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Ch. 14 - Infection, Infectious Diseases, and Epidemiology
Bauman - Microbiology with Diseases by Taxonomy 6th Edition
Bauman6th EditionMicrobiology with Diseases by TaxonomyISBN: 9780134832302Not the one you use?Change textbook
Chapter 14, Problem 8

The nature of bacterial capsules ___________ .
a. Causes widespread blood clotting
b. Allows phagocytes to readily engulf these bacteria
c. Affects the virulence of these bacteria
d. Has no effect on the virulence of bacteria

Verified step by step guidance
1
Step 1: Understand what a bacterial capsule is. A bacterial capsule is a gelatinous outer layer that surrounds the cell wall of some bacteria, composed mainly of polysaccharides.
Step 2: Consider the role of the capsule in bacterial interactions with the host immune system. Capsules often help bacteria evade the host's immune defenses.
Step 3: Analyze how capsules affect phagocytosis. Capsules can inhibit phagocytosis by preventing phagocytes from easily engulfing the bacteria.
Step 4: Connect the presence of a capsule to bacterial virulence. Since capsules help bacteria avoid immune responses, they typically increase the bacteria's ability to cause disease (virulence).
Step 5: Evaluate the answer choices based on this understanding: the capsule does not cause blood clotting, does not facilitate phagocytosis, and definitely affects virulence.

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Key Concepts

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

Bacterial Capsule Structure and Composition

A bacterial capsule is a gelatinous outer layer composed mainly of polysaccharides, sometimes proteins, that surrounds the cell wall. It provides protection against environmental threats and helps bacteria adhere to surfaces. This structure is distinct from the cell wall and slime layer, contributing to bacterial survival.
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The Glycocalyx: Capsules & Slime Layers

Role of Capsules in Immune Evasion

Capsules help bacteria evade the host immune system by inhibiting phagocytosis, making it difficult for immune cells like macrophages and neutrophils to engulf and destroy the bacteria. This immune evasion enhances bacterial survival within the host.
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Capsules and Bacterial Virulence

The presence of a capsule often increases bacterial virulence, meaning the bacteria's ability to cause disease. Capsules protect bacteria from host defenses, allowing them to establish infections more effectively, which is why encapsulated bacteria are often more pathogenic.
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