A Gram-positive coccus in chains that is PYR positive and lacks hemolysis on blood agar points to which genus?

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Multiple Choice

A Gram-positive coccus in chains that is PYR positive and lacks hemolysis on blood agar points to which genus?

Chains of Gram-positive cocci that are PYR positive and show no hemolysis on blood agar point to Enterococcus. The chain arrangement keeps you in the Streptococcus/Enterococcus group, while gamma-hemolysis rules out the beta-hemolytic streptococci like group A or B, and Staphylococcus doesn’t form chains. The PYR test is a key discriminator here because Enterococcus species are PYR positive, helping separate them from other gamma-hemolytic streptococci that are PYR negative. So this combination most specifically identifies Enterococcus spp.

Chains of Gram-positive cocci that are PYR positive and show no hemolysis on blood agar point to Enterococcus. The chain arrangement keeps you in the Streptococcus/Enterococcus group, while gamma-hemolysis rules out the beta-hemolytic streptococci like group A or B, and Staphylococcus doesn’t form chains. The PYR test is a key discriminator here because Enterococcus species are PYR positive, helping separate them from other gamma-hemolytic streptococci that are PYR negative. So this combination most specifically identifies Enterococcus spp.

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