70 likes | 248 Views
MRSA. Resistance = the ability to survive exposure to a dose of a chemical poison that is usually lethal. MRSA stands for methycillin-resistant Staphylococcus aureus, which is a common skin bacterium that is resistant to a range of antibiotics.
E N D
MRSA Resistance = the ability to survive exposure to a dose of a chemical poison that is usually lethal
MRSA stands for methycillin-resistant Staphylococcus aureus, which is a common skin bacterium that is resistant to a range of antibiotics. 'Methycillin-resistant' means the bacteria are unaffected by methycillin, a type of antibiotic that used to be able to kill them. They make make an enzyme to break down the antibiotic An MRSA infection means the bacteria have got into the body through a break in the skin (see below) and multiplied, causing 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.
MRSA can also be passed on between bacteria of the same species during conjugation - plasmids passed into bacteria that have not themselves encountered the antibiotic. • The number of antibiotic-resistant bacteria has increased in recent years due to: • People not finishing the full course of antibiotics they have been prescribed, which allows some bacteria to survive, develop a resistance to the antibiotic and then multiply • Antibiotics being overused, often inappropriately (e.g. prescibed for a viral disease) - the more a bacterium is exposed to a chemical, the more likely a resistant form will occur • Use of broad spectrum antibiotics in agriculture (prophylaxis) e.g. poultry
Sequence: - random mutations occur - made more likely by the rapid rate of reproduction (about once every 20 mins) a beneficial dominant allele would confer a selective advantage selection pressure - those without the advantageous form of allele will die when the antibiotic is administered the resistant form rapidly multiply and over successive generations will become more numerous (the “norm”) - natural selection
Skin infection • Most Staphylococcus aureus (SA) infections are skin infections, including: • boils (infection of the hair follic • abscesses (pockets of pus under the skin), • styes (infection of the eyelid glands), • carbuncles (large pus-filled lumps under the skin), • cellulitis (infection of the deep layer of the skin and the fat and tissues that lie beneath), and • impetigo(a highly contagious skin infection that produces blisters). • You should keep an eye on minor skin problems like spots, cuts or burns. If you have a wound that becomes infected, see your doctor. • An MRSA-infected wound will become red, swollen and tender, with yellow pus seeping from it. Skin ulcers, such as pressure ulcers, are often sites of infection.
Bloodstream infection • If MRSA bacteria enter into the bloodstream from your skin, they can affect almost any part of the body. They can cause: • septicaemia (blood poisoning), • septic shock (widespread infection of the blood that leads to a fall in blood pressure and organ failure), • septic arthritis (severe joint problems), • osteomyelitis(bone marrow infection), • abscesses deep within the body, • meningitis, • pneumonia, or • endocarditis(infection of the heart lining).