Infection Flashcards

1
Q
A
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2
Q

Bacteria

A

Lack cell organelles and have a cell wall. Can be aerobic or anaerobic and Gram +/-ve. Cocci are round while bacilli are rods. Most are extracellular.

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3
Q

Besides our skin, what is our primary line of defence to pathogens?

A

Enzymes, acids, detergents, IgA, coughing, cilia, and macrophages.

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4
Q

Can the immune response cause tissue toxicity?

A

Yes.

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5
Q

Cytopathic-cytoproliferative inflammation

A

Caused by virus-mediated damage. Causes: a) viral aggregates (inclusion bodies - w/i cells - like cold sores) b) cell fusion (like Measles) c) discohesion B blisters d) proliferation of host cells (neoplasia, like in HPV)

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6
Q

Describe the body response to helminths:

A

Lay eggs and cause inflammation to them.

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7
Q

Direct toxicities

A

Includes viral lysis, enzymatic degradation of cellular structures, and cell damage upon invasion.

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8
Q

Diseases associated with prions:

A

CJD - Creutzfeld-Jacob disease Mad Cow disease (variant of CJD) BSE - bovine spongiform encephalopathy

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9
Q

Diseases associated with viruses:

A

Acute (colds, influenza), chronic (hep B/C), latent (herpes zoster) Can also cause neoplasia.

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10
Q

Do bacteria form inclusion bodies?

A

Nope. They form clumps of cells.

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11
Q

Ectoparasites

A

Usually insects or arachnids. They attach to and live on the skin. Examples include ticks, fleas, lice (what is an arthropod vector??) Can cause disease directly or be vectors.

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12
Q

Fungi

A

Thick cell walls and cell membranes; many are flora; likely a culprit in opportunistic infections.

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13
Q

Give an example of a flora that is beneficial to the host.

A

Flora that produce Vitamin K in humans.

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14
Q

Granulomatous inflammation B

A

Occur usually with fungal infection or TB. Contains lymphocytes, macrophages, and histocytes (altered macrophages).

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15
Q

Helminths

A

Multicellular parasitic worms of three classes: 1) roundworms (nematodes - ascaris, hookworms) 2) flatworms (cestodes - pork, beef, fish, tapeworms) 3) flukes (trematodes - schistosomes)

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16
Q

How do cytokines influence our immune system (hum oral)?

A

They primarily initiate an inflammatory reaction. They can activate inflammatory cells or regulate their growth and differentiation.

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17
Q

Humoral immunity usually combats what kind of infection?

A

Bacterial infections

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18
Q

In what case can body flora cause an infectious response, and give an example?

A

When one is immunocompromised - opportunistic infection. The fungus Candida albicans.

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19
Q

In what case can viruses be seen via light microscopy?

A

When they form inclusion bodies.

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20
Q

Indirect toxicities

A

Include release of toxins with remote effects including cell damage, cellular dysfunction, vascular damage, and ischemic necrosis.

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21
Q

List all the stains that can be used on some infectious agents.

A

Gram (+ means thick cell wall), acid-fast, silver, specific Ab-labelled immunohistochemical stains.

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22
Q

List Koch’s postulates:

A

The organism: 1) must be found in lesions of the disease 2) must be isolated and cultured in vitro 3) must transmit the disease to another animal 4) must be recovered from lesions in that animal

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23
Q

List three methods that infectious agents use to cause tissue damage:

A

1) directly cause cell death 2) release toxins and enzymes 3) induce host cellular responses

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24
Q

Mononuclear and granulomatous inflammation

A

Response to viruses, intracellular bacteria, or parasites. Characteristic of lymphocytosis (increase in []).

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25
Q

Name the 3 main types of bacteria that are atypical or intracellular:

A

1) chlamydia (don’t produce ATP either) 2) Rickettsia (can be arthropod vectors - lice, ticks, mice) 3) mycoplasma (no cell wall)

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26
Q

Name the types of mobile genetic elements that usually affect bacteria:

A

1) transposons 2) plasmids 3) bacteriophages

27
Q

Name three characteristics of skin that allow it to be resistant:

A

Dry, low in pH, and presence of fatty-acids that inhibit microbial growth.

28
Q

Prions

A

Abnormal forms of host prion proteins that can resist degradation by proteases. They are infectious in large quantities.

29
Q

Protozoa

A

Single-celled. Have a complex lifecycle (replicate in various places at various stages).

30
Q

Supparative inflammation

A

When neutrophils are attracted by chemoattractants. Cause pus. This is usually acute.

31
Q

T/F: IgA is contained in mucous secretions.

A

True!

32
Q

T/F: In a healthy person, skin infection is due to high virulence and deep infections are due to injury.

A

False! Other way around ;)

33
Q

T/F: Measles is characteristic of cell fusion via cytopathic-cytoproliferative inflammation.

A

True.

34
Q

Treatment of infectious disease is most effective when:

A

You’ve identified the organism and it’s site of infection.

35
Q

True/False: In hep B/C, the host merely contains the infection and doesn’t destroy it.

A

True!

36
Q

Viruses

A

Obligate intracellular organisms that take over the host genetic machinery. Genome is surrounded by protein capsid.

37
Q

What are examples of virus that form inclusion bodies (w/i cells)?

A

CMV (cytomegalovirus), herpes - these can be seen by light microscopy.

38
Q

What are some ways that infection can spread?

A

a) planes of least resistance b) lymphatics c) axonal transport d) infected cells are carried distantly Note: the pathogen MUST be able to leave the host organism and cause infection at this new site - this is called transmission.

39
Q

What are the 6 virulence factors:

A

1) colonization in the host 2) ability to evade defences 3) ability to cause immunosuppresion 4) the ability to obtain nutrition from the host 5) ability to cause tissue injury 6) ability to proliferate

40
Q

What are the five major patters of tissue reaction?

A

1) Supparative inflammation 2) Mononuclear and granulomatous inflammation 3) Cytopathic-cytoproliferative inflammation 4) Necrotizing inflammation 5) Chronic inflammation and scarring

41
Q

What are the three main host defences?

A

1) epithelial (mucous) and epidermal (skin) 2) immune system (humoral or cellular) 3) exogenous factors (antibiotics, antivirals, etc.)

42
Q

What are the typical clinical features of an infection?

A

Leukocytosis, erythema (redness caused by hyperaemia), pain, swelling, fever, hypotension, shock.

43
Q

What can compromise the defences of the GI tract?

A

Low acidity, mechanical obstruction, and death of flora (usually by antibiotics) Also, non-enveloped bacteria can evade bile and pancreatic enzymes.

44
Q

What causes influenza?

A

Infection of the upper and lower respiratory tract by ____. Invades epithelial cells and causes lysis via replication. Disrupts the mucous lining and can cause 2ndary bacterial infections.

45
Q

What causes malaria?

A

The protozoa plasmodium falciparum. It replicates in an insect vector before transmission to humans. Sporozoites from the insect enter the bloodstream and form merozoites and rupture liver cells. Causes inflammation of the liver. Can also invade RBCs and cause anemia.

46
Q

What causes the overlap in the infectious response to various organisms?

A

The immune system’s limited mechanisms of response.

47
Q

What determines whether you will get an infection?

A

The organism’s virulence and the host’s defences

48
Q

What happens in sepsis (proliferation through the blood stream)?

A

You can affect the recruitment of inflammatory cells, circulation, thermoregulation, and coagulation.

49
Q

What influences the ability of a pathogen to colonize in a host?

A

1) size of innoculum 2) ability to adhere to surfaces (viruses bind to cell-surface receptors, while bacteria express gene product to attach to the cell-surface)

50
Q

What influences the ability of an organism to evade host defences?

A

Reproduction rate, overwhelming immune response, being difficult to digest (i.e., B-encapsulated bacteria and viruses).

51
Q

What influences the ability of an organism to proliferate?

A

1) availability of nutrients, moisture, oxygen, pH, etc. 2) ability to evade host defences 3) ability to compete with flora

52
Q

What is an infection?

A

When one shows the signs and symptoms of an infectious disease

53
Q

What is necessary for cellular immunity?

A

Antibody production by B cells and opsonization.

54
Q

What is the main mechanism of survival of threatened pathogens?

A

Genetic mutation or acquisition.

55
Q

What is the mean mechanism of defence in the respiratory tract, and what can compromise it?

A

The cillliary blanket can trap bacteria. It can be compromised by smoking, CF, alcohol, or intubation. In addition, some organisms can adhere to epithelial cells.

56
Q

What is the method of action of bacteria to cause tissue damage?

A

They release endotoxins (component of cell wall of Gram -ve bacteria) or exotoxins (secreted; disrupts cell membranes and metabolism).

57
Q

What is the method of action of viruses to cause tissue damage?

A

Enter cells and replicate at their expense. They kill the cells by: a) inhibiting host cell metabolic function b) disruption the plasma membrane c) lysis d) destruction by immune cells e) induce cell proliferation and transformation

58
Q

What is the most common form of organic and cellular pathology?

A

Infectious pathology.

59
Q

What is the purpose of Koch’s postulates?

A

To determine whether disease has an infectious origin

60
Q

What kind of immunity usually combats viral infections?

A

Acquired immunity (T cells)

61
Q

What kinds of bacteria usually cause opportunistic infections?

A

Those of low virulence. Viruses include CMV and herpes. Bacteria include pneumococous. Fungi include Candida and Aspergillus. Protozoa include toxoplasm and pneumocystis.

62
Q

What the defensive mechanisms in the GI tract?

A

1) gastric juice; 2) mucous layer of the gut (viscous) 3) lytic pancreatic enzymes and bile 4) IgA antibodies 5) competition with microflora 6) defensius protein (antimicrobial peptides)

63
Q

Why are laboratory studies and radiographic examination of bacteria important?

A

To identify and determine the drug sensitivity of the organism in a majority of cases

64
Q

Why is DNA sequence analysis becoming more popular in bacterial identification?

A

For those that are very virulent and difficult to grow in culture.