Question 1

Which of the following best describes the morphology and lifestyle of Rickettsia species?

Accepted Answer

Gram-negative pleomorphic rods, obligate intracellular parasites

Question 2

A patient presents with a non-itchy petechial rash on the palms and soles, fever, and a history of a tick bite in the Northeastern United States. Which organism is most likely responsible?

Accepted Answer

Rickettsia rickettsii

Question 3

Which virulence factor allows Rickettsia rickettsii to escape from the phagosome into the host cell cytosol?

Accepted Answer

Digestive enzyme that lyses the endocytic vesicle

Question 4

The Weil-Felix test is used in the diagnosis of which disease?

Accepted Answer

Rocky Mountain spotted fever

Question 5

Which of the following is the recommended treatment for Rocky Mountain spotted fever in non-pregnant adults?

Accepted Answer

Doxycycline

Question 6

Treponema pallidum is best described as:

Accepted Answer

A Gram-negative, spiral-shaped, endoflagellated bacterium

Question 7

A painless, ulcerated lesion (chancre) at the site of inoculation is characteristic of which stage of syphilis?

Accepted Answer

Primary syphilis

Question 8

Which of the following is a hallmark of secondary syphilis?

Accepted Answer

Rash on palms and soles, condylomata lata

Question 9

A newborn presents with saddle nose, Hutchinson incisors, and a maculopapular rash. Which infection is most likely responsible?

Accepted Answer

Congenital syphilis

Question 10

Which test is specific for the detection of anti-treponemal antibodies in syphilis?

Accepted Answer

FTA-ABS

Question 11

Borrelia burgdorferi, the causative agent of Lyme disease, is transmitted to humans primarily by which vector?

Accepted Answer

Ixodes tick

Question 12

The classic 'bull’s eye' or target rash (erythema chronicum migrans) is most closely associated with which disease?

Accepted Answer

Lyme disease

Question 13

Which of the following is a distinguishing feature of Vibrio cholerae?

Accepted Answer

Gram-negative, comma-shaped, oxidase positive, polar flagellum

Question 14

The pathogenesis of cholera involves which of the following mechanisms?

Accepted Answer

Cholera toxin activates adenylate cyclase, increasing cAMP and causing ion and water loss

Question 15

A patient presents with watery, colorless, odorless diarrhea described as 'rice water stool.' Which organism is most likely responsible?

Accepted Answer

Vibrio cholerae

Question 16

Which of the following is the most effective initial treatment for cholera?

Accepted Answer

Oral rehydration therapy with glucose and sodium

Question 17

Which of the following best explains why Borrelia burgdorferi can survive in human tissues and fluids?

Accepted Answer

It uses manganese instead of iron for its enzymes and proteins

Question 18

A patient with a history of hiking in the Northeast presents with fever, headache, and a spreading annular rash. Weeks later, they develop facial paralysis and joint pain. Which is the most likely diagnosis?

Accepted Answer

Lyme disease

Question 19

Which of the following is a key preventive measure for Rocky Mountain spotted fever?

Accepted Answer

Early detection and removal of ticks

Question 20

Which of the following best describes the motility mechanism of spirochetes such as Treponema pallidum?

Accepted Answer

Corkscrew motion due to rotation of axial filaments (endoflagella)

Rickettsias, Chlamydias, Spirochetes, and Vibrios: Pathogenic Gram-Negative Bacteria

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