Question 1

Which of the following best explains why Gram-negative sepsis can lead to septic shock?

Accepted Answer

The release of lipopolysaccharide (LPS) from lysed Gram-negative bacteria triggers macrophages to release cytokines, causing widespread inflammation and activation of coagulation and complement pathways.

Question 2

A patient develops fever, anemia, and a new heart murmur after a dental procedure. Which organism is most likely responsible for subacute bacterial endocarditis in this scenario?

Accepted Answer

Alpha-hemolytic streptococci

Question 3

Which of the following is a key virulence factor of Bacillus anthracis that contributes to its pathogenicity?

Accepted Answer

A capsule and three exotoxins

Question 4

A veterinarian develops undulating fever after assisting with the birth of a goat. Which diagnostic finding is most likely in this case?

Accepted Answer

Granulomas in the liver

Question 5

Which of the following best describes the pathogenesis of rheumatic fever?

Accepted Answer

Antibodies against group A β-hemolytic streptococci cross-react with heart tissue, leading to inflammation.

Question 6

A patient presents with a painless ulcer and swollen lymph nodes after handling animal hides. Which form of anthrax is most likely?

Accepted Answer

Cutaneous anthrax

Question 7

Which of the following is the primary vector for the transmission of Yersinia pestis, the causative agent of plague?

Accepted Answer

Fleas

Question 8

A patient develops a bull’s eye rash and flu-like symptoms after hiking in the Northeast US. Which diagnostic test is most appropriate for confirming Lyme disease?

Accepted Answer

Indirect serological tests such as ELISA and Western blot

Question 9

Which of the following statements about Rocky Mountain Spotted Fever (RMSF) is correct?

Accepted Answer

It is caused by Rickettsia rickettsii and presents with a maculopapular rash that starts on the palms and soles.

Question 10

Which of the following best explains why sickle cell trait provides protection against malaria?

Accepted Answer

Plasmodium cannot efficiently infect and reproduce in sickled red blood cells.

Question 11

A patient with a history of untreated strep throat develops joint pain and carditis. Which of the following could have prevented this complication?

Accepted Answer

Prompt antibiotic treatment of the initial streptococcal infection

Question 12

Which of the following is the most common route of transmission for Brucella species to humans?

Accepted Answer

Contact with infected farm animals or ingestion of contaminated milk products

Question 13

Which of the following best describes the life cycle of the Lyme disease vector, Ixodes tick?

Accepted Answer

It involves larval, nymph, and adult stages, with nymphs and adults feeding on mammals and transmitting Borrelia burgdorferi.

Question 14

Which of the following is a distinguishing feature of Plasmodium falciparum infection compared to other Plasmodium species?

Accepted Answer

It is associated with the highest mortality and severe complications.

Question 15

A patient presents with fever, vomiting, and a history of travel to a malaria-endemic region. Which laboratory finding would confirm the diagnosis of malaria?

Accepted Answer

Identification of Plasmodium ring forms inside red blood cells on a blood smear

Question 16

Which of the following best explains why prompt treatment of early Lyme disease is critical?

Accepted Answer

Early treatment prevents dissemination to the heart, nervous system, and joints.

Question 17

Which of the following is a common complication of untreated puerperal sepsis caused by Streptococcus pyogenes?

Accepted Answer

Progression to peritonitis or septicemia

Question 18

Which of the following cytokines is NOT typically released by macrophages in response to LPS from Gram-negative bacteria?

Accepted Answer

Interferon-gamma (IFN-γ)

Question 19

A patient presents with a rapidly progressing infection and destruction of heart valves. Which organism is most likely responsible for acute bacterial endocarditis?

Accepted Answer

Staphylococcus aureus

Question 20

Which of the following best describes the mechanism by which LPS from Gram-negative bacteria leads to activation of the coagulation pathway?

Accepted Answer

LPS binds to LPS-binding protein, which interacts with CD14 on macrophages, triggering cytokine release and subsequent activation of the coagulation pathway.

Microbial Diseases of the Cardiovascular and Lymphatic Systems

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