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Microbiology > Lecture #12 part 2 > Flashcards

Lecture #12 part 2 Flashcards

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Biology 101 flashcards
1
Q

Koch’s postulates were developed based on what?

A

The germ theory of disease

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2
Q

What do koch’s postulates do?

A

Allow the determination of the specific microorganisms that cause the disease

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3
Q

What are 4 ‘rules’ that need to be followed in order for koch’s postulates to work?

A
  1. The same pathogen should be present in every case of the disease
  2. Pathogen must be isolated and grown in pure culture
  3. Pathogen from pure culture should cause disease when inoculated into a lab animal
  4. The same microbe should be isolated again for the individual inoculated
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4
Q

What are 4 exceptions to koch’s postulates?

A
  1. Some bacteria will not grow in pure culture
  2. Some pathogens cannot be used to infect lab animals
  3. Sometimes several different microorganisms cause the same disease
  4. Sometimes one pathogen can cause many different diseases
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5
Q

What is an example of a bacteria that cannot grow in pure culture?

A

Treponema Pallidum

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6
Q

What is an example of a pathogen that cannot be used to infect lab animals?

A

HIV

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7
Q

What is an example of several microorganisms that can cause the same disease?

A

Pneumonia

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8
Q

What is an example of one pathogen that can cause many diseases?

A

Streptococcus pyogenes (strep throat, skin infections, scarlet fever)

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9
Q

What are two mechanisms of pathogenesis?

A
  1. Adherence

2. Invasiveness

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10
Q

What is adherence in regards to pathogens?

A

Surface molecules that allow a pathogen to stick to the surface (adesins)

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11
Q

Where do pathogens stick to?

A

Specific receptors on the host cell surface (capsules, pili and fimbre)

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12
Q

What does invasiveness mean in regards to pathogens

A

The ability of a pathogen to invade and multiply in healthy tissues

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13
Q

What are two types of molecules that promote invasiveness in pathogens

A
  1. Extracellular enzymes (exoenzymes)

2. Invasins

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14
Q

What are 3 types of exoenzymes?

A
  1. Fibrinolysn
  2. Collagense
  3. Coagulase
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15
Q

What does fibrinolysn enzyme do?

A

Degrades fibrin clots allowing spread of virus

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16
Q

What does collagense enzyme do?

A

degrades connective tissue

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17
Q

What does coagulase enzyme do?

A

promotes blood clots around bacterial cell which then tricks the immune system as thinking it is just a blood clot and not bacteria

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18
Q

Since extracellular enzymes degrades the body, what is the benefit of this?

A

Products of degradation are used as a source of food and protect the microbe from host defences

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19
Q

What are invasins (mechanism of pathogens) and what do they do?

A

Surface proteins that cause the rearrangement of the host cell cytoskeleton which forces the host cell to take in the bacterium

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20
Q

What is an example of an invasion?

A

Salmonella

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21
Q

How do microorganisms enter a host generally

A

Germs must first penetrate host defences in order to damage tissues and cause disease

22
Q

What is the most common way of entry for microorganisms? How?

A

Respiratory tract, inhaled through the nose and mouth (colds, influenza)

23
Q

How do microorganisms enter the gastrointestinal tract? What makes it difficult to enter it?

A

Through food or water. Most are destroyed by the acid of the stomach or bile of intestine

24
Q

What is an example of a genitourinary tract infection?

A

STI

25
Q

How do pathogens enter?

A

Most by broken membrane but others can penetrate unbroken membranes

26
Q

What is conjunctiva?

A

the membrane covering the eye

27
Q

How do some microorganisms gain access of skin?

A

Either wound entry or through hair follicles

28
Q

How do pathogens enter through the parenteral route? Give examples

A

Deposited directly into tissues when skin or membrane is broken
Ex. tick bite, IV, contaminated syringe

29
Q

How does a bacteria do direct damage to their host? Indirect?

A

Direct: production of exozymes or toxins
Indirect: Introducing an immune response and causing inflammation

30
Q

What is a bacterial toxin?

A

A poisonous substance produced by a microorganism

31
Q

What is a toxoid?

A

An inactive toxin

32
Q

What is one example of a toxoid?

A

DPT vaccine contains 3

33
Q

What is an exotoxin?

A

A toxin which is secreted from the bacterial cell

34
Q

Are exotoxins heat sensitive?

A

Yes

35
Q

Are exotoxins toxic?

A

Can be extremely toxic (some of the most lethal known substances)

36
Q

What is an example of an exotoxin?

A

Clostridium Botulinum causing botulism

37
Q

What are 3 types of exotoxins? What do they each do

A
  1. Neurotoxins (at neuromuscular junction)- interfere with nerve impulses
  2. Enterotoxins- interfere with salt absorption in small intestine
  3. Cytotoxins- Kill cells
38
Q

What are two types of neurotoxins?

A
  1. Botulinum Toxin

2. Tetanus Toxin

39
Q

What is botulinum toxin caused by and what does it do?

A

Caused by clostridium botulinum and causes muscles to permanently relax which causes heart to stop and you to die

40
Q

What does tetanus toxins do and what is it caused by?

A

Caused by clostridium tetani and causes uncontrollable muscle spasms and everything to lock up

41
Q

What does enterotoxins cause?

A

The body tries to counteract high salt concentrations and the intestine pumps out water which causes watery diarrhea

42
Q

How do cytotoxins work to kill cells?

A

Interfere with protein synthesis (where they are effecting, not whole body) and kill all types of cells

43
Q

What do endotoxins attach to?

A

outer membrane of gram negative cells

44
Q

What is another word for endotoxin?

A

Lipopolysaccharide

45
Q

When the endotoxin is in the membrane what happens? When cell dies?

A
  • No problems when in membrane

- when dies, it is released cause worsening symptoms (fever, hemorrhaging and shock)

46
Q

Which are stronger endo or exotoxins?

A

Exotoxins more toxins

more endotoxin is needed to cause symptoms

47
Q

How does salmonellosis fall into the endotoxin category ( what occurs)

A
  1. Food poisoning due to millions of dead bacteria

2. Symptoms occur because the endotoxin is released from all the endotoxins

48
Q

Exotoxins- protein or lps

  • when is it released
  • toxic or not so toxic?
A

Protein, released outside of cell, extremely toxic

49
Q

Endotoxin- protein or lps

  • when is it released
  • toxic or not so toxic
A

lps, released when cell dies, not so toxic

50
Q

What are 6 cytopathic effects of viral infections?

A
  1. Disruptions of cell processes
  2. Destruction of intracellular structure
  3. Virus can form inclusion bodies which consist of viral parts
  4. Giant cell formation from cells fusing together
  5. Infection when host cell dies
  6. indirect damage causes inflammatory response
51
Q

What can cause giant cell formation?

A

Colds

Microbiology (16 decks)

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