Question 1

Which of the following statements best explains why Gram-positive bacteria such as Staphylococcus and Micrococcus predominate as normal flora on human skin?

Accepted Answer

They are resistant to drying and high salt concentrations.

Question 2

A patient presents with a vesicular rash along a single dermatome. Which pathogen is most likely responsible for this presentation?

Accepted Answer

Varicella-zoster virus (Human herpesvirus 3)

Question 3

Which of the following is a distinguishing feature of Streptococcus pyogenes compared to Staphylococcus aureus?

Accepted Answer

It is catalase negative and sensitive to bacitracin.

Question 4

A 6-year-old child develops impetigo with honey-colored crusts. Which organism is most commonly responsible for this condition?

Accepted Answer

Staphylococcus aureus

Question 5

Which of the following best describes the mechanism by which Clostridium botulinum toxin causes paralysis?

Accepted Answer

It blocks the release of neurotransmitter at the neuromuscular junction.

Question 6

A patient with a history of rose gardening develops a subcutaneous nodule that spreads along lymphatic channels. Which organism is most likely responsible?

Accepted Answer

Sporothrix schenckii

Question 7

Which of the following is the most common cause of blindness worldwide due to infection?

Accepted Answer

Chlamydia trachomatis (trachoma)

Question 8

Which of the following statements about prion diseases is correct?

Accepted Answer

They are caused by self-replicating proteins with no nucleic acid content.

Question 9

A patient presents with fever, headache, stiff neck, and photophobia. Gram stain of cerebrospinal fluid reveals Gram-negative diplococci. What is the most likely diagnosis?

Accepted Answer

Meningococcal meningitis (Neisseria meningitidis)

Question 10

Which of the following best explains why antibiotics are often ineffective in treating infections of the central nervous system?

Accepted Answer

The blood-brain barrier prevents passage of many antimicrobial drugs.

Question 11

A newborn develops conjunctivitis after passing through the birth canal. Which organism is most likely responsible, and what is the best preventive measure?

Accepted Answer

Neisseria gonorrhoeae; treat newborn's eyes with antibiotics

Question 12

Which of the following is a key virulence factor of Streptococcus pyogenes that helps it evade phagocytosis?

Accepted Answer

M-protein

Question 13

A patient presents with a painless, disfiguring nodule on the skin and loss of sensation in the affected area. Acid-fast rods are seen on biopsy. What is the most likely diagnosis?

Accepted Answer

Leprosy (Mycobacterium leprae)

Question 14

Which of the following is the most effective way to prevent transmission of poliovirus?

Accepted Answer

Vaccination with enhanced-inactivated polio vaccine

Question 15

A patient with a history of burns develops a blue-green pus at the wound site. The causative organism is oxidase positive and Gram negative. What is the most likely pathogen?

Accepted Answer

Pseudomonas aeruginosa

Question 16

Which of the following best describes the pathogenesis of Reye’s syndrome as a complication of chickenpox?

Accepted Answer

It is associated with aspirin use in children with viral infections.

Question 17

Which of the following dermatophytes is most likely to cause tinea capitis?

Accepted Answer

Trichophyton spp.

Question 18

A patient presents with a rapidly spreading infection of the fascia and severe tissue destruction. Which organism is most commonly associated with necrotizing fasciitis?

Accepted Answer

Streptococcus pyogenes

Question 19

Which of the following is a characteristic of diseases caused by prions?

Accepted Answer

They cause spongiform degeneration of the CNS.

Question 20

A patient presents with a macular rash and Koplik's spots in the oral mucosa. Which virus is responsible for these findings?

Accepted Answer

Measles virus (Rubeola)

Microbial Diseases of the Skin, Eyes, and Nervous System: Study Notes

Study Guide - Practice Questions

Study Guide - Flashcards