What Is MRSA?

While there are many strains of the bacterium Staphylococcus aureus, or staph, methicillin-resistant Staphylococcus aureus (MRSA) is particularly notable because it is resistant to many standard antibiotics and may cause serious infections.

Staph normally lives on the skin and sometimes in nasal passages. If an opening in the skin occurs, bacteria may enter the body and cause an infection. While MRSA infections are well-known to occur in people in care settings, such as hospitals, anyone can get MRSA.

MRSA Types and Symptoms

There are two ways a person can have MRSA: They can be a carrier or have an active infection.

• A carrier means that a person has no symptoms, but the MRSA bacteria are living in their nose or on their skin. This is also called colonization.
• An active infection means that the MRSA bacteria has entered the body through an opening (usually, a cut, scrape, or wound) and that person now has symptoms.

There are also two types of MRSA infections, depending on where the MRSA was acquired. These two types are:

• Community-acquired MRSA (CA-MRSA) infections
• Healthcare-associated MRSA (HA-MRSA) infections

Community-Acquired MRSA Infections

Community-acquired MRSA infections occur in healthy individuals in the absence of exposure to a healthcare setting, like a hospital, dialysis center, or long-term care facility. Usually, CA-MRSA infections are skin infections, such as folliculitis, furuncles, carbuncles, and cellulitis.

Symptoms of a MRSA skin infection are sometimes mistaken for a spider bite and include one or more of the following:

• Swelling
• Skin warmth
• Skin redness
• Tenderness within or surrounding the infected area
• Thick, yellowish drainage (pus) from the center of the infected area, especially if a large, red lump is present
• Fever

Healthcare-Associated MRSA Infections

Healthcare-associated MRSA infections refer to either an infection that occurs more than 48 hours following hospitalization or an infection that occurs outside of the hospital within 12 months of being exposed to a healthcare facility.

Healthcare-associated MRSA infections are generally more serious and invasive than CA-MRSA infections and often result from surgical wound openings. A HA-MRSA skin or wound infection is often:

• Red and swollen
• Painful

• Drain pus and take on the appearance of an abscess or boil
• Be accompanied by fever, chills, muscle aches/or fatigue

Healthcare-associated MRSA infections may also occur in the bloodstream and cause sepsis. This is a phenomenon in which the body launches an extreme inflammatory response to an infection, triggering numerous symptoms and signs, such as:

• Fever
• Sweating
• Rapid heart and breathing rate
• Confusion
• Organ failure due to impaired blood flow (septic shock)

Once in the bloodstream, MRSA can land on and infect various tissues or organs, like a heart valve (endocarditis), a bone (osteomyelitis), a joint (septic joint), or the lungs (pneumonia).

Once infected, symptoms unique to that tissue or organ will develop. For instance, in the case of MRSA pneumonia, a person may experience fever, chills, muscle aches, shortness of breath, chest pain, and a cough.

Causes

MRSA is a bacterium that, with exposure to antibiotics over time, has mutated to become a strong, super-resistant bug. That said, while many people are colonized with Staphylococcus aureus (about 33% of the population), only about 2% are colonized with MRSA.

The truth is that anyone can become a carrier of MRSA and then get infected, although your risk increases if you spend a lot of time in places that are crowded and/or entail shared equipment or supplies.

Some of these places include:

• Healthcare settings
• Daycare centers
• Athletic facilities
• Military barracks
• Prisons

If one person in a household has MSRA, it commonly spreads to other household members.

Besides environmental factors, there are others that increase your risk of getting a MRSA infection. Some of these include:

• Prior antibiotic use
• Having a weak immune system
• Sharing needles or razors
• History of injection drug use

Within a hospital, there are additional risk factors for becoming infected with hospital-acquired MRSA, such as:

• Having an open wound, catheter, or breathing tube
• Being in the hospital for a long period of time
• Residence in a long-term care facility
• Recent surgery
• Receiving dialysis  

Diagnosis

The definitive way to diagnose a MRSA skin or wound infection is to perform a bacterial culture on pus from the infected site. Culture results are usually available within 24 to 72 hours.

Blood cultures are used to diagnose MRSA bloodstream infections. For suspected infections of the lung, bone, joint, or heart valve, imaging studies will be ordered. For instance, a chest X-ray or a computed tomography (CT) scan can diagnose pneumonia, while an echocardiogram may diagnose endocarditis.

Finally, to diagnose potential carriers of MRSA (this is mainly only done within hospitals or other healthcare facilities), swabs of each patient's nostrils may be performed and sent to a lab for analysis.

Treatment

The mainstay treatment for a MRSA infection is to take an antibiotic. But since the bacterium has come to "outsmart" many of these drugs, certain potent types are considered—and more than one may need to be tried to successfully eradicate the infection.

Antibiotics typically used to treat MRSA infections include:

• Septra or Bactrim (trimethoprim-sulfamethoxazole)
• Cleocin HCl (clindamycin)
• Cubicin (daptomycin)
• Zyvox (linezolid)
• Sumycin (tetracycline)
• Dynacin or Minocin (minocycline)
• Vibramycin or Doryx (doxycycline)
• Vancocin (vancomycin)

The antibiotic your healthcare provider chooses will depend on the severity of your illness, as well as any local resistance patterns and available culture data.

It's important to take your antibiotic as instructed by your healthcare provider. Be sure to contact your healthcare provider right away if you are experiencing any adverse effects from the medication, or if your infection is not improving or is worsening.

Drainage and one or more antibiotics are used for more serious infections. If your illness is severe, you may require hospitalization and an intravenous (IV) antibiotic. You may also require other treatments in the hospital, such as:

• Intravenous fluid administration
• Dialysis (if your kidneys are failing as a result of the MRSA infection)
• Ventilator placement (to help with breathing, if your lungs are failing as a result of the infection)

Decolonization

For patients in the hospital who are found to be carriers of MRSA, a decolonization treatment plan may be initiated at hospital discharge. The main goals of decolonization are to prevent MRSA transmission and future infection.

This treatment may be given for five days, twice per month for six months and consist of the following three therapies:

• 4% rinse-off chlorhexidine for daily bathing or showering
• 0.12% chlorhexidine mouthwash twice daily
• 2% nasal mupirocin twice daily  

For people within the community, decolonization may be recommended for those who keep getting MRSA infections despite optimizing their hygiene practices and/or if there is ongoing MRSA transmission to household members.

Note, however, that decolonization—especially within the community—is still an evolving practice with no set guidelines.

Protect Your Skin

It's important to not squeeze, pop, or try to drain any boil or "pimple" on your own, as this can worsen the infection.

Prevention

Personal hygiene measures are key to preventing MRSA infections.

Follow these guidelines:

• Cover cuts scrapes and wounds with a bandage until healed.
• Don't touch another person's cuts, scrapes, or wounds.
• Don't share personal items like towels, razors, washcloths, clothing, deodorant, or makeup.
• Clean hands often and for at least 20 seconds using soap and water (if not available, use an alcohol-based hand sanitizer).
• Clean your body regularly, especially after exercise.
• Ensure your healthcare provider washes their hands with soap and water before examining you.
• Wipe down exercise equipment before and after use with an alcohol-based solution.

A Word From Verywell

MRSA is a bacteria that healthcare providers continue to worry about, considering the serious infections it may cause and its resistance to numerous traditional antibiotics. To protect yourself from MRSA, remain proactive in your hand and body hygiene and be sure to see your healthcare provider right away if you think you have a MRSA infection. Prompt attention is key to eliminating this superbug.

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.

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2. Centers for Disease Control and Prevention. Sepsis.
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• Anderson DJ. (2019). Methicillin-resistant Staphylococcus aureus (MRSA) in adults: Epidemiology. Sexton DJ, ed. UpToDate. Waltham, MA: UpToDate Inc.
• Harris A. (2019). Methicillin-resistant Staphylococcus aureus (MRSA) in adults: Prevention and control. Sexton DJ, ed. UpToDate. Waltham, MA: UpToDate Inc.
• Huang SS et al. Decolonization to Reduce Postdischarge Infection Risk among MRSA Carrier. N Engl J Med. 2019 Feb 14;380(7):638-50. doi:10.1056/NEJMoa1716771
• Miller LG, Kaplan SL. Staphylococcus aureus: a community pathogen.Infectious Disease Clinics of North America. 2009 Mar;23(1):35-52. doi:10.1016/j.idc.2008.10.002
• Septimus EJ, Schweizer ML. Decolonization in Prevention of Health Care-Associated Infections. Clin Microbiol Rev. 2016 Apr;29(2):201-22. doi:10.1128/CMR.00049-15

By Heather L. Brannon, MD
Heather L. Brannon, MD, is a family practice physician in Mauldin, South Carolina. She has been in practice for over 20 years.

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