At a Glance
Why Get Tested?
To determine your methicillin resistant Staphylococcus aureus (MRSA) carrier status
When to Get Tested?
Swab of the nose; occasionally, swab of wound infection site or skin lesion
Test Preparation Needed?
The Test Sample
What is being tested?
Methicillin resistant Staphylococcus aureus (MRSA) are strains of Staphylococcus aureus, or "staph," bacteria that are resistant to the antibiotic methicillin as well as to related "beta lactam" antibiotics such as oxacillin, penicillin, amoxicillin, and cephalosporins that are used to treat ordinary staph infections. These tests detect the presence of MRSA in a patient's sample.
Staphylococcus aureus frequently colonizes the human skin and is present in the nose of about 25-30% of U.S. adults. It does not usually cause harm or symptoms. However, if there is a break in someone's skin from a wound or surgery, or if someone's immune system is weakened, then colonizing S. aureus can cause an infection.
Widespread use of antibiotics over the past several decades have led to the development of antibiotic-resistant strains of S. aureus. Infection with these strains can cause skin infections and potentially more severe, life-threatening infections such as pneumonia, bloodstream infections, or infections at a surgical site. However, according to the Centers for Disease Control and Prevention (CDC), less than 2% of the population carries the type of staph bacteria known as MRSA. [For more on this, see the article Staph Wound Infections and Methicillin Resistant Staphylococcus aureus.]
MRSA can be spread in health care settings and in the community. Contaminated hands, medical equipment, and surfaces in places such as hospitals, clinics, or nursing homes allow the spread of MRSA from colonized or infected patients. In the community, MRSA is usually spread by sharing personal care items, participating in contact sports, or living or working in a place where there is close contact with others – anything that allows for skin-to-skin contact.
Most hospitals have instituted measures to attempt to eradicate MRSA and to control the spread of MRSA from person to person. Nine U.S. states mandate MRSA screening of all patients in the intensive care unit (ICU) of a hospital. Those who test positive for MRSA may be isolated to prevent the spread to others and/or decolonized with a nasal antibiotic ointment and daily cleansing with special antimicrobial wipes. A study comparing prevention strategies for bloodstream infections found, however, that decolonizing ICU patients who are MRSA-positive based on screening tests was not as effective at reducing these infections as decolonizing all patients admitted to the ICU. As a result, hospital policies may change in the future and less MRSA screening may be performed in these settings. However, the state regulatory requirement for MRSA screening would have to be changed before hospitals in those states with the mandate could adopt a "no MRSA screening" policy.
How is the sample collected for testing?
A nasal swab is collected by rotating a swab inside each nostril. Occasionally, a swab of a wound infection site or skin lesion is collected.
NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.
Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.
Is any test preparation needed to ensure the quality of the sample?
No test preparation is needed.
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NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used.
Sources Used for Current Review
Susan S. Huang, et al. Targeted versus Universal Decolonization to Prevent ICU Infection. NEJM 368;24. June 13, 2103.
MayoClinic.com. MRSA infection. Available online at http://www.mayoclinic.com/health/mrsa/DS00735 through http://www.mayoclinic.com. Accessed July 2013.
KidsHealth.org. MRSA. Available online at http://kidshealth.org/parent/infections/bacterial_viral/mrsa.html through http://kidshealth.org. Accessed July 2013.
FamilyDoctor.org. Methicillin-resistant Staphylococcus aureus (MRSA). Available online at http://familydoctor.org/familydoctor/en/diseases-conditions/methicillin-resistant-staphylococcus-aureus-mrsa.html through http://familydoctor.org. Accessed July 2013.
Centers for Disease Control and Prevention. Methicillin-resistant Staphylococcus Aureus (MRSA) Infections. Available online at http://www.cdc.gov/mrsa/ through http://www.cdc.gov. Accessed July 2013.
Sources Used in Previous Reviews
Harbarth, S. et. al. (2006 February 27). Evaluation of Rapid Screening and Pre-Emptive Contact Isolation for Detecting and Controlling Methicillin-Resistant Staphylococcus Aureus in Critical Care, An Interventional Cohort Study. [On-line information]. Available online at http://www.medscape.com/viewarticle/523530 through http://www.medscape.com.
(2005 February 2). Laboratory Detection of: Oxacillin/Methicillin-resistant Staphylococcus aureus. CDC [On-line information]. Available online at http://www.cdc.gov/ncidod/dhqp/ar_lab_mrsa.html through http://www.cdc.gov.
(2005 February 3). Community-Associated MRSA Information for Clinicians. CDC [On-line information]. Available online at http://www.cdc.gov/ncidod/dhqp/ar_mrsa_ca_clinicians.html through http://www.cdc.gov.
(2006 March 7). The Growing Menace of Community-Acquired Methicillin-Resistant Staphylococcus aureus. Annals of Internal Medicine v144 (5).
Seybold, U. et. al. (2006 March 1). Emergence of Community-Associated Methicillin-Resistant Staphylococcus aureus USA300 Genotype as a Major Cause of Health Care-Associated Blood Stream Infections. CID 2006:42 pp 647-654 [On-line journal].
Fridkin, S. (2005 April 7). Methicillin-Resistant Staphyloccus aureus Disease in Three Communities. N Engl J Med 352;14.
Case, M. (2006 March 15). Fast staph test limits spread, at a high price. Post-gazette.com [On-line information]. Available online at http://www.post-gazette.com/pg/pp/06074/670567.stm through http://www.post-gazette.com.
Peck, P. (2006 February 6). Fast MRSA Test Cuts Infection Rate in Medical ICU. Medpage Today [On-line information]. Available online at http://www.medpagetoday.com/tbprint.cfm?tbid=2623 through http://www.medpagetoday.com.
Waknine, Y. (2006 March 31). Highlights from MMWR: Outbreaks of MRSA Infection in Newborns and More [On-line information]. Available online at http://www.medscape.com/viewarticle/528952 through http://www.medscape.com.
Kuehnert, M. et. al. (2005). Methicillin-Resistant Staphylococcus aureus Hospitalizations, United States. Medscape from Emerg Infect Dis 11 (6) [On-line information]. Available online at http://www.medscape.com/viewarticle/505669 through http://www.medscape.com.
Creech II, C. et. al. (2005 July). Increasing Rates of Nasal Carriage of Methicillin-Resistant Staphylococcus aureus in Health Children. The Pediatric Infectious Disease Journal v24 (7) 617-621.
Bradley, S. (2006 February 22). Staphylococcus aureus Pneumonia: Emergence of MRSA in the Community. Medscape from Semin Respir Crit Care Med [On-line information]. Available online at http://www.medscape.com/viewarticle/521338 through http://www.medscape.com.
(2006). "Search and Destroy" Strategy Can Reduce Nosocomial MRSA Prevalence. Medscape from Reuters Health Information [On-line information]. Available online at http://www.medscape.com/viewarticle/527548 through http://www.medscape.com.
(2006). New Test Diagnoses MRSA in One Day. Medscape from Reuters Health Information [On-line information]. Available online at http://www.medscape.com/viewarticle/523635 through http://www.medscape.com.
Goossens, H. (2006). Antibiotic Resistance: Highlights of the 16th European Congress on Clinical Microbiology and Infectious Diseases. Medscape [On-line information]. Available online at http://www.medscape.com/viewarticle/530824 through http://www.medscape.com.
Bartlett, J. (2005). Methicillin-Resistant Staphylococcus aureus and Clostridium difficile - Deal Bacterial Threats. Medscape [On-line information]. Available online at http://www.medscape.com/viewarticle/520186 through http://www.medscape.com.
(2006). Community-Acquired MRSA a Leading Cause of Skin and Soft-Tissue Infections. Medscape from Reuters Health Information [On-line information]. Available online at http://www.medscape.com/viewarticle/524998 through http://www.medscape.com.
David, M. et. al. (2006 April 21). Contrasting Pediatric and Adult Methicillin-resistant Staphylococcus aureus Isolates. Medscape from Emerg Infect Dis 12(4): 631-637. Available online at http://www.medscape.com/viewarticle/529448 through http://www.medscape.com.
(Updated 2009 September 28). Recognize and Prevent MRSA Infections. Centers for Disease Control and Prevention [On-line information]. Available online at http://www.cdc.gov/Features/MRSAInfections/ through http://www.cdc.gov. Accessed March 2009.
(Updated 2009 June 18). FDA Clears First Quick Test For Drug-Resistant Staph Infections, Test Identifies MRSA Bacterium in Two Hours. U.S. [On-line information]. Available online at http://www.fda.gov/NewsEvents/Newsroom/PressAnnouncements/ucm161552.htm through http://www.fda.gov. Accessed March 2009.
Dugdale, D. et. al. (Updated 2009 May 30). MRSA. MedlinePlus Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/007261.htm. Accessed March 2009.
(2010 January 21). Genetics Used to Track Transmission of MRSA Bacteria. MedlinePlus HealthDay [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/news/fullstory_94379.html through http://www.nlm.nih.gov. Accessed March 2009.
(Updated 2009 July 22) MRSA and the Workplace. National Institute for Occupational Safety and Health [On-line information]. Available online at http://www.cdc.gov/niosh/topics/mrsa/ through http://www.cdc.gov. Accessed March 2009.
Martinez, J. (Updated 2009 December 16). MRSA Skin Infection in Athletes. eMedicine [On-line information]. Available online at http://emedicine.medscape.com/article/108972-overview through http://emedicine.medscape.com. Accessed March 2009.