An Overview of Methicillin-Resistant Staphylococcus Aureus (MRSA)

hand washing

Staphylococcus aureus is one of a group of bacteria which are directly and indirectly responsible for infections ranging in severity from mild to life-threatening. Staph, as it is commonly called, directly causes infections of the skin and tissues. It can indirectly cause illnesses, such as food poisoning, as a result of the toxins it generates.

A staph infection is traditionally treated with antibiotics, which under normal circumstances work effectively.

However, certain strains of staph have developed genetic mutations which make them resistant to many antibiotic drugs. Such bacteria are referred to as methicillin-resistant staphylococcus aureus (MRSA), meaning that it is resistant to the antibiotics methicillin, oxacillin, amoxicillin, and penicillin.

Causes & Risk

In the U.S. as many as 75,000 cases of MRSA are identified each year. The majority of these infections were seen in people who were hospitalized (85 percent), followed by those living in a nursing home or who have a weakened immune system.

Healthy people who have not been recently hospitalized can also get MRSA. About 14 percent of all MRSA infections fit into this category called community-associated MRSA infections (CA-MRSA). These infections are characterized by such symptom as skin infections, abscesses, boils, and pus-filled lesions.

Does HIV Increase Risk?

While a definitive link between MRSA and HIV has not been established, a study presented at the 2006 International AIDS Conference reported that people with HIV have an 18-fold increase in their risk for CA-MRSA.

Many of these infections appeared clustered around men who have sex with men (MSM), with some suggesting that shared needles (common with crystal methamphetamine use) may contribute to the disproportionately high rate of infection.

Symptoms & Diagnosis

MRSA can be found in many parts of the body, making control a bit more difficult.

Some places you can commonly find MRSA are:

  • Nasal passages (most common)
  • Moist folds in the groins and perineum
  • Surface of the skin, especially the hands
  • In and around the anus
  • Bed linens
  • Clothing
  • Hospital equipment

MRSA is easy to spread from person to person, or by contacting contaminated linen or equipment. For this reason, it is extremely important to observe strict hand-washing and hygiene, including the use of antibacterials.

The most common signs are MRSA are red, swollen and painful blisters or boils which can sometimes contain pus or discharge. More serious infections can spread throughout the body, causing pneumonia, bloodstream infections, or surgical wound septicemia.


Despite its resistance to Methicillin type antibiotics, MRSA is treatable. Strong antibiotics are given intravenously, most commonly vancomycin, which may clear the infection completely from the body.

However, clearance is often difficult, with some individuals becoming asymptomatic "carriers" able to unwittingly spread MRSA to others. As such, antibiotic therapy is often accompanied with the use of antibiotic creams, skin shampoos and soaps to rid any lingering bacteria from skin surfaces.


MRSA is best controlled by avoiding infection.

Because MRSA is related primarily to hospitalizations, the medical profession has placed an emphasis on stopping the spread of MRSA by:

  • Enforcing thorough hand-washing by medical staff
  • Cleansing hands with either an alcohol-based hand gel or antibacterial soap and water between patients
  • Prescribing antibiotic only when absolutely indicated and in line with established antibiotic guidelines
  • Improving the cleaning and inspection of patient care units
  • Caring for people with MRSA in private rooms until the MRSA infection has cleared
  • Establishing an infection control policy regarding MRSA management

Screening hospital patients prior to admission has not been shown to be effective in reducing MRSA risk.

From an individual perspective, people who are hospitalized, have been hospitalized, or have been in contact with a hospitalized individual can reduce their risk of MRSA by taking the following prevention steps:

  • Ensure good overall hygiene, ideally antibacterial soaps and cleanser.
  • Keep cuts and scrapes clean and covered until healed.
  • Avoid contact with other people’s wounds or bandages
  • Do not share clothes or personal care items
  • Make sure that hospital staff washes their hands between patients

And finally, always be certain that any course of antibiotics is completed as prescribed. Never stop early, even if symptoms are fully resolved, as the practice can give rise to antibiotic-resistant bacteria.


Ball, S. "Methicillin-resistant Staphylococcus aureus Infection in a Man with HIV Disease." The AIDS Reader.

U.S. Centers for Disease Control and Prevention. "Community-Associated MRSA Information for the Public."  Atlanta, Georgia.

Harbath, S. "Universal screening for methicillin-resistant staphylococcus aureus at hospital admission and nosocomial infection in surgical patients." JAMA. March 2008; 299(10).

Crum-Cianflone, N.; Hale, B.; Burgi, A.; et al. "Increasing rates of CA-MRSA infection among HIV infected persons." XVI International AIDS Conference; Toronto, Canada.