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Methicillin Resistant Staphylococcus Aureus (MRSA)

MRSA is a methicillin-resistant strain of the Staphylococcus Aureus bacteria that was first discovered in 1961 in England. The first cited case of MRSA in the United States occurred in the late 1960s and became common ten to fifteen years after the introduction of methicillin, in 1960. MRSA strains are resistant to all beta-lactam agents, including but not limited to, cephalosporins and carbapenems. MRSA strains are also resistant to treatment by penicillin, amoxicillin,and oxacillin.

MRSA belongs to the genus Staphylococcus and the bacterial family Stahylococcaceae or Micrococcaceae . Staphylococci are catalase-positive, Gram-positive, spherical bacteria, which cluster together and when viewed under a microscope, they look like grapes. Each bacteria tends to be about one micrometer in diameter. and they divide in two planes, which is why they form clusters. The bacteria tend to reside dormantly in the nose and skin of humans. All Staphylococcus Aureus bacterias appear as a yellowish color. Staphylococcus Aureus forms a large yellow colony on rich medium and it tends to be hemolytic on blood agar. All Staphylococci are fucultative anaerobes and they grow by either aerobic respiration or fermentation.



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Sources Used and Helpful Links:

Center for Disease Control