Chapter 25: Microbial Diseases of Digestive System

Question 1

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

Answer 1

• Microbes that live in the gut prevent disease from colonizing
• 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

• Food is contaminated by a worker with staphylococcus on hands
• Food is left at room temp for the bacteria to incubate long enough to release toxins
• Food contaminated toxins are eatten
• In 1-6hrs, staphylococcal intoxination occurs (food poisoning)

Question 5

What is the enzyme used by
H. pylori to survive the acidic pH of the stomach? You should 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

Causes “rice water stools”

Can lose 12-20 liters of fluid per day

Causes shock, collapse, organ failure and death

Question 7

what are the pros/cons of stool transplants?

Answer 7

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 8

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

Answer 8

Enterrohemorrhagic E. coli (EHEC)

Shiga-toxin producing E. coli

Question 9

What is a common source of
Salmonella?

Answer 9

eggs or in general contaminated food

Question 10

How is Hepatitis A virus (HAV) transmitted?

Answer 10

transmitted via fecal-oral route

Question 11

How is Hepatitis B virus (HBV) transmitted?

Answer 11

– transmitted via blood and bodily fluids

Question 12

Hepatitis C virus (HCV) transmitted?

Answer 12

transmitted via blood

Question 13

how is Hepatitis D virus transmitted?

Answer 13

requires coinfection with HEB

Question 14

how is Hepatitis E virus (HEV)

Answer 14

transmitted by fecal-oral transmission

Question 15

• Know the characteristics of the different varieties of hepatitis viruses.

Answer 15

• 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 HEB
• Hepatitis E virus (HEV) - transmitted by fecal-oral transmission

Question 16

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

Answer 16

Inflammation of the liver

Question 17

• Which type of hepatitis causes the most severe syndrome?

Answer 17

Hep C

Question 18

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

Answer 18

Drinking alcohol

Question 19

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

Answer 19

Hepatitis B

Question 20

• Which forms of hepatitis are more likely to become chronic?

Answer 20

Hepatitis B, very rare
Hepatitis C

Question 21

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

Answer 21

People with untreated HIV infections and injection drug users

Question 22

• What are some of the treatments for hepatitis C?

Answer 22

Treatment with HCV protease and polymerase inhibitors, interferon and ribavirin

Question 23

• Which form of hepatitis requires coinfection with hepatitis B?

Answer 23

Hepatitis D virus

Question 24

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

Answer 24

cirrhosis of the liver