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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
What occurs after the pathogen has gained entrance into a host, and begins colonization?
1. colonization consists of microbial reproduction, not always causing tissue damage or invasion
26
What are two most commonly seen structures used for adherence?
1. pili 2. fimbriae - bind to complementary receptors on host cell surface
27
What type of adherence mechanism do E. coli use?
1. type I fimbriae to bind on sugar residue in instestine
28
What type of adherence mechanism do streptococcus pyogenes use?
1. Protein F on the upper respiratory tract
29
What type of adherence mechanism do streptococcus mutans use?
1. sugar residue to bind salivary glycoproteins on teeth
30
Infectivity?
ability to create a discrete point of infection
31
Invasiveness?
ability to spread to adjacent tissues
32
What forms of penetration exist?
1. active | 2. passive
33
When is active penetration most commonly used?
1. passing through lytic substances
34
How will active penetration work to pass through the lytic substances?
1. attack extracellular matrix, and basement membrane of integument and intestinal linings 2. degrade carb-protein complexes 3. disrupt host cell surfaces
35
How will passive penetration occur?
1. skin lesion 2. insect bites 3. wounds
36
Is passive penetration superficial, or does it include deep tissue also?
1. superficial | 2. deep tissue is affected in proper proteins/enzymes are formed from the organism
37
Toxigenicity?
ability of microbe to produce toxins
38
Toxin?
substance that damages host
39
Intoxication?
disease that result from entry of a toxin into a host. | - toxin must be preformed. (Tetanus)
40
Toxemia?
condition of toxins located in the blood of host
41
What is an endotoxin?
soluble, heat-labile, protein
42
Where do endotoxins come from and where do they go?
1. from gram negative normally | 2. go to surroundings while pathogen grows
43
What does the presence of endotoxins produce?
1. stimulate antitoxins production
44
What is a chemically inactivated exotoxin?
immunogenic toxoid
45
Will exotoxins produce a fever?
no
46
What is a normal lethal dose 50 of exotoxins?
very small
47
What are the different classes of exotoxins?
1. AB 2. specific host site 3. membrane-disrupting 4. superantigens
48
Which exotoxin subunit is responsible for binding to the target cell?
B subunit
49
Which exotoxin subunit is responsible for generating the toxic effects?
A subunit
50
Why has the endotoxin received the name that it has?
portion of the bacterium is released during lysis
51
What is the disease causing portion of endotoxins?
lipid A which is common in lipopolysaccharrides from gram negative bacterium
52
How is an endotoxin different than exotoxin?
1. heat stable 2. weakly immunogenic 3. toxic in small amounts 4. from gram negative
53
What are the effects of certain amount of endotoxin release?
1. fever 2. weakness 3. inflammation 4. intestinal hemorrhage 5. fibrinolysis
54
What is fibrinolysis?
1. enzymatic breakdown of fibrin | - prevents formation of blood clots
55
Since endotoxins are weakly immunogenic and exotoxins are highly immunogenic, what does this mean in terms of LD50?
1. endotoxins have large LD50 | 2. Exotoxins have low LD50
56
How is a biofilm able to produce chronic infections?
1. have increased virulence of bacterium 2. decrease sensitivity to antibiotics 3. increase the bacterium's resistant to host defenses
57
What are common methods to resist host defenses?
1. produce decoy proteins, neutralizing Ab | 2. lengthen O-chain to prevent detection
58
Coagulase?
coagulate fibrinogen
59
Kinases?
digest fibrin clot
60
Hyaluronidase?
hydrolyzes hyaluronic acid
61
Collagenase?
hydrolyze collagen
62
IgA proteases?
destroy IgA antibodies
63
Which type of pathogen transmission has low virulence?
direct contact
64
Which type of pathogen transmission has high virulence?
vector-borne being benign in the vector
65
Tropism?
pathogen must transmit the factor to the proper tissue site for infection to occur
66
What are indirect methods of pathogen transmission?
1. contact via fomites 2. food, biological products 3. airborne
67
What are direct methods of contact transmission?
1. horizontal (kissing, sex) 2. airborne droplets 3. vertical contact (mother to fetus) 4. vector borne
68
What is an airborne particle and how is it best transferred?
1. small particle generally from respiratory tract 2. travels long distances 3. therefore has long airborne time, and high virulence
69
Direct contact transmission
1. physical interaction between host and source | 2. kissing, physical contact
70
Indirect contact transmission
1. involves and inanimate intermediate to transfer
71
Droplet spread transmission
1. occurs with large particle that are unable to travel more than 1 meter
72
How does external vector-borne transmission occurring?
1. passive carriage of pathogen on body of vector | 2. no pathogen growth during transmission
73
What is harborage internal transmission?
1. transfer of a pathogen inside a vector | 2. no changes to the pathogen occur while in the vector
74
What is biologic internal transmission?
1. transfer of pathogen inside a vector | 2. changes to the pathogen occur while in the vector
75
What are a few examples of vertical transmission?
1. gonorrhea 2. herpes 3. german measles 4. toxoplasmosis - commonly transferred from mother to fetus
76
Cytopathology
1. study of cellular changes | 2. used to observes cells in tissue cultures and observe death rates, rather than in an entire organism
77
Where will extracellular pathogens most likely grow?
1. outside cells in the blood/tissue fluids
78
Where are intracellular pathogens most likely to be found?
1. facultative intracellular grow inside or outside a cell | 2. obligate intracellular grow only insides cells
79
What two main factors contribute to host susceptibility?
1. pathogenicity of pathogen 2. host's immune response - nutrition, genetic disposition, stress have roles in susceptibility
80
What are common portals of exit in the body?
1. respiratory tract 2. GI tract 3. genitourinary tract 4. skin 5. blood

Microbiology (14 decks)

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