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0

What are the Gram-positive cocci?

1) Streptococcus (and Enterococcus)
2) Staphlycoccus

1

What are 2 tests to differentiate between the Gram-positive cocci?

1) appearance on Gram stain: Streptococci appear as chains(strips), and Staphylocci appear as clusters
2) catalase: Streptococci is catalase-negative, Staphyloccus is catalase-positive

2

How to differentiate between Gram-positive cocci based on morphology?

Streptococci appear as chains(strips)
Staphylococci appear as clusters

3

How to differentiate between Gram-positive cocci based on catalase test?

Streptococci are catalase-negative.
Staphylococci are catalase-positive.

4

Streptococci are classified according to what ability?

hemolysis

5

alpha hemolytic - defn

partially lyse RBCs (on blood agar) leaving a greenish discoloration of the culture medium surrounding the colony (which contains unlysed RBCs and a green-colored metabolite of hemoglobin)

6

What type of hemolysis partially lyses RBCs and leaves a greenish discoloration of blood agar?

alpha hemolysis

7

beta hemolysis - defn

completely lyses RBCs, leaving a clear zone of hemolysis around the colony on blood agar

8

What type of hemolysis completely lyses RBCs and leaves a clear zone surrounding the colony?

beta hemolysis

9

gamma hemolysis - defn

non-hemolytic

10

What type of hemolysis is non-hemolytic (unable to lyse RBCs)?

gamma-hemolytic

11

What bacteria are alpha hemolytic when grown on blood agar? (2)

1) Streptococcus pneumoniae
2) Viridans streptococcus

12

S. pneumoniae displays what type of hemolysis when grown on blood agar?

alpha hemolytic (partial hemolysis)
Streptococci pneumoniae

13

S. viridans displays what type of hemolysis when grown on blood agar?

alpha hemolysis (partial hemolysis)
Streptococci viridans

14

What streptococci display beta hemolysis when grown on blood agar?

1) Group A Streptococcus (S. pyogenes)
2) Group B Streptococcus (S. agalactiae)

15

Group A strep displays what kind of hemolysis when grown on blood agar?

beta (complete) hemolysis
Group A = Strep pyogenes

16

S. pyogenes displays what kind of hemolysis when grown on blood agar?

beta (complete) hemolysis
Streptococci pyogenes = Group A strep

17

Group B streptococci display what type of hemolysis when grown on blood agar?

beta (complete) hemolysis
Group B strep = Streptococci agalactiae

18

S. agalactiae displays what kind of hemolysis when grown on blood agar?

beta (complete) hemolysis
Streptococci agalactiae = Group B strep

19

What streptococci are gamma-hemolytic? (2)

Group D strep: Enterococci and Nonenterococci
gamma hemolytic = non hemolytic

20

Group D streptococci display what type of hemolysis when grown on blood agar?

gamma-hemolytic (non-hemolytic)

21

What type of streptococci are non-hemolytic?

Group D strep: enterococcus, nonenterococcus
Gamma hemolytic = non-hemolytic

22

Which two antibiotics can differentiate among species of streptococci?

1) optochin
2) bacitracin

23

Optocochin is used to differentiate among which type of hemolytic streptococci?

alpha-hemolytic

24

The alpha-hemolytic streptococci are differentiated based on sensitivity to which antibiotic?

optocochin

25

Optochin is used to differentiate among which bacteria?

Streptococci alpha hemolytics: S.pneumoniae and S. viridans
S. viridans is resistant
S. pneumo is sensitive
"OVRPS" (overpass)

26

S. pneumoniae is (sensitive, resistant) to optochin

sensitive
"OVRPS"

27

Which alpha hemolytic streptococcus is optochin sensitive?

S. pneumoniae
"OVRPS"

28

Which alpha hemolytic streptococcus is optochin resistant?

S. viridans
"OVRPS"

29

S. viridans is (sensitive, resistant) to optochin.

resistant
"OVRPS"