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Bacteriology Practice Questions > LAB FINAL > Flashcards

LAB FINAL Flashcards

1
Q

What is needed on every plate?

A

Name

Instructor’s name

Date

Name of organism

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2
Q

For sterilizing wire loops, what color must the flame be?

A

blue

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3
Q

Why should you let a hot loop cool after flaming before picking up the organism?

A

A hot loop will kill the cells

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4
Q

What is the first step in transferring from one medium to a second sterile medium?

A

Check to make sure the organism you’re transferring is the correct one

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5
Q

T/F:

Always place a cap directly on the table face up to prevent contamination

A

False

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6
Q

T/F:

Always incubate the plates taped together and upside down

A

TRUE

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7
Q

What is the purpose of quadrant streaking?

A

To obtain isolated colonies from an inoculum

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8
Q

What materials are needed for quadrant streaking?

A

inoculum

agar plates

inoculating loops

propane tanks

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9
Q

How many quadrants are there in quadrant streaking?

A

4….duh.

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10
Q

How long is the incubation for a quadrant streaked plate?

A

24 hours

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11
Q

What type of growth is seen in the 4th quadrant?

A

single colonies

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12
Q

What type of growth is seen on the 2nd quadrant?

A

dense growth

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13
Q

What solution should you use to disinfect your work station?

A

70% ethanol

10% bleach

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14
Q

How should solid waste be disposed?

A

placed in a biohazard bag

and autoclaved

before being thrown out with the regular trash

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15
Q

What is the purpose of aseptic technique?

A

prevent environmental contamination

maintain pure stock cultures

isolation of a single species from a mixed culture

prevent lab microbes from being released into environment

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16
Q

What are the 3 plating techniques?

A

pouring plate

spreading plate

streaking plate

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17
Q

What is TSA (trypticase soy agar) used for?

A

general purpose medium allowing for a variety of organisms to grow

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18
Q

What is blood agar used for?

A

To grow fastidious organisms

and

differentiate bacteria based on hemolytic properties

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19
Q

What is MacConkey agar used for?

A

Grow gram negative bacteria

and

differentiate lactose from non-lactose fermenters

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20
Q

What color are lactose fermenters on MacConkey agar?

A

red/pink

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21
Q

What color are non-lactose fermenters on MacConkey agar?

A

white/colorless

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22
Q

What is the purpose of Hektoen enteric agar?

A

differentiate *Salmonella *and *Shigella *from enteric bacteria

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23
Q

What causes green, moist, raised colonies on Hektoen enteric agar

A

Shigella

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24
Q

On Hektoen enteric agar, what causes blue-green colonies with or without black centers?

A

Salmonella

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25
Q

What bacteria is Brilliant Green agar selective for?

A

Salmonella

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26
Q

What color is Salmonella on XLD (Xylose Lysine Deoxycholate) agar?

A

red colonies with a black center

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27
Q

What color are E. coli colonies on Eosin Methylene Blue agar?

A

metallic sheen

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28
Q

What is another name for the iodine in gram staining?

A

mordant

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29
Q

What are the steps (in order) of gram staining?

A

Crystal Violet

Iodine

Decolorizer

Safranin

(CIDS)

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30
Q

What is the most critical step of gram staining?

A

Decolorizer

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31
Q

T/F:

Gram positive bacteria stain pink/ red with gram staining

A

false – gram positive bacteria stain purple/ blue

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32
Q

How does heat fixing occur with gram staining?

A

Pass slide over open flame 3x

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33
Q

When should you stop adding decolorizer?

A

When the runoff becomes clear

or after

10-20 seconds

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34
Q

What power on the microscope should be used to look at gram stained samples?

A

100x (oil)

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35
Q

T/F Bacilli come in clusters, chains, pairs, and tetrads

A

FALSE

COCCI come in clusters, chains, pairs, or tetrads

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36
Q

What is the purpose of the oxidase test?

A

Used to ID bacteria that produce

cytochrome oxidase

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37
Q

T/F

you should always mark delayed reactions in an oxidase test

A

FALSE

delayed reactions should always be ignored

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38
Q

T/F:

A positive oxidase test changes colors to dark purple

A

TRUE

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39
Q

What is the purpose of the catalase test?

A

detects the enzyme catalase that converts hydrogen peroxide to water and gaseous oxygen

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40
Q

T/F catalase activity is present in obligate anaerobic bacteria

A

false – catalase activity is present in most aerobic bacteria but not in obligate anaerobes

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41
Q

What is indicative of a positive catalase test?

A

immediate bubbling

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42
Q

T/F Anaerobes are oxidase negative

A

TRUE

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43
Q

What are the possible results in a motility test?

A

positive

negative

uninoculated

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44
Q

What is the medium for a Urease test?

A

Christenson medium

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45
Q

What does a positive Indole test look like?

A

reagent layer (on the top) is a deep red, remainder is clear

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46
Q

What is tested for in a Methylene Red test?

A

small molecular weight acids

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47
Q

What color is a positive Methylene Red test?

A

red

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48
Q

What is being tested for in a Voges-Proskauer test?

A

Acetoin derived from glucose

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49
Q

What color is positive in a Voges-Proskauer test?

A

red

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50
Q

What is tested for in a Simmons citrate test?

A

ability to use citrate as a sole carbon source

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51
Q

What color is positive on a Simmons citrate test?

A

blue

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52
Q

What is API 20E?

A

standardized identification system for enterobactericeae which are gram negative, oxidase negative, rods

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53
Q

Why use API 20E?

A

biochemical identification of an unknown organism

54
Q

T/F

in preparing for the API 20E the organism suspension should have a clearly visible turbidity equal to the 0.5 McFarland turbidity standard.

A

TRUE

55
Q

T/F with API 20E you should accept a result >80%

A

false – you should accept a result of >90%

56
Q

T/F the morphology and staining characteristics of the Enterics are similar, making it difficult to distinguish them

A

True

57
Q

T/F

in the Enterics antimicrobial susceptibility is difficult to predict

A

true

58
Q

What media grow Enteric species?

A

Blood

MacConkey

XLD

Hektoen

Brilliant Green

59
Q

What is the purpose of antimicrobial susceptibility tests?

A

to determine if a course of treatment will work in vivo

60
Q

How is antimicrobial susceptibility tested?

A

Kirby-Bauer, Minimal Inhibitory Concentration (MIC)

61
Q

The E-test and the Broth microdilution are part of which type of antimicrobial susceptibility test?

A

MIC

62
Q

Which organization wrote interpretation criteria for antimicrobial susceptibility tests?

A

Clinical and Laboratory Standards Institute (CLSI)

63
Q

T/F a clinical outcome can easily be predicted from an antimicrobial susceptibility test:

A

false – Predicting clinical outcome based on susceptibility testing is extremely difficult due to other factors (site of infection, pharmacodynamics, etc)

64
Q

Which susceptibility method(s) create(s) a zone size?

A

Kirby- Bauer

65
Q

What is the standard agar base used to carry out antimicrobial susceptibility testing?

A

Mueller Hinton plate

66
Q

T/F antimicrobial susceptibility testing should only be performed on clinically significant bacteria

A

True

67
Q

Which susceptibility method(s) create(s) an MIC?

A

E-test and Broth microdilution

68
Q

What is the definition of an “intermediate” result in antimicrobial susceptibility testing?

A

may still be effective against the bacterium but less so than a susceptible isolate

69
Q

During a Kirby-Bauer test, how many times should the plate be streaked?

A

3 times and then the plate should be rimmed

70
Q

T/F you should carefully move a disk with a loop on the Kirby-Bauer test if the dispenser put it in the wrong location

A

false – once the disk touches the agar, it should not be moved

71
Q

How is an E-test measured?

A

read at the point where the clear area (ellipse) meets the strip

72
Q

What is reported in an E-test?

A

the MIC and the interpretive criteria (sensitive, intermediate, resistant)

73
Q

What is one of the most important components of PCR?

A

a pair of synthetic oligonucleotides to primer DNA synthesis

74
Q

T/F before synthesizing a primer it is prudent to scan DNA databases to check that the proposed sequence occurs only in the desired gene and not in vectors or undesired genes

A

True

75
Q

How long should a primer be?

A

18-35 nucleotides

76
Q

T/F members of a primer pair should not be more than 8 base pairs longer than each other

A

false – members of a primer pair should not be more than 5 base pairs

77
Q

How much of a primer should constitute C+G?

A

40 - 60%

78
Q

What is the danger of repeated and self complementary sequences longer than 3 base pairs in a primer?

A

tends to make hairpin structures and prevent

primer binding to the target

79
Q

What is the danger of complementarity between primer pairs?

A

primer dimers will form and result in no or low product yield

80
Q

What is the formula for melting temperature of primers?

A

Tm (in celcius) = 2(A+T) + 4(G+C)

81
Q

How many degrees difference can the melting temperature between primer pairs be?

A

5 degrees

82
Q

. T/F it is necessary to add restriction sites to primers

A

false – this is dependent on what you are supposed to do with the PCR product

83
Q

Which end of the primer do you add the restriction sites?

A

5’

84
Q

Why are base pairs added to the end of the restriction sites?

A

To increase efficacy of cleavage

85
Q

What does ELISA stand for?

A

Enzyme Linked ImmunoSorbent Assay

86
Q

What is detected by ELISA?

A

antigens or antibodies of interest

87
Q

What are the different forms of the ELISA?

A

direct, indirect, sandwich

88
Q

T/F the basic concept of the ELISA is the qualitative and immunological detection of antigen or antibodies in a clinical sample

A

false – the basic concept of the ELISA is the immunological detection and quantitation of antigen or antibodies in a clinical sample

89
Q

What is direct ELISA?

A

used to detect an antigen after it has attached to the solid phase

90
Q

What are the steps of direct ELISA?

A

Coating, blocking, detection, read results

91
Q

What is an indirect ELISA?

A

primary antibody attaches to an antigen.

secondary antibody is attached to the primary antibody with a label, allowing for reading the sample

92
Q

What is a sandwich ELISA?

A

a capturing antibody is absorbed into the solid phase

        and it is

used to determine an unknown microbial infection

93
Q

Why is it important in sandwich ELISA to use an antibody from a different animal species?

A

it prevents same-species antibody binding

94
Q

Which types of ELISA require stringent optimization?

A

indirect

and

sandwich

95
Q

What is the purpose of the decolorizer when Gram staining

A

Clear the color from selective bacteria

96
Q

What is the purpose of the counterstain of the Gram stain?

A

To color GRAM NEGATIVE bacteria

97
Q

Which of the following bacteria is not KOH positive?

A

Any gram (+) bacteria will be (-) for KOH

*Staphylococcus *spp.

98
Q

What is the reagent used in the catalase test?

A

Hydrogen peroxide

99
Q

T/F

The differences between Pseudomonas and E.coli are the smell of grapes and the fact that Pseudomonas was oxidase negative

A

FALSE

Pseudomonas is oxidase POSITIVE

100
Q

What does the dispersion on the MOI medium mean?

A

Motility

101
Q

What does TSI not selective for?

A

Motility

102
Q

Which sugar is not a part of the TSI medium?

A

MALTOSE

(glucose, sucrose and lactose ARE)

103
Q

Which of these does not include the specific antigen-antibody complex?

A

*PCR

104
Q

T/F

Fungi are stained by all of the following

Gram, Cotton, PAS

A

TRUE

105
Q

Non selective media?

A

Sabauraud’s Dextrose Agar

106
Q

What AA is involved in indole?

A

tryptophan

107
Q

Oil immersion lens magnifies how much?

A

100x

108
Q

What bacteria is metallic green on Eosin-Methylene Blue agar?

A

E. coli

109
Q

T/F

When finding the zone of inhibition, you measure the radius of lysis on the plate

A

FALSE

diameter

110
Q

In an oxidase/fermentation test, the results were 2 yellow tubes.

What bacteria do you have?

A

Facultative anaerobe

111
Q

How do you differentiate between Enterobacteria and Pseudomonas?

A

Oxidase test (Pseudomonas is Oxidase +)

112
Q

How do you

Distinguish Streptococcus from Rhodococcus?

A

Catalase Test

Streptococcus is (-)

113
Q

T/F

You should collect blood samples minutes apart

A

FALSE!

HOURS apart

114
Q

T/F

Plates are incubated inverted

A

TRUE

115
Q

When do you check a

Micro ID?

A

After 4 hours

116
Q

What is the 3rd reagent in Gram staining?

A

Alcohol

117
Q

T/F

PCR tests for antibodies

A

FALSE

DNA/RNA

118
Q

T/F

Fungi can’t grow on MacConkey agar (it is selective)

A

TRUE

119
Q

Mannitol salt agar is used to grow what bacteria?

A

Staphylococcus

and it is a selective medium for this

120
Q

What is chlorahexidine?

A

A bench cleaner

121
Q

Dog has abscess, you take a swab from the outside and plate it. Results showed growth of coagulase negative staphylococci. You take a sterile aspirate of the center of the abscess and plate it. Results show Staphylococcus aereus. What can you tell your client?

A

Organism on the outside is Non-pathogenic while

Staphylococcus aereus is Pathogenic

122
Q

Dog comes into a clinic, you suspect UTI what diagnostic test do you first perform?

A

Plate on blood agar

123
Q

T/F

Kirby Bauer is a low cost test

A

TRUE

124
Q

What are the 3 Methods for antimicrobial susceptibility testing?

A

Kirby Bower Disc Diffusion, Microdilution Broth, E Test

125
Q

Who uses Kovac’s Reagent?

A

Oxidase test and MIO

126
Q

You perform TSI and your results show a yellow slant, negative for gas production and a black butt. You write the report and include the following for your findings:

A

Acid Slant, Acid Butt, positive H2S production

127
Q

Real Time PCR process is Denaturation, Annealing and Extension. What temp for Denaturation?

A

92°C (in notes it’s 94°C but no choices are close to this other than 92 °C)

128
Q

E.coli turns the medium Yellow with yellow colonies

in what medium?

A

XLD agar

129
Q

XLD is Selective and Differential for Enteric Pathogens, Especially to distinguish

______ from _____

A

*Salmonella *from Shigella

130
Q

Crystal Violet and Bile Salts Inhibit Gram (+) and many Gram (-)

on what medium?

A

MacConkey agar

131
Q

XLD agar and TSI , what is used by Salmonella to produce H2S (Hydrogen Sulfide)?

A

Sodium Thiosulfate

Salmonella (or other bacti) + Sodium Thiosulfate–> H2S
H2S + Ferric Ammonium Citrate–> Black Color

Bacteriology Practice Questions (16 decks)

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