Staph and Strep

Question 1

What is the gram stain morphology that represents staphlococci?

Answer 1

Gram positive cocci in clusters

Question 2

Which is the most virulent species of staphlococci?

Answer 2

S. aureus

Question 3

Where can S. epidermidis be found normally on the body?

Answer 3

skin surface and mucus membranes

Question 4

How will S. aureus appear on sheep blood agar?

Answer 4

Creamy, white or light gold, buttery looking

May be beta hemolytic (species dependent)

Question 5

Name 2 supportive media and 2 selective media that may be useful when cultivating staphylococci.

Answer 5

Supportive - Blood agar and chocolate agar

Selective - CNA and PEA agar

Question 6

Which staphylococcus is associated with UTI in young females?

Answer 6

S. saprophyticus

Question 7

Which simple test will separate Staphylococci from Streptococci?

Answer 7

Catalase

Question 8

How can you differentiate Micrococcus from coagulase negative staphylococci like S. epidermidis?

Answer 8

Microdase disk

Question 9

Staphylococci is considered resistant to Novobiocin if the zone is less than ______?

Answer 9

< 10 mm

Question 10

Which organism may give a pseudocatalase positive result?

Answer 10

E. faecalis

Question 11

Why is it useful to perform both a slide and tube coagulase?

Answer 11

To tell the difference between bound and free coagulase.

Question 12

Staphylococcus aureus morphology

Answer 12

Gram positive cocci clusters; beta hemolytic

Question 13

Streptococcus pneumonia morphology

Answer 13

Gram positive cocci in pairs; alpha hemolytic

Question 14

Staphylococcus epidermidis morphology

Answer 14

Gram positive cocci clusters; gamma hemolytic

Question 15

Streptococcus pyogenes morphology

Answer 15

Gram positive cocci in chains; beta hemolytic

Question 16

Micrococcus luteus morphology

Answer 16

Gram positive cocci in clusters; gamma hemolytic

Question 17

Enterococcus faecalis morphology

Answer 17

Gram positive cocci in chains; alpha or gamma hemolytic

Question 18

What reagent is used to determine the presence of catalase?

Answer 18

Hydrogen Peroxide

Question 19

Which organisms will be differentiated with the catalase test?

Answer 19

Staphylococcus and streptococcus

Question 20

Expected results of catalase positive

Answer 20

Bubbles

Question 21

Expected results of catalase negative

Answer 21

No bubbles

Question 22

Expected results of Tube coagulase negative

Answer 22

Clotting

Question 23

Expected results of Slide coagulase positive

Answer 23

Clumping

Question 24

The microdase test will differentiate between which 2 organisms?

Answer 24

Micrococci and staphlococci

Question 25

Which enzyme is detected by the microdase reagent?

Answer 25

Oxidase enzyme

Question 26

Which organism is lysed by optochin?

Answer 26

S. pneumoniae

Question 27

Name a beta hemolytic streptococcus that is PYR positive.

Answer 27

S. pyogenes

Question 28

What are the expected results of positive bile esculin?

Answer 28

blackening of the media

Question 29

What are the expected results of negative salt tolerance?

Answer 29

No turbidity and no color change

Question 30

What are the expected results of positive salt tolerance?

Answer 30

Visible turbidity in the broth, with or without a color change