Flashcards in Host-Microbe Interactions (complete) Deck (15):
What is an infection?
- When a microbe enters into a relationship w/ the host
- May or may not cause disease
What is an infectious disease?
- Disease caused by an infection w/ a microbe
- Some are communicable (transferred from person to person)
- Others are not communicable
What does pathogenicity mean?
Capacity of a microbe to damage a host
What does virulence mean?
Relative capacity of microbe to damage a host
Explain how a microbe is shown to be the cause of a specific disease
- Specific microbes present regularly in characteristic lesions of the disease
- Specific microbes can be isolated and grown in vitro
- Injection of cultured microbes into animals reproduces the disease in humans
- Specific microbes can be re-isolated from lesions of the disease in animals
However this may not be possible to do with each disease
What are the typical stages in pathogenesis of an infectious disease?
Describe the encounter phase of pathogenesis.
THINK: how the agent meets host
- Contracted endogenously or exogenously?
- Route of infection
- Infectious dose
Describe the entry phase of pathogenesis.
THINK: how the agent enters host
- Colonization of body surfaces (contributes to extent/stability of colonization)
- Adherance (mediated by specific binding of pili or non-pili to receptors on host tissues)
Describe the spread phase of pathogenesis.
Microbial products can inhibit or promote spread
- Hyaluronidase, elastase, collagenase (spreading factors)
- Coagulase (inhibits )
Types of spread:
4) Zoonoses (bug vector, vertebrate, bug--> vertebrate)
Describe the multiplication phase of pathogenesis.
THINK: how it multiplies in host
Replicating rates in hosts must exceed their clearance by defense mechanisms --- clearance done by innate/adaptive immunity
Describe the damage phase of pathogenesis.
- Some microbial products causes direct damage
- Some contribute to host damage by blocking/interfering w/ host defense mechanisms
- Most that cause direct damage are surface components, products secreted into medium,
*** CLARIFY THIS LAST ONE***
Describe the outcome phase of pathogenesis.
Overall what is the outcome after all is said and done
Doesn't include much of a description
Describe the composition and importance of the microbiome in the body
Composed of bacteria in skin, oropharynx, large intestine, vagina
Factors that affect microbiome:
3) Anatomic abnormalities
4) Genetic differences
1) Effects on tissue/organ differentiation
2) Vitamin production by gut flora
3) Biochemical conversions
4) Competition with pathogens for colonization of body surfaces
Compare several disease paradigms that illustrate selected mechanisms of pathogenesis
1) Toxin mediated: cholera
2) Acute inflammation caused by invasive extracellular bacteria: pneumonia
3) Infection by facultative intracellular bacterium: TB
4) Pathology mediated by immune response: Rheumatic fever