Question 1

Which of the following is NOT a function of the normal gut microbiota in the human digestive system?

Accepted Answer

Directly digesting proteins in the stomach

Question 2

A patient presents with severe, watery diarrhea after a course of broad-spectrum antibiotics. Which pathogen is most likely responsible, and what is a key feature of its transmission?

Accepted Answer

Clostridioides difficile; transmission via fecal-oral route and resistant spores

Question 3

Which of the following best describes the difference between diarrhea and dysentery?

Accepted Answer

Diarrhea is watery stool, while dysentery involves severe, bloody diarrhea with mucus

Question 4

Which of the following is the most common route of transmission for intestinal pathogens?

Accepted Answer

Fecal-oral route via contaminated food or water

Question 5

A 4-year-old child develops acute onset of vomiting and watery diarrhea in January. Which viral agent is most likely responsible, and what is a key prevention strategy?

Accepted Answer

Rotavirus; vaccination of infants

Question 6

Which of the following statements about Hepatitis B virus (HBV) is TRUE?

Accepted Answer

It can cause both acute and chronic liver infections

Question 7

A patient is diagnosed with peptic ulcers. Which bacterium is most likely responsible, and what is a major virulence factor that allows it to survive in the stomach?

Accepted Answer

Helicobacter pylori; production of urease to neutralize stomach acid

Question 8

Which of the following best explains why antibiotics are NOT recommended for E. coli O157:H7 infections?

Accepted Answer

Antibiotics increase Shiga toxin production, raising the risk of hemolytic uremic syndrome

Question 9

Which of the following is a key feature of Vibrio cholerae infection?

Accepted Answer

Production of an AB exotoxin that causes massive watery diarrhea ('rice water stools')

Question 10

A patient presents with jaundice, fatigue, and elevated liver enzymes. They recently traveled to a country with poor sanitation and ate raw shellfish. Which hepatitis virus is most likely responsible?

Accepted Answer

Hepatitis A virus (HAV)

Question 11

Which of the following is a major risk factor for developing Clostridioides difficile infection (CDI) in a hospital setting?

Accepted Answer

Recent use of broad-spectrum antibiotics

Question 12

Which of the following best describes the life cycle of Giardia lamblia?

Accepted Answer

Ingestion of cysts, excystation in the small intestine, trophozoite attachment, encystation, and shedding in feces

Question 13

Which of the following is the most effective way to prevent tapeworm infection in humans?

Accepted Answer

Cooking meat to at least 145°F (63°C) or freezing at -4°F (-20°C) for 7 days

Question 14

A child presents with intense perianal itching at night. Which parasite is most likely responsible, and what is the best diagnostic method?

Accepted Answer

Enterobius vermicularis (pinworm); tape test for eggs

Question 15

Which of the following is a distinguishing feature of hepatitis D virus (HDV) infection?

Accepted Answer

Requires co-infection with hepatitis B virus (HBV) to replicate

Question 16

Which of the following best explains why norovirus outbreaks are common in places like cruise ships and nursing homes?

Accepted Answer

Norovirus is highly contagious, stable on surfaces, and spreads rapidly in close-contact settings

Question 17

Which of the following is a key difference between foodborne infection and food poisoning?

Accepted Answer

Foodborne infection involves pathogen growth in the host; food poisoning is caused by preformed toxins

Question 18

A patient develops severe dehydration and hypovolemic shock after a GI infection. Which of the following best explains the pathophysiology?

Accepted Answer

Rapid loss of fluids and electrolytes due to diarrhea and/or vomiting

Question 19

Which of the following is the most common helminth infection in the United States?

Accepted Answer

Enterobius vermicularis (pinworm)

Digestive System Infections: Microbiology Study Notes

Study Guide - Practice Questions

Study Guide - Flashcards