Which organism is beta-hemolytic on blood agar?

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Multiple Choice

Which organism is beta-hemolytic on blood agar?

Beta-hemolysis on blood agar means complete destruction of red blood cells around the colony, producing a clear halo. Listeria monocytogenes is known for this pattern because it makes a hemolysin called listeriolysin O that lyses RBCs in the surrounding medium. On a standard blood agar plate, its colonies are typically surrounded by a clear zone, indicating beta-hemolysis. The other organisms listed either do not hemolyze blood on this medium or are fastidious and do not produce that clear hemolysis pattern, so they don’t show the characteristic beta-hemolysis seen with Listeria.

Beta-hemolysis on blood agar means complete destruction of red blood cells around the colony, producing a clear halo. Listeria monocytogenes is known for this pattern because it makes a hemolysin called listeriolysin O that lyses RBCs in the surrounding medium. On a standard blood agar plate, its colonies are typically surrounded by a clear zone, indicating beta-hemolysis. The other organisms listed either do not hemolyze blood on this medium or are fastidious and do not produce that clear hemolysis pattern, so they don’t show the characteristic beta-hemolysis seen with Listeria.

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