Question 1

A 35-year-old patient presents with a persistent cough, night sweats, and weight loss. A chest X-ray reveals cavitary lesions in the upper lobes of the lungs. Which pathogen is most likely responsible for this disease, and what is the most common method of transmission?

Accepted Answer

Mycobacterium tuberculosis; transmitted via airborne droplets

Question 2

Which of the following best describes the primary virulence factor of Staphylococcus aureus that allows it to evade the host immune response?

Accepted Answer

Production of coagulase, which causes clotting of plasma

Question 3

A child develops a sandpaper-like rash, fever, and sore throat. Laboratory tests reveal the presence of Streptococcus pyogenes. Which enzyme produced by this organism is responsible for breaking down hyaluronic acid in host tissues?

Accepted Answer

Hyaluronidase

Question 4

A patient presents with severe muscle spasms and lockjaw after stepping on a rusty nail. Which vaccine would have prevented this disease, and what type of vaccine is it?

Accepted Answer

Tetanus toxoid; inactivated toxoid vaccine

Question 5

Which of the following diseases is caused by a protozoan and is transmitted by the tsetse fly?

Accepted Answer

African Sleeping Sickness (Trypanosoma brucei)

Question 6

A patient is diagnosed with peptic ulcers. Which bacterium is most commonly associated with this condition, and what is a key virulence factor it uses to survive in the stomach?

Accepted Answer

Helicobacter pylori; production of urease

Question 7

Which of the following is the most common cause of fungal pneumonia in immunocompromised patients, and what is its primary mode of transmission?

Accepted Answer

Histoplasma capsulatum; inhalation of spores from bird droppings

Question 8

A sexually active adult presents with a painless genital ulcer followed by a generalized rash. Which organism is responsible, and what is the name of the diagnostic test commonly used to confirm this infection?

Accepted Answer

Treponema pallidum; Rapid Plasma Reagin (RPR) test

Question 9

Which of the following best explains why Clostridium botulinum causes flaccid paralysis, while Clostridium tetani causes spastic paralysis?

Accepted Answer

C. botulinum toxin inhibits acetylcholine release; C. tetani toxin inhibits inhibitory neurotransmitter release

Question 10

A patient with HIV is at increased risk for which of the following opportunistic infections, and what type of cell does HIV primarily target?

Accepted Answer

Pneumocystis jirovecii pneumonia; CD4+ T lymphocytes

Question 11

Which of the following is the most common intestinal protozoan infection in the United States, and what is its primary mode of transmission?

Accepted Answer

Giardia lamblia; ingestion of cysts in contaminated water

Question 12

A hospital outbreak of diarrhea is traced to a spore-forming, Gram-positive anaerobe. Which organism is most likely responsible, and what is a key prevention strategy?

Accepted Answer

Clostridium difficile; strict hand hygiene and limiting antibiotic use

Question 13

A 7-year-old child presents with a vesicular rash that started on the trunk and spread to the face and limbs. Which virus is responsible, and what is a potential complication later in life?

Accepted Answer

Varicella-zoster virus; shingles (herpes zoster)

Question 14

Which of the following diseases is transmitted by Ixodes ticks and is characterized by a bull's-eye rash?

Accepted Answer

Lyme disease (Borrelia burgdorferi)

Question 15

A patient presents with severe watery diarrhea after returning from a trip to a developing country. Laboratory analysis reveals a curved, Gram-negative rod. Which organism is most likely responsible, and what is the primary mechanism of disease?

Accepted Answer

Vibrio cholerae; production of cholera toxin that increases cAMP

Question 16

Which of the following best describes the reservoir and vector for Plasmodium falciparum, the causative agent of malaria?

Accepted Answer

Reservoir: humans; Vector: Anopheles mosquito

Question 17

A newborn develops conjunctivitis and pneumonia shortly after birth. The mother is asymptomatic. Which organism is most likely responsible, and what is a key characteristic of this pathogen?

Accepted Answer

Chlamydia trachomatis; obligate intracellular bacterium

Question 18

Which of the following diseases is most commonly acquired in hospitals and is associated with antibiotic resistance?

Accepted Answer

Methicillin-resistant Staphylococcus aureus (MRSA) infection

Question 19

A patient presents with fever, jaundice, and hemorrhagic symptoms after traveling to West Africa. Which viral disease is most likely, and what is the primary mode of transmission?

Accepted Answer

Ebola virus disease; direct contact with body fluids

Question 20

Which of the following diagnostic tests is most appropriate for detecting latent tuberculosis infection?

Accepted Answer

Tuberculin skin test (Mantoux test)

Microbiology Study Guide: Infectious Diseases of Organ Systems (Chapters 16-21)

Study Guide - Practice Questions

Study Guide - Flashcards