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Bacteriology > Lecture 8 - Colonization > Flashcards

Lecture 8 - Colonization Flashcards

1
Q

Describe commensalism.

A

The host is unaffected while the microbe benefits.

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2
Q

Describe parasitism.

A

The host is harmed while the bacteria benefits.

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3
Q

What does symbiosis mean?

A

Living together.

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4
Q

Where can normal microbiota be found on the body?

A 
Skin 
Conjunctiva 
Respiratory tract 
Urogenital tract 
GI tract
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5
Q

What type of symbiosis occurs with natural microbiota?

A

Mutalists + Commensals

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6
Q

What are the characteristics of normal microbiota?

A

Stable, polymicrobial communities

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7
Q

What are the benefits of normal microbiota?

A

Can prevent the colonization of exogenous pathogens by forming a barrier.

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8
Q

Name the example given in lecture of an opportunistic pathogen.

A

Fusobacterium necrophorum

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9
Q

What is an opportunistic pathogen?

A

Normally does not cause disease in host, but if conditions change that favor growth of bacteria it can cause problems. (ie. ulcerations in stomach, alopecia in dogs, etc.)

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10
Q

What is pathogenicity?

A

It is the ability for the bacteria to cause damage in the host. Can the pathogen cause harm or not.

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11
Q

What is virulence?

A

The relative capacity of the pathogen to cause disease. How bad is the disease that is caused by the pathogen.

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12
Q

What is transmissibility?

A

How well the pathogen can spread from one host to a new host. Not whether or not the pathogen once in the host can cause an infection.

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13
Q

What size has the best transmission to the new host?

A

infectious droplet nuclei. this is why biological weapons are aerosolized.

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14
Q

How far can infectious droplet nuclei “fly”?

A

5 to 160+ feet

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15
Q

What is infectivity?

A

How well the pathogen, once in the new host, can settle down and cause disease. How well cell to cell spread of the bacterium occurs.

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16
Q

Describe what virulence factors are.

A

Traits that the microbe has that are able to cause pathogenicity. Basically what makes the bacteria/microbe dangerous to the host.

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17
Q

What are the common characteristics of genes that cause good virulence factors?

A

They are expressed as needed (faculatative)
They are distributed unevenly among strains of species
Can be spread via horizontal transfer
Cluster in pathogenicity islands

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18
Q

What do the virulence factors specifically aim to help the pathogen do?

A 
Colonize host 
Evade host defenses 
Grow
Invade cells/tissues 
Cause damage
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19
Q

What are the three major categories of virulence factors?

A

Adhesins + Capsules + Toxins

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20
Q

What are adhesins?

A

Macromolecules that bind bacteria to host cells/tissues

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21
Q

Where are the adhesins located on the microbe?

A

Surface structures such as fimbriae, pili, glycocalyx

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22
Q

Describe in detail how the adhesins work.

A

Bind to receptors on target cells with high specificity causing a receptor-ligand interaction. This allows for the microbe to cause changes within the host cell.

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23
Q

What is important to know about the specificity of the adhesins? (What do they allow for)

A

Tissue tropism + Host specificity

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24
Q

What are E. Coli K88 infections limited to?

A

PIGS

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25
Q

What is tissue tropism?

A

The microbe can only bind to a certain tissue. Things that are specific for the respiratory tract can’t infect the GI tract (most of the time)

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26
Q

What is K88?

A

Adhesin on a strain of E. Coli that can only bind to certain receptors on the brush border of the pig enterocytes

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27
Q

What is one result, given in lecture, of the receptor-ligand interactionof adhesin to the host cell?

A

Causes the pathogen to be taken up by the host cell = increased chance of infection

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28
Q

What is the function of the capsule?

A

Impairs phagocytosis
Mediates biofilm formation
Prevents dessication

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29
Q

What is an example of a bacteria found on dental plaque?

A

Streptococcus mutans

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30
Q

What is used in a capsule stain?

A

India ink

31
Q

What are two methods in which bacteria toxins cause damage to host?

A

At site of colonization/invasion

At sites remote from original point of invasion

32
Q

What are the two major types of toxins that bacteria have?

A

Exotoxin + Endotoxin

33
Q

What kind of bacteria tend to have exotoxins?

A

G+ and G-

34
Q

What kind of bacteria tend to have endotoxin?

A

G-

35
Q

When are endotoxins normally released?

A

Once cell is lyse, since these are found on the inside of the cell need the cell to “explode” in order for them to be exposed to the host.

36
Q

What are the general effects of exotoxins?

A

Normally enzymes so they tend to have highly specific effects on the target cells and tissue they are involved with.

37
Q

What general effects are normally caused by endotoxins?

A

Produced generalized, inflammatory related damage to the host.

Hint: think of it this way. the body isn’t exposed to these unless they are released. Therefore, immune response will be started.

38
Q

What specifically on a gram-negative bacteria are considered endotoxins?

A

Lipid A which is present on LPS

39
Q

What exactly does Lipid A cause in the body?

A

Stimulate leukocytes to release high levels of cytotoxin
Activate compliment cascade
Activate coagulation cascade

40
Q

What are the side effects seen in the host from endotoxin release?

A

Fever + Chills + Weakness + Myaldia + Hypotension + DIC + Shock

41
Q

What are the three components of LPS?

A

O-polysaccharide (O-antigen)
Core polysaccharide
Lipid A

42
Q

What are the four major categories (effects) seen in exotoxins?

A

Enzymes that degrade the ECM
Enzymes that act on plasma membrane
Enzymes that act inside host cell
Toxins that promote immune response = SUPERANTIGENS

43
Q

What are the three components that make up an exotoxins name?

A

Host cell attacked
Associated disease
What microbe is responsible for the toxin

44
Q

What is alpha-hemolysin?

A

Pore-forming toxin

45
Q

What bacteria produces alpha-hemolysin?

A

Staphylococcus aureus

46
Q

What medical importance do exotoxins have?

A

Inactivated forms can be used and turned into a toxoid that can be given as a vaccine.

47
Q

What are the three basic steps in pathogenesis?

A

Colonization + Invasion + Damage

48
Q

What are the portals of entry?

A

Mucous membrane
Skin
Direct deposition under the skin/membrane

49
Q

What is it called when there is deposition under the skin or mucous membranes?

A

Paraenteral route

50
Q

What are the two general methods that microbes can attach to host cells?

A

Non-specific + Specific

51
Q

What is an example of non-specific adherence to host cells by microbes?

A

Capsules + bioflims

52
Q

During colonization, what are three basic ways that microbes can evade the immune system?

A

Impair phagocytosis
Evade complement
Hydrolysis/break down of key immune components

53
Q

What are ways that a microbe ensure nutrients to grow within their host?

A

Co-opt host nutrients + acquire nutrients via damage to host cells/tissues

54
Q

What are siderophores?

A

Steal iron from iron-transport proteins in the host

55
Q

What is an important characteristic of biofilms?

A

Facilitate quorum sensing + Allow development of high cell densities

56
Q

What is quorum sensing?

A

Biofilm inhabitants are able to coordinate cellular activities

57
Q

What is an important enzyme for invasion of the host by the microbe?

A

Invasins

58
Q

What are three big examples of invasins used to invade the host?

A

Hyaluronidases
Collagenases
Elastases

59
Q

What do invasins do?

A

Cause local damage to host cells + ECM

60
Q

What are two methods that the microbes breach the epithelial barrier?

A

Paracellular + Transcellular

61
Q

What are ways that pathogens spread in the body, organ to organ?

A

Peritoneal + Pleural cavities

62
Q

What are the four basic ways that pathogens cause damage to the host?

A

Take up the host’s nutrition
Cause direct damage due to colonization/invasion
Toxins
Immune response due to presence of the pathogen

63
Q

What is a subclinical infection?

A

Does not cause a noticeable illness within the host. Showing that infection does not always lead to disease.

64
Q

What is an example given in lecture of subclinical infection?

A

Leptospira infections in dogs

65
Q

What is an acute disease?

A

Quick to show signs and quick to end

66
Q

What was an example of an acute disease given in the lecture?

A

Campylobacteriosis in dogs + cats

67
Q

What is a chronic disease?

A

Tends to take a long time to show signs in the host. Can lay dormant for years. Can reactivate with stress or old age.

68
Q

What was an example of chronic disease given in the lecture?

A

Tuberculosis in cattle

69
Q

What are the portals of exit?

A

Normally pathogenic effects, commonly from the same route that it enters the body
IE. coughing, sneezing, skin lesions. etc.

70
Q

What are carriers? Why is it important to know about carriers?

A

These hosts show no signs or symptoms but are contagious and can pass the disease on to others. Dangerous because you could be exposed without even knowing it.

71
Q

What is the pathogenesis of equine strangles?

A

Upper respiratory tract = nasal discharge

72
Q

How is equine strangles transmitted?

A

direct or indirect transfer within nasal discharge

73
Q

When does shedding of the bacteria responsible for equine strangles start?

A

1 to 2 days after onset of pyrexia, lasts for about 2-3 weeks

74
Q

Describe mutualism.

A

Both the host and microbe benefit.

Bacteriology (28 decks)

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