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Ex. 14: Skin Cultures and Importance of Selective and Differential Media for Isolating Gram-Positive Cocci. Objectives??. MSA: Selective and Differential Medium for Gram + Cocci.
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Ex. 14: Skin Cultures and Importance of Selective and Differential Media for Isolating Gram-Positive Cocci Objectives??
MSA: Selective and Differential Medium for Gram + Cocci Composition: meat extract, casein, peptones; 7.5% NaCl, mannitolas only fermentable carbohydrate, phenol red indicator.
Control Organisms Skin Inoculum
CatalaseTest H2O2 is by-product of aerobic respiration. Lethal to the cells. Most aerobic organisms produce catalase for protection Catalase test differentiates among morphologically similar Gram+ cocci.
Coagulaseactivates fibrin and leads to clot formation Protective barrier around bacterial cells Virulence factor • Test determines presence of coagulase enzyme • Used for differentiating S. aureus from other Staphylococci. CoagulaseTest
Tube Coagulase Test Tests for bound of free coagulase check no later than 24 hours after inoculation!
Slide Coagulase Test • Tests for bound coagulase • Positive if agglutination within 1 to 2 minutes