Methicillin-resistant Staphylococcus aureus (MRSA) is a type of drug-resistant staph infection. MRSA most commonly causes relatively mild skin infections that are easily treated.
However, if MRSA gets into your bloodstream, it can cause infections in other organs like your heart, which is called endocarditis. It can also cause sepsis, which is the body’s overwhelming response to infection.
If these situations occur and they aren’t or can’t be treated, you can die from MRSA.
Staphylococcus aureus (SA) is a very common bacteria that lives on your skin and inside your nose without causing a problem.
However, if it gets into your skin through an opening like a cut or scrape, it can cause a skin infection. Fortunately, antibiotics can easily cure most infections.
Over time, some SA strains have become resistant, or immune, to a class of antibiotics called beta-lactams, or β-lactams.
This class includes penicillin and similar antibiotics like amoxicillin. It also includes cephalosporins. These antibiotics are most often used to treat skin infections.
Antibiotic resistance was first discovered with a penicillin-like antibiotic called methicillin. That’s why they’re called “methicillin-resistant” even though that antibiotic isn’t used anymore.
MRSA skin infections usually aren’t serious and typically respond to treatment.
But when MRSA gets inside your body, which is called invasive MRSA, it can cause a serious infection in your bloodstream or other organs. This is a life-threatening infection and more difficult to treat.
types of mrsa
MRSA is divided into two types based on where you come in contact with MRSA.
- Healthcare-associated MRSA (HA-MRSA). This type occurs in a health care setting such as a hospital or long-term care facility and is more likely to cause an invasive infection.
- Community-associated MRSA (CA-MRSA). This type occurs in healthy people in the community and usually causes mild skin infections but can also cause serious infections.
Symptoms vary depending on where the infection is located.
An MRSA skin infection is sometimes mistaken for a large pimple, impetigo, or spider bite due to their similar appearance. Some types of skin infections it can cause are:
- boil (furuncle)
It consists of one or more raised lumps or sore spots on your skin. Other symptoms may include:
- skin breakdown or ulceration (necrosis)
There may be signs that it contains pus such as:
- yellowish or white center
- the top comes to a point, or “head”
- oozing or draining pus
MRSA can cause severe pneumonia if it gets into your lungs. Pus-filled lung abscesses and empyema can form. Symptoms include:
MRSA can infect the inside of your heart. This can quickly damage your heart valves. Some symptoms are:
- fever and chills
- muscle and joint aches
- night sweats
- chest pain
- heart murmur that’s new or has changed
- leg swelling, or peripheral edema and other signs of congestive heart failure
Bacteremia means there are bacteria in your bloodstream. It’s a very serious and life-threatening condition that can lead to sepsis and septic shock. Symptoms may include:
- fever and chills
- low blood pressure (hypotension)
- rapid heart rate
- rapid breathing
- little to no urine production, or anuria
Osteomyelitis is another name for a bone infection. When MRSA causes an infection in a bone, symptoms include:
- fever and chills
- redness and swelling in the skin and tissue around the infected bone
MRSA is very contagious. It’s transmitted through contact with a person who has the infection or any object or surface that has MRSA on it.
Having MRSA on your skin doesn’t mean you have an infection.
People who have MRSA but aren’t sick are said to be colonized. They’re called carriers, and they can transmit MRSA to others. They’re also more likely to develop an infection.
MRSA only causes an infection when it finds an opening such as a cut and enters your skin or body.
risk factors for mrsa infection
- participating in activities that require contact with others like playing sports
- living close to many people such as in a correctional facility or college dormitory
- sharing items such as towels, razors, sports equipment, and sauna benches
- being very young or a much older adult
- having a weakened immune system
- working in a healthcare setting
- living in a household with someone who has MRSA
- having a medical product or device inserted or inside your body like a urinary catheter or IV
- having recently been hospitalized
- living in a long-term care facility
- having an extended-stay hospitalization
- having a surgical wound
- having prolonged or frequent use of antibiotics
- using IV drugs
MRSA is transmitted through contact with someone who has the infection or any object or surface that has the bacteria on it.
The two types of MRSA are transmitted in different ways.
CA-MRSA can be quickly transmitted in places where you’re in close contact with other people. This includes:
- daycare centers
- military bases
- correctional facilities
- your home
- sports facilities, especially where high-contact sports like football and wrestling are played
It’s also easily transmitted when equipment is shared like at a gym or on amusement park rides.
You usually get HA-MRSA from a colonized healthcare worker or a healthcare worker who has acquired the infection. Visitors to a healthcare facility can also spread MRSA.
MRSA’s more likely to cause an infection when there’s a pathway for the bacteria to enter your body. This may be:
- a C-PAP machine
- urinary catheter
- surgical wound
- dialysis port
- an intravenous (IV) or central venous line
- endotracheal tube
There are things you can do to help prevent MRSA from being transmitted.
- Wash your hands with soap and water often.
- When water isn’t available, use hand sanitizer.
- Keep the MRSA-infected wound covered with a bandage until it heals.
- Wear disposable gloves when you clean the wound or change the bandage.
- Change your clothes every day and wash them before you wear them again.
- Change your bed sheets and towels every week.
- Don’t share personal items like razors and sports equipment.
- Don’t play contact sports like football or wrestling, or go to a gym until the infection has cleared up.
When MRSA is suspected to be the cause of an infection, a sample of the bacteria-containing fluid or tissue is obtained and grown in a dish, or cultured.
The bacteria grows and can be identified by looking at it under a microscope. The sample could be:
- pus from a skin infection
- sputum from a lung infection
- blood for bacteremia
- bone biopsy for osteomyelitis
Special tests called susceptibility testing are done to determine which antibiotics the bacteria are resistant to and which can be used to kill it and stop the infection.
Other tests might be done to look at the infection inside an organ. They may include:
- echocardiogram (heart)
- bronchoscopy (lungs)
MRSA-causing infections can look very similar to those caused by other nonresistant bacteria. If MRSA isn’t suspected, it could be misdiagnosed and treated with an antibiotic that it’s resistant to.
Your doctor will usually culture the wound when they see the infection didn’t improve or got worse. They can then use this culture to correctly diagnose MRSA and determine the appropriate treatment.
Obtaining an accurate diagnosis is critical because prompt and appropriate treatment significantly lowers the risk of the infection getting worse and becoming invasive.
Most MRSA skin infections are opened via an incision, and the pus is drained. This is usually enough to cure the infection. Antibiotics are often given after drainage if:
- your infection is severe or the abscess is larger than 2 centimeters
- you’re very young or a much older adult
- your immune system is compromised
- the infection couldn’t be completely drained
- your infection doesn’t get better with drainage alone
- you begin to have symptoms of invasive MRSA
The pus is cultured to determine the most effective antibiotic, but this can take a few days.
In the meantime, you’ll be given empiric antibiotics. This means you’ll be given an antibiotic that your doctor thinks will be effective based on MRSA susceptibility in your area.
There are several antibiotics that work on MRSA. They include:
- clindamycin (Cleocin)
- doxycycline (Doryx)
- trimethoprim-sulfamethoxazole (Bactrim)
- linezolid (Zyvox)
Rifampin (Rifadin) is another antibiotic used in treating MRSA. It’s not typically used alone. It’s usually used in combination therapy.
There are pros and cons for each antibiotic. Your doctor will give you the one that’s best for you.
Always take all of the antibiotic pills that are prescribed even if your wound looks healed. If you don’t, the strongest bacteria may survive. This can create bacteria that are more resistant to a wider variety of antibiotics.
Never try to pop or drain the pus from a skin infection yourself. You can push the MRSA deeper into your skin or into your bloodstream, which can cause an invasive infection.
When MRSA gets into your body, it can cause a serious and life-threatening infection in your bloodstream or an organ.
Invasive infections are treated in the hospital with one or more IV antibiotics. Vancomycin (Vancocin) is usually one of the antibiotics used.
Invasive MRSA infections can overwhelm your immune system and can be very hard to treat. Many people die.
Additional support is usually needed in severe infections while the body tries to heal. It may include:
- a ventilator
- medications to keep your blood pressure up, or vasopressors
- surgery for heart or bone infections
when to see your doctor
See your doctor right away if you:
- think you have an MRSA skin infection
- have a skin infection that looks like a spider bite
- have a skin infection that’s red, warm, and looks like it contains or is draining pus
- you have a skin infection and a fever
If you have a MRSA infection that was treated, see your doctor right away if:
- you develop new or worsening symptoms
- your infection doesn’t get better
- your infection goes away but comes back
- you develop symptoms such as high fever and chills, low blood pressure, chest pain, or shortness of breath, indicating an invasive MRSA infection
The outlook depends on the infection site.
MRSA skin infections can be cured with prompt and appropriate treatment. If you have recurrent skin infections you can be tested and treated for MRSA colonization, which should stop the infections.
The outlook for invasive MRSA infections depends on the severity.
Less severe infections are more likely to be cured, but it may take a long time. Some infections require weeks of antibiotics to treat. Very severe infections don’t respond well to treatment and aren’t often cured.
Prevention precautions and prompt treatment for skin infections are the best ways to avoid invasive MRSA infections.
MRSA infections that you acquire outside of a healthcare facility are usually easily treatable.
It’s very important to start treatment early and follow your doctor’s instructions on wound care and ways to avoid transmitting the bacteria. It’s also important to take antibiotics as long as prescribed.
Invasive infections are much more serious. They almost always require aggressive treatment with IV antibiotics in the hospital. Even then, you can die from a severe infection.
The best way to increase the likelihood of a good outcome is to see your doctor right away if you think you have a MRSA infection, or you have an infection that’s not getting better after treatment.