At a glance

Also known as

MRSA

Why get tested?

To detect MRSA colonisation; to evaluate for clearance of MRSA bacteria to ensure you no longer carry MRSA if you were previously found to have that organism colonising you or causing an infection

When to get tested?

When your doctor wants to determine if you are colonised with MRSA, often on admission to a health care unit (eg hospital, renal dialysis unit); following prior MRSA colonisation or infection

Sample required?

Swab of nose; occasionally swab of wound infection site or skin lesion, axilla or groin

Test preparation needed?

None

What is being tested?

These tests detect the presence of methicillin resistant Staphylococcus aureus (MRSA). MRSA are strains of Staphylococcus aureus bacteria, sometimes called golden staph, which are resistant to all of the ß lactam class of antibiotics such as flucloxacillin and cephalexin. These antibiotics are commonly used to treat infections caused by Staphylococcus aureus. First appearing in the early 1960s, MRSA cases and outbreaks were a problem in confined populations such as hospitals, prisons and nursing homes. While they continue to be an issue in hospitals and institutions, they have now spread to the wider community. MRSA is often spread by people who are carriers – they have the organism on their body. 

Screening is performed to determine whether someone is carrying MRSA so that measures can be taken to avoid its spread.
 

How is the sample collected for testing?

A swab is collected from a site suspected of harbouring MRSA; for example, from the inside of each nostril, the armpit(s), groin or a wound or skin lesion.
 

Is any test preparation needed to ensure the quality of the sample?

No test preparation is needed.

The Test

How is it used?

An MRSA screen is a test that looks solely for the presence of MRSA and no other pathogens. It is primarily used to identify someone who may be colonised with MRSA. Reasons for screening include determining whether extra precautions are required to ensure the bacteria are not spread, or occasionally to identify the source of an outbreak.

The most widely used test to identify MRSA colonisation is culture. This confirms the presence of MRSA and allows the organisms to be further characterised, however culture often takes one to two days to yield a result.

The material from the swab is put onto a special nutrient medium then incubated in an environment that encourages the bacteria to grow. It is then examined for MRSA colonies. 

Some hospitals have instituted measures to control the spread of MRSA by screening patients they feel are at risk, other hospitals screen all new admissions. When an outbreak of MRSA is under investigation, screening of health care workers, family members and close contacts may be performed to identify the potential source of infection and to help devise a plan of containment. In some settings, such as nursing homes, a large number of people may be screened.

Faster methods of MRSA screening by molecular methods have been developed. These new methods test for the mecA gene that confers resistance to the ß-lactam antibiotics. Molecular tests for MRSA screening have the potential to provide results within hours instead of the days required by culture and are being used more commonly. 

When is it requested?

A MRSA screening test may be ordered when a doctor, hospital, community health department, or researcher wants to evaluate potential MRSA colonisation in an individual, their family members, and/or a group of people in the community as the source of a MRSA infection. A person who has been treated for MRSA infection or for MRSA colonisation will often be screened several times to determine whether MRSA is still present or whether the person has "cleared" their carriage.

What does the test result mean?

If MRSA is detected from a screening swab, the person is colonised with MRSA.  Failure to detect MRSA from a screening swab means that MRSA is either not present or is present in numbers too low to be detected by the test. If this is following treatment or eradication of MRSA in someone, several swabs will be collected over time and the repeated failure to detect MRSA will tell the healthcare team that this person has cleared their carriage of MRSA. 

Is there anything else I should know?

Further testing may be performed on MRSA bacteria when they are isolated in a culture. These additional research tests can identify the type and subtype of S. aureus strains. Although the typing may not be used to determine treatment of the patient, it provides information to track the pattern of disease spread of the infection and characterise the toxins and other virulence factors present in the bacteria.

Common Questions

Can I get MRSA more than once?

Yes, being successfully treated for MRSA colonisation does not prevent you from getting it again.

Can I be colonised with MRSA and not know it?

Yes, those people who are carriers are often healthy individuals who have no signs or symptoms of infection.

Can I get rid of the MRSA if I am colonised with it?

In certain settings, an antimicrobial ointment may be applied or an antiseptic body wash may be used. It is thought that eliminating carriage may protect a patient from MRSA infection following, for example, cardiac surgery, and/or prevent them spreading MRSA.

How can I protect myself from getting a MRSA infection?

Standard hygiene practice can reduce your risk of becoming colonised or infected with MRSA. You should wash your hands frequently, avoid sharing personal items, such as towels, soap, or equipment, and always cover an open wound with a protective bandage.


Last Review Date: October 13, 2016