Question 1

Which of the following statements best describes the blood-brain barrier and its significance in nervous system infections?

Accepted Answer

It is a specialized barrier that restricts passage of most molecules, making CNS infections rare and requiring pathogens to have special virulence factors.

Question 2

A 7-year-old child presents with vesicular lesions and fever. The lesions do not cross the midline of the body. Which pathogen is most likely responsible for this presentation?

Accepted Answer

Varicella zoster virus (VZV)

Question 3

Which of the following is the most appropriate prevention strategy for Clostridium botulinum infection in infants?

Accepted Answer

Avoiding honey in infants under 1 year old

Question 4

A patient presents with fever, headache, stiff neck, and a blue-black rash. Gram-negative diplococci are isolated from the CSF. What is the most likely diagnosis?

Accepted Answer

Meningococcal meningitis caused by Neisseria meningitidis

Question 5

Which of the following best explains why vaccine development for African trypanosomiasis is challenging?

Accepted Answer

Trypanosomes undergo antigenic variation by switching variable surface glycoprotein (VSG) genes.

Question 6

Which diagnostic test is most appropriate for confirming a case of poliovirus infection?

Accepted Answer

RT-PCR for viral mRNA

Question 7

A newborn develops meningitis five days after birth. The mother had a mild gastrointestinal illness during pregnancy. Which pathogen is most likely responsible?

Accepted Answer

Listeria monocytogenes

Question 8

Which of the following is a key virulence factor of Listeria monocytogenes that allows it to escape from the phagosome?

Accepted Answer

Listeriolysin O (LLO)

Question 9

A patient presents with muscle stiffness, lockjaw, and severe muscle spasms following a puncture wound. Which toxin is responsible for these symptoms?

Accepted Answer

Tetanospasmin

Question 10

Which of the following best describes the pathogenesis of rabies virus after an animal bite?

Accepted Answer

The virus replicates in muscle cells, then travels up the peripheral nervous system to the CNS.

Question 11

Which of the following is a distinguishing feature of Streptococcus pneumoniae meningitis compared to Neisseria meningitidis meningitis?

Accepted Answer

Absence of a rash in Streptococcus pneumoniae meningitis

Question 12

Which of the following is the most common route of transmission for Toxoplasma gondii?

Accepted Answer

Ingestion of oocysts from contaminated meat, cat feces, or soil

Question 13

Which of the following is a major complication of untreated lepromatous leprosy?

Accepted Answer

Irreversible tissue damage, including bone and cartilage decay

Question 14

Which of the following best describes the mechanism of action of botulinum toxin?

Accepted Answer

Blocks acetylcholine release at neuromuscular junctions, causing flaccid paralysis

Question 15

A 65-year-old man develops fever, confusion, and limb paralysis during a summer mosquito outbreak. Which pathogen is most likely responsible?

Accepted Answer

West Nile virus

Question 16

Which of the following is a key reason why humans are considered 'dead-end' hosts for most arboviruses?

Accepted Answer

Humans develop low viral loads, insufficient for further transmission by vectors.

Question 17

Which of the following is the most effective prevention strategy for tetanus?

Accepted Answer

Vaccination with tetanus toxoid

Question 18

Which of the following best describes the pathogenesis of paralytic polio?

Accepted Answer

The virus travels up motor neurons to the CNS, causing lysis of infected neurons and inflammation.

Question 19

A patient presents with fever, malaise, and a sore throat. She is pregnant and has a cat at home. Which pathogen should be considered due to risk of fetal neurological damage?

Accepted Answer

Toxoplasma gondii

Question 20

Which of the following is a distinguishing feature of Mycobacterium leprae compared to other nervous system pathogens?

Accepted Answer

It is an acid-fast bacillus that thrives at lower temperatures, especially in the extremities.

Infections of the Nervous System: Pathogens, Syndromes, and Clinical Microbiology

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