Question 1

Which of the following best describes the shape and staining characteristics of Corynebacterium diphtheriae?

Accepted Answer

Gram-positive, irregular club-shaped rod

Question 2

A patient presents with a sore throat, swollen lymph nodes, and a thick gray pseudomembrane in the throat. Which exotoxin mechanism is most responsible for these symptoms?

Accepted Answer

Exotoxin that inhibits protein synthesis

Question 3

Which diagnostic method is most specific for confirming Corynebacterium diphtheriae infection in a patient with suspected diphtheria?

Accepted Answer

Serological assay for diphtheria toxin

Question 4

A child is exposed to diphtheria but remains asymptomatic. What is the most effective prevention strategy to reduce the risk of developing diphtheria?

Accepted Answer

Toxoid vaccine series and boosters

Question 5

Which of the following is NOT a characteristic of Mycobacterium tuberculosis?

Accepted Answer

Forms spores under stress

Question 6

A patient with untreated tuberculosis develops symptoms outside the lungs, including kidney and brain involvement. What form of tuberculosis is this?

Accepted Answer

Disseminated (extrapulmonary) tuberculosis

Question 7

Which virulence factor allows Mycobacterium tuberculosis to survive inside macrophages?

Accepted Answer

Complex waxes and cord factor

Question 8

A patient with a history of tuberculosis presents with violent coughing and bloody sputum years after initial infection. What is the most likely explanation?

Accepted Answer

Reactivation of latent tuberculosis (secondary TB)

Question 9

Which population is at highest risk for developing clinical tuberculosis in the United States?

Accepted Answer

Recent immigrants

Question 10

What is the primary route of transmission for both Corynebacterium diphtheriae and Mycobacterium tuberculosis?

Accepted Answer

Airborne respiratory droplets

Question 11

A laboratory technician is asked to identify Mycobacterium tuberculosis in a sputum sample. Which staining technique should be used?

Accepted Answer

Acid-fast stain

Question 12

Which of the following best explains why untreated tuberculosis can have a mortality rate as high as 60%?

Accepted Answer

Slow progression with eventual organ failure

Question 13

A patient with diphtheria is treated with penicillin. What is the primary mechanism by which penicillin acts against Corynebacterium diphtheriae?

Accepted Answer

Disrupts cell wall synthesis

Question 14

Which equation best represents the rate of bacterial growth for Mycobacterium tuberculosis, given its slow doubling time compared to other bacteria?

Accepted Answer

$$N = N_0$ 	imes 2$$^{t/d}$$

Question 15

A patient with cutaneous diphtheria develops a secondary infection. Which organ system is most at risk due to diphtheria toxemia?

Accepted Answer

Cardiac and nervous systems

Question 16

Which of the following is a common misconception about Mycobacterium tuberculosis?

Accepted Answer

It forms spores under stress

Question 17

A patient with malnutrition and compromised immunity is exposed to Mycobacterium tuberculosis. What is the most likely outcome?

Accepted Answer

Higher risk of developing clinical tuberculosis

Question 18

Which treatment is most appropriate for a patient diagnosed with diphtheria?

Accepted Answer

Diphtheria antitoxin and penicillin or erythromycin

Question 19

After 3-4 weeks of primary tuberculosis infection, what immune response leads to the formation of tubercles?

Accepted Answer

Attack by macrophages and T cells

Question 20

Which of the following best explains why acid-fast staining is used for Mycobacterium tuberculosis?

Accepted Answer

The cell wall contains complex waxes that retain the stain

Bacterial Pathogens: Corynebacterium diphtheriae and Mycobacterium tuberculosis

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