MRSA Action UK | What is MRSA?

About MRSA

This information has been produced to help you understand MRSA. It is designed to answer some of the questions patients, the public and those who come into contact with people who have MRSA often ask. It also discusses the diagnosis and treatment of MRSA.

The information is also designed to help inform partners, friends, families and carers, and anyone who is concerned about how MRSA affects people and what can be done to treat it.

Treatments for MRSA including antibiotic therapy and other treatment is also discussed, as is the reason for screening for MRSA and other bacteria that can cause infection, for example MSSA. The information discusses what is involved in screening, diagnosis, treatment and how each of these may help you.

MRSA affects people in and outside of hospital, there is also information on how to deal with MRSA outside of hospital here. Information about how MRSA is dealt with in hospital is listed below.

This information is not a substitute for qualified medical care, if you are unwell please seek medical advice. The information is intended to complement information that should be provided by your doctors and nurses caring for you.

Content

What is MRSA?
What is Staphylococcus aureus?
What is colonisation?
How infection can happen
Who is most at risk?
Screening for MRSA
Symptoms and treatment for MRSA infection
References
Other useful information about MRSA

What is MRSA?

"MRSA" stands for Meticillin-Resistant Staphylococcus aureus

Infection with MRSA bacteria mainly occurs in people who are already ill, and can occur wherever healthcare is given. This can be in hospital, and in the community setting, such as in care homes, nursing homes and at home. Options to treat MRSA infection can be more limited as MRSA bacteria are resistant to a particular group of antibiotics that would commonly be used to treat Staphylococcus aureus infections. So, technically, this means the bacteria are unaffected by Meticillin, a type of antibiotic that used to be able to kill them.

What is Staphylococcus aureus?

Staphylococcus aureus is a bacterium (germ). It is often just called 'S. aureus' or 'Staph' or 'Staph aureus'. Staph aureus is commonly found on human skin and the site in which it may be most often found is the nose. Approximately one in three humans carry this organism harmlessly. Although carriage of this germ normally results in no harm to people, when they are having healthcare treatments and the skin is broken (for example during surgery or by using a drip to give fluids or drugs) there is an increased risk as the germ can get access to areas that it normally cannot.

Staph aureus is one of the causes of skin infections such as boils, pimples, impetigo, skin abscesses, and is a common cause of wound infections.

In some people, Staph aureus can sometimes get into the bloodstream and travel to internal parts of the body to cause more serious infections. For example, blood poisoning (septicaemia), lung infection (pneumonia), bone infection (osteomyelitis), or heart valve infection (endocarditis). These serious infections are more likely to occur in people who are already unwell or debilitated, or who have a poor immune system. These infections need to be treated with antibiotics.

In summary, an MRSA infection means the bacteria have got into the body through a break in the skin and multiplied, causing harmful symptoms. The symptoms of MRSA infection vary depending on which part of the body is infected, but there is often redness and swelling at the site of infection.

What is colonisation?

About one in three of us carry the Staphylococcus aureus bacteria in our nose or on the surface of our skin (especially in folds like the armpit or groin) without developing an infection. This is known as being colonised by the bacteria and there are no symptoms and no harm is caused.

The proportion of people colonised by MRSA tends to be higher in hospitals and nursing homes because of the more widespread use of antibiotics that wipe out a person's normal skin microbes leaving gaps for the MRSA to occupy.

People can carry MRSA for a few hours or days or sometimes for weeks or months. They are unaware they are carriers because the bacteria do not harm them or cause symptoms, unlike people who are infected with MRSA.

How infection can happen

If Staph aureus bacteria get into the body through a break in the skin, they can cause infections such as boils, an abscess or impetigo. If they get into the bloodstream they can cause more serious infections, such as blood poisoning.

Who is most at risk?

MRSA will not normally infect a healthy person. Although it is possible for people outside hospital to become infected, MRSA infections can be more common in people who are already in hospital. This is because:

they often have an entry point for the bacteria to get into their body, such as a surgical wound or a catheter
they tend to be older, sicker and weaker than the general population, which makes them more vulnerable to infection, and
they are surrounded by a large number of other patients and staff, so the bacteria can spread easily through direct contact with other patients or staff, or via contaminated surfaces. This is usually caused through touch, and this is why hand hygiene at the right time is a critical action to stop the spread of MRSA from one person to another. Since staff touch many patients in their day-to-day work it is particularly important that they clean their hands at the right time. Contaminated surfaces can also be a way in which people contaminate their hands with MRSA, making cleaning of the environment important in addition to cleaning of hands.

So in summary, those who are most at risk of MRSA infection are those who:

have a weakened immune system, such as the elderly, new born babies, or those with a long-term health condition such as diabetes
have an open wound
have a catheter (a plastic tube inserted into the body to drain fluid) or an intravenous drip
have a burn or cut on their skin
have a severe skin condition such as leg ulcer or psoriasis
have recently had surgery, or
have to take frequent courses of antibiotics.

Although MRSA infections usually develop in those being treated in hospital, particularly patients in intensive care units and on surgical wards, it is possible for hospital staff or visitors to become infected if they are in one of the most at risk of MRSA infection groups described in the previous section. Further information can be found at Symptoms and treatment for MRSA infection

References

The information on this page has been adapted by MRSA Action UK from original content supplied by NHS Choices - Page last reviewed: 09/09/2021 Next review due: 29/09/2024

NHS Choices: MRSA infection

Health Protection Agency:MRSA information for patients in hospital - March 2010

Department of Health: MRSA screening