Methicillin-resistant Staphylococcus aureus (MRSA) is a bacterium that does not respond to several antibiotics. The symptoms can present differently depending on which part of the body is infected.
People have the Staphylococcus aureus bacteria naturally present on their skin. It is usually harmless. However, it can cause infection when it finds its way into broken skin.
The Centers for Disease Control and Prevention (CDC) state that the bacteria typically causes skin infections. However, MRSA can also lead to infections in other parts of the body.
Keep reading to learn more about MRSA, the symptoms of an infection, and how doctors treat it.
The CDC note that the symptoms will depend on the part of the body that has the infection.
A 2020 article states that MRSA most commonly affects the skin and soft tissues.
It can then lead to internal infections, including:
- osteomyelitis, which is an infection of the bone and bone marrow
- lung abscess
- empyema, which is a condition that causes pus to gather in between the lungs and chest wall
- endocarditis, which is the inflammation of the heart’s inner lining
- sepsis, which is an infection in the blood
If the infection spreads further into the body than the skin, a person can experience:
- high fever
- aches and pains
For skin infections, a person may notice a bump or lesion on the skin that is:
- full of pus
They may also experience a fever.
Some lesions may cause the surrounding tissue to die, known as necrosis, and can eventually progress to abscesses and cellulitis.
An older 2011 article notes that adults and children may develop different presentations of an MRSA skin infection.
MRSA causes scalded skin syndrome in children and some cases of impetigo. Scalded skin syndrome is a type of skin infection that occurs due to the staphylococcus aureus bacterium. Sometimes an open wound from eczema, ulcers, or lacerations may become infected with MRSA in children.
MRSA can cause pneumonia, lung abscesses, and empyema.
Symptoms of pneumonia include:
- shortness of breath
- fever and chills
- rapid breathing
- sharp or stabbing pain in the best
The symptoms of a lung abscess can be similar to those of pneumonia. They include:
- shortness of breath
- an unproductive cough
- night sweats
- weight loss
- chest pain
Symptoms of empyema include:
- chest pain
Bones and joints
MRSA can cause infections of the bone and joint, including osteomyelitis of the spine, and in the bones of the upper and lower extremities.
It can also cause septic arthritis.
Symptoms may include:
- pain in the affected area
Some people may present with an MRSA infection and a blood infection with septic shock.
When the bacteria enters the bloodstream, it can lead to bacteremia.
Symptoms include chills and fever.
Septicemia is a severe form of bacteremia and can cause the following symptoms:
- low blood pressure
- altered mental status
- decreased urination
It can then spread to the other organs, causing acute respiratory distress syndrome (ARDS) and acute kidney injury.
When bacteria settles on the heart, it can lead to endocarditis.
The symptoms of endocarditis include:
- fever of 102–104ºF
- night sweats
- aching joints
- fast heart rate
- swelling of the feet, abdomen, or legs
MRSA can look similar to other conditions. They include:
The CDC note that MRSA skin infections can look similar to a spider bite. If a person did not see a spider that caused an apparent bite, they should check with a doctor as it may be MRSA instead.
Cellulitis is a bacterial skin infection. MRSA can cause cellulitis.
Symptoms include an area of skin that is:
- warm to the touch
- painful to touch
A person may also feel tired or have a fever.
A 2020 article notes that children may develop impetigo from MRSA. Impetigo also can affect adults, although this is less common.
Impetigo may appear as red patches with a surrounding yellow crust. The patches may also be itchy.
While other bacteria can lead to impetigo, such as Staphylococcus aureus and group A beta-hemolytic Strep, MRSA-caused impetigo is becoming more common outside hospital settings.
The CDC state that it is not possible to tell if a skin infection is caused by MRSA infection just from looking at it.
If someone has an infected wound that is taking a long time to heal or seems to be getting a lot of little skin infections often, they could possibly have MRSA and should seek medical attention as soon as possible.
A person with a skin infection who develops a fever also requires immediate medical attention.
People should avoid picking at, or popping, any sore.
Until a person can see a doctor, they should cover the area with a clean and dry bandage and wash their hands often.
MRSA is a dangerous pathogen because it is very contagious, difficult to treat, and can cause severe infection in some people. It can cause outbreaks leading to large epidemics.
Each time the bacteria causes an outbreak, it has the potential to produce mutations that promote its survival. This means that the bacteria become more infectious and more difficult to treat.
Researchers are trying to determine the mechanisms that lead to MRSA mutations that allow the bacteria to thrive.
People infected with MRSA may transmit the resistant bacterium to others through skin-to-skin contact. That can include contact with a contaminated wound or sharing towels, razors, or other items that touched infected skin.
A person with an MRSA skin infection can prevent spreading the bacteria to others by:
- covering the wound with clean and dry bandages until the infection has cleared
- not picking at the sores
- throwing away bandages and tape used to cover the infection in the trash
- washing hands frequently, especially after changing a bandage, touching dirty clothes, or touching an infected wound
- washing laundry before others use it
Anyone can become infected with MRSA, but certain activities present higher risks. Situations that increase a person’s risk of infection include:
- being in crowded spaces, like schools, daycares, and prisons
- activities where skin-to-skin contact is unavoidable, such as certain sports
- sports where athletes may use the same equipment or supplies
According to the CDC, about 5% of people in hospitals in the United States carry MRSA in their nose or on their skin.
Doctors describe two types of MRSA infections— community-acquired and hospital-acquired MRSA.
In community-acquired MRSA, the bacteria typically causes skin infections. In some cases, it can cause pneumonia and other infections. If a person does not get treatment, it can lead to sepsis.
Recently, some communities may have observed an increase in MRSA infections due to the opioid crisis. Experts suggest that people who inject illicit drugs are 16 times more likely to become infected with MRSA.
In healthcare settings, such as a hospital, MRSA can cause bloodstream infections, pneumonia, or surgical site infections.
Antibiotics can treat MRSA, but not penicillin-derived antibiotics.
Depending on the severity of infection and the age of the person, doctors will choose different treatments for MRSA infections.
People with simple abscesses or boils may be candidates for incision and drainage. The doctor will make a small cut in the infection to remove the pus. They will also send a sample of the pus to the lab to test for MRSA and other bacteria. This procedure is performed in a sterile setting. What comes from an abscess or boil can be very contagious, so people should avoid draining boils at home.
Oral antibiotics recommended for adults with community-acquired MRSA infections include:
- doxycycline or minocycline
In more serious infections requiring hospitalization, some people may require intravenous antibiotics, including:
Children with impetigo or open wounds infected with MRSA may receive antibacterial creams such as mupirocin 2%.
In more serious infections requiring hospitalization, doctors can prescribe vancomycin. Intravenous clindamycin is another option. The doctor may switch the child to oral linezolid thereafter.
To prevent MRSA infection, the CDC recommend:
- practicing appropriate hand and body hygiene
- washing hands thoroughly and often
- showering or bathing regularly, particularly after exercising
- keeping broken skin clean and covered until it has healed
- not sharing personal items like razors and towels
People should seek medical attention if:
- they suspect they were in contact with a person carrying MRSA
- have symptoms of a skin infection
Until the person sees a medical provider, they should cover the wound to prevent exposing others to the harmful bacteria.
An MRSA test can involve:
- a wound sample
- nasal swab
- blood test
- urine test
Tests typically take 24–48 hours to provide results. New tests may be able to deliver results in approximately 5 hours but are still not readily available. The most common and reliable tests are the nasal and wound swabs.
If the doctor suspects an MRSA infection, they will start treating the person with MRSA treatments before receiving confirmation from lab testing.
According to Johns Hopkins, the outlook for someone with a MRSA infection is good providing a person receives treatment in time.
A 2020 article notes that mortality rates vary from 5–60%. This depends on a variety of factors, such as the site of infection, a person’s age, and other medical conditions they may have.
MRSA is a bacterial infection that is resistant to some antibiotics.
While MRSA typically causes a skin infection, other infections may occur from exposure to MRSA, such as pneumonia and blood infections.
If a person develops a skin infection, they may notice a lump, lesion, or abscess that is painful and warm to the touch. They may also notice inflamed skin, pus, and a fever.
Early diagnosis and treatment is important.