Textbook Question
Compare and contrast the following aspects of endotoxins and exotoxins: bacterial source, chemistry, toxigenicity, and pharmacology. Give an example of each toxin.
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Ch. 15 - Microbial Mechanisms of Pathogenicity
Tortora14th EditionMicrobiology: An IntroductionISBN: 9780138200398
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Table of contents
- Ch. 1 - The Microbial World and You18
- Ch. 2 - Chemical Principles20
- Ch. 3 - Observing Microorganisms Through a Microscope18
- Ch. 4 - Functional Anatomy of Prokaryotic and Eukaryotic Cells21
- Ch. 5 - Microbial Metabolism20
- Ch. 6 - Microbial Growth20
- Ch. 7 - The Control of Microbial Growth20
- Ch. 8 - Microbial Genetics19
- Ch. 9 - Biotechnology & DNA Technology20
- Ch. 10 - Classification of Microorganisms15
- Ch. 11 - The Prokaryotes: Domains Bacteria and Archaea14
- Ch. 12 - The Eukaryotes: Fungi, Algae, Protozoa, and Helminths17
- Ch. 13 - Viruses, Viroids, and Prions20
- Ch. 14 - Principles of Disease and Epidemiology21
- Ch. 15 - Microbial Mechanisms of Pathogenicity19
- Ch. 16 - Innate Immunity: Nonspecific Defenses of the Host20
- Ch. 17 - Adaptive Immunity: Specific Defenses of the Host20
- Ch. 18 - Practical Applications of Immunology20
- Ch. 19 - Disorders Associated with the Immune System19
- Ch. 20 - Antimicrobial Drugs19
- Ch. 21 - Microbial Diseases of the Skin and Eyes21
- Ch. 22 - Microbial Diseases of the Nervous System19
- Ch. 23 - Microbial Diseases of the Cardiovascular and Lymphatic Systems20
- Ch. 24 - Microbial Diseases of the Respiratory System20
- Ch. 25 - Microbial Diseases of the Digestive System20
- Ch. 26 - Microbial Diseases of the Urinary and Reproductive Systems19
- Ch. 27 - Environmental Microbiology20
- Ch. 28 - Applied and Industrial Microbiology19
Tortora14th EditionMicrobiology: An IntroductionISBN: 9780138200398Not the one you use?Change textbook
Chapter 15, Problem 7
A drug that binds to mannose on human cells would prevent
a. the entrance of Vibrio enterotoxin.
b. the attachment of pathogenic E. coli.
c. the action of botulinum toxin.
d. streptococcal pneumonia.
e. the action of diphtheria toxin.
Verified step by step guidance1
Step 1: Understand the role of mannose in microbial pathogenesis. Mannose residues on human cell surfaces often serve as binding sites for certain bacteria or their toxins, facilitating attachment or entry.
Step 2: Identify which pathogens or toxins specifically interact with mannose residues. For example, some pathogenic strains of Escherichia coli use mannose-sensitive fimbriae (pili) to attach to host cells.
Step 3: Analyze each option in the question to determine if the pathogen or toxin binds to mannose on human cells. For instance, Vibrio enterotoxin and botulinum toxin do not typically bind mannose; their mechanisms differ.
Step 4: Recognize that preventing binding to mannose would block the initial attachment step for pathogens that rely on mannose-mediated adhesion, such as certain pathogenic E. coli strains.
Step 5: Conclude that a drug binding to mannose would most likely prevent the attachment of pathogenic E. coli, as this bacterium uses mannose-sensitive adhesion to colonize host cells.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Role of Mannose in Bacterial Adhesion
Mannose residues on human cell surfaces serve as binding sites for certain bacterial adhesins, facilitating attachment. Pathogenic bacteria like some strains of E. coli use mannose-specific fimbriae to adhere to host cells, initiating infection. Blocking mannose can prevent this attachment, hindering colonization.
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Adhesion Molecules
Mechanism of Bacterial Toxins
Bacterial toxins such as enterotoxins, botulinum, and diphtheria toxins have distinct modes of action, often independent of mannose binding. For example, botulinum toxin inhibits neurotransmitter release, while diphtheria toxin inhibits protein synthesis. Understanding these mechanisms helps differentiate toxin effects from adhesion processes.
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Pathogenesis of Vibrio and Streptococcal Infections
Vibrio enterotoxins cause diarrhea by disrupting ion transport in intestinal cells, but their entry does not rely on mannose binding. Streptococcal pneumonia involves bacterial colonization and immune evasion mechanisms unrelated to mannose-mediated adhesion. Recognizing these differences clarifies which pathogens are affected by mannose-binding drugs.
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Related Practice
Textbook Question
Label this diagram to show how the Shiga toxin enters and inhibits protein synthesis in a human cell.
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Textbook Question
Describe the factors contributing to the pathogenicity of fungi, protozoa, and helminths.
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Textbook Question
The earliest smallpox vaccines were infected tissue rubbed into the skin of a healthy
person. The recipient of such a vaccine usually developed a mild case of smallpox, recovered, and was immune thereafter. What is the most likely reason this vaccine did not kill more people?
a. Skin is the wrong portal of entry for smallpox.
b. The vaccine consisted of a mild form of the virus.
c. Smallpox is normally transmitted by skin-to-skin contact.
d. Smallpox is a virus.
e. The virus mutated.
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Textbook Question
Which of the following genera is the most infectious?
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Textbook Question
The ID₅₀ for Campylobacter sp. is 500 cells; the ID₅₀ for Cryptosporidium sp. is 100 cells. Which of the following statements is false?
a. Both microbes are pathogens.
b. Both microbes produce infections in 50% of the inoculated hosts.
c. Campylobacter is more virulent than Cryptosporidium.
d. Campylobacter and Cryptosporidium are equally virulent; they cause infections in the same number of test animals.
e. Cryptosporidium infections are acquired more easily than Campylobacter infections.