Question 1

Which of the following best explains why fungal infections of the central nervous system (CNS) are more common in immunocompromised patients than in healthy individuals?

Accepted Answer

Immunocompromised patients lack the immune defenses necessary to control fungal growth.

Question 2

A patient with HIV/AIDS presents with neurological symptoms and is diagnosed with cryptococcosis. Which of the following is the most likely source of infection?

Accepted Answer

Inhalation of aerosolized bird droppings

Question 3

Which of the following statements about Trypanosoma brucei gambiense, the causative agent of African sleeping sickness, is correct?

Accepted Answer

It is transmitted by the tsetse fly and causes a chronic form of the disease.

Question 4

Which of the following best describes the mechanism by which Naegleria fowleri causes primary amoebic meningoencephalitis (PAM)?

Accepted Answer

It enters the nasal passages, burrows into the mucosa, and migrates to the brain via the olfactory nerves.

Question 5

A pregnant woman is advised not to clean her cat’s litter box to avoid infection with which protozoan, and why?

Accepted Answer

Toxoplasma gondii; because it can cross the placenta and infect the fetus

Question 6

Which of the following is a distinguishing feature of prion diseases such as Creutzfeldt-Jakob disease (CJD)?

Accepted Answer

They are caused by infectious proteins that induce abnormal folding of normal proteins.

Question 7

Which of the following best describes the progression of African sleeping sickness?

Accepted Answer

The parasite enters the blood, crosses the blood-brain barrier, infects the CNS, and disrupts sleep patterns.

Question 8

Which of the following is the most common means of fecal-oral transmission of gastrointestinal pathogens?

Accepted Answer

Contaminated food or water

Question 9

Which of the following is NOT a function of the normal gut microbiota?

Accepted Answer

Causing hypovolemic shock

Question 10

A patient presents with severe diarrhea containing blood and mucus, abdominal pain, and fever. Which clinical term best describes this condition?

Accepted Answer

Dysentery

Question 11

Which of the following best explains why prevention of all fungal diseases is almost impossible?

Accepted Answer

Fungal spores are ubiquitous in the environment (dirt, air, water).

Question 12

Which of the following is a key defense mechanism of the stomach against microbial colonization?

Accepted Answer

Acidic gastric juices

Question 13

Which of the following statements about the Human Microbiome Project findings is correct?

Accepted Answer

Streptococcus species are the most common residents in the mouth.

Question 14

Which of the following best describes the mechanism of disease in transmissible spongiform encephalopathies (TSEs)?

Accepted Answer

Abnormal prion proteins (PrPSC) induce normal prion proteins (PrPC) to misfold, leading to neuronal death.

Question 15

Which of the following is a primary function of bile in the digestive system?

Accepted Answer

Aids in fat digestion and inhibits the growth of Gram-positive bacteria

Question 16

A patient presents with confusion, seizures, and psychiatric symptoms. They are found to be immunocompromised and have a history of exposure to cat feces. Which pathogen is most likely responsible?

Accepted Answer

Toxoplasma gondii

Question 17

Which of the following best describes the role of mucosa-associated lymphoid tissue (MALT) in the digestive system?

Accepted Answer

It provides immune surveillance and defense against pathogens entering through the GI tract.

Question 18

Which diagnostic tool would be most appropriate for identifying protozoan eggs in a patient with gastrointestinal symptoms?

Accepted Answer

Microscopic examination of fecal samples

Question 19

Which of the following equations best represents the relationship between dehydration, fluid loss, and hypovolemic shock in severe gastrointestinal infections?

Accepted Answer

$$ 	ext{Hypovolemic Shock} \propto 	ext{Dehydration} \propto 	ext{Fluid Loss} $$

Question 20

Which of the following best explains why water sanitation is critical in preventing gastrointestinal infections in developing nations?

Accepted Answer

Most intestinal pathogens are transmitted via the fecal-oral route, often through contaminated water.

Nervous and Digestive System Infections: Microbiology Study Notes

Study Guide - Practice Questions

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