Ch. 18 - Nervous System Infections

Norman-McKay- Microbiology: Basic and Clinical Principles 2nd Edition

Norman-McKay2nd EditionMicrobiology: Basic and Clinical PrinciplesISBN: 9780137661619Not the one you use?Change textbook

Norman-McKay 2nd Edition

Ch. 18 - Nervous System Infections

Problem 2

Chapter 18, Problem 2

Viral meningitis is more common than other forms of meningitis because
a. these infectious agents are all intracellular, evading the immune system.
b. there are more types of viruses than bacteria because they evolve more quickly.
c. the small size of viruses makes them able to pass more easily through the blood–brain barrier.
d. viruses are spread person to person more easily than bacteria, fungi, or protozoans.

Verified step by step guidance

Step 1: Understand the context of viral meningitis and why it is more common compared to other forms of meningitis caused by bacteria, fungi, or protozoans.

Step 2: Analyze option (a): Consider whether the intracellular nature of viruses helps them evade the immune system and if this contributes to their higher incidence in meningitis cases.

Step 3: Analyze option (b): Reflect on the diversity and rapid evolution of viruses compared to bacteria, and how this might affect the frequency of viral meningitis.

Step 4: Analyze option (c): Evaluate if the small size of viruses allows them to cross the blood–brain barrier more easily than other pathogens, leading to more cases of viral meningitis.

Step 5: Analyze option (d): Consider the modes of transmission of viruses compared to bacteria, fungi, and protozoans, and whether easier person-to-person spread explains the higher prevalence of viral meningitis.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Blood–Brain Barrier and Pathogen Entry

The blood–brain barrier is a selective barrier that protects the brain from pathogens and toxins. Its structure limits the passage of many microorganisms, but some viruses can cross it due to their small size or specific mechanisms, influencing the incidence of viral meningitis.

Viral Evolution and Diversity

Viruses evolve rapidly due to high mutation rates and genetic recombination, leading to a wide variety of viral types. This diversity increases the likelihood of viruses adapting to infect humans and cause diseases like meningitis more frequently than other pathogens.

Modes of Transmission of Infectious Agents

The ease with which infectious agents spread between people affects disease prevalence. Viruses often transmit efficiently via respiratory droplets, fecal-oral routes, or direct contact, making viral meningitis more common compared to bacterial, fungal, or protozoan causes.

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Related Practice

Textbook Question

A patient’s lab data report has come back with a positive ELISA for pneumococcal C polysaccharide from CSF samples. The MOST appropriate next step for a health professional to recommend is to

a. culture from the CSF sample to test for antibiotic resistance.

b. administer tetracycline.

c. administer cephalosporin.

d. wait for RT-PCR confirmation before antibiotic treatment.

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Textbook Question

A patient under one year old is vomiting, drowsy, floppy (flaccid), and unresponsive. Both infant botulism and infant meningitis caused by other bacteria are suspected. Which piece of information would best help narrow down the possible diagnosis?

a. The child has spent almost no time outside the home.

b. The child is being breast-fed.

c. The child was born one month ago.

d. The child has a very high fever.

Textbook Question

CSF glucose levels are often assessed to differentiate between bacterial and viral meningitis. This is because

a. bacteria cells use glucose and lower the overall concentration in the CSF.

b. viral meningitis causes inflammation that blocks glucose transport into the CSF.

c. viral infection of the meninges causes cell lysis, releasing glucose into the CSF.

d. None of the above.

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Textbook Question

A patient is admitted who is complaining of headache, disorientation, and numbness in his left arm. He was bitten by a raccoon two days before. The FIRST step taken to help this patient would be

a. retrieving and testing the raccoon’s brain tissues for the rabies virus.

b. collecting a CSF sample from the patient.

c. performing a tissue biopsy on the patient to look for Negri bodies.

d. administering an anti-rabies vaccine as well as anti-rabies antibodies.

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