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Staphylococcus aureus Infection: MRSA


Staphylococcus aureus (S. aureus) is a bacterium that is usually found on people’s skin or in the nose. Generally harmless in healthy people, Staphylococcus aureus can sometimes cause infections. These infections are treated with antibiotics.

Staphylococcus aureus infections frequently occur in healthcare facilities, especially hospitals. Procedures such as venous or urinary catheterization or surgery can promote the entry of bacteria into the bloodstream and wounds.

Methicillin-resistant Staphylococcus aureus, also called MRSA, is a type of staphylococcus that has developed resistance to many antibiotics, including methicillin. This means that methicillin is not effective for treating a MRSA infection. MRSA causes the same infections as other staphylococci. However, the fact that it is resistant to many antibiotics limits the treatment options.

There is a higher risk of exposure to MRSA in a healthcare setting. However, MRSA strains are found in the community and can be spread in groups of people who have close contact with one another, for example, athletes who do contact sports or injection drug users.


A person can be a MRSA carrier without being ill or showing any signs or symptoms of infection. Being a carrier of the bacteria is not a risk for healthy people.

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

If these symptoms occur, a specimen (e.g., from a wound or a blood sample) may be collected. Laboratory testing will determine if MRSA is responsible.


Based on the type of infection and test results, the doctor will determine which antibiotics will be effective and prescribe the appropriate treatment for the infected person. Most patients recover from the infection.


Depending on the nature of the infection, a MRSA infection can lead to serious complications. Some may be life threatening.


MRSA is spread mainly by direct contact with the contaminated hands of a carrier or infected person or those of care providers or with contaminated surfaces and objects. A person can be a MRSA carrier for several months, sometimes even for several years.

The risk of a carrier transmitting MRSA to their family members is very low.

Protection and prevention

Hygiene measures at home

To avoid spreading MRSA at home, take the following hygiene measures:

  • Wash your hands often with soap and water or with an antiseptic product. This is the simplest and most effective measure and must be applied by both the carrier or infected person and their family members;
  • Wash the carrier’s or infected person’s clothes and bed linen in warm or hot water with household laundry detergent;
  • Avoid using a carrier’s or infected person’s personal items, such as a towel or shaver;
  • Use regular household cleaning products to clean the environment and any objects that may have been contaminated by the carrier or infected person;
  • Dispose of dressings soiled with the carrier’s or infected person’s secretions in a sealed plastic bag and wash your hands afterwards.

If you are receiving home care, make sure care providers take special precautions when treating you. Gloves and a gown may be required to avoid spreading the bacteria to other people.

You will find additional hygiene measures on the Preventing transmission of viruses and bacteria page.

Measures put in place in healthcare facilities

If you are having a consultation or are being admitted to hospital, a medical clinic or a nursing home, you must inform the healthcare staff that you are a MRSA carrier.

When a hospital admits a person who is a carrier or is infected with MRSA, various measures must be put in place:

  • Isolate the person in a private room or in a room with other patients who are carriers or are infected with MRSA;
  • Clean and disinfect the carrier’s or infected person's room and bathroom more frequently;
  • 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 members and visitors to wash their hands and follow the measures put in place.

These measures are maintained until laboratory test results show that the patient is no longer a carrier of the bacteria.

When the carrier leaves the healthcare facility, they must inform their doctor or the health professional if another person at home is ill or has a weakened immune system. Additional measures may be necessary at home to protect the person.

In nursing homes, measures are adapted to the setting and the person's condition.

People at risk

In healthcare settings, MRSA infections most commonly affect:

  • people who have a chronic illness, such as diabetes or cancer;
  • people who have had surgery or have an intravenous catheter, for example, for dialysis;
  • people who have a weakened immune system.

Special conditions

Since 2006, surveillance of MRSA infections has been mandatory in Québec hospitals. The surveillance program was established by the Ministère de la Santé et des Services sociaux and is part of the Provincial program for the surveillance of healthcare-associated infections. Healthcare-associated infections are infections acquired during an episode of care provided by a professional in the healthcare network, irrespective of the institution in which the care was provided.

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

Last update: November 23, 2018


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