Question 1

Which bacterium is most commonly associated with dental caries due to its ability to ferment sugars and produce acid that degrades tooth enamel?

Accepted Answer

Streptococcus mutans

Question 2

A patient presents with severe watery diarrhea after drinking contaminated water in a developing country. Laboratory tests reveal the presence of curved, Gram-negative rods. Which pathogen is most likely responsible?

Accepted Answer

Vibrio cholerae

Question 3

Which of the following best explains why fluoride in toothpaste helps prevent dental caries?

Accepted Answer

Fluoride modifies enamel, making it resistant to acid

Question 4

A patient develops severe abdominal cramps, bloody diarrhea, and hemolytic uremic syndrome after eating undercooked ground beef. Which E. coli strain is most likely responsible?

Accepted Answer

Enterohemorrhagic E. coli (EHEC)

Question 5

Which of the following is a key virulence factor produced by Vibrio cholerae that leads to massive water loss in the intestines?

Accepted Answer

Cholera toxin

Question 6

A hospital patient develops severe diarrhea after a course of broad-spectrum antibiotics. Colonoscopy reveals pseudomembranous colitis. What is the most effective treatment for recurrent cases?

Accepted Answer

Fecal microbiota transplant

Question 7

Which of the following statements about Hepatitis B is TRUE?

Accepted Answer

It can integrate its DNA into the host genome, leading to chronic infection and liver cancer.

Question 8

A child presents with fever, swelling of the salivary glands, and loss of appetite. Which virus is most likely responsible, and how can it be prevented?

Accepted Answer

Mumps virus; live attenuated vaccine

Question 9

Which of the following best describes the pathogenesis of Shigella infection?

Accepted Answer

Bacteria invade intestinal epithelial cells, causing cell death and inflammation

Question 10

A patient with a history of intravenous drug use develops chronic liver disease and is diagnosed with cirrhosis 20 years after infection. Which hepatitis virus is most likely responsible?

Accepted Answer

Hepatitis C virus

Question 11

Which protozoan is responsible for 'beaver fever' and is commonly transmitted by drinking water contaminated with animal feces?

Accepted Answer

Giardia lamblia

Question 12

Which of the following best explains why Clostridium difficile infections are often associated with hospitals?

Accepted Answer

Antibiotic use disrupts normal microbiota, allowing C. difficile to colonize

Question 13

Which of the following is a distinguishing feature of viral gastroenteritis caused by rotavirus or norovirus?

Accepted Answer

Self-limiting diarrhea and vomiting, often in epidemic outbreaks

Question 14

A patient presents with indigestion, nausea, and flatulence after a camping trip. Which treatment is most appropriate if Giardia lamblia is identified?

Accepted Answer

Metronidazole

Question 15

Which of the following best describes the mechanism by which Shiga toxin causes hemolytic uremic syndrome?

Accepted Answer

It is a cytotoxin that kills cells in capillaries and kidneys

Question 16

Which of the following is the most effective way to prevent cholera outbreaks in a community?

Accepted Answer

Providing clean, chlorinated drinking water

Question 17

A patient develops a cold sore on the lip that recurs several times a year. Which statement about the causative agent is TRUE?

Accepted Answer

It establishes a latent infection in nerve cells

Question 18

Which of the following best explains why hepatitis A does not cause chronic liver disease?

Accepted Answer

It causes only acute, self-limiting infections

Question 19

Which of the following pathogens is most resistant to chlorine disinfection and must be removed from water using ozone or UV treatment?

Accepted Answer

Cryptosporidium

Question 20

A patient with a history of antibiotic use develops severe, recurrent diarrhea. Laboratory tests confirm Clostridium difficile infection. Which of the following best explains why fecal transplants are effective in treating this condition?

Accepted Answer

They restore normal microbiota, which outcompetes C. difficile

Digestive System Infections: Microbiology Study Notes

Study Guide - Practice Questions

Study Guide - Flashcards