Question 1

Which of the following best explains why cerebrospinal fluid (CSF) is collected from the lower back during a lumbar puncture rather than higher up the vertebral column?

Accepted Answer

The lower vertebral column does not contain the spinal cord, reducing the risk of damaging the CNS.

Question 2

A patient presents with sudden high fever, severe headache, stiff neck, and a milky appearance of CSF. Which pathogen is most likely if the Gram stain reveals Gram-negative cocci with a polysaccharide capsule?

Accepted Answer

Neisseria meningitidis

Question 3

Which of the following is a key virulence factor that allows Listeria monocytogenes to survive and multiply within host cells?

Accepted Answer

Synthesis of listeriolysin O

Question 4

Which of the following best describes the action of botulism toxin at the neuromuscular junction?

Accepted Answer

It blocks the release of acetylcholine, preventing muscle contraction.

Question 5

A newborn develops meningitis shortly after birth. The mother’s vaginal swab is positive for a Gram-positive coccus. Which organism is most likely responsible?

Accepted Answer

Streptococcus agalactiae

Question 6

Which of the following statements about the blood-brain barrier is correct?

Accepted Answer

It is composed of tightly joined cells that prevent most microbes and large molecules from entering the CSF.

Question 7

Which of the following best explains why viral meningitis is often referred to as 'aseptic meningitis'?

Accepted Answer

It is characterized by the absence of bacteria in the CSF.

Question 8

A patient with a history of eating undercooked beef develops insomnia, weight loss, and progressive muscle control loss. Laboratory tests confirm the presence of abnormal prion protein. What is the most likely diagnosis?

Accepted Answer

Variant Creutzfeldt-Jakob Disease

Question 9

Which of the following best describes the pathogenesis of tetanus?

Accepted Answer

The toxin blocks inhibitory neurotransmitters, resulting in unregulated muscle contraction.

Question 10

Which of the following is the primary vector for transmission of African sleeping sickness?

Accepted Answer

Tsetse fly

Question 11

Which of the following is a distinguishing feature of lepromatous leprosy compared to tuberculoid leprosy?

Accepted Answer

It results in progressive loss of facial features and other body structures.

Question 12

Which of the following is the most common cause of viral meningitis?

Accepted Answer

Enteroviruses

Question 13

A patient presents with fever, headache, and confusion after a mosquito bite. Laboratory tests reveal the presence of West Nile virus-specific antibodies in the CSF. What is the most likely diagnosis?

Accepted Answer

Arboviral encephalitis

Question 14

Which of the following is a key reason why infants under 1 year old should not consume honey?

Accepted Answer

Honey may contain Clostridium botulinum endospores, which can cause infant botulism.

Question 15

Which of the following best describes the mechanism by which Mycobacterium leprae evades destruction by the immune system?

Accepted Answer

It grows within phagocytes and has a cell wall rich in mycolic acid.

Question 16

Which of the following is the leading cause of bacterial meningitis in children under 5 years old and the elderly?

Accepted Answer

Streptococcus pneumoniae

Question 17

Which of the following is a characteristic sign of rabies infection in the brain, detectable postmortem?

Accepted Answer

Negri bodies

Question 18

Which of the following best explains why humans and horses are considered dead-end hosts for arboviral encephalitis?

Accepted Answer

The virus does not reach high enough concentrations in their blood to infect mosquitoes.

Question 19

Which of the following is the causative agent of trachoma, the leading cause of nontraumatic blindness?

Accepted Answer

Chlamydia trachomatis

Question 20

A patient presents with hallucinations, seizures, and hydrophobia after being bitten by a wild animal. Which of the following is the most appropriate immediate treatment?

Accepted Answer

Cleansing the wound, injecting human rabies immunoglobulin, and giving rabies vaccine

Microbial Diseases of the Nervous System and Eye: Structure, Pathogenesis, and Clinical Aspects

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