T10 Bacterial Pathogenesis

This set of flashcards covers key concepts in bacterial pathogenesis and virulence, including definitions, examples, mechanisms, and the implications for human health.

What is the definition of pathogenicity?

The ability of an organism to cause disease.

What is virulence?

The relative ability of a pathogen to cause disease.

What does LD50 stand for?

Lethal dose 50, the dose at which 50% of hosts die.

What does ID50 represent?

The infectious dose required to cause symptoms in 50% of hosts.

Name the three major mechanisms for intracellular invasion.

Zipper mechanism, Trigger mechanism, Coiling phagocytosis.

What are endotoxins?

Toxic heat-stable lipopolysaccharides (LPS) found in the outer membrane of Gram-negative bacteria.

Give an example of an exotoxin.

Cholera toxin or Staphylococcus aureus toxic shock syndrome toxin.

What is a key characteristic of superantigens?

They can activate a large percentage of T-cells (up to 25%).

What do biofilms contribute to infections?

They are associated with 60% of infections and up to 80% of chronic infections.

What is a spreading factor in bacterial pathogens?

An enzyme that affects the physical properties of tissue matrices to promote pathogen spread.

What are the two types of adhesins?

Specific and non-specific adhesins.

How does Neisseria gonorrhoeae attach to host cells?

Using Type IV pili that bind to glucosamine-galactose carbohydrates on host cells.

What is a characteristic of obligate intracellular pathogens?

They often evade nutrients and immune responses that challenge extracellular pathogens.

What type of bacterial structure is hyaluronic acid part of?

It is a component of the capsule of some bacteria.

What is a biofilm?

A collection of microorganisms that stick to each other and/or to surfaces.

What mechanisms do pathogens use to invade epithelial layers?

They can either bud off from epithelial cells or penetrate between them.

What role do siderophores play in bacterial virulence?

They strip iron from host proteins, crucial for bacterial growth.

What is one reason why colonization doesn't always lead to virulence?

Nutrient availability, competition from normal flora, or physical space limitations.

How do pathogens commonly disseminate within the body?

Through the bloodstream, lymphatic system, or cerebrospinal fluid.

What is a characteristic of Class III exotoxins?

They are multisubunit toxins that interfere with host cell functions.

What is the function of hemolysins in bacteria?

They destroy host cells by lysis.

What type of pathogen is associated with Type I toxins?

Superantigens.

What happens during the process of bacterial adherence?

Bacteria use adhesins to attach to host cells through specific or non-specific interactions.

How do bacterial capsules contribute to virulence?

Capsules can prevent host immune recognition.

What is the trigger mechanism in bacterial invasion?

A process involving major rearrangements of host cell membranes.

What role does the immune system play in bacterial infections?

It acts as a defense mechanism against invading pathogens.

Why is understanding pathogenicity important for public health?

It helps determine strategies for controlling and preventing diseases.

What is the impact of horizontal gene transfer in bacteria?

It can lead to increased virulence and antibiotic resistance.

How do environmental factors influence bacterial growth?

Adverse conditions like low pH or high temperatures can restrict growth.

What is an example of an intracellular pathogen?

Chlamydia or Treponema.