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Flashcards in Introduction Deck (90)
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1
Q

Purposes of Clinical Microbiology

A
  • control epidemics
  • prevention
  • treat infections
2
Q

invasion by and multiplication of microorganisms in body tissue

A

infection

3
Q

alteration that disrupts normal body function

A

disease

4
Q

Causes of disease

A
  • pathogens
  • inheritance
  • environment
5
Q

Types of pathogens

A
  • prions
  • viruses
  • bacteria
  • fungi
  • parasites
6
Q

Ways to acquire infections

A
  • nosocomial (hospital) infections
  • community-acquired infections
  • endogenous infections
  • exogenous infection
7
Q

non-infectious organisms

A
  • normal flora
  • opportunists
  • contaminants
8
Q

Germ Theory

A
  • suggested by Louis Pasteur and Robert Koch

- first to say that diseases are caused by microorganisms

9
Q

Koch’s Postulates

A
  • pathogens are found in sick organisms, not healthy ones
  • pathogen must be isolated and grown in pure culture
  • purified pathogen should cause same disease when injected in a new host
  • injected pathogen should be re-isolated and identical to the original
10
Q

Body as a growth environment

A
  • has nutrients
  • moist, watery environment
  • optimal temperature
  • supports flora and pathogens
11
Q

Disease process

A
  1. enter body
  2. disrupt function
  3. cause symptoms
12
Q

Signs of infection

A

fever, chills, fatigue, weight loss, vasodilation, increased WBC count, abnormal peripheral blood differential, increased sedimentation rate type-specific antibodies

13
Q

sedimentation rate

A

rate at which RBC’s settle out of blood in one hour; altered by inflammatory proteins, making RBC’s heavier and faster to fall

14
Q

Modes of infection transmission

A
  • direct transmission

- indirect transmission

15
Q

direct transmission of infection

A
  • congenital, sexual and physical contact

- hand-to-hand contact with body secretions and respiratory droplets

16
Q

indirect transmission of infection

A
  • contaminated food & water
  • fomites
  • airborne
  • animals
  • insects/arthropods
17
Q

How infections disrupt body function

A
  • produce toxins
  • remove nutrients
  • destroy tissue
18
Q

Types of toxins

A

neurotoxins, cytotoxins, enterotoxins, endotoxins

19
Q

Ways to fight infection

A
  • prevention
  • antibiotics, anti-fungals, anti-viremic, anti-parasitics
  • host defense mechanism (immune system)
20
Q

Purpose of the Immune System

A
  • protection
  • prevent disease
  • destroy disease-causing agent
21
Q

Components of the Immune System

A
  • non-specific defenses

- specific defenses

22
Q

Components of non-specific defense

A
  • 1st line of defense (physical barriers)

- 2nd line of defense (inflammatory response)

23
Q

1st Line of Defense

A

physical barriers, chemical barriers (i.e., sweat), secretions containing lysozymes, reflexes, secretions

24
Q

2nd Line of Defense

A

inflammatory response to allow WBC’s to enter site of infection, WBC production, fever, interferon

25
Q

What happens during an inflammatory response?

A

blood vessels near wound expand, WBC’s leak from vessel into infected tissue and engulf bacteria (phagocytosis)

26
Q

Why is fever involved in the 2nd Line of Defense immune response?

A
  • increased temperature isn’t ideal for some pathogens
  • increases heart rate, allowing WBC’s to travel to site of infection more quickly
  • increases rate of chemical reactions, to help repair tissue damage
27
Q

interferon

A

antiviral that blocks viral replication by inhibiting the synthesis of viral proteins

28
Q

Specific immunity

A
  • immune response triggered by an antigen that involves phagocytosis of the antigen cells
  • divided into cell-mediated immunity and humoral immunity
29
Q

What is an antigen?

A

carbohydrates, lipids and proteins on the surfaces of bacteria, viruses, parasites and fungi

30
Q

What is the function of monocytes/macrophages in the immune response?

A

phagocytosis; antigen presenting cells

31
Q

What is the function of granulocytes in the immune response?

A
  • Neutrophils: phagocytosis, inflammation
  • Eosinophils: allergies, helminth destruction
  • Basophils: allergic reactions (IgE receptors)
32
Q

What is the function of lymphocytes in the immune response?

A
  • T cells: cellular immunity, helper/cytotoxic or suppressor functions
  • B cells: antibody production
  • Large granular lymphocytes: natural killing
33
Q

What is the function of mast cells, Langerhans cells, and Dendritic cells in the immune response?

A
  • Mast cells: allergic reactions
  • Langerhans cells: antigen presenting cells in skin
  • Dendritic cells: antigen presenting cells in lymph tissue
34
Q

Humoral Immunity

A

Deals with viral and bacterial infections

35
Q

Cell-mediated Immunity

A

Deals with protozoal and some bacterial infections

36
Q

Ways to classify organisms

A
  • prokaryotic or eukaryotic
  • size and physical properties
  • characteristics (i.e., cell wall)
  • site of infection in the body
37
Q

Bacteria can be identified based on appearance

A

Gram-stain reaction, special features (i.e., flagella), and colony morphology

38
Q

Bacteria can be identified based on growth requirements

A
  • Nutritional: fastidious, special growth factors, cell culture
  • Atmospheric: oxygen, no oxygen, carbon dioxide, etc.
  • Temperature
39
Q

strict aerobe

A

oxygen required for respiration

40
Q

falcultative anaerobe

A

prefer oxygen for respiration but can obtain energy through fermentation if oxygen is not available

41
Q

microaerophilic

A

grow under reduced oxygen

42
Q

anaerobic

A

cannot grow in the presence of oxygen

43
Q

capnophilic

A

grow in the presence of 5-10% carbon dioxide

44
Q

psychrophile

A

organisms whose ideal growth temperature is 4 - 20 degrees Celsius

45
Q

mesophile

A

organisms whose ideal growth temperature is 30 - 45 degrees Celsius

46
Q

thermophile

A

organisms whose ideal growth temperature is >40 degrees Celsius

47
Q

Bacteria can be identified based on metabolism

A

enzymes, CHO usage, and amino acid usage

48
Q

techniques used in clinical microbiology

A
  • culture in media
  • cell culture
  • serology tests
  • molecular biology (PCR)
49
Q

types of media

A

supportive media, enriched media, enrichment broths, differential media, selective media, antibiotic media

50
Q

supportive media

A
  • grows most non-fastidious organisms
  • no advantage to any particular bacteria
  • Trypticase soy agar (TSA), Trypticase soy broth (TSB), Nutrient agar, Nutrient broth
51
Q

enriched media

A
  • contains nutritional enhancements for the growth of fastidious organisms
  • Sheep blood agar (SBA), Chocolate agar (CA), Buffered charcoal yeast extract (BCYE)
52
Q

Sheep blood agar (SBA)

A
  • contains blood cells
  • good plate for identifying hemolysis
  • Neisseria meningitidis
53
Q

Chocolate agar (CA)

A
  • contains lysed blood cells that release NAD
  • IsoVitalex enrichment: dextrose, cysteine, Vit. B12, thiamine, ferric nitrate
  • Neisseria gonorrhoeae
54
Q

enrichment broths

A
  • liquid medium that will grow a small number of an organism and suppress normal flora
  • Gram-negative broth, selenite broth
55
Q

Gram-negative broth

A
  • contain bile salt (as sodium desoxycholate), which is toxic to gram-positive organisms and inhibitory to fecal flora
  • selective for pathogens (i.e., Salmonella and Shigella)
56
Q

differential media

A
  • allows grouping based on characteristics demonstrated on the medium
  • MacConkey agar (Mac), Eosin methylene blue (EMB)
57
Q

MacConkey agar (Mac)

A
  • contains lactose, bile salts, neutral red indicator, crystal violet (selective differential media)
  • lactose-fermenters appear pink
  • non-lactose-fermenters appear colorless
58
Q

Why are bile salts and crystal violet used in media?

A

They inhibit the growth of gram-positive organisms

59
Q

selective media

A
  • supports the growth of one type of organism, but not another type
  • Hektoen enteric media (HE), Salmonella-Shigella agar (SS), Xylose-lysine-deoxycholate agar (XLD), phenyl ethyl alcohol (PEA)
60
Q

Hektoen enteric media (HE), Salmonella-Shigella agar (SS), and Xylose-lysine-deoxycholate agar (XLD)

A
  • inhibit growth of gram-positives and gram-negative coliform bacteria
  • permit isolation of stool pathogens
61
Q

phenyl ethyl alcohol (PEA)

A
  • inhibits growth of aerobes and falcultative gram-negative rods
  • allows growth of gram-positive cocci
62
Q

antibiotic media

A
  • selective for certain organisms through addition of specific antibiotics
  • Modified Thayer-Martin media (MTM)
63
Q

Modified Thayer-Martin media

A
chocolate agar with antibiotics:
- vancomycin inhibits gram-positives
- colistin inhibits gram-negatives
- nystatin inhibits yeasts
- trimethoprim inhibits swarming Proteus
selects for Neisseria gonorrhoeae
64
Q

Gram stain

A

detects nearly all clinically significant bacteria

65
Q

Organisms that won’t gram stain

A
  • organisms that exist almost exclusively within host cell (i.e., chlamydia)
  • organisms that lack a cell wall (i.e., mycoplasma and ureaplasma)
  • organisms that can’t be resolved by microscopy (i.e., spirochetes)
66
Q

WBC’s and epithelial cells gram stain ________

A

pink

67
Q

Gram stain reagents

A

crystal violet (primary stain), Gram’s iodine, decolorizer, safranin (counterstain)

68
Q

Gram-positive organisms

A
  • cell walls contain thick peptidoglycan
  • retain crystal violet dye and resist decolorization
  • stain purple
69
Q

Gram-negative organisms

A
  • cell walls contain thinner layer of peptidoglycan
  • allow crystal violet to wash out with decolorizer
  • retain safranin counterstain
  • stain pink or red
70
Q
  • suggested by Louis Pasteur and Robert Koch

- first to say that diseases are caused by microorganisms

A

Germ Theory

71
Q
  • pathogens are found in sick organisms, not healthy ones
  • pathogen must be isolated and grown in pure culture
  • purified pathogen should cause same disease when injected in a new host
  • injected pathogen should be re-isolated and identical to the original
A

Koch’s Postulates

72
Q

rate at which RBC’s settle out of blood in one hour; altered by inflammatory proteins, making RBC’s heavier and faster to fall

A

sedimentation rate

73
Q

antiviral that blocks viral replication by inhibiting the synthesis of viral proteins

A

interferon

74
Q
  • immune response triggered by an antigen that involves phagocytosis of the antigen cells
  • divided into cell-mediated immunity and humoral immunity
A

specific immunity

75
Q

Deals with viral and bacterial infections

A

humoral immunity

76
Q

Deals with protozoal and some bacterial infections

A

cell-mediated immunity

77
Q
  • grows most non-fastidious organisms
  • no advantage to any particular bacteria
  • Trypticase soy agar (TSA), Trypticase soy broth (TSB), Nutrient agar, Nutrient broth
A

supportive media

78
Q
  • contains nutritional enhancements for the growth of fastidious organisms
  • Sheep blood agar (SBA), Chocolate agar (CA), Buffered charcoal yeast extract (BCYE)
A

enriched media

79
Q
  • contains blood cells
  • good plate for identifying hemolysis
  • Neisseria meningitidis
A

Sheep Blood Agar (SBA)

80
Q
  • contains lysed blood cells that release NAD
  • IsoVitalex enrichment: dextrose, cysteine, Vit. B12, thiamine, ferric nitrate
  • Neisseria gonorrhoeae
A

Chocolate Agar (CA)

81
Q
  • liquid medium that will grow a small number of an organism and suppress normal flora
  • Gram-negative broth, selenite broth
A

enrichment broth

82
Q
  • contain bile salt (as sodium desoxycholate), which is toxic to gram-positive organisms and inhibitory to fecal flora
A

Gram-negative broth

83
Q
  • allows grouping based on characteristics demonstrated on the medium
  • MacConkey agar (Mac), Eosin methylene blue (EMB)
A

differential media

84
Q
  • contains lactose, bile salts, neutral red indicator, crystal violet (selective differential media)
  • lactose-fermenters appear pink
  • non-lactose-fermenters appear colorless
A

MacConkey agar (Mac)

85
Q
  • supports the growth of one type of organism, but not another type
  • Hektoen enteric media (HE), Salmonella-Shigella agar (SS), Xylose-lysine-deoxycholate agar (XLD), phenyl ethyl alcohol (PEA)
A

selective media

86
Q
  • inhibit growth of gram-positives and gram-negative coliform bacteria
  • permit isolation of stool pathogens
A

Hektoen enteric media (HE), Salmonella-Shigella agar (SS), Xylose-lysine-deoxycholate agar (XLD)

87
Q
  • inhibits growth of aerobes and falcultative gram-negative rods
  • allows growth of gram-positive cocci
A

phenyl ethyl alcohol (PEA)

88
Q
  • selective for certain organisms through addition of specific antibiotics
  • Modified Thayer-Martin media (MTM)
A

antibiotic media

89
Q
  • cell walls contain thick peptidoglycan
  • retain crystal violet dye and resist decolorization
  • stain purple
A

Gram-positive organisms

90
Q
  • cell walls contain thinner layer of peptidoglycan
  • allow crystal violet to wash out with decolorizer
  • retain safranin counterstain
  • stain pink or red
A

Gram-negative organisms