Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Microbiology Unit 2 > (8-19) Host-Microbe Interactions > Flashcards

(8-19) Host-Microbe Interactions Flashcards

1. Define normal flora and list ways that it plays a protective role in the health of the host. 2. Define the following: Pathogen, Virulence, Opportunistic Infection, Inapparent disease, Disease, Primary infection, Secondary infection, Communicable disease 3. Describe the course of an infectious disease including the following periods: Incubation period, Phase of illness, Period of convalescence 4. Define or identify: Acute disease, Chronic disease, Latent disease 5. List Koch’s postulates a

You may prefer our related Brainscape-certified flashcards:
Biology 101 flashcards
1
Q

What does colonization of a host by a microorganism imply?

A

Colonization of a host by a microorganism implies that the microbe has become established and is multiplying.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

If colonized microorganisms derive benefit at the expense of a host, it is termed what?

A

An infection

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Does an infection always lead to noticeable adverse effects?

A

No

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are two terms for symptoms that do not appear or are mild enough to go unnoticed?

A
  1. subclinical
  2. inapparent
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

An infection that results in disease is termed what?

A

An infectious disease

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the term for a noticeable impairment of body function?

A

Disease

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

An initial disease is termed what?

A

primary infection

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are additional infections resulting from primary infection called?

A

secondary infection

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are (Primary) Pathogens?

A

Organisms that can cause disease in otherwise healthy people

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are opportunistic pathogens?

A

Organisms that cause disease when the body’s defenses are down.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Where do opportunistic pathogens come from?

A

They may be part of normal flora or common in environment.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is virulence?

A

It is quantitative term referring to a pathogen’s disease-causing ability.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Which organisms have a high degree of pathogenicity and are more likely to cause disease?

A

Highly virulent organisms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are the 2 terms for a disease that spreads from host to host?

A
  1. communicable
  2. contagious
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What 3 stages does a disease course follow?

A
  1. Incubation
  2. Illness
  3. Convalescence
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the incubation stage?

A

The time between introduction of organism to onset of symptoms.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is the illness stage?

A

The period when an individual experiences the symptoms of disease.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is the convalescence stage?

A

The period of recuperation and recovery (many infectious agents can still be spread)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What are the Classifications regarding Timing and Duration of symptoms of a disease?

A
  1. Acute
  2. Latent
  3. Chronic
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Describe an acute virus and give one example.

A

Symptoms have a rapid onset and last only a short time
~ ex. strep throat

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Describe a chronic virus and give one example.

A

Symptoms develop slowly and persist
~ ex. tuberculosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Describe a latent virus and give one example.

A

Infection never completely eliminated, and the infection can later reactivate with either similar or different symptoms
~ ex. tuberculosis, chicken pox → shingles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Who found a way to grow bacteria in pure cultures (colonies on infusions + agar)?

A

Robert Koch

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Who identified the bacterium that cause the disease anthrax (B. anthracis)?

A

Robert Koch

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What is the purpose of Koch’s Postulates?

A

They establish the cause of infectious disease.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What are Koch’s (4) Postulates?
[Hint: P.C.D.R.]

A
  1. The microorganism must be PRESENT in every case of disease
  2. Microorganism must be grown in pure CULTURE from diseased host
  3. Inoculation of sample of culture into health animal must produce same DISEASE.
  4. Microorganism must be RECOVERED from inoculated animal
27
Q

Koch’s Postulates could be carried out for which of the following infections: Treponema pallidum, M. tuberculosis, C. botulinum, Meningitis, or HIV?

A

Clostridium botulinum

[Rationale: Treponema pallidum cannot be cultured; M. tuberculosis can cause several diseases; Meningitis can be caused by several organisms; HIV does not have an animal model. Clostridium botulinum is the only option that fits Koch’s Postulates, in that it would 1) be present in every case of disease, 2) be able to be grown in pure culture from diseased host, 3) produce same disease upon inoculation into a healthy individual, and 4) be able to be recovered from the inoculated animal. ]

28
Q

Can Koch’s Postulates be carried out in organisms that cannot be cultured? Cite 2 examples of such organisms.

A

No.
~ ex. Treponema pallidum
~ ex. Mycobacterium leprae

29
Q

Can Koch’s Postulates be carried out for viruses that don’t have animal models? Give one example.

A

No.
~ex. HIV

30
Q

What is Shigella’s distinct sign/ symptom?

A

Bloody diarrhea

31
Q

Is Meningitis caused by a single organism?

A

No, it is a disease that can be caused by several organisms.

32
Q

What do we currently use to identify cause of infection?

A

Molecular Techniques

33
Q

What are the 3 basic Mechanisms of Pathogenesis?

A
  1. Adherence
  2. Invasion
    3.Avoidance of host defenses
34
Q

What must pathogens first do, in order to establish infection?

A

Pathogen must adhere to host cells

35
Q

What do bacteria use in order to bind to specific host receptors?

A

Adhesins

36
Q

Which 2 places are bacterial adhesions located?

A
  1. At the tip of pili (fimbriae)– more often
  2. Can also be part of capsule (glycocalyx)
37
Q

What does the bacterial Invasion stage consist of?

A

Breaching Anatomical Barriers

38
Q

Because penetration of skin is difficult, bacteria that penetrate via this route rely on what?

A

Trauma that destroys skin integrity

39
Q

Which is the more common route of entry for a microbe invasion: skin, or mucous membranes?

A

Mucous membranes

40
Q

What are the 2 general mechanisms of penetration of mucous membranes?

A
  1. Directed uptake
  2. Exploitation of antigen sampling
41
Q

What is Directed Uptake of cells, with regards to pathogenesis?

A

Directed uptake is an induction by non-phagocytic cells to engulf pathogens by “injection” of signaling molecules into cell.

42
Q

How does Salmonella breach anatomical barriers in order to enter a host? Elaborate.

A
  1. Salmonella utilizes Directed Uptake.
  2. It induces mucosal epithelial cells of intestine to engulf it by endocytosis through their apical surface,
  3. They multiply within the pseudstratified columnar epithelium, and then exit the basal surface of the cell via exocytosis.
43
Q

How does Shigella breach anatomical barriers in order to enter a host? Elaborate.

A
  1. Shigella enters an M-cell (non-villiated intestinal epithelial cell) via endocytosis.
  2. It survives being phagocytosed by the macrophage waiting outside the basal surface.
  3. It reenters a new epithelial cell, then is propelled horizontally from cell to cell via the action of actin filaments.
  4. It can thus effectively hide from the immune system.
44
Q

What is antigen sampling? Why is it performed?

A
  1. M cells in intestine collect antigen and pass to macrophages, macrophages can then present antigen to lymphocytes located below mucosa.
  2. It is performed so that the body can be prepared for whatever might be invading the lumen of the small intestine (ex. cestodes).
45
Q

What organism can escape from and survive phagocytosis by a macrophage?

A

Shigella

46
Q

In which 3 ways can a pathogen avoid destruction by phagocytes?

A
  1. Survive within the phagocyte
  2. Produce compounds that kill phagocytes
  3. Avoid phagocytoses
47
Q

How does Shigella survive within a phagocyte?

A

Shigella lyses the phagosome before if fuses with the lysosme

48
Q

Which compound does Streptococcus pyogens produce in order to kill phagocytes?

A

Streptococcus pyogens produces “streptolysin O” that damages cell membranes of phagocytes

49
Q

How does Streptococcus pneumoniae avoid phagocytosis?

A

Streptococcus pneumoniae produces a capsule that prevents complement-mediated phagocytosis.

50
Q

How does Neisseria gonorrhoeae avoid complement?

A

~ Normal body cells bind a protein that protects against complement-mediated destruction.
~ Neisseria gonorrhoeae binds this protein to, protecting against complement

51
Q

How does Neisseria gonorrhoeae avoid antibodies?

A

Neisseria gonorrhoeae has an enzyme that degrades IgA

52
Q

Which 4 general types of defenses do pathogens avoid, once they have invaded a host?

A
  1. Destruction by phagocytes
  2. Complement-binding
  3. Antibody detection
  4. Viral avoidance of TC-cell killing
53
Q

Which 2 ways can pathogens avoid antibodies?

A
  1. Degrading IgA
  2. Antigenic variation
    ~ ex. of pili
54
Q

How does Cytomegalovirus avoid being killed by a TC cell after invading a host’s cell?

A

Cytomegalovirus makes a “counterfeit” MHC I to display on the surface of cell.

55
Q

Which 2 types of toxin damage a host?

A
  1. Endotoxin
  2. Exotoxin
56
Q

What is exotoxin?

A

A protein with specific damaging effects.

57
Q

What is endotoxin?

A

The LPS of Gram-negative outer membrane.

58
Q

In which 2 ways is exotoxin released?

A
  1. Either secreted
  2. Released when bacterium is lysed by host immune response
59
Q

What are the disease symptoms associated with endotoxin?

A

Disease symptoms associated with vigorous immune response, which can lead to septic shock.

60
Q

Which type of toxin is heat stable?

A

Endotoxin

61
Q

Cite 2 examples of exotoxin?

A
  1. Botulinum toxin from Clostridium botulinum
  2. Steptolysin O from Streptococcus pyogenes
62
Q

What is Botulinum toxin?

A

A heat labile neurotoxin that causes paralysis.

63
Q

How does Steptolysin O effect cell membranes? Cite 2 specific cell types that it affects.

A

Steptolysin O makes pores in cell membranes.
~ Lyse red blood cells to release iron – hemolysis
~ Lyse leukocytes to avoid host defense

Microbiology Unit 2 (13 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions