Ch. 22 - Microbial Diseases of the Nervous System

Tortora - Microbiology: An Introduction 14th Edition

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Tortora 14th Edition

Ch. 22 - Microbial Diseases of the Nervous System

Problem 5

Chapter 22, Problem 5

Endotoxin is responsible for symptoms caused by which of the following organisms?
a. N. meningitidis
b. S. pyogenes
c. L. monocytogenes
d. C. tetani
e. C. botulinum

Verified step by step guidance

Understand what an endotoxin is: Endotoxins are lipopolysaccharides (LPS) found in the outer membrane of Gram-negative bacteria. They are released when the bacteria die and cause symptoms such as fever, inflammation, and shock.

Identify which organisms in the list are Gram-negative: Among the options, Neisseria meningitidis (N. meningitidis) is a Gram-negative bacterium, while the others are Gram-positive.

Recall that Gram-positive bacteria do not have an outer membrane and therefore do not produce endotoxins; instead, they may produce exotoxins.

Match the organism that produces endotoxin with the symptoms caused by endotoxin: Since N. meningitidis is Gram-negative, it produces endotoxin responsible for symptoms like meningitis and septic shock.

Conclude that the correct organism responsible for symptoms caused by endotoxin is N. meningitidis.

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Key Concepts

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

Endotoxins

Endotoxins are toxic components of the outer membrane of Gram-negative bacteria, primarily lipopolysaccharides (LPS). They are released when the bacteria die or multiply, triggering strong immune responses such as fever, inflammation, and septic shock.

Gram-negative vs. Gram-positive Bacteria

Gram-negative bacteria have an outer membrane containing endotoxins, while Gram-positive bacteria lack this outer membrane and instead produce exotoxins. This distinction is crucial for understanding which organisms cause symptoms via endotoxins.

Pathogenic Organisms Listed

Among the listed organisms, Neisseria meningitidis is Gram-negative and produces endotoxins. The others (S. pyogenes, L. monocytogenes, C. tetani, C. botulinum) are Gram-positive and cause disease mainly through exotoxins, not endotoxins.

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Textbook Question

After receiving a corneal transplant, a patient developed dementia and loss of motor function, then became comatose and died. Cultures were negative. Serological tests were negative. Autopsy revealed spongiform degeneration of brain tissue. The patient most likely had

a. Rabies.

b. Creutzfeldt-Jakob disease.

c. Botulism.

d. Tetanus.

e. Leprosy.

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Textbook Question

Why is the following description used for wounds that are susceptible to C. tetani infection: “. . . Improperly cleaned deep puncture wounds . . . ones with little or no bleeding . . .”?

Textbook Question

Provide the following information on poliomyelitis: etiology, method of transmission, symptoms, prevention. Why aren’t the Salk and Sabin vaccines considered treatments for poliomyelitis?

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Textbook Question

The increased incidence of encephalitis in the summer months is due to

a. Maturation of the viruses.

b. Increased temperature.

c. The presence of adult mosquitoes.

d. An increased population of birds.

e. An increased population of horses.

Textbook Question

Match the following choices to the statements in questions 7 and 8:

a. antirabies antibodies

b. HDCV