What Is The Relationship Between The Presence Of Capsules And Bacterial Pathogenicity?

What are the steps of phagocytosis?

The Steps Involved in PhagocytosisStep 1: Activation of the Phagocyte.

Step 2: Chemotaxis of Phagocytes (for wandering macrophages, neutrophils, and eosinophils) …

Step 3: Attachment of the Phagocyte to the Microbe or Cell.

Step 4: Ingestion of the Microbe or Cell by the Phagocyte..

What do some bacteria use for motility?

Motility is required for the virulence of many bacteria, particularly those infecting mucosal surfaces. Bacterial motility is mediated by beating flagella that consist mainly of the protein flagellin.

What are the 4 types of pathogenic bacteria?

A variety of microorganisms can cause disease. Pathogenic organisms are of five main types: viruses, bacteria, fungi, protozoa, and worms.

Can bacteria survive without a capsule?

There are a number of bacteria that lack capsule. In the respiratory tract and oral cavity there are several species without capsular material on their surface. … The advantage would be that they require less energy use to produce the capsule and can use that energy for other things.

What are examples of virulence factors?

Factors that are produced by a microorganism and evoke disease are called virulence factors. Examples are toxins, surface coats that inhibit phagocytosis, and surface receptors that bind to host cells.

How do you observe bacterial motility?

Procedure:Prepare a semisolid agar medium in a test tube.Inoculate with a straight wire, making a single stab down the center of the tube to about half the depth of the medium.Incubate under the conditions favoring motility.Incubate at 37°C.More items…•

What are mechanisms of pathogenicity?

Pathogenicity is the ability to produce disease in a host organism. … The outcome of such a relationship depends on the virulence of the pathogen and the relative degree of resistance or susceptibility of the host, due mainly to the effectiveness of the host defense mechanisms.

How does the presence of capsule make the bacteria more pathogenic?

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. … They also exclude bacterial viruses and most hydrophobic toxic materials such as detergents.

Can the presence of a capsule always be correlated with virulence?

Can one always correlate the presence of a capsule on pathogenic species with virulence? No. Capsule just gives sticky nature to the coloneys of bacteria while slime layer provides pathogenicity. … Capsules of many pathogenic bacteria impair phagocytosis and reduce the action of complement-mediated killing.

What is the role of bacterial capsule?

The capsule helps the bacteria to adhere to surfaces, camouflages the bacteria from the immune system by mimicking the host tissues, and makes the bacteria resistant to complement invasiveness. A capsule protects cells from desiccation and toxic metabolites in the environment (heavy metal ions and free radicals).

Is capsule stain positive or negative?

This is a negative staining technique that is essentially used to identify the presence of capsules. Because of its acidic nature, India ink (or Congo red, nigrosin) stains the background dark.

What are the 3 types of phagocytes?

There are three main groups of phagocytes: monocytes and macrophages, granulocytes, and dendritic cells, all of which have a slightly different function in the body.

What is the process of phagocytosis?

Phagocytosis, process by which certain living cells called phagocytes ingest or engulf other cells or particles. The phagocyte may be a free-living one-celled organism, such as an amoeba, or one of the body cells, such as a white blood cell.

Do all bacterial cells have capsules?

Not all bacterial species produce capsules; however, the capsules of encapsulated pathogens are often important determinants of virulence. Encapsulated species are found among both Gram-positive and Gram-negative bacteria.

What is the function of capsule in disease pathogenesis?

Capsules have a significant role in determining access of certain molecules to the cell membrane, mediating adherence to surfaces, and increasing tolerance of desiccation. Furthermore, capsules of many pathogenic bacteria impair phagocytosis (22, 29, 30) and reduce the action of complement-mediated killing (7, 31, 35).

What is the dual function of copper sulfate in capsule staining?

A 20% copper sulfate solution serves a dual role as both the decolorizing agent and counterstain. It decolorizes the capsule by washing out the crystal violet, but will not decolorize the cell.

What is bacterial motility?

Motility is the ability of a cell or organism to move of its own accord by expending energy. Many single-celled and microscopic organisms are also motile, using methods such as flagellar motility, amoeboid movement, gliding motility, and swarming motility. …

What are the steps involved in pathogenesis?

The stages of pathogenesis include exposure, adhesion, invasion, infection, and transmission.

What is the staining method of choice for bacterial capsules?

In the capsule staining method, copper sulfate is used as a decolorizing agent rather than water. The copper sulfate washes the purple primary stain out of the capsular material without removing the stain bound to the cell wall.

How does capsule protect the bacteria?

Capsules can protect a bacterial cell from ingestion and destruction by white blood cells (phagocytosis). While the exact mechanism for escaping phagocytosis is unclear, it may occur because capsules make bacterial surface components more slippery, helping the bacterium to escape engulfment by phagocytic cells.

What are the ways in which an organism can evade phagocytosis?

Summary. Some bacteria resist phagocytic destruction by preventing fusion of the lysosome with the phagosome. Some bacteria resist phagocytic destruction by escaping from the phagosome before the lysosome fuses. Some bacteria resist phagocytic destruction by preventing acidification of the phagosome.

Is Crystal Violet acidic or basic?

The Crystal violet stain is a basic substance, and Congo red stain is an acidic substance. During the lab you are able to compare the colors to the ph scale, allowing it to show youthat red substances end up being a 4 on the scale, and the violet substances are a 10 on thescale.

What does a positive motility test mean?

A positive motility test is indicated by a diffuse zone of growth flaring from the line of inoculation. A negative motility test is indicated by growth confined to the stab line. Motility Test Medium with TTC. A positive motility test is indicated by a pink color diffusing from the line of inoculation.

What is an example of pathogenesis?

Types of pathogenesis include microbial infection, inflammation, malignancy and tissue breakdown. For example, bacterial pathogenesis is the mechanism by which bacteria cause infectious illness. Most diseases are caused by multiple processes.