Chapter 4: [Gram-Positive Bacteria] Streptococcus

Question 1

How would you describe the appearance of streptococci on a gram stain?

Answer 1

Streptococci (strep-ta-cock-eye) line up one after the other like a STRIP of candies.
(p. 27)

Question 2

How would you describe the appearance of staphylococci on a gram stain?

Answer 2

Staphylococci (staff-i-low-cock-eye) appear as a cluster that can be visualized as a group of hospital STAFF posing for a group picture.
(p. 27)

Question 3

What enzyme do staphylococci produce that streptococci do not?

Answer 3

Catalase (remember that Cat is a staff member who joined in for the group picture)
(p. 27)

Question 4

What does catalase do?

Answer 4

It converts H2O2 (hydrogen peroxide), which is used by macrophages and neutrophils, into H2O and O2.
(p. 27)

Question 5

The streptococci can be classified based on the antigenic characteristics of the _ ____________ (found on the ____ ____). These antigens are called __________ ________ and are given letter names from _ through _.

Answer 5

C carbohydrate
cell wall
Lancefield antigens
A through S
(p. 27)

Question 6

The primary classification of streptococci is based on their specific _________ _______.

Answer 6

hemolytic ability

p. 27

Question 7

Which group of streptococci completely lyse the RBCs, leaving a clear zone of hemolysis around the colony?

Answer 7

Beta-hemolytic

p. 27

Question 8

Which group of streptococci partially lyse the RBCs, leaving a greenish discoloration of the culture medium surrounding the colony?

Answer 8

Alpha-hemolytic

p. 27

Question 9

Which group of streptococci are unable to hemolyze the RBCs? Other name?

Answer 9

Gamma-hemolytic
(Because they are unable to hemolyze the RBCs, we shouldn’t really use the word ‘hemolytic’, therefore the term ‘non-hemolytic streptococci’ is often used to avoid confusion.)
(p. 27)

Question 10

Streptococcus pneumoniae is also known as…

Answer 10

…the pneumococcus

p. 33

Question 11

Streptococcus pneumoniae, or “the pneumococcus” is the most common cause of _________ and _________ __________ in adults, and the most common cause of ______ _____ in children.

Answer 11

pneumonia
bacterial meningitis

otitis media
(p. 33)