Staphylococcus Aureus ( Mrsa )

2192 WordsMar 3, 20159 Pages
Introduction Staphylococcus aureus is a Gram-positive coccal bacterium which is estimated to have colonised 20-30% of the human population.1,2,3 S. aureus is normally found in the anterior nares and mucous membranes of these individuals. For the majority, this is not a problem as these people are colonised, not infected.2,3 However S. aureus is an opportunistic pathogen and if it contaminates a breach in the skin or mucous membranes, it can go on to infect any tissue in the body.3 Infection may lead to serious life threatening diseases such as pneumonia.4 Over time strains of S. aureus were able to develop resistance to antibiotics, resulting in strains known as methicillin resistant Staphylococcus aureus (MRSA). 1.1 A brief history Before the discovery of penicillin, infection with S. aureus had a fatality rate of approximately 70%. After penicillins discovery and development, treatment of S. aureus infections became routine resulting in the death rate falling to 25%.5 However, penicillin use provided an inadvertent selection pressure which resulted in the bacteria mutating and becoming resistant to its effects. The penicillin-resistant S. aureus strains produced enzymes known as penicillinases which break penicillin down. In 1959, the antibiotic methicillin was developed to battle penicillin-resistant S. aureus infections. At first it was effective, but with increasing use of methicillin S. aureus once again acquired resistance through the process of natural selection
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