MRSA: Causes, Symptoms, and Treatment

A magnification of the MRSA (methicillin-resistant Staphylococcus aureus) superbug.

What is MRSA?

Methicillin-resistant Staphylococcus aureus (MRSA) are shown in this scanning electron microscope picture. Strains of these bacteria (commonly termed "staph") may cause infection in almost any part or organ system in humans. MRSA strains are further characterized as superbugs because MRSA strains are resistant to many different antibiotics

MRSA skin infection.

Symptoms of a MRSA Skin Infection

Initially, MRSA infections in the skin resemble minor skin infections; they appear as a red bump, pimple, or boil on the skin that may be painful, swollen, or warm to the touch. Occasionally, these infections may open and have pus drain from the area. Although most MRSA skin infections are mild, some progress and spread further into the skin and to other areas or organ systems.

A spider bite vs. MRSA infection.

Is It MRSA, a Spider Bite, or Something Different?

Bug bites, insect bites, spider bites, rashes, and stings are often difficult to distinguish from MRSA infections because they have similar appearances or symptoms. However, if the person never viewed a spider or other entity causing the lesion, there is a good chance the skin lesion may be caused by MRSA, especially if the lesion area spreads or does not start getting better after about two to three days of treatment with common antibiotics.

Cellulitis on the hands.

MRSA Skin Infection and Cellulitis

Often, the first indication of MRSA infection is a spread of the infection into the surrounding skin, producing skin that is pink or reddish and often is warm, tender, and swollen. Such an infected skin area is termed cellulitis and represents infection spread into deeper skin layers. Cellulitis can rapidly advance (over a few hours) in some individuals.

Abscess from MRSA.

MRSA Skin Infection: Abscess

MRSA may be somewhat contained by the body by attempting to wall off the invading bacteria by making a pocket of pus surrounded by cells trying to kill or stop the MRSA from advancing. This deeper skin infection is termed an abscess and can spread like cellulitis in some instances. Abscesses usually require drainage (sometimes done with warm compresses, sometimes with a needle, while others require surgical drainage) and antibiotics; your doctor should be consulted as you should not attempt to treat MRSA infections by yourself.

A woman uses a gym bar to stretch.

How Do People Catch MRSA?

MRSA is easily spread to other individuals by people with the organisms on their skin. Usually, either skin-to-skin contact or contact with towels, razors, or even doorknobs or benches can transfer MRSA to another person. Some people, termed carriers, have MRSA strains on their body but have no symptoms; however, these people can still transfer MRSA to others by direct and indirect contact (towels or clothing that carriers have used).

Surgeons operate on a patient.

Who Can Get MRSA?

Some individuals are at higher risk to get MRSA than others. People who have a chronic medical condition (for example, cancer, HIV, or any immune depression), the elderly, individuals in hospitals, or those who have had recent surgery are at higher risk for MRSA infections.

A hospital sign warns about hand hygiene.

How Safe Are Hospitals?

Hospitals used to have a reputation as an area to get MRSA infections. However, in recent years, with guidelines established and followed by hospital staff, visitors, and patients, there have been far fewer MRSA infections occurring in hospitals. Simple changes in hygiene policies and utilization of more strict hand-washing procedures have made a positive impact in reducing MRSA infections in hospitals and other institutions like nursing homes and even in community areas such as athletic facilities.

Two men work out in the gym.

Can Healthy People Get MRSA?

MRSA can easily infect healthy people. Outbreaks have been documented at many areas where people are crowded together (for example, gyms, dormitories, barracks, prisons, and day-care centers). The type of MRSA obtained by healthy people outside of health-care facilities is often termed community-associated or community-acquired MRSA (usually termed CA-MRSA) by many clinicians.

It is possible to transfer MRSA to pets.

MRSA in Dogs and Cats

MRSA can be transferred to pets such as cat or dogs (the animals may have no symptoms like human MRSA carriers) and, unfortunately, may reinfect the pet owners or other people. Only CA-MRSA strains have been documented to do this with pets.

A child plays in the sand.

MRSA on the Beach

MRSA strains survive fairly well for some time on objects handled or worn by carriers or infected individuals. MRSA has been found even in sand and beach water on occasion. How MRSA arrived there is unclear, but the practice of good hygiene (covering skin scrapes, frequent hand washing, and showering with soap after going to the beach or engaging in another water activity) is the best way to reduce the chance of getting a MRSA infection from objects in the environment.

A petri dish with Staphylococcus aureus.

How Is MRSA Diagnosed?

Definitive diagnosis of MRSA is not difficult. However, it may take a few days because, after S. aureus is cultured from an infected site, the bacteria then need to be tested against antibiotics to determine not only what the bacteria are resistant to but also what antibiotic(s) might be effective.

A doctor applies a bandage to a patient's foot.

How Is MRSA Treated?

A doctor should guide treatment of MRSA infections. Most treatment methods depend on the severity of the infection and the resistance pattern of the bacteria. Some minor sores or small abscesses may need only warm compresses for pus drainage (if present) and cleaning and coverage with a small bandage. Many clinicians will prescribe an oral antibiotic that some MRSA are usually sensitive to (for example, sulfamethoxazole and trimethoprim [Bactrim], linezolid [Zyvox], or clindamycin [Cleocin T]). More invasive or severe infections might respond to oral antibiotics, but many clinicians may choose to treat such infections with IV drugs such as vancomycin (Vancocin), possibly along with a second IV antibiotic. Most severe infections are treated in consultation with an infectious disease specialist.

One antibiotic pill in a medication bottle.

MRSA Skin Infection and Home Care

If you are diagnosed with MRSA and sent home with antibiotics, you are strongly advised to take all of the antibiotics prescribed, even if you feel fine, to prevent the infection from reoccurring. Following your doctor's advice about warm compresses and wound care is also important to help you recover. In addition, you need to be careful to dispose of or disinfect items you contact to prevent passing MRSA to others.

A doctor injects medicine into a woman's IV drip.

MRSA Complications

MRSA infections (especially those associated with health-care facilities) can be dangerous; they can spread rapidly to other body areas and organs and cause serious organ damage or death. At their peak, reports indicated there were about 19,000 deaths in a year due to MRSA, but recently, this rate has decreased because of good hospital practices according to the CDC.

Cleaning supplies in the gym.

How to Avoid MRSA

Avoiding or reducing the chance of getting infected with a MRSA strain of S. aureus is fairly easy -- the cardinal rule is frequent hand washing with soap and water. Using an alcohol-containing hand sanitizer can also reduce infection risk. Avoid skin-to-skin contact with others if possible. Don't share towels and never touch bandages or wounds on other people, especially if they are hospitalized. Again, hand washing and showering with soap and water is the key to reducing MRSA (and other) infections. Disinfecting surfaces and other items also reduces the chances for infection.



  1. Photo Courtesy of CDC
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  5. Scott Camazine/Photo Researchers Inc.
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  • Centers for Disease Control and Prevention: "Cleaning & Disinfecting for MRSA"
  • Centers for Disease Control and Prevention: "Diagnosis and Testing of MRSA Infections"
  • Centers for Disease Control and Prevention: "Methicillin-resistant Staphylococcus aureus (MRSA) Infections"
  • Centers for Disease Control and Prevention: "MRSA Prevention"
  • Centers for Disease Control and Prevention: "MRSA Statistics"
  • Centers for Disease Control and Prevention: "MRSA Symptoms"
  • Centers for Disease Control and Prevention: "MRSA Treatment"
  • Centers for Disease Control and Prevention: "People at Risk of Acquiring MRSA Infections"
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