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BIO 202 > Epidemiology and Pathogenesis > Flashcards

Epidemiology and Pathogenesis Flashcards

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1
Q

In addition to IDing the microbe, what else must be done to conclude that a microbe causes a particular disease?

A

ID the strain’s virulence factors and genes for virulence

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2
Q

What does the term Incidence mean in epidemiology?

A

new cases

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3
Q

What does the term prevalence mean in epidemiology?

A

total cases

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4
Q

How is endemic disease characterized?

A

By regional location and periodic outbreaks

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5
Q

How are epidemic and pandemic diseases characterized?

A

By…
-widespread occurrence (scale is definitive)
-rapid outbreak

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6
Q

What is a reservoir?

A

Where the disease is when it is not happening (active)

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7
Q

What are disease reservoirs considered?

A

Sources of ongoing infection/”where pathogens come from”

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8
Q

What are human reservoirs?

A

ill persons/carriers

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9
Q

What are nonliving reservoirs?

A

soil, waters air

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10
Q

What are animals and vectors-living character of disease that is not human?

A

ticks, mosquitos, etc

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11
Q

What is direct contact transmission?

A

by physical contact with infected person/animal (can be vertical or horizontal)

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12
Q

What is indirect contact transmission?

A

by contact with a contaminated material (fomite)

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13
Q

What is droplet contact transmission?

A

contaminated droplets contact membranes (short range)

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14
Q

What is vehicle transmission?

A

by exposure to contaminated water/air/food (may involve fecal-oral mode and long-distance)

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15
Q

What is vector transmission?

A

by saliva/feces from an insect/arthropod/animal

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16
Q

What is a nosocomial infection?

A

An infection that occurs in a healthcare setting when the first stage of immune defenses is bypassed (barrier defenses)

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17
Q

What is pathogenicity?

A

the ability to cause disease

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18
Q

What is virulence?

A

the degree of ability to cause disease

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19
Q

True or False:
Virulence factors are not essential for causing disease

A

False, they are essential for causing disease

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20
Q

Can virulence be quantified?

A

Yes, depends on the # of microbes (“load”) ID50 and LD50

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21
Q

What is ID50?

A

How many organisms it takes to infect half the population

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22
Q

What is LD50?

A

The lethal dose- how many organisms it takes to kill half the population

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23
Q

True or False:
The lower the number of ID50, the more virulent it is.

A

True

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24
Q

What are cons of virulence factors?

A

-enables microbe to establish itself in host
-enhances microbes ability to cause disease

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25
Q

What are pros of virulence factors?

A

-they are often antigenic
-may be used serologically
-may be inactivated by the immune system

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26
Q

What are primary pathogens?

A

-they cause disease upon infection
-NOT typically associated with host
(ex: influenza)

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27
Q

What are opportunistic pathogens?

A

-they cause disease under some circumstances
-often members of normal flora
(ex: e.coli)

28
Q

What are the important cocci gram-positive flora organisms?

A

-Staph aureus
-Staph epidermis
-Strep pyogenes
-Viridians Strep

29
Q

What is the important spore forming bacilli gram positive flora organism?

A

Clostridium

30
Q

What is the important cocci gram negative flora organism?

A

Neisseria meningitidis

31
Q

What are the important bacilli gram negative flora organisms?

A

E. coli, Bacteroides, Pseudomonas, lactobacilli

32
Q

What is the important acid-fast flora organism?

A

mycobacterium

33
Q

What is the important fungi flora organism?

A

Candida albicans

34
Q

True or False:
Flora organisms defend you, but some of them could be opportunistic pathogens

A

True

35
Q

True or False:
Disease from opportunistic infections is common in immunocompetent persons

A

False- it is uncommon in immunocompetent persons

36
Q

How can opportunistic infection be promoted?

A

-Immunodeficiency or Immunosuppression
-Flora microbes being “out of place”
-Disturbance of “normal flora balance”

37
Q

Internal tissues, organs, and body fluids should be what?

A

Free of ALL microbes (sterile)

38
Q

What are the transmissions to a Portal of Entry?

A

-Respiratory Tract (RT) membranes
-Gastrointestinal tract (GIT) membranes
-Genitalurinary tract (GUT) membranes
-Skin (Paraenteral)
Both vertical and Horizontal transmission are appropriate

39
Q

What is the first step to colonization?

A

Attachment by…
-Pili
-Virus spikes
-Capsules
-Teichoic acids
-Surface proteins

40
Q

What does attachment do in colonization?

A

The specificity determines the host range

41
Q

What does neutralization do?

A

Neutralizing antibodies can stop attachment

42
Q

What is colonization?

A

-Multiplication and Maintenance
-Primary pathogens are “not in place”

43
Q

What are barriers to colonization?

A

-Competition with the normal flora (will defend you to some extent- has squatter rights to some parts of your body)
-Barriers’ defenses:
-bile, stomach acid, skin secretion, competition for iron, etc

44
Q

After initial colonization, how do you avoid phagocytosis?

A

by capsules

45
Q

After initial colonization, how do you avoid antibodies?

A

-antigenic variation
-acquiring an intracellular lifestyle

46
Q

What do enzymes that degrade tissue, antibodies, etc do?

A

Promote further invasion into tissues
NOT TOXINS

47
Q

How is reduced phagocytosis reached?

A

Capsule production on surface of bacteria reduces “exposure” to complement proteins

48
Q

What can antigenic variation be due to?

A

-many antigen variants in a population
-change of surface antigens over time

49
Q

What are the outcomes of antigenic variation?

A

-Immune system evasion
-Possible re-infection (ex: flu, covid)

50
Q

What is the result of avoiding antibodies?

A

reduced exposure to the humoral immune response

51
Q

True or False:
In avoiding antibodies, some intracellular microbes survive within phagocytes, other cells.

A

True

52
Q

What are exotoxins?

A

-external
-secreted proteins
-mostly gram positive
-VERY potent
-Cytotoxic and tissue specific
-Soluble
-Strongly antigenic
-protective antibodies = neutralization

53
Q

What does heat labile mean?

A

can make toxoids

54
Q

True or False:
Exotoxins are not heat labile

A

False, exotoxins are heat labile

55
Q

What are two problems presented with exotoxins?

A

You have an infection occurring, and you have exotoxin affects occurring that have to be treated simultaneously

56
Q

Where are the exotoxin genes encoded?

A

plasmid or phage-encoded

57
Q

What is a super-antigen?

A

an exotoxin that…
-bind to MHC 11 proteins and presented without antigen processing
-leads to polyclonal T cell stimulation
-excess inflammatory cytokines

58
Q

What do excess inflammatory cytokines look like?

A

Low BP -> shock -> multi-organ failure (Toxic Shock Syndrome)

59
Q

True or False:
The immune system must be highly regulated

A

True

60
Q

What do T-helper cells do?

A

express cytokines that are pro-inflammatory

61
Q

What are endotoxins?

A

-LPS
-Gram negative
-not a protein and not secreted
-highly antigenic
-LPS is heat-stable

62
Q

What are the two problematic components of LPS?

A

-Lipid A: toxic in bloodstream/membrane
-O antigen (polysaccharide) is antigenic

63
Q

What does Lipid A do?

A

-prompts macrophages (immune cell stimulation) to express pro-inflammatory cytokines
-induces fever and shock
-Widespread coagulation

64
Q

True or false:
Endotoxin genes are bacterial

A

False, endotoxin genes are chromosomal

65
Q

True or False:
Endotoxins can’t be denatured

A

True

66
Q

Infection may lead to….

A

shock

67
Q

How can infection lead to shock?

A

Decreased perfusion of blood -> decreased tissue oxygen -> multiple organ failure

BIO 202 (7 decks)

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