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Methicillin-resistant Staphylococcus aureus: MRSA (S. aureus)


Staphylococci, including Staphylococcus aureus (S. aureus), are bacteria usually found on people’s skin or in their noses. Although generally harmless in healthy people, staphylococci can sometimes cause infections. These staph infections are then treated with an antibiotic.

Methicillin-resistant Staphylococcus aureus, known as MRSA (or “Mursa”), is a staphylococcus that has become resistant to a number of antibiotics, including methicillin. Given that this antibiotic is not effective for treating MRSA infections, this limits the choice of treatment.  MRSA causes the same infections as other staphylococci.

The risk of exposure to MRSA is greater in healthcare facilities. However, MRSA strains are present in the community and can spread within groups of people in close contact with one another, such as athletes who play contact sports and people who inject illicit drugs.

People at risk

Healthcare facilities, especially hospitals, are places conducive to S. aureus infections, because of the type of care they provide. In healthcare facilities, the people who are most at risk of being colonized (carriers) or infected with MRSA are:

  • people recently treated with antibiotics
  • people sharing their care area with another person who is a MRSA carrier or infected with it.
  • people living with chronic conditions, such as diabetes or cancer, or people who have weakened immune systems.
  • people who have had surgery or who use a medical device, such as an intravenous catheter or a urinary catheter
  • people with surgical wounds
General notice

Taking antibiotics, while necessary for treating infections, disrupts all the bacteria in the body, the good as well as the bad. Because this natural barrier has been weakened, it is much easier for a micro-organism such as MRSA to colonize or infect a person. In the event of a MRSA infection, the doctor will choose antibiotics that are effective against the bacterium.


A person can be a MRSA carrier without being sick or showing any signs or symptoms of infection. Being a MRSA carrier does not pose a risk to healthy people and does not require any treatment.

In infected people, MRSA can cause a skin or wound infection or, very rarely, pneumonia, a bloodstream infection or meningitis.

When such symptoms appear, a specimen (from a wound or a blood sample) may be collected to determine if MRSA is the cause.


Depending on the type of infection and the test results, the doctor will choose effective antibiotics and will prescribe the appropriate treatment. Most people recover from this infection.


Depending on its nature, a MRSA infection may result in serious complications, such as pneumonia, a bone infection or a bloodstream infection. Some may even be life threatening for infected people.


MRSA is mainly spread through direct contact with the contaminated hands of a carrier, an infected person, or healthcare personnel, or with contaminated surfaces and objects.

Healthcare facilities, especially hospitals, are places conducive to staph infections. In fact, the insertion of I.V. and urinary catheters, along with surgeries, are procedures that enable bacteria to enter the bloodstream and wounds.

A person can be a MRSA carrier for many months and sometimes even a few years.

The risk that a carrier may spread MRSA to other household members is low if they are healthy.

Protection and prevention

Hygiene practices

To prevent the spread of MRSA, adopt these hygiene practices:

  • Wash your hands often with water and soap or an antiseptic. This practice, which is the easiest and most effective, must be applied not only by carriers or infected people but also by the members of their households.
  • Do not use the personal items of a carrier or infected person, including towels and razors.
  • Use regular household cleaning products to clean the areas and objects potentially contaminated by the carrier or infected person
  • Make sure to keep wounds clean and covered, as directed by your healthcare professional. Dispose of soiled dressings in a sealed plastic bag. Then wash your hands.
  • Make sure that a carrier or infected person maintains good personal hygiene by bathing with water and soap or by having them take a shower.
  • Wash a carrier’s or infected person’s clothing and bed linen in a washing machine with warm or hot water and household laundry detergent

If you receive home care or have appointments in a healthcare facility or medical clinic, inform the healthcare staff that the person you are accompanying or you yourself are a carrier or infected with MRSA. During the treatment, the staff may need to wear gloves and a protective gown to avoid spreading the bacteria to other people.

Measures in healthcare facilities

Any hospital that admits or identifies a carrier or a person infected with MRSA must put in place different measures:

  • Isolate the person in a private room or in a room with other patients who are MRSA carriers or infected with MRSA.
  • Clean and disinfect the carrier’s or infected person's room and bathroom more frequently.
  • Clean and disinfect all healthcare equipment not reserved for the person, and clean and disinfect any item that will be taken out of the room (e.g., wheelchair, walker).
  • Require staff and visitors to wear gloves and long-sleeved gowns, depending on the situation.
  • Post a sign on the door of the carrier’s or infected person’s room to remind staff and visitors to wash their hands and follow the measures put in place.

These measures must be maintained until laboratory test results show that the person is no longer a MRSA carrier.

In long-term care or rehabilitation centres, measures are adapted to the facility and the person's condition.

Information about MRSA should be given to carriers or infected people, including the measures to follow when they return home. Before leaving the healthcare facility, patients must inform their doctor or the healthcare professional if another person at home is ill or has a weakened immune system. Additional measures may be needed at home to protect that person.

Noteworthy information

The surveillance of bacteremia (infections, bacteria in the bloodstream) caused by MRSA has been mandatory in Québec hospitals since 2006. This surveillance program, introduced by the Ministère de la Santé et des Services sociaux, is part of the provincial program for the surveillance of healthcare-associated infections.  These infections are acquired during episodes of care provided by a healthcare professional, regardless of the facility that administered the care.

In addition, MRSA outbreaks in Québec healthcare facilities must be reported to public health authorities.

Last update: October 16, 2023


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