Streptococci

Question 1

Beta hemolysis on blood agar plate

Answer 1

Complete or true lysis of RBCs - clear zone surrounds colony of bacteria

Question 2

Alpha hemolysis on blood agar plate

Answer 2

Colonies surrounded by green or brownish discoloration (reduction in RBC hemoglobin to methemoglobin) - not true lysis; historically referred to as “partial hemolysis”

Question 3

Gamma hemolysis on blood agar plate

Answer 3

No hemolysis - no reaction in surrounding medium

Question 4

Beta-hemolytic streptococci

Answer 4

S. pyogenes, S. agalactiae, S. dysgalactiae, S. equi, S. canis, S. anginosus, S. constellatus, S. porcinus, S. iniae, S. phocae, S. didelphis

Question 5

Group A streptococci

Answer 5

S. pyogenes, S. dysgalactiae subsp. equisimilis, S. anginosus (group)

Question 6

Group B streptococci

Answer 6

S. agalactiae

Question 7

Group C streptococci

Answer 7

S. dysgalactiae subsp. dysgalactiae and subsp. equisimilis, S. equi subsp. equi and subsp. zooepidemicus, S. anginosus (group), S. constellatus subsp. pharyngis, S. phocae

Question 8

Group E streptococci

Answer 8

S. porcinus

Question 9

Group D streptococci

Answer 9

S. equinus (S. bovis), S. gallolyticus (S. bovis I), S. pasteurianus (S. bovis II.2), S. infantarius (S. bovis II/1), S. lutetiensis

Question 10

Group F streptococci

Answer 10

S. anginosus (group), S. phocae

Question 11

Group G streptococci

Answer 11

S. dysgalactiae subsp. equisimilis, S. anginosus (group)

Question 12

Lancefield groups for viridans streptococci

Answer 12

Groups A, C, G, and F