MRSA, VRE and ESBL bacteria
Last Updated March 2005
MRSA rarely infects healthy people, and is most often seen in hospitals.
MRSA stands for methicillin-resistant Staphylococcus aureus, a common type of bacteria that has become resistant to certain types of antibiotics.
This type of bacteria is commonly found on the skin and in the noses of healthy people. In these places, the bacterium is usually harmless, but it can cause infection if it gets into the body through a cut or during surgery.
When penicillin was first used, it was highly effective against Staphylococcus aureus infections, but most strains of the bacterium are now resistant to the antibiotic.
Now, such staph infections are treated with methicillin and flucloxacillin, which must be given through an IV. However, some strains are resistant to these treatments, as well.
MRSA rarely infects healthy people, and is most often seen in hospitals. The infection can develop in an open wound such as a bedsore or when there is a tube such as a urinary catheter that enters the body. People with long-term illnesses or who have compromised immune systems are at increased risk of infection.
MRSA infections are treated with an antibiotic called vancomycin, which is derived from soil bacteria found in India and Indonesia. Vancomycin is extremely irritating to human tissue, so it is only used as a last resort. Still, some bacteria have become resistant even to this antibiotic, such as vancomycin-resistant Staphylococcus aureus (VRSA) and [[vancomycin-resistant enterococcus]] (VRE).
Vancomycin-resistant enterococci (VRE)
Enterococcus is a normally benign bacterium that lives in the intestine. Enterococcus infections can occur in the urinary tract, in the blood and in wounds, including surgical wounds.
VRE is thought to be passed to people through contact with animals or by eating animal meat.
While these infections can usually be treated with antibiotics such as ampcillin and vancomycin, a strain that is resistant to both was first discovered in France in 1986. Similar strains can now be found all over the world.
Vancomycin-resistant enterococcus (VRE) is thought to be passed to people through contact with animals or by eating animal meat. Once the meat is eaten, the bacteria sit dormant in the person's gut until they come into contact with an antibiotic. At that point the VRE can spread to the rest of the body.
Since many patients in hospitals are put on some kind of antibiotic therapy during the course of their treatment, VRE infections often occur in hospitals.
What are ESBL-producing bacteria?
ESBL stands for extended spectrum beta-lactamase, which are enzymes that have developed a resistance to antibiotics like penicillin.
Enzymes are proteins produced by living organisms. The proteins speed up biochemical reactions.
ESBL enzymes are most commonly produced by two bacteria Escherichia coli (otherwise known as E. coli) and Klebsiella pneumoniae. But ESBL enzymes can also be found in bacteria such as Salmonella, Proteus, Morganella, Enterobacter, Citrobacter, Serratia, and Pseudomonas.
In most cases, the body successfully fights off ESBL-producing bacteria. However, because of the enzymes' ability to fight off antibiotics, people with weak immune systems are at risk. This includes children, the elderly and people with other illnesses.
ESBL-producing bacteria are spread through feces either by self-infection or direct contact with feces of an infected person. It can, for example, spread from patient to patient on the hands of healthcare workers or the patients themselves. This is why hospitals and seniors' homes are particularly prone to outbreaks.
Washing hands and anything else that comes into contact with an infected person is important to preventing the spread of bacteria.
ESBL enzymes can also spread by passing from one bacterium to another.
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