Chapter 25: Microbial Diseases of Digestive System

Question 1

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

Answer 1

• can release chemicals that kill pathogens
  
  • outcompete for nutrients/space
  • can provide us nutrients like vitamin 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

Converts sucrose to lactic acid and releases dextran. Dextran is the main sugar that forms plaque. Dextran is then food for all other species of bacteria. Lactic acid wears away enamel of tooth and then also effect dentin

Question 4

You should be able to describe the mechanism behind S. aureus caused food poisoning.

Answer 4

Bacteria is introduced by food server, bacteria incubate in food at room temp, bacteria produce toxins, we eat the contaminated food and get food poisoning within 1-6 hours, toxins cannot be destroyed by boiling so if we reheat the food, we can still get sick

Question 5

What is the enzyme used by H. pylori to survive the acidic pH of the stomach? You should know the reaction. (cross-over from lab)

Answer 5

urease
urea -> ammonia (basic) + CO2
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 – rice is clumps of mucus

Question 7

What is the most common form of E. coli? What toxin is produced by this particular E.coli?

Answer 7

Enterrohemorrhagic E. coli (EHEC)
EHEC serotype 0157:H7 (Most outbreaks) releases Shiga-toxin

Question 8

What is a common source of Salmonella?

Answer 8

Salmonella enterica within eggs/ reptiles

Question 9

how does salmonella poisoning effect through our body?

Answer 9

invade mucus of intestinal tract, then passes through M cells and enters lymphatics/blood stream and replicates in macrophages

Question 10

what are the pros/cons of stool transplants?

Answer 10

pro: effectiveness of 90% to treat C. diff infections
cons: FDA considers it a drug and only allows it to be used for treating C. diff even though there are many other potential uses for it that just haven’t been able to be tested/ only 3% of applicants can actually be donors b/c of need to have rigorous screening for pathogenic microbiota

Question 11

Know the characteristics of the different varieties of hepatitis viruses.

Answer 11

• Hepatitis A virus (HAV) – transmitted via fecal-oral route
• Hepatitis B virus (HBV) – transmitted via blood and bodily fluids
• Hepatitis C virus (HCV) – transmitted via blood
• Hepatitis D virus - requires coinfection with HBV
• Hepatitis E virus (HEV) - transmitted by fecal-oral transmission/ endemic to areas with poor sanitation

Question 12

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

Answer 12

Inflammation of the liver

Question 13

Which type of hepatitis causes the most severe syndrome?

Answer 13

Hepatitis C virus (HCV) – kills more in the US than AIDS

Question 14

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

Answer 14

Can drink too much alcohol/ chemotherapy

Question 15

Which type of hepatitis virus uses a DNA-based genome?

Answer 15

Hepatitis B virus (HBV)

Question 16

Which forms of hepatitis are more likely to become chronic?

Answer 16

Hepatitis B & C

Question 17

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

Answer 17

drug users

Question 18

What are some of the treatments for hepatitis C?

Answer 18

HCV protease and polymerase inhibitors, interferon, and ribavirin

Question 19

Which form of hepatitis requires coinfection with hepatitis B?

Answer 19

Hepatitis D virus

Question 20

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

Answer 20

cirrhosis of the liver