tailieunhanh - Chapter 129. Staphylococcal Infections (Part 2)

S. aureus Infections Epidemiology S. aureus is a part of the normal human flora; ~25–50% of healthy persons may be persistently or transiently colonized. The rate of colonization is higher among insulin-dependent diabetics, HIV-infected patients, patients undergoing hemodialysis, and individuals with skin damage. The anterior nares are the most frequent site of human colonization, although the skin (especially when damaged), vagina, axilla, perineum, and oropharynx may also be colonized. These colonization sites serve as a reservoir of strains for future infections, and persons colonized with S. aureus are at greater risk of subsequent infection than are uncolonized individuals. . | Chapter 129. Staphylococcal Infections Part 2 5. aureus Infections Epidemiology S. aureus is a part of the normal human flora 25-50 of healthy persons may be persistently or transiently colonized. The rate of colonization is higher among insulin-dependent diabetics HIV-infected patients patients undergoing hemodialysis and individuals with skin damage. The anterior nares are the most frequent site of human colonization although the skin especially when damaged vagina axilla perineum and oropharynx may also be colonized. These colonization sites serve as a reservoir of strains for future infections and persons colonized with S. aureus are at greater risk of subsequent infection than are uncolonized individuals. Overall S. aureus is a leading cause of nosocomial infections. It is the most common cause of surgical wound infections and is second only to CoNS as a cause of primary bacteremia. Increasingly nosocomial isolates are resistant to multiple drugs. In the community S. aureus remains an important cause of skin and soft tissue infections respiratory infections and among injection drug users infective endocarditis. The increasing prevalence of home infusion therapy is another cause of community-acquired staphylococcal infections. Most individuals who develop S. aureus infections are infected with their own colonizing strains. However S. aureus may also be acquired from other people or from environmental exposures. Transmission most frequently results from transient colonization of the hands of hospital personnel who then transfer strains from one patient to another. Spread of staphylococci in aerosols of respiratory or nasal secretions from heavily colonized individuals has also been reported. In the past 10 years numerous outbreaks of community-based infection caused by methicillin-resistant S. aureus MRSA in individuals with no prior medical exposure have been reported. These outbreaks have taken place in both rural and urban settings in widely separated regions