Table of Contents
- 1 Why are some bacteria more virulent than others?
- 2 What is the difference between slime layer and capsule?
- 3 What is the relationship between the presence of capsule and bacterial pathogenicity?
- 4 What is the relationship between the presence of flagella and bacterial pathogenicity?
- 5 What are non-capsulated bacteria?
- 6 How do polysaccharide capsules confer virulence to bacteria?
Why are some bacteria more virulent than others?
In the previous section, we explained that some pathogens are more virulent than others. This is due to the unique virulence factors produced by individual pathogens, which determine the extent and severity of disease they may cause.
How would Opsonins affect the pathogenicity of a capsule?
How would opsonins affect the pathogenicity of a capsule? It would lessen the chance for the bacterial call to cause disease.
How might a flagella contribute to pathogenicity?
Flagella contribute to virulence of pathogenic bacteria through chemotaxis, adhesion to and invasion of host surfaces. Thus, flagellin is constituted of a conserved domain widespread in bacterial species dedicated to filament polymerization.
What is the difference between slime layer and capsule?
Many bacterial cells secrete some extracellular material in the form of a capsule or a slime layer. A slime layer is loosely associated with the bacterium and can be easily washed off, whereas a capsule is attached tightly to the bacterium and has definite boundaries.
Are most bacteria pathogenic?
Most bacteria are not pathogenic. Those that are contain specific virulence genes that mediate interactions with the host, eliciting particular responses from the host cells that promote the replication and spread of the pathogen.
Why are some bacteria pathogenic?
They include factors that help the bacteria to adhere to and invade cells and tissues. Some bacteria are well equipped to evade the body’s defense mechanisms, and some produce toxins that cause symptoms and disease.
What is the relationship between the presence of capsule and bacterial pathogenicity?
What is the relationship between the presence of capsules and bacterial pathogenicity? The Capsule helps the bacteria attach to the host organism.
Why are the capsules resistant to phagocytic digestion?
Capsules can resist unenhanced attachment by by preventing pathogen-associated molecular patterns or from binding to endocytic pattern-recognition receptors on the surface of the phagocytes. The capsules of some bacteria interfere with the body’s complement pathway defenses.
Are flagella pathogenic?
Flagella are essential structures in the pathogenic bacteria, by providing motility. However, flagella are involved in bacterial pathogenicity not just by conferring motility but also through other pathways.
What is the relationship between the presence of flagella and bacterial pathogenicity?
Flagella confers bacterial pathogenicity not only by providing propulsion or motility to the cell but also plays multiple functions such as surface sensing which is required for colonization through biofilm formation, adhesion or invasion to host epithelial cells, secretion of virulence factor, chemotaxis, and …
What are capsulated bacteria?
Capsulate bacteria cause the majority of community-acquired pneumonia presenting to hospital world-wide, at all ages. They are united by the virulence factor of their differing capsular polysaccharides, enabling them to evade phagocytosis.
How can the presence of a capsule make a bacterial cell more pathogenic?
Function. The capsule is considered a virulence factor because it enhances the ability of bacteria to cause disease (e.g. prevents phagocytosis). The capsule can protect cells from engulfment by eukaryotic cells, such as macrophages. A capsule-specific antibody may be required for phagocytosis to occur.
What are non-capsulated bacteria?
Non-capsulated bacteria are bacteria that lack a capsule. A capsule is a protective outer covering on certain gram-negative and gram-positive bacteria that increases virulence. The capsule acts to prevent dessication and phagocytosis.
What is a bacterial capsule?
The bacterial capsule is a large structure common to many bacteria. It is a polysaccharide layer that lies outside the cell envelope, and is thus deemed part of the outer envelope of a bacterial cell. That bacteria leads to virulence, as mutant versions of them without a polysaccharide capsule do not cause disease.
What are encapsulated bacteria and how do they work?
Encapsulated bacteria have an outer covering made of polysaccharides. This covering is smooth and negatively charged, making the bacteria difficult to swallow by phagocytes (immune cells that engulf pathogens).
How do polysaccharide capsules confer virulence to bacteria?
Polysaccharide capsules confer virulence, in part because they enable bacteria to evade adaptive and specific immune defence mechanisms. 2 Capsules inhibit phagocytosis, obscure phosphoryl-choline residues in the cell wall from recognition by C reactive protein, and offer resistance to the lytic action of complement.