Lecture 19 to 21

Question 1

What is meant by a “commensal bacteria”?

Answer 1

Bacteria part of normal gut flora. Does not cause disease an can be potentially health promoting

Question 2

What is meant by the term “opportunistic pathogen”?

Answer 2

Occasionally can cause disease. Depends on the host immunity and other various factors.

Question 3

What is meant by the term “primary pathogen”?

Answer 3

Highly virulent pathogen

Question 4

What are the two main genetic components of bacteria?

Answer 4

Bacterial chromosome- composed of DNA, circular and sometimes linear
Extrachromosomal DNA- jump from one DNA to another very easily

Question 5

What is the function of the capsule?

Answer 5

Surrounds the cell and is involved in immune-recognition, has a significant role in pathogenicity

Question 6

What is the function of the pilli and the fimbrae?

Answer 6

Involved in transmission from one bacteria to another

Question 7

What colour will gram positive DNA stain?

Answer 7

Purple

Question 8

What colour will gram negative DNA stain?

Answer 8

Pink

Question 9

What is the function of the capsule?

Answer 9

Protect the cell contents from an immune response

Question 10

Name a routine media:

Answer 10

Blood agar

Question 11

When would an enrichment media be used?

Answer 11

When the bacteria is very low in concentration or when the organism has been swamped by another bacteria

Question 12

What is the appearance of alpha bacteria on a blood agar plate?

Answer 12

partial haemolysis

Question 13

What is the appearance of beta bacteria on a blood ajar plate?

Answer 13

complete haemolysis

Question 14

What is the appearance of gamma bacteria on a blood ajar plate?

Answer 14

no haemolysis