国和全球都日益升高。[4]Crum NF, Lee RU, Thornton SA, et al. Fifteen-year study of the changing epidemiology of methicillin-resistant Staphylococcus aureus. Am J Med. 2006;119:943-951.http://www.ncbi.nlm.nih.gov/pubmed/17071162?tool=bestpractice.com[5]Styers D, Sheehan DJ, Hogan P, et al. Laboratory-based surveillance of current antimicrobial resistance patterns and trends among Staphylococcus aureus: 2005 status in the United States. Ann Clin Microbial Antimicrob. 2006;5:2.http://www.ann-clinmicrob.com/content/5/1/2http://www.ncbi.nlm.nih.gov/pubmed/16469106?tool=bestpractice.com[6]Zinn CS, Westh H, Rosdahl VT; Sarisa Study Group. An international multicenter study of antimicrobial resistance and typing of hospital Staphylococcus aureus isolates from 21 laboratories in 19 countries or states. Microb Drug Resist. 2004;10:160-168.http://www.ncbi.nlm.nih.gov/pubmed/15256032?tool=bestpractice.com美国原住民和太平洋岛屿居民发生社区相关性 MRSA 的风险更高。相比于白人和其他人种,非洲裔美国人感染侵袭性社区相关性 MRSA 和医院相关性 MRSA 的风险更高。CDC: MRSA homepage[7]Klevens RM, Morrison MA, Nadle J, et al. Invasive methicillin-resistant Staphylococcus aureus infections in the United States. JAMA. 2007;298:1763-1771.http://jama.ama-assn.org/cgi/content/full/298/15/1763http://www.ncbi.nlm.nih.gov/pubmed/17940231?tool=bestpractice.com在美国, MRSA 携带者的患病率约在 1% 到 2% 之间。MRSA 携带相关的危险因素包括:近期住院史、近期曾于门诊就诊、看护中心暴露、合并慢性疾病、非法使用静脉毒品或与有已知危险因素的人群接触。在美国,对于无医疗卫生相关危险因素者,MRSA 定植的流行率估计为 1.25%。[8]Gorwitz RJ, Kruszon-Moran D, McAllister SK, et al. Changes in the prevalence of nasal colonization with Staphylococcus aureus in the United States, 2001-2004. J Infect Dis. 2008;197:1226-1234.http://www.ncbi.nlm.nih.gov/pubmed/18422434?tool=bestpractice.com儿童和年轻成人(中位年龄 22 岁)通常更易感染社区相关性 MRSA,而老人(中位年龄 64 岁)则更易罹患医院相关性 MRSA 感染。[4]Crum NF, Lee RU, Thornton SA, et al. Fifteen-year study of the changing epidemiology of methicillin-resistant Staphylococcus aureus. Am J Med. 2006;119:943-951.http://www.ncbi.nlm.nih.gov/pubmed/17071162?tool=bestpractice.com[9]Elston DM. Community-acquired methicillin-resistant Staphylococcus aureus. J Am Acad Dermatol. 2007;56:1-16.http://www.ncbi.nlm.nih.gov/pubmed/17190619?tool=bestpractice.com[10]Naimi TS, LeDell KH, Como-Sabetti K, et al. Comparison of community- and health care-associated methicillin-resistant Staphylococcus aureus infection. JAMA. 2003;290:2976-2984.http://jama.ama-assn.org/cgi/content/full/290/22/2976http://www.ncbi.nlm.nih.gov/pubmed/14665659?tool=bestpractice.com定植被认为发生于 MRSA 感染之前,因此,是侵袭性 MRSA 感染的一个危险因素。MRSA 定植的主要部位是前鼻孔,但也可定植于非鼻孔部位(例如咽喉、腋窝、腹股沟区和直肠周围区域)。