Chapter 25: Microbial Diseases of Digestive System

Question 1

Why is the microbiome important for fighting pathogens in the gut?

Answer 1

Having a microbiome is beneficial against invading pathogens. It outcompetes for nutrients and space, releases chemicals that kill pathogens, also microbiome prevents disease from colonizing and provides us with nutrients (Vit K)

Question 2

Which bacterium grows in the mouth and causes tooth decay?

Answer 2

Streptococcus mutans

Question 3

How does sucrose in the mouth contribute to tooth decay?

Answer 3

Streptococcus mutans converts sucrose to lactic acid, which then produces DEXTRAN, a polysaccharide that forms plaque. Dextran serves as food for other bacteria, resulting in enamel being degraded because of too much acid released, then a dental caries.

Question 4

Describe the mechanism behind S. aureus causing food poisoning

Answer 4

• Normally caused by how food is handled.
• Food containing protein is cooked (bacteria usually killed)
• Poor handling of food by a worker results in food being contaminated.
• Food then is left at room temp, incubating bacteria (temp abuse) where toxins are produced.
  reheating will kill staphylococci, not the toxin
• Contaminated food with toxins is eaten.
• Takes 1-6 hrs for symptoms.

Question 5

What is the enzyme used by H. pylori to survive the acidic pH of the stomach? (know the reaction)

Answer 5

Urease

Bacteria break down urea to produce ammonia which is basic and protects them in the HCL of our stomach

Question 6

What is a distinct sign of cholera?

Answer 6

“rice water stools”
- You can lose 12-20 L of fluids a day.
- Causes shock, collapse, organ failure and death

Question 7

What is the most damaging form of E. coli? What toxin produces?

Answer 7

Enterohemorrhagic E. coli (EHEC)

Shiga-toxin (passed by conjugation) producing E. coli
Cattle is main reservoir

Question 8

What is a common source of Salmonella?

Answer 8

raw or undercooked meat, poultry, and eggs or egg products

Question 9

Hepatitis A

Answer 9

• Most contagious
• Transmitted via fecal-oral route
• not washing hands

Question 10

Hepatitis B

Answer 10

• Transmitted via blood and body fluids
• Most infectious
• Sharing needles
• Resembles HIV
• No cure, but there’s a vaccine

Question 11

Hepatitis C

Answer 11

• Most severe
• Transmitted via blood/needles, also sexually
• Can be cured, but expensive

Question 12

Hepatitis D

Answer 12

• requires co-infection with type B

Question 13

Hepatitis E

Answer 13

• Transmitted via fecal-oral
• Similar to HA
• poor sanitation

Question 14

Describe the general syndrome caused by any type of viral hepatitis:

Answer 14

They all cause inflammation to the liver.

Question 15

Which type of hepatitis causes the most severe syndrome?

Answer 15

C

Question 16

What are some other non-infectious ways to get hepatitis?

Answer 16

Drinking alcohol

Question 17

Which type of hepatitis are more likely to become chronic?

Answer 17

Hepatitis B

Question 18

Which group of people is most likely to be infected with hepatitis C?

Answer 18

People with untreated HIV infections and injection drug users

Question 19

What are some of the treatments for hepatitis C?

Answer 19

HCV protease and polymerase inhibitors, interferon and ribavirin
- Very expensive

Question 20

Which form of hepatitis requires coinfection with hepatitis B?

Answer 20

hepatitis D

Question 21

What is the technical term to describe sudden onset, catastrophic liver failure?

Answer 21

Cirrhosis of the liver