Microbiology > Introduction > Flashcards

Introduction Flashcards

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1
Q

Purposes of Clinical Microbiology

A
  • control epidemics
  • prevention
  • treat infections
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2
Q

invasion by and multiplication of microorganisms in body tissue

A

infection

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3
Q

alteration that disrupts normal body function

A

disease

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4
Q

Causes of disease

A
  • pathogens
  • inheritance
  • environment
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5
Q

Types of pathogens

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

Ways to acquire infections

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

non-infectious organisms

A
  • normal flora
  • opportunists
  • contaminants
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8
Q

Germ Theory

A
  • suggested by Louis Pasteur and Robert Koch

- first to say that diseases are caused by microorganisms

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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
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10
Q

Body as a growth environment

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

Disease process

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

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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

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14
Q

Modes of infection transmission

A
  • direct transmission

- indirect transmission

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15
Q

direct transmission of infection

A
  • congenital, sexual and physical contact

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

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16
Q

indirect transmission of infection

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

How infections disrupt body function

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

Types of toxins

A

neurotoxins, cytotoxins, enterotoxins, endotoxins

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19
Q

Ways to fight infection

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

Purpose of the Immune System

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

Components of the Immune System

A
  • non-specific defenses

- specific defenses

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22
Q

Components of non-specific defense

A
  • 1st line of defense (physical barriers)

- 2nd line of defense (inflammatory response)

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23
Q

1st Line of Defense

A

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

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24
Q

2nd Line of Defense

A

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

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25
What happens during an inflammatory response?
blood vessels near wound expand, WBC's leak from vessel into infected tissue and engulf bacteria (phagocytosis)
26
Why is fever involved in the 2nd Line of Defense immune response?
- 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
interferon
antiviral that blocks viral replication by inhibiting the synthesis of viral proteins
28
Specific immunity
- immune response triggered by an antigen that involves phagocytosis of the antigen cells - divided into cell-mediated immunity and humoral immunity
29
What is an antigen?
carbohydrates, lipids and proteins on the surfaces of bacteria, viruses, parasites and fungi
30
What is the function of monocytes/macrophages in the immune response?
phagocytosis; antigen presenting cells
31
What is the function of granulocytes in the immune response?
- Neutrophils: phagocytosis, inflammation - Eosinophils: allergies, helminth destruction - Basophils: allergic reactions (IgE receptors)
32
What is the function of lymphocytes in the immune response?
- T cells: cellular immunity, helper/cytotoxic or suppressor functions - B cells: antibody production - Large granular lymphocytes: natural killing
33
What is the function of mast cells, Langerhans cells, and Dendritic cells in the immune response?
- Mast cells: allergic reactions - Langerhans cells: antigen presenting cells in skin - Dendritic cells: antigen presenting cells in lymph tissue
34
Humoral Immunity
Deals with viral and bacterial infections
35
Cell-mediated Immunity
Deals with protozoal and some bacterial infections
36
Ways to classify organisms
- prokaryotic or eukaryotic - size and physical properties - characteristics (i.e., cell wall) - site of infection in the body
37
Bacteria can be identified based on appearance
Gram-stain reaction, special features (i.e., flagella), and colony morphology
38
Bacteria can be identified based on growth requirements
- Nutritional: fastidious, special growth factors, cell culture - Atmospheric: oxygen, no oxygen, carbon dioxide, etc. - Temperature
39
strict aerobe
oxygen required for respiration
40
falcultative anaerobe
prefer oxygen for respiration but can obtain energy through fermentation if oxygen is not available
41
microaerophilic
grow under reduced oxygen
42
anaerobic
cannot grow in the presence of oxygen
43
capnophilic
grow in the presence of 5-10% carbon dioxide
44
psychrophile
organisms whose ideal growth temperature is 4 - 20 degrees Celsius
45
mesophile
organisms whose ideal growth temperature is 30 - 45 degrees Celsius
46
thermophile
organisms whose ideal growth temperature is >40 degrees Celsius
47
Bacteria can be identified based on metabolism
enzymes, CHO usage, and amino acid usage
48
techniques used in clinical microbiology
- culture in media - cell culture - serology tests - molecular biology (PCR)
49
types of media
supportive media, enriched media, enrichment broths, differential media, selective media, antibiotic media
50
supportive media
- grows most non-fastidious organisms - no advantage to any particular bacteria - Trypticase soy agar (TSA), Trypticase soy broth (TSB), Nutrient agar, Nutrient broth
51
enriched media
- contains nutritional enhancements for the growth of fastidious organisms - Sheep blood agar (SBA), Chocolate agar (CA), Buffered charcoal yeast extract (BCYE)
52
Sheep blood agar (SBA)
- contains blood cells - good plate for identifying hemolysis - Neisseria meningitidis
53
Chocolate agar (CA)
- contains lysed blood cells that release NAD - IsoVitalex enrichment: dextrose, cysteine, Vit. B12, thiamine, ferric nitrate - Neisseria gonorrhoeae
54
enrichment broths
- liquid medium that will grow a small number of an organism and suppress normal flora - Gram-negative broth, selenite broth
55
Gram-negative broth
- 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
differential media
- allows grouping based on characteristics demonstrated on the medium - MacConkey agar (Mac), Eosin methylene blue (EMB)
57
MacConkey agar (Mac)
- contains lactose, bile salts, neutral red indicator, crystal violet (selective differential media) - lactose-fermenters appear pink - non-lactose-fermenters appear colorless
58
Why are bile salts and crystal violet used in media?
They inhibit the growth of gram-positive organisms
59
selective media
- 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
Hektoen enteric media (HE), Salmonella-Shigella agar (SS), and Xylose-lysine-deoxycholate agar (XLD)
- inhibit growth of gram-positives and gram-negative coliform bacteria - permit isolation of stool pathogens
61
phenyl ethyl alcohol (PEA)
- inhibits growth of aerobes and falcultative gram-negative rods - allows growth of gram-positive cocci
62
antibiotic media
- selective for certain organisms through addition of specific antibiotics - Modified Thayer-Martin media (MTM)
63
Modified Thayer-Martin media
``` chocolate agar with antibiotics: - vancomycin inhibits gram-positives - colistin inhibits gram-negatives - nystatin inhibits yeasts - trimethoprim inhibits swarming Proteus selects for Neisseria gonorrhoeae ```
64
Gram stain
detects nearly all clinically significant bacteria
65
Organisms that won't gram stain
- 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
WBC's and epithelial cells gram stain ________
pink
67
Gram stain reagents
crystal violet (primary stain), Gram's iodine, decolorizer, safranin (counterstain)
68
Gram-positive organisms
- cell walls contain thick peptidoglycan - retain crystal violet dye and resist decolorization - stain purple
69
Gram-negative organisms
- cell walls contain thinner layer of peptidoglycan - allow crystal violet to wash out with decolorizer - retain safranin counterstain - stain pink or red
70
- suggested by Louis Pasteur and Robert Koch | - first to say that diseases are caused by microorganisms
Germ Theory
71
- 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
Koch's Postulates
72
rate at which RBC's settle out of blood in one hour; altered by inflammatory proteins, making RBC's heavier and faster to fall
sedimentation rate
73
antiviral that blocks viral replication by inhibiting the synthesis of viral proteins
interferon
74
- immune response triggered by an antigen that involves phagocytosis of the antigen cells - divided into cell-mediated immunity and humoral immunity
specific immunity
75
Deals with viral and bacterial infections
humoral immunity
76
Deals with protozoal and some bacterial infections
cell-mediated immunity
77
- grows most non-fastidious organisms - no advantage to any particular bacteria - Trypticase soy agar (TSA), Trypticase soy broth (TSB), Nutrient agar, Nutrient broth
supportive media
78
- contains nutritional enhancements for the growth of fastidious organisms - Sheep blood agar (SBA), Chocolate agar (CA), Buffered charcoal yeast extract (BCYE)
enriched media
79
- contains blood cells - good plate for identifying hemolysis - Neisseria meningitidis
Sheep Blood Agar (SBA)
80
- contains lysed blood cells that release NAD - IsoVitalex enrichment: dextrose, cysteine, Vit. B12, thiamine, ferric nitrate - Neisseria gonorrhoeae
Chocolate Agar (CA)
81
- liquid medium that will grow a small number of an organism and suppress normal flora - Gram-negative broth, selenite broth
enrichment broth
82
- contain bile salt (as sodium desoxycholate), which is toxic to gram-positive organisms and inhibitory to fecal flora
Gram-negative broth
83
- allows grouping based on characteristics demonstrated on the medium - MacConkey agar (Mac), Eosin methylene blue (EMB)
differential media
84
- contains lactose, bile salts, neutral red indicator, crystal violet (selective differential media) - lactose-fermenters appear pink - non-lactose-fermenters appear colorless
MacConkey agar (Mac)
85
- 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)
selective media
86
- inhibit growth of gram-positives and gram-negative coliform bacteria - permit isolation of stool pathogens
Hektoen enteric media (HE), Salmonella-Shigella agar (SS), Xylose-lysine-deoxycholate agar (XLD)
87
- inhibits growth of aerobes and falcultative gram-negative rods - allows growth of gram-positive cocci
phenyl ethyl alcohol (PEA)
88
- selective for certain organisms through addition of specific antibiotics - Modified Thayer-Martin media (MTM)
antibiotic media
89
- cell walls contain thick peptidoglycan - retain crystal violet dye and resist decolorization - stain purple
Gram-positive organisms
90
- cell walls contain thinner layer of peptidoglycan - allow crystal violet to wash out with decolorizer - retain safranin counterstain - stain pink or red
Gram-negative organisms
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