MRSA is a strain of Methicillin-resistant Staphylococcus aureus. This is a bacterium which causes infections in different parts of the body. It is tougher to treat than other strains of Staphylococcus aureus – or 'staph' – because it is resistant to some commonly used antibiotics. In fact, it is now resistant to all forms of penicillin and cephalosporin.
The symptoms of MRSA depend on where the infected is. Most often, it causes mild infections on the skin, causing pimples, boils or pus. However, it can also cause more serious skin infections or infect surgical wounds, the bloodstream, the lungs, or the urinary tract.
Though most MRSA infections are not serious, some can be life-threatening. Many public health experts are alarmed by the spread of tough strains of MRSA. Because it is hard to treat, MRSA is sometimes called a "super bug".