This organism stains positive on Gram stain due to thick peptidoglycan layer which absorbs crystal violet.
This bacteria has spherical shape.
Characteristically, Staph aureus is catalase-positive, meaning it produces the enzyme catalase. This enzyme allows the bacterium to convert hydrogen peroxide to water and oxygen. This characteristic is helpful in distinguishing staphylococci from catalase- negative streptococci and enterococci.
Staph aureus can also be differentiated from other Staphylococcal organisms, like Staph epidermidis and Staph saprophyticus, because it is coagulase-positive. The enzyme coagulase is thought to play a role in clotting plasma and coating the bacterial cell, which may prevent phagocytosis.
This organism is beta-hemolytic, which results in a complete lysis of red blood cells in the blood culture media.
This bacteria contains protein A, which is a structure anchored to the peptidoglycan cell wall. Protein A is an IgG binding protein that binds to the Fc region of the antibody and plays a role in inhibiting phagocytosis.
Protein A is an IgG binding protein that binds to the Fc region of the antibody, and plays a role in inhibiting phagocytosis.
Methicillin-resistant Staph aureus (MRSA) is strain of Staph aureus that has become resistant to most antibiotics. These strains are often found in hospitals, but are becoming more and more prevalent in community-acquired infections.
The mechanism of resistance in MRSA is altered penicillin binding proteins (PBPs). Because of the altered structure, many classes of antibiotics are unable to bind to the bacterium to kill the pathogen.
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