Lab Exercise 14:

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Lab Exercise 14
Biochemical Differentiation of some Medically
Important Gram Positive Cocci
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Beta ( ß ) hemolysis (blood agar around bacterial
colonies is completely clear, indicating complete
breakdown and consumption of hemoglobin)
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Alpha (a) hemolysis (blood agar around bacterial
colonies looks greenish-brown, indicating partial
breakdown and consumption of hemoglobin)
Mixed culture from a throat swab note several
ß-hemolytic colonies
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Gamma (?) hemolysis (really means no hemolysis
blood agar around colonies looks normal)
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Side-by-side comparisons of alpha (a), beta (ß),
and gamma (?) hemolysis
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Bacitracin (Taxo A) sensitivity
results with a zone of inhibition
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Coagulase Test

-
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Carbohydrate Fermentation Tests (Glucose and
Mannitol)
- (same as uninoculated media)

Phenol red indicator turns yellow at acid pH
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Catalase Test
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Use the chart on p. 146 and/or the flow chart on
p. 147 of your lab manual to figure out who I am!
Answer Streptococcus pyogenes
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Use the chart on p. 146 and/or the flow chart on
p. 147 of your lab manual to figure out who I am!
G
M
Answer Micrococcus lutea
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Use the chart on p. 146 and/or the flow chart on
p. 147 of your lab manual to figure out who I am!
A
Answer Enterococcus faecalis
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Answer Staphylococcus aureus
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Use the chart on p. 146 and/or the flow chart on
p. 147 of your lab manual to figure out who I am!
Answer Staphylococcus epidermidis
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Use the chart on p. 146 and or the flow chart on
p. 147 of your lab manual to figure out who I am!
Answer Streptococcus pneumoniae
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Use the chart on p. 146 and/or the flow chart on
p. 147 of your lab manual to figure out who I am!
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Answer Streptococcus mutans