MRSA stands for methicillin-resistant Staphylococcus aureus, a type of infectious bacterium resistant to the antibiotic methicillin and other related antibiotics of the penicillin class. MRSA infections are a particular problem in hospitals. Some patients have MRSA on their skin or nose without it doing them any harm (colonised patients). However, these patients may develop infections if the MRSA spreads from the colonised skin area to an open wound.
MRSA mostly affects hospital patients and can be a serious, even fatal, infection. MRSA-related deaths are commoner among the elderly and people with damaged or depressed immune systems, either from chronic disease, such as HIV, or those undergoing chemotherapy, which represses the activity of the immune system.
MRSA can cause fatal blood infections, such as septicaemia, that are hard to treat due to the bacteria's resistance to many antibiotics.
The history of MRSA
MRSA belongs to the Staphylococcus aureus (S. aureus, staph or SA) family of bacteria, which is a common cause of wound and blood stream infections.
SA infections were serious and often fatal before penicillin (an antibiotic) was introduced in the 1940s.
More and more strains of SA became resistant to penicillin and by the end of the 1950s the bacteria evolved the ability to develop an enzyme to destroy penicillin's antibacterial activity.
In the early 1960s, however, a more powerful type of antibiotic, methicillin, was developed for use in penicillin-resistant SA infections. Within a short time, however, some SA strains had again started to adapt to become methicillin resistant too.
Despite being relatively uncommon during the 1960s, 1970s and 1980s, MRSA infection grew dramatically in the mid-1990s, when new strains that were easily transmitted from person to person became established in hospitals across the UK, causing an increasing number of cases.
Health Protection Agency figures on MRSA blood stream infections reveal there were 1,087 cases reported in England during the fourth quarter of 2007, or a 0.6 per cent increase on the previous quarter when 1,080 reports were received (1).
How is MRSA transmitted?
Around 30 per cent (2) of people are colonised by SA naturally, which means bacteria live normally in the nose and throat, and on the surface of the skin, particularly in areas where there are folds, such as the armpit or the groin - without it causing any problems.
When SA bacteria get into the body through a wound, they can cause skin infections, such as boils or abscesses. If they get into the blood stream, they can cause potentially fatal infections, such as septicaemia.
Many SA infections can be treated with common antibiotics, but if you become infected with an MRSA strain, clearing up the infection becomes far more difficult, as the availability of drugs that can treat it is limited.
Hospital patients are usually the most likely to develop MRSA since some may have pressure sores, for instance, or surgical wounds after having operations, such as hip replacements or heart surgery, or are being treated with intravenous drips or urinary catheter - all of which offer opportunities for bacteria to enter the body and cause infection.
How do you get infected with MRSA?
- Exogenous infection
- You can catch MRSA if you have had contact with someone who either has the infection or who is colonised with MRSA bacteria, or by having contact with something that has been contaminated with MRSA bacteria, such as sheets, clothing, sinks, towels and even door handles.
- Endogenous infection
- You can infect yourself, if you are colonised by MRSA and suffer a cut, wound or other type of break in your skin where the bacteria can invade your body.
What are the symptoms of MRSA?
The majority of MRSA infections start as skin infections, such as a wound that does not heal and develops into a boil or an abscess. Ulcers, such as pressure sores, varicose ulcers and diabetic ulcers can often be colonised by MRSA infection.
MRSA is far more serious when it enters the blood stream, causing septicaemia, septic shock, septic arthritis, deep (or internal) abscesses, meningitis, pneumonia, osteomyelitis (bone infection) and endocarditis (infection of the heart lining) (3).
Deeper abscesses can affect parts of the body, such as the kidneys, liver and spleen, causing low blood pressure, shivers, weight loss and organ failure (4).
Septicaemia, which is the type of MRSA infection that has the highest death rate, includes severe symptoms such as high body temperature, shaking and organ failure.
How is MRSA treated?
MRSA infection is detected by a blood or urine test. Also, sometimes a wound swab can check for the presence of MRSA bacteria. If the diagnosis is confirmed, you may need further tests to check to which types of antibiotics the bacteria are resistant.
Certain antibiotics, such as vancomycin, teicoplanin or linezolid, are still effective in treating MRSA. These drugs are usually injected directly into a vein or fed into the blood stream via a drip. The doses are much higher than those given for other types of infection and you may need several weeks' worth of hospital-based treatment.
Can MRSA be prevented?
Steps are being taken in hospitals around the country to control and minimise the spread of MRSA in patients.
For example, hospital workers are expected to wash their hands thoroughly before and after having contact with patients. Visitors also are encouraged to wash their hands before entering the wards and on their way out too.
If you are going to visit somebody in hospital, there should be antibacterial gels in dispensers near patients' beds, as well as next to main and ward doors.
If you see antibacterial gel dispensers on a ward or hospital door use them.
If you are going into hospital for treatment, a few sensible measures may reduce your risk. Make sure your hands are clean at all times. Keep a pack of antibacterial hand wipes by your bed and use them each time you come into contact with anyone or anything that could possibly be contaminated with bacteria (after using the toilet, for instance), as well as before and after having a meal.
Make sure anyone who visits you washes their hands thoroughly too, when they first arrive and before they leave.
Many hospitals also routinely test new patients for MRSA colonisation, and you may have swabs taken from your skin and nose, as well as being required to give urine and blood samples before you can receive any treatment.
If you test positive, you will be given an antibiotic skin cream and antiseptic shampoo and soap to get rid of the bacteria, so that you are clear before you are admitted.
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