Question 1

A patient presents with a rapidly progressing illness characterized by high fever, chills, and hypotension. Blood cultures reveal the presence of gram-negative rods, and the patient develops uncontrollable decreased blood pressure despite treatment. Which of the following best describes the condition and its underlying pathophysiology?

Accepted Answer

Septic shock; systemic inflammatory response with uncontrollable decreased blood pressure due to sepsis

Question 2

A 35-year-old woman develops endocarditis after a dental procedure. The most likely causative agent is an alpha-hemolytic streptococcus. Which of the following best describes the pathogenesis of this infection?

Accepted Answer

Bacteria from the oral cavity enter the bloodstream and impair the function of heart valves

Question 3

Which of the following virulence factors of Bacillus anthracis is responsible for binding toxins to target cells, thereby permitting their entry?

Accepted Answer

Protective antigen

Question 4

A laboratory worker accidentally inhales endospores of Bacillus anthracis. Which type of anthrax is most likely to develop, and what is the expected mortality rate without treatment?

Accepted Answer

Inhalational (pulmonary) anthrax; near 100% mortality rate

Question 5

A patient is bitten by a rat flea and develops swollen lymph nodes (buboes), fever, and chills. Which organism is most likely responsible, and what is the vector?

Accepted Answer

Yersinia pestis; rat flea (Xenopsylla cheopis)

Question 6

A 10-year-old child presents with a bull’s-eye rash and flulike symptoms after a camping trip in the northeastern United States. Which organism is the most likely cause, and what is the vector?

Accepted Answer

Borrelia burgdorferi; Ixodes tick

Question 7

A patient with a history of travel to Africa presents with fever, chills, and severe anemia. Blood smear reveals infected red blood cells. Which Plasmodium species is most likely responsible for the most severe form of malaria?

Accepted Answer

Plasmodium falciparum

Question 8

Which form of the Plasmodium parasite is injected into humans by Anopheles mosquitoes, and what is the next step in the parasite’s life cycle?

Accepted Answer

Sporozoite; enters liver cells

Question 9

A patient develops severe dengue after a second infection with a different serotype of dengue virus. Which immunological phenomenon explains the increased severity?

Accepted Answer

Antibody enhancement, where antibodies from a previous infection facilitate viral entry into host cells

Question 10

Which of the following best explains how climate change can influence the transmission of vector-borne diseases such as malaria and dengue?

Accepted Answer

By expanding the habitat range of insect vectors, increasing human exposure

Question 11

A patient presents with fever, chills, and a papule that ulcerates and leaves a scar after returning from the Middle East. Which Leishmania species is most likely responsible, and what is the most common form of the disease?

Accepted Answer

Leishmania tropica; cutaneous leishmaniasis

Question 12

Which of the following best describes the role of the amino acid capsule in Bacillus anthracis pathogenesis?

Accepted Answer

It helps the bacterium evade the host immune response

Question 13

A patient develops urinary schistosomiasis after swimming in freshwater in Africa. Which organism is required for completion of the Schistosoma life cycle, and what form infects humans?

Accepted Answer

Freshwater snail; cercariae

Question 14

A 22-year-old college student is diagnosed with infectious mononucleosis. Which virus is responsible, and what other diseases are associated with this agent?

Accepted Answer

Epstein-Barr virus; multiple sclerosis, Hodgkin’s lymphoma, nasopharyngeal cancer

Question 15

A patient presents with fever, chills, and inflamed lymph vessels visible as red streaks under the skin. What is the most likely diagnosis?

Accepted Answer

Lymphangitis

Question 16

Which of the following equations best represents the relationship between the number of infected individuals ($$I$$), the transmission rate ($$\beta$$), and the susceptible population ($$S) in a $$simple epidemic model?

Accepted Answer

$$\frac{dI}{dt} = \beta S I$$

Question 17

A patient develops a systemic infection after a dog bite. Which of the following organisms is most commonly associated with systemic diseases caused by animal bites and scratches?

Accepted Answer

Pasteurella multocida

Question 18

A 40-year-old man presents with fever, chills, and a history of eating undercooked, contaminated meat. He is diagnosed with gastrointestinal anthrax. Which statement about the mortality rate of this form of anthrax is correct?

Accepted Answer

It has a mortality rate greater than 50% without treatment

Question 19

Which of the following best defines a zoonotic disease?

Accepted Answer

An infection transmitted from animals to humans caused by bacteria, viruses, parasites, or fungi

Question 20

A patient is diagnosed with Schistosoma mansoni infection. What is the primary cause of tissue damage in this disease?

Accepted Answer

Eggs released by the parasite

Systemic Microbial Infections: Cardiovascular and Lymphatic Diseases

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