Question 1

Which of the following is a primary physical barrier against infectious agents in the human body?

Accepted Answer

Constantly shedding layer of skin cells

Question 2

Staphylococcus aureus is able to evade host defenses in the skin primarily by:

Accepted Answer

Secreting proteins and toxins that kill phagocytic cells

Question 3

Which bacterial factor is responsible for the formation of clots in blood during Staphylococcus aureus infection?

Accepted Answer

Coagulase

Question 4

A patient presents with a localized region of pus surrounded by inflamed tissue on the skin. Which term best describes this lesion?

Accepted Answer

Pustule

Question 5

Which of the following statements about Group A Streptococci (GAS) is correct?

Accepted Answer

They are differentiated into groups based on antigenic cell wall carbohydrates

Question 6

A newborn develops conjunctivitis after passing through the birth canal. Which organism is most likely responsible if the infection is characterized by a purulent discharge and risk of blindness?

Accepted Answer

Neisseria gonorrhoeae

Question 7

Which of the following is a major virulence factor for Haemophilus influenzae in causing meningitis?

Accepted Answer

Capsule formation

Question 8

A patient with a history of deep puncture wound develops muscle spasms and lockjaw. Which organism is most likely responsible, and what is the recommended prevention?

Accepted Answer

Clostridium tetani; DTaP vaccine

Question 9

Which of the following best explains why Mycobacterium tuberculosis is resistant to drying and many disinfectants?

Accepted Answer

It has a cell wall rich in lipids

Question 10

A positive tuberculin skin test indicates:

Accepted Answer

Current or previous infection with Mycobacterium tuberculosis

Question 11

Which equation best represents the calculation of the attack rate for a respiratory infection in a population?

Accepted Answer

$$Attack\ Rate = \frac{Number\ of\ new\ cases}{Population\ at\ risk} 	imes 100$$

Question 12

Which of the following is a common cause of viral pneumonia in infants and can lead to life-threatening disease in older adults?

Accepted Answer

Respiratory Syncytial Virus (RSV)

Question 13

Which of the following is NOT a typical feature of Streptococcus pneumoniae?

Accepted Answer

Obligate intracellular parasite

Question 14

A patient presents with a tough grayish membrane in the throat, which is blocking the passage of air. The causative agent produces a toxin only when lysogenized. What is the most likely diagnosis?

Accepted Answer

Diphtheria

Question 15

Which of the following best describes the pathogenesis of tuberculosis in the lungs?

Accepted Answer

Bacteria are isolated in walled-off tubercles, which may later break down and release bacteria

Question 16

Which of the following is a fungal infection of the respiratory system that is highly endemic in certain regions of the United States and is associated with bat droppings?

Accepted Answer

Histoplasmosis

Question 17

Which of the following is a key difference between viral and bacterial meningitis?

Accepted Answer

Bacterial meningitis often requires immediate antibiotic treatment before diagnosis

Question 18

Which of the following best explains why the ciliary escalator is important in respiratory tract defense?

Accepted Answer

It moves particles toward the throat to be expelled or swallowed

Question 19

Which of the following is a common complication of influenza virus infection?

Accepted Answer

Bacterial pneumonia

Question 20

A patient with HIV develops a severe fungal pneumonia. Which organism is most likely responsible, and what does its presence indicate?

Accepted Answer

Pneumocystis jirovecii; indicator of AIDS

Infectious Diseases of the Skin, Eyes, Respiratory, and Nervous Systems

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