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Staph Wound Infections and Methicillin Resistant Staphylococcus aureus

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Also known as: Staph; Staph aureus; MRSA (pronounced "Mursuh")

What are staph wound infections?

Staphylococcus aureus, also called S. aureus or "staph," is a bacterium that frequently colonizes the human skin and is present in the nose of about 25-30% of U.S. 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 if there is a suppression of a person's immune system, then colonizing S. aureus can cause an infection.

Staph frequently causes localized skin infections, such as infected hair follicles or boils (folliculitis, furuncles), and impetigo. It can also cause abscesses and spread into the bones (osteomyelitis), lungs (staphylococcal pneumonia), blood (bacteremia or sepsis), heart (endocarditis), and other organs. Staph may also infect others as it can be passed from both infected and colonized people to other people through skin contact or through sharing contaminated objects, such as towels or razors.

Healthcare-associated infections
Staph infections that are acquired while a person is in a hospital, long-term care facility, or other health care setting have been a challenge for many years. The confined population and the widespread use of antibiotics have led to the development of antibiotic-resistant strains of S. aureus. These strains 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 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-colonized patient or health care worker, being in the hospital more than 48 hours, and having an indwelling catheter or other medical device that goes through the skin. 

Community-acquired infections
MRSA infections have increased in importance in the community in 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: 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. A significant number of those affected have had to be hospitalized for what appears to be a simple but persistent skin infection or for pneumonia that develops after a bout of influenza.

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 over-the-counter triple-antibiotic ointments or, when more severe, with a standard course of antibiotics. They did not routinely order cultures to identify the microorganism and its antibiotic susceptibility profile unless the infection appeared extensive or the initial treatment was unsuccessful. With CA-MRSA, however, these conventional therapies have frequently failed. A significant number of those affected have required hospitalization and a few previously healthy people have died.

Investigations of these outbreaks have revealed that the CA-MRSA was spread from infected or colonized 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 healthcare-associated MRSA; they are genetically distinct. The CA-MRSA are resistant to methicillin and related antibiotics (oxacillin, dicloxacillin, nafcillin) and erythromycin but remain susceptible to many other antibiotics.

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