Chapter 25

Question 1

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

Answer 1

• The microbiome is crucial for fighting pathogens in the gut because it provides a protective barrier against harmful microorganisms.
• Beneficial bacteria in the microbiome outcompete and inhibit the growth of potential pathogens

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 is bacteria that will convert sucrose into lactic acid. Lactic acid will lower the pH in the mouth. The newly acidic environment attracts other bacteria that will eventually lead to tooth decay.

Question 4

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

Answer 4

Staphylococcus aureus causes food poisoning through the production of an enterotoxin. The enterotoxin, when present in contaminated food, is resistant to boiling. Upon ingestion, the toxin induces symptoms of food poisoning, such as nausea, vomiting, abdominal cramps, and diarrhea. The toxins are produced when the organism is allowed to incubate in food, particularly under conditions of temperature abuse.

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 (enzyme) is used to produce ammonia and carbon dioxide. Ammonia will increase pH, making it more alkaline, this allows H. pylori to survive acidic environments.
• Urea→Ammonia+Carbon dioxide

Question 6

What is a distinct sign of cholera?

Answer 6

The production of “rice water stools.”

Question 7

What is the most damaging form of E. coli? (This is the one that causes the most outbreaks in the US) What toxin is produced by this particular E.coli?

Answer 7

• Enterohemorrhagic E. coli (EHEC), serotype O157:H7
• Shiga toxin is produced

Question 8

What is a common source of Salmonella?

Answer 8

Commercial chicken and egg production

Question 9

What are the viral characteristics of the different varieties of hepatitis viruses?

Part 1: Hepatits A-C

Answer 9

• Hepatits A virus (HAV): Single-stranded RNA, non-enveloped. Entry via oral route
• Hepatits B virus (HBV): Double-stranded DNA, enveloped, resembles retroviruses. Transmitted via blood and body fluids
• Hepatitis C virus (HCV): Single-stranded RNA, enveloped. Transmitted via transfusion. Destroys liver. No vaccine

Question 10

What are the viral characteristics of the different varieties of hepatitis viruses?

Part 2: Hepatitis D & E

Answer 10

Hepatitis D virus (HDV): Requires co-infection with hepatitis B. Acute and chronic forms.
Hepatitis E virus (HEV): Spread by fecal-oral transmission, similar to hepatitis A. Endemic in areas with poor sanitation.

Question 11

What is the general syndrome that can be caused by any type of viral hepatitis?

Answer 11

Hepatitis results in inflammation of the liver.

Question 12

Which type of hepatitis causes the most severe syndrome?

Answer 12

Hepatitis C (HCV) is known to cause the most severe syndrome. It can lead to chronic infection, liver cirrhosis, and an increased risk of liver cancer.

Question 13

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

Answer 13

Non-infectious ways to get hepatitis include drug or chemical toxicity, cancer.

Question 14

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

Answer 14

Hepatitis B virus (HBV)

Question 15

Which forms of hepatitis are more likely to become chronic?

Answer 15

Hepatitis B and C are more likely to become chronic infections. Chronic hepatitis can lead to long-term liver damage, cirrhosis, and an increased risk of liver cancer.

Question 16

How is Hepatitis A transmitted?

Answer 16

Hepatitis A is transmitted via the oral route. It enters the body through contaminated food or water and multiplies in the epithelial lining of the intestinal tract.
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Question 17

How is Hepatitis B transmitted?

Answer 17

Hepatitis B is transmitted via the blood and bodily fluids. It can be spread through unprotected sexual contact, sharing of needles, and from an infected mother to her baby during childbirth.

Question 18

How is Hepatitis C transmitted?

Answer 18

Hepatitis C is often transfusion-transmitted, but it can also be transmitted through the sharing of needles and other drug paraphernalia. It can be transmitted sexually but is less common.

Question 19

What are some of the treatments for hepatitis C?

Answer 19

HCV protease and polymerase inhibitors, interferon, and ribavirin.

Question 20

Which form of hepatitis requires coinfection with hepatitis B?

Answer 20

Hepatitis D (HDV)

Question 21

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

Answer 21

Cirrhosis

Question 22

What is dysbiosis? How do Fecal Microbiota Transplants (FMT) help this?

Answer 22

• Dysbiosis refers to an imbalance in the microbial community of the gut.
• Fecal Microbiota Transplants (FMT) help dysbiosis by introducing a healthy and diverse microbial community from a donor’s feces into the recipient’s gastrointestinal tract. This can restore the balance of the microbiome and improve gut health.

Question 23

What are some pros and cons we discussed for FMTs?

Answer 23

• Pros of FMTs:
  Effectively treat recurrent Clostridium difficile infections.
  Can restore a healthy microbiome.
  Potential for treating other gastrointestinal conditions.
• Cons of FMTs:
  Risk of transmitting unknown infections from the donor.
  Lack of standardized protocols.
  Ethical concerns regarding donor screening.