Overview of MRSA Infection

Methicillin-resistant Staphylococcus aureus (MRSA) is a type of bacteria that is resistant to certain antibiotics, including methicillin, penicillin, and amoxicillin. Infection with Staphylococcus bacteria often is referred to as a "staph infection." MRSA infection is a specific type of staph infection that is difficult to treat and can be life threatening. The spread of MRSA is a serious, worldwide health problem.

According to the National Institutes of Health (NIH), the Centers for Disease Control and Prevention (CDC), and the World Health Organization (WHO), approximately 30% of people normally have Staphylococcus aureus (S. aureus) bacteria on the skin surrounding mucous membranes (e.g., nose, anus, vagina). These bacteria are usually harmless; however, if they enter the body (e.g., through a cut or break in the skin, or a surgical wound), they can cause staph infection.

Staph infections can be mild and localized or severe and widespread. They usually originate in hair follicles and affect the skin and soft tissues (e.g., muscle, connective tissue). Staph infections often cause pimple-like sores or lesions that may resemble infected insect or spider bites.

Most staph infections are treated successfully with antibiotics. Methicillin-resistant Staphylococcus aureus infections do not respond to antibiotics that are commonly used to treat staph infections. MRSA infections often result in tissue death (necrosis) and cause other serious complications.

Patients who have a medical condition that weakens the immune system (e.g., HIV/AIDS, cancer, lupus), patients who have recently undergone a medical procedure (e.g., surgery, catheterization, dialysis), and patients in hospitals or other long-term health care facilities (e.g., nursing homes, dialysis centers) are at increased risk for developing staph infections, including MRSA. This type of methicillin-resistant Staphylococcus aureus infection is called health care-associated MRSA (HA-MRSA).

Recently, MRSA infections have increased in the general population (e.g., people who have not been hospitalized or undergone a medical procedure within the past year). This type of methicillin-resistant Staphylococcus aureus infection is called community-associated MRSA (CA-MRSA).

Community-associated MRSA can spread in a number of different settings, including childcare, health clubs, military barracks, and prisons. This type of MRSA infection often is transmitted through skin-to-skin contact or contact with contaminated items, such as towels, exercise equipment, and razors. Recently, the rate of MRSA infection has increased in men who have sex with men (MSM).

Publication Review By: Stanley J. Swierzewski, III, M.D.

Published: 20 Feb 2008

Last Modified: 16 May 2011