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MICR 262 > (LE3) Pathogenesis > Flashcards

(LE3) Pathogenesis Flashcards

1
Q

What is a pathogen?

A

disease-causing organism

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2
Q

What is an infection?

A

Invasion by pathogens
- pathogen uses host as source of carbon energy

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3
Q

What is an infectious disease?

A

pathogen growth or toxin production is responsible for disruption of homeostasis

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4
Q

What is commensal symbiosis?

A

neither organism is harmed or benefited by the relationship

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5
Q

What type of symbiosis describes our normal flora? Define it.

A

Mutual symbiosis: both organisms benefit from the relationship

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6
Q

What type of relationship describes pathogens? Define it.

A

Parasitic relation: one organism benefits at the other’s expense
- keeps host alive for benefits

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7
Q

How do commensal organisms (i.e. our normal flora) protect the host from pathogens? What are the two most common clinical pathogens our normal flora protects us from?

A

Compete with transient or opportunistic microbes for limited resources
- C. diff & MRSA

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8
Q

What are opportunistic infections?

A

infections caused by pathogens that take advantage of an opportunity not normally available

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9
Q

What are some causes for opportunistic infections?

A
  1. immunocompromised host
  2. Wounds/trauma introduce microbe to a new location
  3. Alteration of normal flora population
  4. Organ transplants
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10
Q

What are Koch’s postulates?

A
  1. Isolate & identify suspected pathogen in all cases of disease
  2. Grow pathogen in pure culture
  3. Upon exposure, the susceptible test animal suffers the same disease
  4. Re-isolate the same pathogen from the sick/dead test animal
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11
Q

What two pathogens are exemptions to Koch’s postulate, and which exact postulate?

A

Exemption to second postulate: grow pathogen in pure culture
- Mycobacterium leprae
- viruses

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12
Q

What is a communicable disease? Provide examples

A

Disease that can spread from one host to another
ex/ HIV, TB

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13
Q

What is a contagious disease? Provide examples

A

Communicable, but spreads quickly and easily
ex/ common cold, flu and COVID-19

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14
Q

What is a noncommunicable disease? Provide examples

A

Disease that does not spread from host to host
ex/ Tetanus, Botulism

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15
Q

What is a disease reservoir and what are the different types?

A

Continuous source of the pathogen
1. Humans with an active infection
2. Animals
3. Non-living reservoir

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16
Q

What pathogens utilize humans as a disease reservoir? What are carriers?

A

COVID, flu, cold, smallpox

Carriers harbor pathogens and can transmit, but they have no symptoms (asymptomatic)
ex/ Typhoid, walking pneumonia, covid

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17
Q

What is zoonosis? Provide examples

A

Diseases that can be transmitted from animals to humans

ex/ Rabies, Lyme disease

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18
Q

What are non-living reservoirs? Provide examples

A

some aspect of the environment (ex/ water or soil)
ex/ Tetanus, Giardiasis

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19
Q

What is a portal of entry?

A

The way by which a pathogen enters the host to cause an infection

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20
Q

What are the different portals of entry?

A
  • Mucus membranes
  • urethra, vagina, anus (STDs)
  • placenta or breast milk
  • parenteral: via a wound or trauma, broken skin, injection site, etc.
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21
Q

What is a portal of exit?

A

the way by which the pathogen leaves the host to infect a new host
- may be the same or different than portal of entry

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22
Q

What is the portal of entry and exit for the common cold?

A

entry and exit are both respiratory tract

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23
Q

What is the portal of entry and exit for Cholera?

A

Fecal-oral transmission
entry: mouth
exit: fecal matter

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24
Q

What are the different modes of disease transmission?

A

Contact transmission
Vehicle Transmission
Vector Transmission

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25
Q

What is direct contact transmission?

A

Form of contact transmission
Bite from an infected animal, sex, touch, etc.

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26
Q

What is indirect contact?

A

Contact transmission

occurs via fomites (nonliving objects that can harbor pathogens and transmit)

ex/ toe fungus

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27
Q

What are droplets?

A

Contact transmission (requires close contact)

Saliva from cough, sneeze, or talking

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28
Q

What are the different types of vehicle transmission?

A

Waterborne: drinking or interacting with water (Cholera)
Airborne: droplets stay in the air. Doesn’t require proximity like droplets. (measles)
Foodborne: pathogen in food (Typhoid, Botulism)

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29
Q

What are the different types of vector transmission?

A

Mechanical vector: pathogen carried on the body of an animal that is not infected. Ex/ fly “feet” (E. coli)
Biological vector: spread by the bite of an insect (usually) that is not infected

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30
Q

What is the mode(s) of transmission for Lyme disease?

A

Biological vector transmission

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31
Q

What is the mode(s) of transmission for Gonorrhea?

A

direct contact

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32
Q

What is the mode(s) of transmission for Cholera?

A

Waterborne

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33
Q

What is the mode(s) of transmission for Athlete’s foot (fungus)?

A

indirect fomite transmission

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34
Q

What is the mode(s) of transmission for influenza?

A

Droplet, contact, or indirect transmission

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35
Q

What is the mode(s) of transmission for Hantavirus?

A

Airborne

36
Q

Describe the flow progression of the disease process

A
37
Q

What is ID50?

A

infectious dose that will cause infection in 50%of susceptible test animals. (doesn’t need to cause illness)

38
Q

What concept of the disease process is pictured? Describe it

A

Tissue/cell adherence
Ligand on microbe binds receptor on target cell
- specific receptor targets leads to host specificity

39
Q

What are Ligands mostly composed of?

A

Mostly glycoproteins
- adhesins
- fimbriae
- capsules

40
Q

What is virulence?

A

Severity of a disease

41
Q

What is virulence factor?

A

A characteristic of a pathogen that allows it to be virulent

42
Q

What are two types of virulence factor methods employed by pathogens?

A
  • tissue penetration to help colonize new areas
  • evasion/destruction of host’s immune response
43
Q

What does Hyaluronidase do?

A

Digests basement membranes

44
Q

What does collagenase do?

A

breaks down connective tissues

45
Q

What do Streptokinase and Staphylokinase do?

A

Frees pathogen from blood clots

46
Q

What does Coagulase do?

A

Specific to S. aureus
- stimulates clot formulation to hide pathogen from immune system

47
Q

What cytotoxin does Stapylococcus secrete to kill RBCs?

A

Hemolysins

48
Q

What cytotoxin produced by Staphylococcus destroys WBCs?

A

Leukocidins

49
Q

What is M Protein?

A

Specific to Streptococcus - super-antigen
- resists phagocytosis, adheres to epithelial tissues, microcolony formation, and invasion of epithelial cells, etc.

50
Q

What is LD50?

A

the dose of pathogen /toxin required to kill 50% of susceptible test animals
- measure of virulence

51
Q

What is often the cause of cell damage to host?

A

toxins produced by bacteria
- exotoxins
- endotoxins

52
Q

What are exotoxins?

A

Mostly in G+ (can be in AF or G-)
Secreted by cell
- specific targets
- cause specific symptoms, e.g. Botulism toxin (flaccid paralysis)

53
Q

What are endotoxins?

A

Part of the G- cell wall
- LPS: no target
- all have same general symptoms, e.g. fever, malaise

54
Q

What is the chemical make-up of an endotoxin vs exotoxin?

A

Endotoxin: Lipid portion of LPS

Exotoxin: protein

55
Q

Heat stability of an endotoxin vs exotoxin?

A

Endotoxin: heat stabile

Exotoxin: Heat labile

56
Q

Relative toxicity of an endotoxin vs exotoxin?

A

Endotoxin: Low (high LD50)

Exotoxin: High (low LD50)

57
Q

Immune response of an endotoxin vs exotoxin?

A

Endotoxin: weak
- no memory, no vaccines

Exotoxin: strong
- can develop immunity

58
Q

What are some examples of an endotoxin vs exotoxin?

A

Endotoxin: Most UTIs, Salmonella

Exotoxin: Tetanus and botulism - neurotoxin

59
Q

How is cell damage by viruses different from cell damage by bacteria?

A

Bacteria have toxins that cause damage

Viruses directly kill cell by taking over and reproducing inside cells (cytopathic effects)

60
Q

What is occurring in the image?

A

Fibroblasts that usually make fiber protein (collagen) become infected with viruses and stop producing collagen to produce virus cells instead

61
Q

How do fungi cause cell damage?

A

Digests cells/tissues
- exoenzymes (digestive enzymes)
- toxins

62
Q

How do protozoans cause cell damage?

A
  • invade cells and destroy them for reproduction, like viruses (malaria)

or

  • ingest tissues/cells (amoebas)
63
Q

How do worms cause cell damage?

A

release toxic wastes, eat our food, etc.

64
Q

What is hypersensitivity in terms of cell damage? Provide an example

A

Damage occurs due to immune system response (cytokines), not pathogens

e.g., inflammatory reactions in third-stage syphilis cause blindness and deafness

65
Q

Define signs, symptoms, and syndrome

A

Signs: objective, observable, measurable presentation of disease
Symptoms: subjective (to the patient)
Syndrome: multiple concurring symptoms

66
Q

What is an acute disease? Provide an example

A

Come on quickly and resolve quickly

e.g. cold, flu, covid

67
Q

What is a chronic disease? Provide an example

A

Develop slowly and resolve slowly

e.g. TB, Related Hansen’s disease

68
Q

What is a latent disease? Provide an example

A

Remains hidden and occasionally arises
e.g. HSV 1 & 2

69
Q

What are subacute (subclinical) or asymptomatic diseases?

A

Disease that does not show any signs or symptoms

70
Q

What is a localized infection? Give an example

A

Disease is isolated to one spot. Easier to treat.

e.g. anthrax

71
Q

What is a systemic infection?

A

Disease is found in several places of the body and may be spreading to other parts

72
Q

Bacteremia vs. Septicemia

A

Bacteremia: bacteria spreading in blood, but not growing

Septicemia: bacteria is growing in the blood. (virulence factor)

73
Q

What is a primary infection?

A

Initial colonization by pathogen

74
Q

What is a secondary infection?

A

Follows primary infection, often when the host is weakened

75
Q

What is a superinfection? Provide an example

A

When changes in the environment allow an opportunistic pathogen to thrive and cause disease
e.g. C. diff infection of the bowel following clindamycin treatment

76
Q

What stage of disease progression is indicated on the chart? What is happening in this stage?

A

Incubation period
- when infection first occurs
- no S/S

77
Q

What stage of disease progression is indicated on the chart? What is happening in this stage?

A

Prodromal phase
- vague symptoms

78
Q

What stage of disease progression is indicated on the chart? What is happening in this stage?

A

Invasive phase
- severe signs and symptoms

79
Q

What stage of disease progression is indicated on the chart? What is happening in this stage?

A

Acme
- most severe of signs and symptoms
- immune system is catching up to eliminate and expel disease

80
Q

What stage of disease progression is indicated on the chart? What is happening in this stage?

A

Decline phase
- declining signs and symptoms

81
Q

What stage of disease progression is indicated on the chart? What is happening in this stage?

A

Convalescence period
- no longer exhibiting signs or symptoms
- expelling last of pathogens

82
Q

During what phase of disease progression is adherence to tissue target occurring?

A

Incubation phase

83
Q

During what phase of disease progression are colonization, growth, and immune system avoidance occurring?

A

Prodromal phase

84
Q

During what phase of disease progression is damage to host tissue and cells occurring?

A

Invasive phase

85
Q

What phase of disease progression are patients most contagious?

A

Invasive phase

MICR 262 (30 decks)

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