Question 1

Which of the following best explains why infections of the cardiovascular and lymphatic systems can be particularly serious?

Accepted Answer

Both systems are normally sterile, so infectious agents can rapidly become systemic and spread throughout the body.

Question 2

A patient develops a visible red streak spreading from an infected wound on their arm. What is the most likely diagnosis?

Accepted Answer

Lymphangitis

Question 3

Which of the following statements about subacute bacterial endocarditis (SBE) is CORRECT?

Accepted Answer

It is typically caused by low-virulence organisms and progresses slowly, often involving normal microbiota from the mouth or skin.

Question 4

A hospitalized patient with a urinary catheter develops fever, chills, and low blood pressure. Blood cultures reveal Gram-negative rods. Which of the following best explains why bactericidal antibiotics must be used with caution in this patient?

Accepted Answer

Bactericidal antibiotics may lyse bacterial cells, releasing endotoxin and worsening septic shock.

Question 5

Which of the following is a key virulence factor of Yersinia pestis that allows it to spread through the host and avoid immune defenses?

Accepted Answer

Protease (Pla) that clears clots and inactivates complement, along with YOPs proteins and a capsule to avoid phagocytosis

Question 6

A veterinarian develops fever, enlarged lymph nodes, and malaise after assisting with the birth of a goat. Which zoonotic disease should be suspected, and what is the most likely causative agent?

Accepted Answer

Brucellosis; Brucella melitensis

Question 7

Which of the following best describes the pathogenesis of malaria caused by Plasmodium falciparum?

Accepted Answer

The parasite infects all red blood cells, causing them to become rigid and adhere to capillary walls, leading to vessel blockage and potentially cerebral malaria.

Question 8

A college student presents with fever, sore throat covered with pus, and marked fatigue. Laboratory tests reveal atypical lymphocytes. Which virus is most likely responsible, and what is a potential long-term complication?

Accepted Answer

Epstein-Barr virus; Burkitt's lymphoma

Question 9

Which of the following best explains why dengue hemorrhagic fever (DHF) is more likely to occur during a second infection with a different dengue virus serotype?

Accepted Answer

Preexisting non-neutralizing antibodies facilitate viral entry into macrophages, leading to a cytokine storm (antibody-dependent enhancement).

Question 10

Which of the following is the most effective method for preventing yellow fever in endemic regions?

Accepted Answer

Administration of a highly effective attenuated vaccine

Question 11

A patient presents with fever, chills, and an ulcer at the site of a rabbit bite. Which of the following is the most likely causative agent, and what is a key feature of its pathogenesis?

Accepted Answer

Francisella tularensis; ability to grow within phagocytic cells

Question 12

Which of the following best describes the role of the spleen in the immune response?

Accepted Answer

It filters blood, removes abnormal red blood cells, and contains lymphoid tissue with B and T lymphocytes.

Question 13

Which of the following is a major reason why sepsis is increasingly common in healthcare settings?

Accepted Answer

Increased use of medical equipment where biofilms form, such as catheters and respirators

Question 14

Which of the following best explains why individuals with sickle cell anemia are partially protected against malaria?

Accepted Answer

Their red blood cells lack the receptors required for Plasmodium invasion.

Question 15

Which of the following is a recommended strategy for preventing brucellosis in humans?

Accepted Answer

Pasteurization of dairy products and use of protective gear by veterinarians and slaughterhouse workers

Question 16

A patient with a history of intravenous drug use develops fatigue, low-grade fever, and a sudden stroke. Blood cultures are negative. Which of the following is the most likely diagnosis and why might cultures be negative?

Accepted Answer

Subacute bacterial endocarditis; bacteria may be cleared by lung phagocytes or cannot be cultured in cell-free media

Question 17

Which of the following best describes the pathogenesis of Ebola hemorrhagic fever?

Accepted Answer

The virus causes capillary fragility and disrupts clotting, leading to massive internal and external bleeding and multiorgan failure.

Question 18

Which of the following is a key reason why malaria eradication efforts failed in the mid-20th century?

Accepted Answer

Mosquito vectors developed resistance to insecticides such as DDT.

Question 19

Which of the following best explains why indoor spraying with DDT and use of insecticide-treated bed nets are effective in reducing malaria transmission?

Accepted Answer

They kill or repel Anopheles mosquitoes, which are the only vectors capable of transmitting Plasmodium species.

Chapter 27: Infections of the Genitourinary System – Blood, Lymphatic, and Associated Diseases

Study Guide - Practice Questions

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