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What is methicilllin-resistant Staphylococcus aureus (MRSA)?

Methicillin-resistant Staphylococcus aureus (MRSA) is a bacterium that is resistant to (unaffected by) many commonly used antibiotics. MRSA commonly causes skin infections and can rarely cause serious infections.

Once seen mostly in the healthcare setting, MRSA has more recently emerged as a threat in the community as well. In the community, most MRSA infections are skin infections. When MRSA develops in a healthcare setting, it can cause life-threatening infections of the bloodstream, pneumonia, and infections where a surgical incision is made.

What is Staphylococcus aureus?

Staphylococcus aureus is a bacterium that commonly lives in the nostrils. According to the U.S. Centers for Disease Control and Prevention, about one-third of people carry this bacterium in their nose, mostly without any harm. When this bacterium becomes resistant to commonly used antibiotics, such as methicillin and its related antibiotics, it is called MRSA.

The number of people who get MRSA skin infections in the community is not known. Children can carry MRSA in the nose as well as in the groin area and other sites. The rate of MRSA carriage in children has increased in recent years, and it is common for healthy adults and children to carry MRSA. In most cases, this does not cause any problems.

How is methicilllin-resistant Staphylococcus aureus (MRSA) spread in the community?

MRSA can be spread during activities that involve touching or skin-to-skin contact, such as in household settings, athletics (for example, wrestling and football) and day care. One way of getting MRSA is to make direct contact with a wound infected with MRSA. Also, if someone with a wound infected with MRSA wipes the wound with a towel or other item, the bacteria will spread to that item. Anyone who comes into contact with it risks getting MRSA.

Locker rooms, dorms, schools, and day care centers are especially likely areas for spread of MRSA because there is close person-to-person contact in these settings. Sharing any items with someone who was recently in the hospital or other inpatient setting can also spread MRSA if the hospitalized person came into contact with MRSA.

In a study of patients with MRSA skin infections who were seen in the emergency department, the authors found that the risk of community-acquired MRSA was higher in those who:

  • Used an antibiotic in the past month;
  • Had a history of MRSA infection; or,
  • Had close contact with a person with a similar infection.

Other studies have found that one or more hospital admissions, a recent nursing home admission, or a chronic (long-term) illness increased the risk.