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41 Cards in this Set

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Things that fall into chemical portion of virulence factors:

Enzymes such as:


-collagenase


-hyaluronidase


-proteases


and


TOXINS

How does hyaluronidase help a pathogen invade?

it digests the hyaluronic acid of the matrix of connective tissue, allowing it to penetrate deeper. Generally stops once it reaches fibers, (unless it has other enzymes that also digest those fibers)

What falls under 'Resist host defenses"?

1. resists phagocytosis


2. Gets inside host cell

How does a microorg resist phagocytosis?

Capsules help a microorg resist phagocytosis. The capsule makes the phagocyte unable to adhere to the microorg, therefore it can't engulf it.

How does salmonella resist phagocytosis?

It can be engulfed by a phagocyte. However, it has chemicals (enzymes?) that disable lysosomes to hook up with it to digest it so it remains alive, undigested in the phagocyte

How does Mycobacterium resist phagocytosis?

It can be ingested by a phagocyte, and lysosome can hook up with it. However, since Mycobacterium is acid-fast, it has a waxy layer which makes the lysozyme unable to digest it. So it lives, undigested inside the phagocyte.

How does getting inside host cell help a microorg resist host defenses?

once inside host cell, a phagocyte will view the cell as 'self' and therefore will not engulf it

What types of microorgs can generally use 'getting inside host cell' as a means of resisting host defenses?

viruses (olbigate intracellular parasites)

At what point in the 'causing infectious diseases' process do we generally know that someone is sick? Why/How?

At the 'cause damage' stage


That person will start showing signs and symptoms

Even if a person is exhibiting signs and symptoms, what does their immune response usually do?

Their immune response usually catches up/kicks it up a notch and wins over the infection

What 3 ways does an infectious disease cause damage/3 types of damage?

1. localized damage


2. toxins


3. Host-mediated damage/hypersensitivity

what does localized damage mean?

Localized damage means its harmful effects are generally limited to one part of the body





How does a microorg cause localized damage?

1. use of available nutrients (thereby 'starving' host cells)


2. enzyme production (that digest host tissues)

How does enzyme production cause localized damage?

As the infectious microorg grows, it produces enzyme (specific to each pathogen), that can digest host cells/tissues

Explain how enzyme production works to cause periodontal disease?

a piece of food stuck between teeth allows extra nutrients for normal microbiota that live in gums, causing them to grow rapidly. As they grow, they produce more proteases, that digest protein. Initially these proteases gum tissue causing red, swollen, painful gingivitis. Eventually, if untreated, the proteases can go on to digest ligaments of gums, causing periodontal disease, possibly causing tooth loss and even digestion of jaw bone

What is protease?

An enzyme that digests proteins

Do toxins cause local or distant damage?

Either/both

What types of toxins can cause damage?

1. endotoxins


2. exotoxins


3. others

How do endotoxins cause damage?


Signs and symptoms?

Once englufed by phagocytes or other cells, cell dies and endotoxins are released into the blood stream. This can cause high fever, blocked blood flow, organ damage etc

What type of microorg is capable of causing damage with endotoxins?

gram-negative bacteria because they are the ones that have endotoxins

What are the signs and symptoms of an endotoxin related infection?

high fever


blocked blood flow


organ damage/failure


gangrene


etc

What microorganism can produce exotoxins?

gram pos, gram neg, fungi etc


almost any cellular metabolic organism can produce exotoxins

What type of infection does an exotoxin cause?

often causes systemic infections

What examples of exotoxin types did we study?

neurotoxins


enterotoxins


leukocidins


others

What 2 things are unique about exotoxins?

-each exotoxin is unique to a particular pathogen


- each exotoxin must attach to specific receptors on host cells to cause damage

What two examples of neurotoxins did we study?

Clostridium botulinum


Clostridium tetany

How does the neurotoxin Clostridium botulinum work?

Its exotoxin prevents release of acetocholine at neuro-muscular joint, causing muscles to be unable to contract


sign/symptoms: paralysis, muscle movement problems

How does the neurotoxin Clostridium tetany work?

its exotoxin affects the inhibitory nerves that help muscles relax. As a result, muscles are constantly contracted/spasming


sign/symptoms: spasms, painful, can die from suffocation if it affects diaphragm; can die fm circulatory failure/heart attack if it attacks heart

What do neurotoxins act on?

nerves

What do enterotoxins act on?

intestines

signs/symptoms of enterotoxin infection?

diarrhea, nausea, vomitting, fever


food poisoning

What do leukocidins do?

kill WBCs

Explain the significance of phagocytes being a WBC as it relates to leukocidins?


What does this result in?

Leukocidins can kill phagocytes because they are a white blood cell. As the leukocidins kill off phagocytes, more WBCs are sent to combat the infection, causing more dead WBC and therefore causing pus

Signs/symptoms of leukocidins infection?


Two examples of diseases associated with leukocidins

pus


Strep throat


Staph infections

What is the final way that microorgs can cause damage?

via host-mediated damage/hypersensitivity

What is host-mediated damage/hypersensitivity?

damage is caused by host's own immune response (overreacting)

What is the clinical significance of virulence factors?

The more a microorg has and/or the more powerful the virulence factor is, the more damage the microorg can cause,


- more host immune response tools will be involved with fighting the infection off

Why are we concerned with portals of exit for a microorg infection?

It's a concern in regard to public health. One person's portal of exit can transmit the disease to the next person's portal of entry

Entry/exit portals: flu:

entry: mucous membrane


exit: mucous membrane

Giardia entry/exit portals:

entry: fecal-oral route


exit: diarrhea

What is generally true about the relationship between a disease causing microorg's portal of entry and its portal of exit?

- might be same body part


- generally at least the same body system


(ie enters via mouth, exits via anus in form of diarrhea)