Question 1

A patient receives a kidney transplant and is placed on immunosuppressant therapy. Which of the following is the most significant risk associated with this therapy?

Accepted Answer

Increased risk of opportunistic infections due to suppressed immune response

Question 2

Which of the following best describes a Type I hypersensitivity reaction?

Accepted Answer

It involves IgE antibodies binding to mast cells, leading to degranulation and release of histamine.

Question 3

A patient develops anaphylactic shock after eating shellfish. Which of the following best explains why shellfish and peanuts are common causes of anaphylaxis?

Accepted Answer

They are often ingested, leading to systemic exposure and a more severe immune response.

Question 4

Which of the following statements correctly differentiates between Type II and Type III hypersensitivity reactions?

Accepted Answer

Type II involves antibodies binding to cell surfaces and activating complement, while Type III involves immune complexes depositing in tissues.

Question 5

Which of the following bacteria is a Gram-negative diplococcus and is known to cause sexually transmitted infections?

Accepted Answer

Neisseria gonorrhoeae

Question 6

Endotoxins are associated with which component of Gram-negative bacteria, and what is their primary effect?

Accepted Answer

Lipid A of lipopolysaccharide; they can cause fever and septic shock

Question 7

Which of the following best describes the function of bacterial endospores?

Accepted Answer

They allow bacteria to survive harsh environmental conditions by entering a dormant state.

Question 8

A patient develops gas gangrene after a traumatic injury. Which organism is most likely responsible, and what is a key virulence factor?

Accepted Answer

Clostridium perfringens; production of alpha toxin

Question 9

Which of the following is a major concern regarding Group B Streptococcus (Streptococcus agalactiae) in pregnancy?

Accepted Answer

It can cause neonatal sepsis and meningitis if transmitted during childbirth.

Question 10

Which of the following best explains why Mycobacterium tuberculosis infections are difficult to treat?

Accepted Answer

The bacteria have a waxy cell wall rich in mycolic acids, making them resistant to many antibiotics.

Question 11

A patient presents with a bull's-eye rash after a tick bite and later develops neurological symptoms. Which disease is this, and what is the causative agent?

Accepted Answer

Lyme disease; Borrelia burgdorferi

Question 12

Which of the following bacteria is able to grow at refrigeration temperatures and can cross the placental barrier, posing a risk to pregnant women?

Accepted Answer

Listeria monocytogenes

Question 13

Which of the following best describes the mechanism of action of superantigens produced by certain bacteria?

Accepted Answer

They non-specifically activate large numbers of T cells, leading to massive cytokine release.

Question 14

A patient develops watery diarrhea after drinking contaminated water while traveling. Which organism is most likely responsible, and what is the mechanism of disease?

Accepted Answer

Vibrio cholerae; secretion of cholera toxin that increases cAMP in intestinal cells

Question 15

Which of the following best explains why some bacteria are described as 'atypical' in the context of pneumonia?

Accepted Answer

They lack a typical cell wall structure and do not respond to beta-lactam antibiotics.

Question 16

Which of the following is a key difference between Mycoplasma and Chlamydia compared to other bacteria?

Accepted Answer

Mycoplasma lacks a cell wall, and Chlamydia is an obligate intracellular pathogen.

Question 17

A patient with a history of antibiotic use develops a severe abdominal infection with a spore-forming anaerobic bacterium. Which organism is most likely responsible?

Accepted Answer

Clostridioides difficile

Question 18

Which of the following best describes the process of bacterial spore formation and return to the vegetative state?

Accepted Answer

Sporulation occurs under stress, forming a resistant spore; germination occurs when conditions improve.

Question 19

Which of the following is a major virulence factor of Staphylococcus aureus that allows it to evade the immune system?

Accepted Answer

Production of protein A, which binds the Fc region of IgG

Question 20

A patient presents with a painless ulcer (chancre) on the genitals, followed weeks later by a rash on the palms and soles. Which disease is this, and what is the causative agent?

Accepted Answer

Syphilis; Treponema pallidum

Comprehensive Study Notes: Immunology, Bacterial Pathogenesis, and Infectious Diseases

Study Guide - Practice Questions

Study Guide - Flashcards