What is community-acquired MRSA?

Methicillin-resistant Staphylococcus aureus (MRSA) is a type of bacteria. Unlike other Staph bacteria, it can’t be killed by the antibiotic methicillin and other similar medicines. That's why it's called methicillin-resistant, and community-acquired because it means that you didn’t get the infection in a hospital or other healthcare setting. MRSA infections are sometimes very hard to treat.

Your skin and nasal passages are normally coated by millions of different kinds of bacteria. This is called being colonized. Staphylococcus aureus (commonly known as staph) is 1 such type of germ. It is found in about a third of all people in the U.S. These germs normally don’t cause a problem. But certain strains of staph, including some strains of MRSA, can move on their own from the surface of the skin into the skin. This is less likely if your immune system is strong, and your skin stays intact. If your skin is damaged, the bacteria are more likely to enter the tissue. If the germs enter the skin, they might cause a mild infection, like a small pimple, or a larger skin infection, such as cellulitis or an abscess. If they spread from the local tissue into the bloodstream, they can cause more serious widespread problems.

Antibiotics are medicines used to kill a specific type of bacteria. Over time, certain groups of these germs can adapt to the antibiotics, meaning they may no longer respond to them. This is called antibiotic resistance. MRSA are a specific subgroup of staph bacteria. They have become resistant to methicillin and other similar antibiotics. To treat MRSA, other kinds of antibiotics must be used.

MRSA infections were first found in healthcare settings, such as hospitals or nursing homes, in the 1960s. This was soon after methicillin was first used. This source of MRSA infection is still the most common.

Since the 1990s, more and more healthy people living in the community have become colonized with MRSA. Many of those people get infections from MRSA. 

Community-acquired MRSA is more likely to cause serious problems in young children and older adults. That’s also true for people with a weak immune system.

What causes community-acquired MRSA?

MRSA first developed when many strains of bacteria were exposed to standard antibiotics. It caused the surviving strains to become resistant to the antibiotics.

Many people who are colonized with MRSA don’t know it. You might pick up MRSA by:

• Touching someone who has MRSA on their skin

• Being nearby when a person colonized with MRSA coughs or sneezes

• Touching a surface that has MRSA on it

• Touching the contaminated wound of someone with a MRSA infection

These things might cause you to become colonized with MRSA. MRSA can penetrate into your skin on its own, or through a cut or other wound, causing an active MRSA infection.

Who is at risk for community-acquired MRSA?

Some things that make it more likely for you to get community-acquired MRSA are:

• Skin injury

• Skin tattoos, body piercings. or injecting illegal drugs

• Previous infection with MRSA

• Close contact with others who have MRSA colonization or infection

• Sharing equipment or supplies that are not cleaned or laundered between users

Community-acquired MRSA infections are more common in groups of people that spend a lot of time in close quarters. These include:

• People in prisons

• People in the military

• People on an athletic team

You may also have a higher risk of getting it if someone else that you live with already has it. But many people who get a community-acquired MRSA infection have no risk factors for the disease.

What are the symptoms of community-acquired MRSA?

Colonization by MRSA does not lead to symptoms unless the bacteria cause an active infection. Most people who have an active community-acquired MRSA infection show symptoms of a skin infection. You might have a raised, red lump or a large, tender lump that drains pus. This area may get bigger and become more and more tender, red, and swollen. In some cases, you might have many small lumps that look like pimples.

If the MRSA germs enter your bloodstream, it may lead to other problems. These include:

• Fever

• Tiredness (fatigue)

• Pneumonia

• Infection of the brain or spinal cord (meningitis)

• Infection of deeper layers of skin and soft tissue

• Infection of a heart valve

• Infection of a bone or joint

• Infection around a medical device, such as a pacemaker or IV

These problems may cause other symptoms, like pain and swelling around an infected joint. Or you may suffer from coughing and shortness of breath from MRSA-related pneumonia.

How is community-acquired MRSA diagnosed?

Your healthcare provider will ask about your symptoms and your past health problems, including previous MRSA infections. They will also do a physical exam that includes a careful exam of your affected skin.

If your healthcare provider suspects that you might have a staph infection, you will likely need some tests. Based on your symptoms, these might include:

• A skin swab of your affected skin to check it for MRSA. Sometimes swabs are taken from other parts of the body, such as inside the nose, the armpits, or the groin.

• X-ray of the lung, if your provider thinks your lungs may be infected

• Echocardiogram of the heart, if your healthcare provider thinks your heart might be infected

• CT scan or MRI scan to see if any soft tissue, bones, blood, or joints are infected

How is community-acquired MRSA treated?

If a MRSA infection is causing only pimples or a boil (abscess), antibiotics -may not be needed. The main treatment for these is to encourage the infection to drain out. This is done either by applying warm compresses or by having a healthcare provider drain the pus with a needle or cut. You should not drain the boil on your own except with warm compresses, as you may spread the infection.

Antibiotics are needed if the community-acquired MRSA is spreading in the skin or there are signs of possible spread into the blood or other parts of the body. Many times, you will be given an antibiotic for a week or so to get rid of the infection. It may be taken by mouth or given through an IV (intravenous) line. You might be given trimethoprim-sulfamethoxazole, doxycycline, vancomycin, linezolid, or other antibiotics. You cannot take trimethoprim-sulfamethoxazole if you are allergic to sulfa medicines.

If you are prescribed antibiotics, take them exactly as prescribed, even if you are feeling better. If you don’t, you may develop an infection that is even harder to treat.

If you have severe symptoms, you might need to stay in the hospital during your care. In this case, you will almost always be treated with antibiotics through an IV.

Most people recover from MRSA without any problems. That’s especially true for healthy people who get it in a community setting. If the MRSA infection spreads through the bloodstream, there is a chance that it can cause serious illness and even death.

If you have repeated MRSA infections, your healthcare provider might advise ways to get rid of the MRSA growing on your body. These might include using chlorhexidine soap washes on your skin or mupirocin antibiotic ointment in your nose.

Can community-acquired MRSA be prevented?

Some cases of community-acquired MRSA can be prevented. You can do so by:

• Always washing hands thoroughly with soap and water

• Using tissues to cover your mouth when coughing or sneezing

• Keeping cuts and scrapes clean and covered until healed

• Not touching other peoples' wounds

• Not sharing personal items, like razors, towels, or brushes

• Showering after team athletic activities

• Bathing or showering with an antibacterial soap, such as chlorhexidine, if directed by a healthcare provider

If you know you are colonized with MRSA, following the above steps can help you from spreading it. If you don’t have MRSA, following these steps can lower your chances of infection.

When should I call my healthcare provider?

If you have signs of a possible MRSA skin infection, call your healthcare provider right away. Also call or get medical care if you have a MRSA skin infection that has not started to clear up within a week. See a healthcare provider immediately if you have major symptoms. These include:

• Spreading of the rash

• Increasing redness of the skin

• Shortness of breath

• High fever

• Confusion

• Swollen, painful joints

Key points about community-acquired MRSA

• A MRSA infection is caused by a certain type of staph bacteria. It cannot be treated with methicillin and other similar antibiotics. Community-acquired MRSA is a MRSA infection that you get outside of a healthcare setting.

• Most commonly, MRSA causes a skin infection.

• If MRSA germs enter your bloodstream, they can cause major problems, like infection of the heart valves, lungs, bones, or joints.

• Draining the pus is the main treatment for localized infections of the skin. Antibiotics may also be needed to treat MRSA.

• Infection-control precautions can help prevent the spread of MRSA.

Next steps

Tips to help you get the most from a visit to your healthcare provider:

• Know the reason for your visit and what you want to happen.

• Before your visit, write down questions you want answered.

• Bring someone with you to help you ask questions and remember what your provider tells you.

• At the visit, write down the name of a new diagnosis, and any new medicines, treatments, or tests. Also write down any new instructions your provider gives you.

• Know why a new medicine or treatment is prescribed, and how it will help you. Also know what the side effects are.

• Ask if your condition can be treated in other ways.

• Know why a test or procedure is recommended and what the results could mean.

• Know what to expect if you do not take the medicine or have the test or procedure.

• If you have a follow-up appointment, write down the date, time, and purpose for that visit.

• Know how you can contact your provider if you have questions.