Question 1

Which of the following best explains why Streptococcus pneumoniae is a frequent cause of bacterial meningitis?

Accepted Answer

Its capsule allows it to evade phagocytosis and exoenzymes degrade tissues, allowing dissemination into the blood and meninges.

Question 2

A patient presents with fever, headache, stiff neck, and purple spots on the skin (petechiae). Which bacterial pathogen is most likely responsible for these symptoms?

Accepted Answer

Neisseria meningitidis

Question 3

Which of the following statements about Listeria monocytogenes is CORRECT?

Accepted Answer

It is a psychrotroph and can grow in refrigerated foods.

Question 4

A child develops meningitis after consuming unpasteurized dairy products. Which of the following best explains the pathogenesis?

Accepted Answer

The pathogen survives at low temperatures and crosses the placenta, causing meningitis in newborns.

Question 5

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

Accepted Answer

Disfiguring nodules and necrosis of tissues are present due to failed cell-mediated immunity.

Question 6

A patient presents with rigid paralysis and muscle spasms after a puncture wound. Which bacterial toxin is responsible for these symptoms?

Accepted Answer

Tetanospasmin

Question 7

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

Accepted Answer

It causes flaccid paralysis by blocking neurotransmitter release, leading to respiratory and cardiac failure.

Question 8

Which of the following vaccines is a live attenuated vaccine that can rarely revert to a pathogenic form?

Accepted Answer

Oral polio vaccine (OPV)

Question 9

A person is bitten by a bat and seeks medical attention. What is the most appropriate immediate treatment to prevent rabies?

Accepted Answer

Passive immunization with pre-made anti-rabies antibodies and active immunization with inactivated rabies vaccine.

Question 10

Which of the following best explains why the rabies vaccine can be effective after exposure?

Accepted Answer

The long incubation period allows time for the immune system to develop a response before the virus reaches the brain.

Question 11

Which of the following is the primary vector for arboviral encephalitis such as West Nile Virus?

Accepted Answer

Mosquito

Question 12

A patient presents with lethargy, drowsiness, and eventually falls into a coma after traveling to sub-Saharan Africa. Which protozoan disease is most likely?

Accepted Answer

African trypanosomiasis (sleeping sickness)

Question 13

Which of the following best describes the transmission route of poliovirus?

Accepted Answer

Fecal contamination of food and water

Question 14

Which of the following is a key reason why antibiotic resistance is a concern in the treatment of bacterial meningitis?

Accepted Answer

Some bacteria possess capsules that reduce antibiotic penetration and can acquire resistance genes.

Question 15

Which of the following statements about Haemophilus influenzae type b (Hib) is TRUE?

Accepted Answer

It is prevented by a conjugated vaccine given to young children.

Question 16

Which of the following best explains why only some people develop leprosy after exposure to Mycobacterium leprae?

Accepted Answer

Susceptibility depends on the individual's immune response.

Question 17

Which of the following is the most effective prevention strategy for African trypanosomiasis?

Accepted Answer

Vector control to reduce tsetse fly populations

Question 18

A patient develops flaccid paralysis after eating improperly canned food. Which of the following is the most likely cause?

Accepted Answer

Clostridium botulinum

Question 19

Which of the following best describes the role of the capsule in bacterial meningitis pathogens such as Streptococcus pneumoniae and Neisseria meningitidis?

Accepted Answer

It allows the bacteria to evade phagocytosis by the host immune system.

Question 20

Which of the following is a reason why the oral polio vaccine (OPV) is not always preferred over the inactivated polio vaccine (IPV)?

Accepted Answer

OPV can rarely revert to a pathogenic form and cause disease.

Microbial Diseases of the Nervous System: Bacterial, Viral, and Protozoan Infections

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