Microbial Evolution: Staphlococcus Aureus

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Microbial Evolution – Staphylococcus aureus
Name: Sean Lin Class: E8J Date: May 23th, 2016
Introduction:
Staphylococcus aureus is a species of bacteria that belongs to Staphylococcus genus, and it is generally found in the nose, respiratory tracks and on skin. Staphylococcus appears as a form like a grape clusters when looking through a microscope, and it has large, golden colonies. Staphylococcus reproduces by binary fission, which it is asexual. [Cashin, 2010] The symptoms on humans that are caused by the infection of Staphylococcus aureus consist a very wide range, from minor skin problems such as boils or abscesses, to life threatening diseases such as pneumonia, endocarditis or meningitis.

Staphylococcus aureus has been a great concern
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The most common treatment for these infections, caused by Staphylococcus aureus is the antibiotics. There are many kinds of antibiotics using in the modern days, but the first kind of antibiotic being introduced for treating Staphylococcus aureus was Penicillin in 1943. This kind of antibiotic stops the formation of peptidoglycan cross-linkages that makes the bacterial cell well stronger. This eventually makes the cell wall formation and degradation become imbalanced, consequently lead to the cell to die. Other kinds of antibiotic were quick introduced for treating Staphylococcus as well. As more kinds of antibiotics were introduced and people widely used them to kill Staphylococcus aureus bacteria, they become the selective pressure for the…show more content…
However, the amount of Staphylococcus aureus that is antibiotic resistance gradually increased, until the year of 1950, the number rose to 40% of the patients, and 80% of the patients until the year 1960. The mechanism that made the bacteria become resistant to the antibiotic is that, a mutation to an extremely small amount of Staphylococcus aureus. From this mutation the bacteria began to produce an enzyme called penicillinase, which it breaks the molecule within penicillin that makes the antibiotic to function. Consequently, this antibiotic become ineffective and the bacteria eventually survived. This kind of Staphylococcus aureus is called “MRSA”, referred to methicillin-resistant S. aureus. This bacteria are multi-resistant to beta-lactam antibiotics, meaning that they are resistant to different kinds of antibiotics, such as penicillin, methicillin, dicloxacillin and cephalosporin. As the process goes, that normal Staphylococcus aureus are being killed by penicillin antibiotic, and the ones that are resistant survived and keep on reproducing, Staphylococcus aureus bacteria that is penicillin resistant spread in the community and its amount kept on increasing. This made natural selection to occur, which the bacteria that are antibiotic resistance are suitable ones and they survived in

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