Lab Practical Exam Review Flashcards

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1
Q

bacterial spores require temperatures above __ for destruction

A

100°C

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2
Q

bacterial vegetative cells are killed at temperatures of ___ to ___ in __ minutes

A

60°C, 70°C, 10

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3
Q

fungi can be killed at __ to __

A

50 to 60°C

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4
Q

fungal spores require __ to __ in __ minutes for destruction

A

70°, 80°, 10

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5
Q
  • test for hemolysis of colonies
  • primarily to distinguish staphylococci and streptococci
A

blood agar plates

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6
Q
  • tests for staphylococci
  • differential for S. aureus versus avirulent staphylococci
A

mannitol salt agar

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7
Q
  • used for neisseria and haemophilus bacteria
  • neisseria develop pink/purple coloration after oxidase test (addition of p-aminodimethylaniline oxalate)
  • requires CO2
A

chocolate agar

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8
Q
  • demonstrates presence of diptheroids (corynebacteria)
  • tellurite ions diffuse into bacteria and reduce to tellurium metal which preceipitates
A

Mueller-Hinton tellurite agar

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9
Q

blood agar, mannitol salt agar, chocolate agar, mueller-hinton tellurite agar

A

plates for throat microbiota

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10
Q
  • detects yeasts and molds
  • yeasts will be glistening and pigmented or not
  • molds will appear fuzzy or powdery
  • requires 25°C first
A

sabouraud agar

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11
Q

blood agar, mannitol salt agar, sabouraud agar

A

plates for skin microbiota

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12
Q
  • differential test to determine S. aureus
  • converts fibrinogen to fibrin forming a clot
A

coagulase

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13
Q
  • enzyme that degrades DNA; addition of toluidine blue makes pink halo
  • differential for S. aureus
A

DNase

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14
Q
  • golden colored colonies
  • produces coagulase
  • produces DNase
  • beta hemolytic
A

S. aureus

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15
Q

resistant to novobiocin

A

S. saprophyticus

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16
Q

gram-positive cocci including pathogenic and generally non-pathogenic strains

A

streptococci

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17
Q

sole member of the Lancefield group A streptococci often referred to as GAS, or group A strep
- beta hemolysis
- susceptible to bacitracin

A

S. pyogenes

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18
Q

most common cause of life-threatening neonatal sepsis; S. agalactiae

A

group B streptococci (GBS)

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19
Q
  • hemolysis
  • bacitracin test
  • CAMP test
A

tests to identify human streptococcal pathogens

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20
Q

bacitracin antibiotic susceptibility; GAS is susceptible

A

bacitracin test

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21
Q

GBS make a peptide that interacts beta hemolysins of S. aureus causing increased hemolysis

A

CAMP test (peptide)

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22
Q
  • isolation of distinct colonies
  • determine purity of culture
A

streak plate (4 quadrant streak or T-(3) streak)

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23
Q
  1. aseptic technique
  2. labeling
  3. ability to isolate individual colonies
A

steps for a streak plate

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24
Q

Enterococcus faecalis
Staphylococcus aureus
Bacillus cereus

A

gram-positive bacteria

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25
Q

Escherichia coli
Klebsiella aerogenes
Proteus vulgaris
Pseudomonas aeruginosa
Alcaligenes faecalis

A

gram-negative bacteria

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26
Q

primary stain; stains everything strongly in acid-fast stain

A

carbolfuchsin

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27
Q

counter-stain for acid fast staining (non-acid fast cells)

A

methylene blue

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28
Q

used for decolorization for acid-fast staining; removes stain from non acid-fast cells

A

acid alcohol

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29
Q
  • Schaeffer-Fulton method
  • uses primary stain malachite green to visualize cells
A

spore stain

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30
Q

stains cells weakly, steam forces stain into spores; spore retains stain while other bacterial cells lose it

A

malachite green

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31
Q

counterstain for spore stain

A

safranin

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32
Q

spores are resistant to __

A

decolorization

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33
Q

genus for spore stains

A

bacillus and clostridium

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34
Q
  • selective for gram-negative enterics
  • differential for coliforms
  • uses lactose and neutral red pH indicator
A

MacConkey Agar

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35
Q

bacteria exhibit red/pink coloration on their surface on MacConkey Agar

A

lactose fermenters/coliforms

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36
Q

no change on MacConkey Agar; colonies appear uncolored or same color as medium

A

non-lactose fermenters/pathogens

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37
Q

bile salts and crystal violet; inhibit G+ growth

A

selective reasoning for MacConkey Agar

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38
Q

MacConkey Agar-
produces acid by-products from lactose fermentation, which turn the medium surrounding the colony red in the presence of neutral red indicator dye

A

E. coli

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39
Q

MacConkey Agar-
does not ferment lactose but does grow on the plate

A

P. aeruginosa

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40
Q

MacConkey Agar-
does not grow in the presence of bile salts and crystal violet, both of which inhibit the growth of gram-positive bacteria

A

S. epidermidis

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41
Q

selective for staphylococcus and differential for S. aureus

A

mannitol salt agar species

42
Q

high salt concentration (7.5% NaCl)

A

why mannitol salt agar is selective for staphyloccocus

43
Q

the carbohydrate, mannitol, is fermented by S. aureus resulting in acidic end product which turn the phenol red indicator yellow around growth

A

why mannitol salt agar is differential for S. aureus

44
Q

-selective for fastidious bacteria; streptococcus pathogens
-differential for S. pneumoniae, S. pyogenes, and non-pathogenic bacteria (based on hemolysis)

A

blood agar

45
Q

hemolysis

A

lysis of RBCs

46
Q

alpha hemolysis on blood agar; partial clearing and green halo around bacterial colonies

A

streptococcus pneumoniae

47
Q

beta hemolysis on blood agar; complete zone of clearing around colonies

A

streptococcus pyogenes

48
Q

gamma hemolysis on blood agar; no clearing and no color change

A

non-pathogenic bacteria

49
Q

-selective for gram-negative enterics (enterobacteriaceae)
-fecal coliform bacteria
-differential for coliforms vs. non-coliforms

A

Eosin-Methylene Blue (EMB) Agar

50
Q

eosin and methylene blue dyes inhibit growth of most G+ organisms

A

why EMB agar is selective for gram-negative enterics

51
Q

lactose and the eosin and methylene blue dyes

A

what makes EMB agar differential for coliforms vs. non-coliforms

52
Q

thick, mucoid purple/pink colonies due to decreased pH from lactose fermentation

A

lactose fermenters/coliforms on EMB agar

53
Q

Escherichia, Klebsiella, Serratia, Citrobacter

A

examples of lactose fermenters/coliforms

54
Q

colonies are blue-black with a metallic green sheen due to a large quantity of acid made by lactose fermentation that precipitates the dyes onto the colony surface

A

E. coli on EMB agar

55
Q

on EMB agar- no change, colorless colonies- may appear purple due to the color of the medium

A

non-lactose fermenters/pathogens on EMB agar

56
Q

Salmonella, Shigella, Yersinia

A

examples of non-lactose fermenters/pathogens on EMB agar

57
Q

fails to grow in the presence of eosin and methylene blue

A

S. epidermidis

58
Q

able to carry out limited fermentation of the sugars in EMB agar, turning the methylene blue indicator red and imparting a pink color to the colonies

A

K. aerogenes

59
Q

peptone, lactose, sucrose

A

sugars in EMB agar

60
Q

circular bacterial morphology

A

cocci

61
Q

rod bacterial morphology

A

baccili

62
Q

2 cocci together
ex- streptococcus pneumoniae, enterooccus

A

diplococci

63
Q

cocci ex- staphylococcus aureus

A

cocci clusters

64
Q

cocci ex- streptococcus pyogenes

A

cocci chains

65
Q

bacilli ex- salmonella typhi (looks like tails off of rod)

A

flagellate rods

66
Q

bacilli ex- bacillus anthracis (multiple rods next to one another)

A

bacilli chains

67
Q

bacilli ex- clostridium botulinum (contain endospore)

A

spore formers

68
Q

spiral ex- treponema pallidum (normal squiggle)

A

spirochaetes

69
Q

sprial ex- helicobacter pylori (squiggle with tails)

A

spirilla

70
Q

spiral ex- vibrio cholera (curved rod with tail)

A

vibrios

71
Q

obligate aerobes, obligate anaerobes, facultative anaerobes, microaerophiles, aerotolerant anaerobes

A

five classes oxygen metabolism among microorganisms

72
Q

growth only at the top of the tube, closest to oxygen saturation

A

obligate aerobes

73
Q

growth only at the bottoms of the tube, closest to aerobic bottom zone

A

obligate anaerobes

74
Q

growth throughout entire tube but more concentrated at the top near oxygen saturation

A

facultative anaerobes

75
Q

growth only at the bottom portions of the TOP oxygen layer

A

microaerophile

76
Q

even growth throughout entire tube

A

aerotolerant anaerobe

77
Q

(colony count on agar plate) / (total dilution of tube used to make plate for colony x amount plated)

OR

number of colonies on plate x reciprocal of dilution of sample

A

the standard formula for dilutions and spread plates

78
Q
  • product of decarboxylation of certain amino acids
  • hydrolyzed to ammonia and carbon dioxide by bacteria containing enzyme urease
A

urea/urease test

79
Q

differentiate enteric bacteria on their ability to hydrolyze urea with the enzyme urease (rapid/weak/none)

A

reason for differentiation in urease test

80
Q

-only nutrient source- trace 0.0001% of yeast extract
-contains buffers strong enough to inhibit alkalization of the medium
-exception –> rapid urease-positive organisms

A

urea broth

81
Q

Proteus vulgaris
-turns hot pink for positive result

A

organism for urease test

82
Q

simmon’s citrate agar slant

A

medium for citrate utilization test

83
Q

differentiates enteric organisms on their ability to use citrate as a sole carbon source using the enzyme citrase

A

citrate utilization test

84
Q

indicator for citrate utilization test;
turns from green to blue in a basic pH to indicate a positive result

A

acid-base indicator Bromthymol blue

85
Q

conversion of ammonium phosphate to ammonia and ammonia hydroxide

A

reason for alkaline pH in positive citrate utilization test

86
Q

defined medium containing sodium citrate as the sole carbon source and the ammonium ion as the sole nitrogen source

A

simmon’s citrate agar

87
Q

utilization of peptone rather than the sugar in carbohydrate fermentation

A

alkaline metabolic product; color change to a dark pinkish-redish

88
Q

purpose is to differentiate among microorganisms that enzymatically transform different milk substrates (lactose, casein) into varied metabolic end products

A

litmus milks reactions

89
Q

pink medium for litmus milk

A

presence of lactic acid from lactose fermentation

90
Q

oxidized litmus

A

purple litmus color

90
Q

reduced litmus

A

white litmus color

90
Q

indicates proteolysis for litmus reactions

A

yellow/clearish liquid

91
Q

indicated elevated pH due to deamination

A

purple band at the top of yellow liquid for litmus reaction

92
Q

yellowish semisolid bottom medium in litmus reaction

A

curd formation

93
Q

blue top of medium for litmus reaction

A

alkaline conditions

94
Q

alkaline conditions for litmus reaction

A

purple or blue litmus

95
Q

positive presumptive test for LTB broth

A

indicates that coliforms are present in the water sample

96
Q

-selective using bile salts
-lactose for fermentation
-positive is both turbid and gas production
(for coliform test in water sample)

A

BGLB selective medium

97
Q

-streak a lawn (horizontal and vertical) of bacteria using sterile cotton swab saturated in culture
-divide plate into 6 labeled quadrants for disinfectant type
-sterilize tweezers to place dipped disk in quadrants
-look for zone of inhibition
(not quantitative because of varying amounts of chemical on disks)

A

Disinfectants: agar plate sensitivity method steps

98
Q

selectable marker genes in plasmid

A

amp^r and gfp

99
Q

able to grow on plates containing ampicillin and should express GFP

A

cells containing the plasmid