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Staphylococcus aureus, also called S. aureus or “staph,” is a that frequently the human skin and is present in the nose of about 25-30% of adults. S. aureus can exist in this form without harming its host or causing symptoms. However, if there is a break in someone's skin from a wound or surgery or intravenous access device, or if there is a suppression of a person's , then colonising S. aureus can cause an infection.
Staph frequently causes localised skin infections, such as infected hair follicles or boils (, ), and . It can also cause and spread into the bones (osteomyelitis), lungs (staphylococcal pneumonia), blood ( or sepsis), heart (), and other organs. Staph may also infect others as it can be passed from both infected and colonised people to other people through skin contact or through sharing contaminated objects, such as towels or razors.
Hospital- and health-care acquired infections with Staph have been a challenge for many years. The confined population in hospitals and long-term care facilities combined with the widespread use of antibiotics have led to the development and spread of antibiotic-resistant strains of S. aureus. Staph organisms that are resistant to the beta-lactam antibiotics are called methicillin resistant Staphylococcus aureus (MRSA), named after the antibiotic treatment that was developed in 1960 to treat penicillin-resistant strains. Infections caused by MRSA are frequently resistant to a wide variety of antibiotics (“multi-resistant”) and are associated with significantly higher rates of complications and death (morbidity and mortality), higher health care costs, and longer hospital stays than infections caused by methicillin susceptible S. aureus.
Classic risk factors for MRSA infection in the hospital include surgery, prior antibiotic therapy, admission to intensive care, exposure to a MRSA-colonised patient or health care worker, being in the hospital more than 48 hours, and having an indwelling or other medical device that goes through the skin.
MRSA infections in the community are becoming increasingly important, particularly over the last decade. They have been associated with a growing number of outbreaks and deaths in non-medical settings where individuals are in close contact, such as in contact sports, day care facilities, military units, and prisons. These infections are occurring in people who do not have any of the classic MRSA risk factors. Until recently, part of the problem with community-acquired MRSA (CA-MRSA) has been a lack of awareness, both in the medical community and the general population. Historically, doctors have treated staph infections with a standard course of antibiotics. They did not routinely order to identify the and its antibiotic susceptibility profile unless the infection appeared extensive or the initial treatment was unsuccessful. When treating CA-MRSA, conventional therapies have frequently failed. A number of those affected have required hospitalisation for intravenous antibiotics and a few previously healthy people have died.
Investigations of these outbreaks have revealed that the CA-MRSA was spread from infected or colonised people to those around them through skin contact (such as sports-related cuts and abrasions), respiratory droplets (sneezing or coughing), or through exposure to contaminated objects (such as shared sports equipment, towels, toys, or playground equipment). Investigations also revealed that the S. aureus strains involved in CA-MRSA are not the same strains as those that are causing hospital-acquired MRSA; they are genetically distinct. The CA-MRSA are resistant to methicillin and related antibiotics (dicloxacillin, flucloxacillin, cefalexin) but often remain susceptible to many other antibiotics (“non-multiresistant”).
Last Review Date: August 21, 2012