Methicillin-resistant Staphylococcus aureus (MRSA) is an infection caused by Staphylococcus (staph) bacteria. This type of bacteria is resistant to many different antibiotics.

These bacteria naturally live in the nose and on the skin and generally don’t cause any harm. However, when they begin to multiply uncontrollably, a MRSA infection can occur.

MRSA infections typically occur when there’s a cut or break in your skin. MRSA is very contagious and can be spread through direct contact with a person who has the infection.

It can also be contracted by coming into contact with an object or surface that’s been touched by a person with MRSA.

Though a MRSA infection can be serious, it may be treated effectively with certain antibiotics.

MRSA infections are classified as either hospital-acquired (HA-MRSA) or community-acquired (CA-MRSA).

HA-MRSA

HA-MRSA is associated with infections that are contracted in medical facilities, such as hospitals or nursing homes. You can get this type of MRSA infection through direct contact with an infected wound or contaminated hands.

You can also get the infection through contact with contaminated linens or poorly sanitized surgical instruments. HA-MRSA can cause severe problems, such as blood infections and pneumonia.

CA-MRSA

CA-MRSA is associated with infections transmitted through close personal contact with a person who has the infection or through direct contact with an infected wound.

This type of MRSA infection may also develop because of poor hygiene, such as infrequent or improper handwashing.

MRSA symptoms can vary depending on the type of infection.

Symptoms of HA-MRSA

HA-MRSA is generally more likely to cause serious complications, such as pneumonia, urinary tract infections (UTIs), and the blood infection sepsis. It’s important to see your doctor right away if you notice any of the following symptoms:

Symptoms of CA-MRSA

CA-MRSA usually causes skin infections. Areas that have increased body hair, such as the armpits or back of the neck, are more likely to be infected.

Areas that have been cut, scratched, or rubbed are also vulnerable to infection because your biggest barrier to germs — your skin — has been damaged.

The infection usually causes a swollen, painful bump to form on the skin. The bump may resemble a spider bite or pimple. It often has a yellow or white center and a central head.

Sometimes an infected area is surrounded by an area of redness and warmth, known as cellulitis. Pus and other fluids may drain from the affected area. Some people also experience a fever.

Risk factors vary depending on the type of MRSA infection.

Risk factors for HA-MRSA

You’re at an increased risk for HA-MRSA if you:

  • were hospitalized within the past three months
  • regularly undergo hemodialysis
  • have a weakened immune system due to another medical condition
  • live in a nursing home

Risk factors for CA-MRSA

You’re at an increased risk for CA-MRSA if you:

  • share exercise equipment, towels, or razors with other people
  • participate in contact sports
  • work at a day care facility
  • live in crowded or unsanitary conditions

Diagnosis begins with a medical history assessment and physical examination. Samples will also be taken from the site of infection. The types of samples obtained to help diagnose MRSA include the following:

Wound cultures

Wound samples are obtained with a sterile cotton swab and placed in a container. They’re then taken to a laboratory to be analyzed for the presence of staph bacteria.

Sputum cultures

Sputum is the substance that comes up from the respiratory tract during coughing. A sputum culture analyzes the sputum for the presence of bacteria, cell fragments, blood, or pus.

People who can cough can usually provide a sputum sample easily. Those who are unable to cough or who are on ventilators may need to undergo a respiratory lavage or bronchoscopy to obtain a sputum sample.

Respiratory lavage and bronchoscopy involve the use of a bronchoscope, which is a thin tube with a camera attached. Under controlled conditions, the doctor inserts the bronchoscope through the mouth and into your lungs.

The bronchoscope allows the doctor to see the lungs clearly and to collect a sputum sample for testing.

Urine cultures

In most cases, a sample for a urine culture is obtained from a “midstream clean catch” urine specimen. To do this, urine is collected in a sterile cup during urination. The cup is then given to the doctor, who sends it to a lab for analysis.

Sometimes, urine must be collected directly from the bladder. To do this, the healthcare provider inserts a sterile tube called a catheter into the bladder. Urine then drains from the bladder into a sterile container.

Blood cultures

A blood culture requires taking a blood draw and placing the blood on a dish in a laboratory. If bacteria grow on the dish, doctors can more easily identify what bacteria type is causing infection.

Results from blood cultures typically take about 48 hours. A positive test result can indicate the blood infection sepsis. Bacteria can enter the blood from infections located in other parts of your body, such as the lungs, bones, and urinary tract.

Doctors typically treat HA-MRSA and CA-MRSA differently.

Treatment for HA-MRSA

HA-MRSA infections have the capability of producing severe and life-threatening infections. These infections usually require antibiotics through an IV, sometimes for long periods of time depending on the severity of your infection.

Treatment for CA-MRSA

CA-MRSA infections will usually improve with oral antibiotics alone. If you have a large enough skin infection, your doctor may decide to perform an incision and drainage.

Incision and drainage are typically performed in an office setting under local anesthesia. Your doctor will use a scalpel to cut open the area of infection and drain it completely. You may not need antibiotics if this is performed.

Take the following measures to reduce your risk of getting and spreading CA-MRSA:

  • Wash your hands on a regular basis. This is the first line of defense against spreading MRSA. Scrub your hands for at least 15 seconds before drying them with a towel. Use another towel to turn off the faucet. Carry hand sanitizer that contains 60 percent alcohol. Use it to keep your hands clean when you don’t have access to soap and water.
  • Keep your wounds covered at all times. Covering wounds can prevent pus or other fluids containing staph bacteria from contaminating surfaces that other people may touch.
  • Don’t share personal items. This includes towels, sheets, razors, and athletic equipment.
  • Sanitize your linens. If you have cuts or broken skin, wash bed linens and towels in hot water with extra bleach and dry everything at high heat in the dryer. You should also wash your gym and athletic clothes after each use.

People with HA-MRSA are typically placed in temporary isolation until the infection improves. Isolation prevents the spread of this type of MRSA infection. Hospital personnel caring for people with MRSA should follow strict handwashing procedures.

To further reduce their risk for MRSA, hospital staff and visitors should wear protective garments and gloves to prevent contact with contaminated surfaces. Linens and contaminated surfaces should always be properly disinfected.

While many people have some MRSA bacteria living on their skin, excess exposure can lead to serious and potentially life-threatening infections.

Symptoms and treatments can vary based on the type of MRSA infection a person has. Practicing excellent infection prevention techniques, such as washing hands regularly, refraining from sharing personal items, and keeping wounds covered, clean, and dry can help prevent its spread.

Healthline and our partners may receive a portion of revenues if you make a purchase using a link above.