Lab 9- Gram Positive Cocci

Question 1

Mannitol salt agar (MSA) is a selective and differential media used to culture Gram-negative
members of Enterobacteriaceae.

Answer 1

False

Question 2

Development of a yellow color on MSA indicates microbial digestion of mannitol

Answer 2

False

Question 3

Most streptococcal species are catalase negative

Answer 3

True

Question 4

Most staphylococcal species are able to ferment mannitol.

Answer 4

True

Question 5

Strong Beta hemolysis is a characteristic of many staphylococcal species

Answer 5

False

Question 6

The purpose of the gas pack anaerobic jar was to what?

Answer 6

Encourage the growth of beta-hemolytic anaerobic or facultative organisms.

Question 7

Which biological test did we learn that would allow
you to differentiate between S. epidermidis and
S. saprophyticus?

Answer 7

Novobiocin resistance

Question 8

Which of the following is not a characteristic normally
associated with Staphylococcus aureus?

Answer 8

gamma hemolytic

Question 9

Based on our lab results which of the following organisms do you think would be the most
halotolerant? (able to withstand high salt levels)

Answer 9

Staphyloccocus aureus d. Staphylococcus saprophyticus

Question 10

Which of the following is not a disease or aliment that may be caused by group A streptococcal
infection?

Answer 10

None of these choices – these are all diseases caused by group A strep

• Necrotizing fasciitis
  -Toxic shock syndrome
  -Tonsillopharyngitis
• Impetigo
  -Rheumatic fever

Question 11

Which of the following statements is true regarding group A beta hemolytic strep?
(circle all that apply)

Answer 11

• Streptococcal toxic shock syndrome and necrotizing fasciitis are highly lethal, invasive, and group
  Streptococcal infections.
• Only group A strep is beta-hemolytic.
• Most GABHS infections cause severe disease, especially in children between ages 5 and 15
  years of age

Question 12

Could one of the organisms on this BAP be Streptococcus pneumoniae? Why or why not

Answer 12

No, S. pneumoniae is alpha hemolytic

Question 13

What is the Novobiocin test and what organism is used

Answer 13

• Test where we observe zone inhabitation
• Staphylococcus aureus

Question 14

What chemical (s) is (are) present in rabbit plasma that bacterial coagulase enzyme activates (circle
all that apply)?

Answer 14

• coagulating enzyme
• coagulase reacting factor
• fibrinogen
• clumping factor

Question 15

Based on the MSA plate shown below which organisms were able to ferment mannitol?

Answer 15

• S. aureus
• S. saprophyticus

Question 16

Most staphylococcus species are
_______________ positive, while most
streptococcus and enterococcus species
are ________________ negative.

Answer 16

Catalase, catalase

Question 17

What is Gram +
Cocci
Clustered microscopic colony morphology
Catalase positive
Unable to ferment mannitol
Coagulase negative
Novobiacin sensitive
Non halotolerant

Answer 17

Staphylococcus epidermis