Infection with MRSA bacteria mainly occurs in people who are already ill in hospital. It can be difficult to treat as MRSA bacteria are resistant to most types of antibiotics. Many people are carriers of MRSA without even realising it as MRSA often does not cause symptoms in healthy people.
What is Staphylococcus aureus?
Staphylococcus aureus is a bacterium (germ). It is often just called 'S. aureus' or 'staph'. S. aureus bacteria are often found on the skin and in the nose of healthy people. These people are called S. aureus 'carriers'. In healthy people who are carriers, S. aureus is usually harmless.
However, S. aureus bacteria sometimes invade the skin to cause infection. This is more likely if you have a cut or graze which can allow bacteria to get under the surface of the skin. S. aureus is the cause of skin infections such as boils, pimples, impetigo, skin abscesses and is a common cause of wound infections.
In some people, S. aureus can sometimes get into the bloodstream and travel to internal parts of the body to cause more serious infections. For examples, septicaemia (blood poisoning) , pneumonia (lung infection), osteomyelitis (bone infection), endocarditis (heart valve infection), etc. 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.
What is MRSA?
MRSA stands for methicillin-resistant Staphylococcus aureus. It is sometimes known as a "superbug". There are various sub-types (strains) of S. aureus and some strains are classed as MRSA. MRSA strains are very similar to any other strain of S.aureus. That is, some healthy people are carriers and some people develop the types of infections described above.
Most S. aureus infections can be treated with commonly used antibiotics. However, MRSA infections are resistant to an antibiotic called methicillin and also to many other types of antibiotics. Resistance means that the bacteria are not killed by the antibiotic.
MRSA has become much more common since the 1980s. MRSA is now the cause of over 4 in 10 bloodstream infections with S. aureus.
How serious is an MRSA infection?
MRSA strains of bacteria are no more aggressive or infectious than other strains of S. aureus. However, infections are much more difficult to treat because many antibiotics do not work. Infections with MRSA can sometimes become more severe than they may otherwise have been if the cause of the MRSA infection is not diagnosed early and antibiotics that are not effective are given at first.
Who gets MRSA?
MRSA occurs most commonly in people who are already in hospital, especially if they have been in hospital for a length of time. Some wards in the hospital have higher rates of MRSA (for example intensive care units) than others. People who are more prone to MRSA are those who are very ill or have wounds or open sores (for example bed-sores or burns). The wounds or sores may become infected with MRSA and the infection is then difficult to treat. Infections which start in the skin may spread to cause more serious infections. Also, urinary catheters and tubes going into veins or other parts of the body ('drips' etc) are sometimes contaminated by MRSA and can lead to urine or blood infection.
MRSA can also cause infections in people outside hospital, but much less commonly than in hospitalised people.
MRSA can affect you in two ways; either you are a carrier of MRSA or have an infection caused by MRSA.
MRSA colonisation (carrier of MRSA)
This is when MRSA grows in or on your body with no signs or symptoms of an infection. Many people carry MRSA without it causing any symptoms whatsoever. The most common place for colonisation are your armpits, nostrils, skin (especially if you have eczema), throat and urine. This colonisation can act as a reservoir which means that MRSA infections can later either develop in your body or spread to other people.
If you know you are a carrier of MRSA and are due to go into hospital, for example for an operation, then you should let the hospital know before you go in. This will not necessarily delay or prevent your admission.
If you are found to be a carrier of MRSA then you are likely to be offered treatment which will then prevent future infections or the spread of MRSA. This treatment is usually in the form of ointment to put inside the nose or antiseptic washes, depending on where the bacteria have been found on your body. It is still uncertain from clinical trials as to which treatment is the most effective.
MRSA infection
Infections with MRSA are usually associated with high fevers and signs of the infection. As mentioned, most commonly these are infections of the skin and soft tissues (like boils and abscesses). Less commonly, MRSA can cause pneumonia and urine infections.
How is MRSA diagnosed?
If an infection with S. aureus is suspected then, depending on the type of infection, a sample of blood, urine, body fluid or a swab of a wound can be sent to the laboratory. If S.aureus is detected, further tests are done to see which antibiotics will kill the bacteria. MRSA strains can be identified by seeing which antibiotics kill the bacteria found on testing. Healthy people suspected of being carriers of MRSA can have a swab or the nose or skin taken and tested.
How is MRSA spread?
MRSA spreads from person to person usually by direct skin-to-skin contact. MRSA is usually caught from hospitals. Spread may also occur by touching sheets, towels, clothes, dressings, etc, which have been used by someone who has MRSA. Ways to prevent spread of MRSA include:
- Wash your hands regularly. You may be asked to use an alcohol handrub when entering and leaving a hospital.
- Ensure all cuts are covered with a waterproof dressing.
- Wear gloves if you are in contact with a person with MRSA. This does not mean if you are just talking to someone though.
- Avoid sharing towels, facecloths, etc with people who have MRSA.
However, as mentioned, S. aureus (including MRSA strains) will not normally cause an infection if you are well and healthy. The bacteria may get onto your skin, but do no harm. So, for example, people who visit patients with MRSA, or doctors and nurses who treat people with MRSA, are not likely to develop an MRSA infection. However, they may become colonised with the bacteria and may pass it on to someone who is ill, or who has a wound, who then may develop infection.
What is the treatment of MRSA infections?
MRSA infections are usually treated with antibiotics. (Boils or abscesses caused by MRSA may only need to be drained and may not need antibiotics.) However, the choice of antibiotic is limited as most antibiotics will not work. Many MRSA infections can only be treated with antibiotics that need to be given directly into a vein. The course of treatment is often for several weeks. Also, the risk of side-effects with the limited choice of antibiotics is higher than the more 'usual' antibiotics which are used to treat non-MRSA infections.
Can MRSA infections be prevented?
The number of MRSA infections in hospital can be kept down if all hospital staff adhere to good hygiene measures. The most important is to wash hands before and after contact with each patient, and before doing any procedure. This simple measure reduces the chance of passing on bacteria from patient to patient.
Other measures are used in hospitals to reduce the spread of infection. For example, cleaning of bedding, regular cleaning of wards, etc. Patients with an MRSA infection may be kept away from other patients, perhaps in a single bed room or in an isolation unit until the infection has cleared.
If you are found to be a carrier of MRSA then you are usually offered treatment which prevents future infections or the spread of MRSA.
Is MRSA screened for in the UK?
There is not a universal screening programme in the UK as it has not yet shown to be effective in clinical trials. Universal screening for MRSA has recently been suggested by the Department of Health. However, MRSA testing is currently recommended for:
- People at high risk of colonisation. For example, patients being transferred from one hospital to another or re-admitted to the same hospital.
- People with a high risk of infection. Examples are those admitted to intensive care units, orthopaedic and vascular surgery wards.
MRSA screening for all people going into hospital (other than in an emergency) is to be introduced by the end of March 2009. You will not be included in this screening if you:
- Are having a day case operation on your eyes or teeth.
- Are having an endoscopy (for example a gastroscopy) as a day case.
- Are having minor skin procedures. For example, freezing treatment for warts.
- Are a child or are pregnant (unless you are having a planned caesarean section).
Many hospitals already have in place effective screening procedures and treatment for people who are carriers. The government has recently announced that there has been a 57% reduction of MRSA in hospitals since 2004. This has mainly been done by:
- Better infection control between staff in hospitals.
- Improved hand washing.
- Deep cleaning of wards.
The NHS introduced the "cleanyourhands©" campaign in 2005. This is a national initiative in England and Wales to improve the hand hygiene of healthcare workers and help reduce the spread of preventable healthcare associated infections, including MRSA.
Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. EMIS has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions.
© EMIS 2008 Reviewed: 6 Dec 2008
