Bacterial Pathogenesis Final Part 4

Question 1

What some examples of virulence factors?

Answer 1

Adhesins, cytotoxin, flagellum, flagellum H antigen, LPS O antigen, siderophores, invasins, type 1 fimbriae

Question 2

What are koch’s postulates?

Answer 2

1. Pathogen is in all cases of disease, not in healthy people
2. Can be isolated in pure culture
3. Cells from the pure culture can cause disease in a healthy animal
4. Pathogen can be re-isolated from the diseased animal and will be identical to the original

Question 3

What are the molecular koch’s postulates?

Answer 3

1. The gene is only in the pathogen and must be expressed during infection
2. IF Gene encoding the virulence factor is mutated, then virulence is decreased
3. If the mutated gene is complemented, virulence returns
4. If the antibody to the virulence factor is administered, virulence factor is neutralized

Question 4

How are virulence factor genes regulated?

Answer 4

1. Signal chemical (effector)
2. Regulatory protein (effector binds to)
3. DNA regulatory region/sequence at the promoter for the protein to bind to

Question 5

What is the difference between tight binding and loose binding?

Answer 5

Tight: protein spends most/all time bound to DNA
Loose: protein spends most of the time not bound to DNA

Question 6

How does the sensor and regulator work in two component systems?

Answer 6

• The sensor is in the cytoplasmic membrane and autophosphorylates, then adds the phosphate to the regulator
• the regulator is a transcriptional activator

Question 7

How does quorum sensing communication happen?

Answer 7

Autoinducer

Question 8

What kind of bacteria is Streptococcus pneumoniae? Where does it colonize?

Answer 8

• Gram positive, spherical and in pairs

- upper resp tract

Question 9

What is Streptococcus pneumoniae’s 2 virulence factors?

Answer 9

1. Polysaccharide capsule

2. Pneumolysin: secreted protein that forms huge pores in the membrane (exotoxin)

Question 10

How do you test for Streptococcus pneumoniae?

Answer 10

• morphology of sputum test

- 16s rRNA gene sequence in DNA test

Question 11

How is Streptococcus pneumoniae treated?

Answer 11

Penicillin, tetracycline, erythromycin, hospital, rest, fluids, OTC pain relievers

Question 12

How does the Streptococcus pneumoniae capsule vaccine work?

Answer 12

• vaccine is against the capsule

- acts as opsonin and enhances phagocytosis

Question 13

How does the Streptococcus pneumoniae conjugate vaccine work?

Answer 13

• conjugated to proteins, so there is a stronger response

Question 14

How does pnuemolysin damage the host? Why does the bacteria do this?

Answer 14

• Pneumolysin impairs the host’s ability to clear the bacteria trapped in the
  mucus, easier to colonize
• can gain the contents of the cell

Question 15

What is an endotoxin?

Answer 15

Part of the cell wall (usually LPS)

Question 16

What are the 3 kinds of exotoxins?

Answer 16

-cytolytic toxins, neurotoxins, enterotoxins

Question 17

How do endotoxins cause disease?

Answer 17

By triggering a fever, vomiting and diarrhea, septic shock

- they trigger the inflammatory response when the immune system recognizes LPS fragments

Question 18

How do bacterial infections cause septic shock?

Answer 18

The infection causes bacteremia, and toxins damage blood vessels so they leak fluid… this affects the hearts ability to pump blood to your organs

Question 19

What kind of bacteria is Vibrio cholerae? How is it transmitted? What are its virulence factors?

Answer 19

• Gram neg, flagellated
• fecal contamination
• CT, LPS, TCP to adhere, biofilm

Question 20

Is the thiosulfate–citrate–bile salts agar (TCBS)

medium selective or differential for V. cholera?

Answer 20

Both

Question 21

Where is lysozyme found?

Answer 21

Lysozyme, which helps to prevent colonization, is found in all the following body sites and fluids: blood, tears, the oral cavity, and the lower respiratory tract.