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Microbiology > 13, 14 pathogenicity of microorganisms > Flashcards

13, 14 pathogenicity of microorganisms Flashcards

1
Q

What is a parasite?

A
  1. organism that lives on/in host and is metabolically dependent
  2. can cause disease
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2
Q

What is infection?

A
  1. when parasite grows and multiplies on/in a host

2. potential to cause overt infectious disease

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3
Q

What is a primary (frank) pathogen?

A
  1. causes disease by direct interaction with a healthy host
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4
Q

What is an opportunistic pathogen?

A
  1. organism that can exist as normal flora but enter a new tissue site and immunocompromise the host
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5
Q

What is pathogenicity?

A
  1. the ability to cause disease
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6
Q

What are the chain of events for successful infection?

A
  1. proper identity of agent
  2. proper virulence of agent
  3. exposure to the agent
  4. dose of the agent
  5. host susceptible to the agent
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7
Q

What is zoonoses?

A
  1. passing infection from an animal to a humna
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8
Q

What is a reservoir?

A
  1. natural environment of where a pathogen resides
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9
Q

What is a vector?

A
  1. an organism that spreads disease from one host to another
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10
Q

What can cause an infectious disease?

A
  1. virus, bacteria, fungi, protozoa, helminths
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11
Q

What are signs of infection?

A
  1. observable changes in the body
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12
Q

What are symptoms?

A
  1. subjective changes that have no true value of being measured
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13
Q

What is a disease syndrome?

A
  1. a set of characteristics that describe a disease based on signs and symptoms
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14
Q

What is the course of infectious disease?

A
  1. incubation period
  2. prodronal stage
  3. period of illness
  4. convalscence
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15
Q

What is the incubation period?

A
  1. time after pathogen enters, but before sign/symptoms present
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16
Q

What is the prodronal stage?

A
  1. the time of sign/symptom onset

2. no clear diagnosis

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17
Q

What consists of the period of illness?

A
  1. time when disease is worst

2. sign, symptom are clearly present

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18
Q

What is the convalescence stage?

A
  1. time when sign, symptoms begin to disappear
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19
Q

What is required in order for a pathogen to cause disease?

A
  1. suitable environment
  2. source of nutrients
  3. virulence factors to protect against harmful elements.
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20
Q

What is virulence?

A
  1. the ability of a pathogen to cause infection

- - directly related to survival time outside a host

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21
Q

What is a pathogenicity island?

A
  1. contains major virulence factors on large segments of chromosomal or plasmid DNA
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22
Q

What is the effect of a pathogenicity island?

A
  1. increases bacterial virulence
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23
Q

What contributes to the virulence factors of a pathogen?

A
  1. depends on the adherence, colonization, and invasion of the pathogen
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24
Q

What is a parenteral route, that can lead to disease?

A
  1. entrance from a break in any barrier defenses

- IV site, nail through skin…

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25
Q

What occurs after the pathogen has gained entrance into a host, and begins colonization?

A
  1. colonization consists of microbial reproduction, not always causing tissue damage or invasion
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26
Q

What are two most commonly seen structures used for adherence?

A
  1. pili
  2. fimbriae
    - bind to complementary receptors on host cell surface
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27
Q

What type of adherence mechanism do E. coli use?

A
  1. type I fimbriae to bind on sugar residue in instestine
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28
Q

What type of adherence mechanism do streptococcus pyogenes use?

A
  1. Protein F on the upper respiratory tract
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29
Q

What type of adherence mechanism do streptococcus mutans use?

A
  1. sugar residue to bind salivary glycoproteins on teeth
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30
Q

Infectivity?

A

ability to create a discrete point of infection

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31
Q

Invasiveness?

A

ability to spread to adjacent tissues

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32
Q

What forms of penetration exist?

A
  1. active

2. passive

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33
Q

When is active penetration most commonly used?

A
  1. passing through lytic substances
34
Q

How will active penetration work to pass through the lytic substances?

A
  1. attack extracellular matrix, and basement membrane of integument and intestinal linings
  2. degrade carb-protein complexes
  3. disrupt host cell surfaces
35
Q

How will passive penetration occur?

A
  1. skin lesion
  2. insect bites
  3. wounds
36
Q

Is passive penetration superficial, or does it include deep tissue also?

A
  1. superficial

2. deep tissue is affected in proper proteins/enzymes are formed from the organism

37
Q

Toxigenicity?

A

ability of microbe to produce toxins

38
Q

Toxin?

A

substance that damages host

39
Q

Intoxication?

A

disease that result from entry of a toxin into a host.

- toxin must be preformed. (Tetanus)

40
Q

Toxemia?

A

condition of toxins located in the blood of host

41
Q

What is an endotoxin?

A

soluble, heat-labile, protein

42
Q

Where do endotoxins come from and where do they go?

A
  1. from gram negative normally

2. go to surroundings while pathogen grows

43
Q

What does the presence of endotoxins produce?

A
  1. stimulate antitoxins production
44
Q

What is a chemically inactivated exotoxin?

A

immunogenic toxoid

45
Q

Will exotoxins produce a fever?

46
Q

What is a normal lethal dose 50 of exotoxins?

A

very small

47
Q

What are the different classes of exotoxins?

A
  1. AB
  2. specific host site
  3. membrane-disrupting
  4. superantigens
48
Q

Which exotoxin subunit is responsible for binding to the target cell?

49
Q

Which exotoxin subunit is responsible for generating the toxic effects?

50
Q

Why has the endotoxin received the name that it has?

A

portion of the bacterium is released during lysis

51
Q

What is the disease causing portion of endotoxins?

A

lipid A which is common in lipopolysaccharrides from gram negative bacterium

52
Q

How is an endotoxin different than exotoxin?

A
  1. heat stable
  2. weakly immunogenic
  3. toxic in small amounts
  4. from gram negative
53
Q

What are the effects of certain amount of endotoxin release?

A
  1. fever
  2. weakness
  3. inflammation
  4. intestinal hemorrhage
  5. fibrinolysis
54
Q

What is fibrinolysis?

A
  1. enzymatic breakdown of fibrin

- prevents formation of blood clots

55
Q

Since endotoxins are weakly immunogenic and exotoxins are highly immunogenic, what does this mean in terms of LD50?

A
  1. endotoxins have large LD50

2. Exotoxins have low LD50

56
Q

How is a biofilm able to produce chronic infections?

A
  1. have increased virulence of bacterium
  2. decrease sensitivity to antibiotics
  3. increase the bacterium’s resistant to host defenses
57
Q

What are common methods to resist host defenses?

A
  1. produce decoy proteins, neutralizing Ab

2. lengthen O-chain to prevent detection

58
Q

Coagulase?

A

coagulate fibrinogen

59
Q

Kinases?

A

digest fibrin clot

60
Q

Hyaluronidase?

A

hydrolyzes hyaluronic acid

61
Q

Collagenase?

A

hydrolyze collagen

62
Q

IgA proteases?

A

destroy IgA antibodies

63
Q

Which type of pathogen transmission has low virulence?

A

direct contact

64
Q

Which type of pathogen transmission has high virulence?

A

vector-borne being benign in the vector

65
Q

Tropism?

A

pathogen must transmit the factor to the proper tissue site for infection to occur

66
Q

What are indirect methods of pathogen transmission?

A
  1. contact via fomites
  2. food, biological products
  3. airborne
67
Q

What are direct methods of contact transmission?

A
  1. horizontal (kissing, sex)
  2. airborne droplets
  3. vertical contact (mother to fetus)
  4. vector borne
68
Q

What is an airborne particle and how is it best transferred?

A
  1. small particle generally from respiratory tract
  2. travels long distances
  3. therefore has long airborne time, and high virulence
69
Q

Direct contact transmission

A
  1. physical interaction between host and source

2. kissing, physical contact

70
Q

Indirect contact transmission

A
  1. involves and inanimate intermediate to transfer
71
Q

Droplet spread transmission

A
  1. occurs with large particle that are unable to travel more than 1 meter
72
Q

How does external vector-borne transmission occurring?

A
  1. passive carriage of pathogen on body of vector

2. no pathogen growth during transmission

73
Q

What is harborage internal transmission?

A
  1. transfer of a pathogen inside a vector

2. no changes to the pathogen occur while in the vector

74
Q

What is biologic internal transmission?

A
  1. transfer of pathogen inside a vector

2. changes to the pathogen occur while in the vector

75
Q

What are a few examples of vertical transmission?

A
  1. gonorrhea
  2. herpes
  3. german measles
  4. toxoplasmosis
    - commonly transferred from mother to fetus
76
Q

Cytopathology

A
  1. study of cellular changes

2. used to observes cells in tissue cultures and observe death rates, rather than in an entire organism

77
Q

Where will extracellular pathogens most likely grow?

A
  1. outside cells in the blood/tissue fluids
78
Q

Where are intracellular pathogens most likely to be found?

A
  1. facultative intracellular grow inside or outside a cell

2. obligate intracellular grow only insides cells

79
Q

What two main factors contribute to host susceptibility?

A
  1. pathogenicity of pathogen
  2. host’s immune response
    - nutrition, genetic disposition, stress have roles in susceptibility
80
Q

What are common portals of exit in the body?

A
  1. respiratory tract
  2. GI tract
  3. genitourinary tract
  4. skin
  5. blood

Microbiology (14 decks)

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