Infectious Diseases

	Answer 4 S. aureus colonization is common and affects as many as 20% to 40% of the US population. Individuals can harbor S. aureus without showing signs of infection.8 As many as 20% to 40% of Americans are colonized with S. aureus,9 with variable rates of colonization among different segments of the population (related to age, sex, and race/ethnicity). The anterior nares are the most frequent sites of staphylococcal colonization, although the groin, rectum, axilla, and umbilicus as well as wounds, chronic skin lesions, and foreign bodies also are possible sites. During outbreaks of MRSA, the environment does not play a significant role in transmission. MRSA is transmitted most frequently through direct skin-to-skin contact;10 however, the use of shared equipment or other personal items that are not cleaned or laundered between users could be a vehicle for S. aureus transmission. Although patients with breaks in the skin are predisposed to skin and soft tissue infections when they are colonized with S. aureus, infection can manifest in various settings. It has been postulated that the minor skin trauma and abrasions incurred during physical activity, particularly while participating in contact sports or from rubbing against athletic equipment, may explain outbreaks seen in athletic facilities and teams. REFERENCE 9. von Eiff C, Becker K, Machka K, et al. Nasal carriage as a source of Staphylococcus aureus bacteremia. Study Group. N Engl J Med 2001;344:11-6. 10. Centers for Disease Control and Prevention (CDC). Community-associated MRSA information for the public. Available at www.cdc.gov/ncidod/dhqp/ar_mrsa_ca_public.html#10. Accessed 3 Mar 2008. Click here to return to the questions
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