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Completed > Ch 13 Microbe-Human Interactions > Flashcards

Ch 13 Microbe-Human Interactions Flashcards

0
Q

Commensalism

A

An interaction between two species in which one benefits and the other is neutral (not harmed not benefited)
Ex: normal flora

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1
Q

Mutualism

A

An interaction between two species in which both benefit. Ex: normal flora

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2
Q

Parasitism

A

An interaction between two species in which one benefits at the expense or harm to the other

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3
Q

Name the four stages of disease

A

Contact, colonization, infection, disease

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4
Q

Define contact

A

When exposed to the microbe. can be direct or indirect

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5
Q

Does every exposure lead to colonization

A

No

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6
Q

Explain colonization

A

Bacteria is implanted in or on the host as colonies; start to increase growth

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7
Q

Explain infection

A

The pathogenic bacteria penetrate host defenses, enter the tissues, and multiply; rapid increase in growth

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8
Q

Explain disease

A

The disruption of a tissue or organ caused by microbes or their products; growth leads to harm. Ongoing process with a deterioration in health, possible death

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9
Q

Another term for normal flora

A

Resident biota

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10
Q

Describe skin flora

A

Skin is dry salty; in general gram + bacteria; typically large cocci, xerophile, halophile; ex: strep & staph

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11
Q

Describe the oral flora

A

Over 30 different species; mixture of aerobic, facultative and obligate anaerobic. Ex: lysozyme in saliva

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12
Q

Describe Gastrointestinal flora numbers

A

Stomach has very few species due to high acidity; small intestine has a large number due to pH 7; colon Has an even larger number

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13
Q

Examples of G.I. Flora and oxygen requirements

A

E. coli, salmonella; Colon has 300:1 anaerobes:facultatives

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14
Q

Examples of typical upper respiratory flora

A

Strep and staph

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15
Q

Is the lower respiratory tract sterile or unsterile

A

Sterile

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16
Q

Microbial antagonism

A

The antagonistic effect that good microbes have against intruder microbes

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17
Q

Endogenous infection

A

Caused by normal flora that are already present in the body that are introduced to a site that should be sterile or is not where it should be. Ex: UTI caused by E. coli

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18
Q

Another term for endogenous infection

A

Opportunistic

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19
Q

Define pathogen

A

A microbe whose relationship with the host is parasitic

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20
Q

Pathogenicity

A

The microbes potential to cause infection and disease

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21
Q

Virulence

A

The degree of pathogenicity

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22
Q

Three ways to measure virulence

A

Infectivity, invasiveness, toxigenicity

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23
Q

What is infectivity

A

The ability to establish itself in the host

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24
Q

What is invasiveness

A

The ability to spread in the host

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25
Q

What is toxigenicity

A

The ability to cause damage

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26
Q

What is the number one line of defense for a person against microbes

A

Normal flora

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27
Q

A true pathogen can cause disease _____

A

in a healthy person with a normal immune system

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28
Q

An opportunistic pathogen can cause disease ____

A

only when the host defenses are compromised or if they become established in a part of the body that is not natural to them

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29
Q

How are pathogens classified

A

By using biosafety levels. Levels are 1, 2, 3 and 4 (with 4 being the worst)

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30
Q

What is the first step in The stages of disease progression

A

getting in, starts with the portal of entry: The microbe enters the tissues through the characteristic route

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31
Q

Name the 4 types of portals of entry

A

Skin, G.I. tract, respiratory tract, urogenital tract

32
Q

What is an infectious dose

A

Minimum number of microbes to cause an infection. Numbers below that will generally not cause an infection

33
Q

What is step 2 of the four stages of disease progression

A

attaching to the host; adherence

34
Q

Name 4 things that help microbes with adhesion

A

Fimbriae, slime layer, capsule, viral spikes

35
Q

Define adhesion

A

Process by which microbes game a more stable foothold on host tissues

36
Q

What is the 3rd step in the stages of disease progression

A

surviving host defenses (the host, not normal flora!!)

37
Q

Name 4 factors that help bacteria resist phagocytosis

A

Leukocidins, capsules, coagulase, hiding in the host (intracellular parasite)

38
Q

What are leukocidins

A

Substances released by bacteria that are toxic to white blood cells

39
Q

Pyogenic

A

Pus forming bacteria, strep and staph are famous for this

40
Q

Explain how capsules are anti-phagocytic factors

A

Help bacteria to stick better and is similar enough to self cell that the phagocytes ignore it

41
Q

Explain how coagulase is an anti-phagocytic factor and give one example of a bacteria that has it

A

Causes human molecules to clot and cover it up. Ex: staph aureus

42
Q

Explain how an intracellular parasite resists phagocytosis and give 2 examples of bacteria that do this

A

parasite is phagocytized then the bacteria stays hidden in white blood cells not being killed, “hiding”
Ex: TB and malaria

43
Q

Name five digestive enzymes produced by microbes

A

Mucinase, keratinase, collagenase, hyaluronidase, and fibrinolysin (aka: kinase)

44
Q

What does hyaluronidase do

A

Digests the hyaluronic acid (ground substance) between your cells; digests the glue between your cells

45
Q

Name five bacterial toxins

A

Neurotoxin, enterotoxin, hemotoxin, nephrotoxin, respiratory toxin

46
Q

Which hemotoxin causes beta hemolysis

A

Alpha toxin

47
Q

What is more damaging digestive enzymes or bacterial toxins

A

Bacterial toxins

48
Q

Endotoxin

A

Gram - bacteria; in certain genera the lipopolysaccharide (LPS) is the endotoxin

49
Q

How do endotoxins affect a cell

A

They are not secreted only released when a cell dies and sheds its outer membrane

50
Q

Describe symptoms of endotoxins

A

Cause fever, pyrogenic, inflammation, hemorrhage, diarrhea. Could lead to endotoxic shock (aka toxic shock) symptoms tend to be more systemic

51
Q

Name 4 genera of endotoxin formers and describe their shape

A

Salmonella, Shigella, Escherichia are all gram - rods

Neisseria is gram - cocci

52
Q

Endotoxins are typically toxic at what type of concentration (hi or low)

A

Typically only at high concentrations

200-400 mg/ml

53
Q

What effect does he have on endotoxins

A

No matter how long you “cook” it these are stable at high temperatures

54
Q

How do exotoxins affect a cell

A

Are secreted by the bacteria cell, have very specific actions. Tend to travel well

55
Q

Exotoxins are typically toxic at what type of concentration (hi or low)

A

Toxic at low concentrations (micrograms per milliliter)

56
Q

Name two types of neurotoxic exotoxins

A

Clostridium tetani and clostridium botulinum

57
Q

What does Clostridium tetani cause

A

Acts at neuromuscular junction causing spastic paralysis

58
Q

What does Clostridium botulinum cause

A

Act at neuromuscular junction causing flaccid paralysis

59
Q

How does bordetella pertussus work

A

Inactivates respiratory cilia

60
Q

What does vibrio cholera do

A

Causes extreme salt and water loss from intestinal cells

61
Q

Describe a focal infection

A

Infectious agent breaks loose from local infection and is carried into other tissues. Ex: scarlet fever from strep throat

62
Q

Example of a localized infection

A

Wart, pimple

63
Q

Example of a systemic infection

A

Chickenpox

64
Q

Another phrase for mixed infection

A

Polymicrobial

65
Q

Name the four stages of clinical infection

A

Incubation period, prodromal period, Invasive period, Convalescent period

66
Q

The height of an infection occurs during which stage of infection

A

Invasive period

67
Q

Septicemia

A

Microbes are multiplying in the blood and are present in large numbers

68
Q

Bacteremia

A

Small numbers of bacteria are found in the blood but are not multiplying

69
Q

Passive carrier

A

Does not become infected but can transmit to others. Ex: typhoid Mary

70
Q

Asymptomatic vs symptomatic carrier

A

Infected but shows no symptoms

Infected and shows symptoms

71
Q

Biological vs mechanical vectors

A

B: necessary for parasite to survive ex: mosquitos to malaria
M: aren’t infected, just carries it on the outside of its body from place to place.

72
Q

Zoonosis

A

Resides in animals and can cross species. Ex: rabies, HIV

73
Q

4 types of direct transmission

A

Contact, droplet, vertical, biological vector

74
Q

3 types of indirect transmission

A

By vehicle, fomite, or fecal-oral route

75
Q

Endemic

A

Cases are concentrated in one area at a relatively stable rate

76
Q

Epidemic

A

Increased number of cases that often appear in geographical clusters; rapid increase

77
Q

Pandemic

A

Epidemic ranges over more than one continent

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