Question 1

Which of the following best explains why healthy blood is considered axenic?

Accepted Answer

Physical barriers, phagocytes, complement, and organs like the liver and spleen work together to prevent and clear microbial entry.

Question 2

A patient develops sepsis after a urinary tract infection. Which of the following best describes the mechanism by which Gram-negative bacteria can cause septic shock?

Accepted Answer

Lipid A from lipopolysaccharide (LPS) triggers widespread inflammation, leading to vasodilation, capillary leakage, and decreased tissue perfusion.

Question 3

Which of the following scenarios is most likely to result in a healthcare-associated bloodstream infection (HAI)?

Accepted Answer

A patient with a central venous catheter develops a biofilm on the device.

Question 4

Which of the following best distinguishes toxic shock syndrome (TSS) from septic shock?

Accepted Answer

TSS involves superantigen exotoxins that activate large numbers of T cells, while septic shock often involves endotoxin-mediated inflammation.

Question 5

A patient presents with fever, a new heart murmur, and evidence of emboli. Which of the following best explains why damaged or prosthetic heart valves increase the risk of endocarditis?

Accepted Answer

Microbes can more easily attach to abnormal valve surfaces, forming vegetations composed of microbes, platelets, and fibrin.

Question 6

Which of the following is the most effective prevention strategy for malaria in an endemic region?

Accepted Answer

Using insecticide-treated bed nets and taking prophylactic antimalarial medications.

Question 7

A child develops petechiae and laboratory tests show low platelets and abnormal clotting. Which systemic complication is most likely occurring?

Accepted Answer

Disseminated intravascular coagulation (DIC), where widespread clotting consumes platelets and clotting factors, leading to bleeding.

Question 8

Which of the following best explains why avoiding drinking freshwater alone does NOT prevent schistosomiasis?

Accepted Answer

Schistosome larvae can penetrate intact skin during contact with contaminated water.

Question 9

Which of the following diseases is most closely associated with unpasteurized dairy products and can cause undulating fever and joint pain?

Accepted Answer

Brucellosis

Question 10

A patient with a history of organ transplantation develops severe cytomegalovirus (CMV) disease. Which host defense is most likely impaired, allowing reactivation of CMV?

Accepted Answer

Cellular immunity

Question 11

Which of the following best describes the difference in transmission between Chagas disease and malaria?

Accepted Answer

Chagas disease is usually transmitted when triatomine bug feces enter a wound or mucous membrane, while malaria is transmitted by the bite of an infected female Anopheles mosquito.

Question 12

Which of the following is a key reason why cytomegalovirus (CMV) and Toxoplasma gondii are particularly dangerous during pregnancy?

Accepted Answer

They can cross the placenta and cause fetal injury even if maternal illness is mild.

Question 13

Which of the following best explains why a contaminated central line can cause repeated bloodstream infections?

Accepted Answer

Biofilms on the device allow microbes to persist and repeatedly seed the bloodstream.

Question 14

A patient develops fever, rash, and hypotension after using a retained menstrual product. Which of the following is the most likely mechanism?

Accepted Answer

Superantigen exotoxins activate large numbers of T cells, causing excessive cytokine release.

Question 15

Which of the following best describes the main cause of tissue injury in malaria?

Accepted Answer

Destruction of red blood cells during the parasite's life cycle, leading to anemia and inflammation.

Question 16

Which of the following is the most appropriate prevention strategy for Lyme disease?

Accepted Answer

Prompt removal of attached ticks and use of repellents and protective clothing.

Question 17

A patient with infectious mononucleosis is advised to avoid contact sports. What is the main reason for this recommendation?

Accepted Answer

Splenic enlargement increases the risk of rupture with trauma.

Question 18

Which of the following best explains why dengue can cause shock in severe cases?

Accepted Answer

Capillary leakage reduces effective circulating blood volume.

Question 19

Which of the following is the most effective way to prevent transmission of Ebola virus in a healthcare setting?

Accepted Answer

Strict isolation, use of personal protective equipment, and safe handling of contaminated materials and bodies.

Question 20

Which of the following best describes the life cycle connection for schistosomiasis?

Accepted Answer

Eggs reach freshwater, infect snails, larvae leave snails and penetrate human skin, adults occupy blood vessels, and eggs trapped in tissues cause inflammation and fibrosis.

Microbial Cardiovascular and Systemic Diseases: Study Guide

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