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Lab Flashcards

(102 cards)

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1
Q

what antiseptics/disinfectants disrupt the lipid bilayer

A

alcohols, soaps, detergents

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2
Q

what antiseptics/disinfectants are oxidizing agent

A

hydrogen peroxide, halogens, metals, aldehydes, ethylene oxide, benzalkonium chloride

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3
Q

what antiseptics/disinfectants break H bonds

A

acids and bases

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4
Q

what is the function of pasteurization

A

heat to reduce number of microbes but not to zero

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5
Q

besides time, what is the main difference between vat, high temperature, and ultra pasteurization

A

temperature

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6
Q

what are the temperature differences between vat, high temperature, and ultra pasteurization

A

vat= 145F (63C)
high temp= 161F (72C)
ultra= 280F (138C)

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7
Q

how does an autoclave work

A

it holds water at 121C and 2x atmospheric pressure for 15 minutes to destroy all microbes including spores

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8
Q

what type of setting is UV radiation used in for sterilization

A

hospital

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9
Q

how does ionizing/gamma radiation work

A

creates free radicals to damage DNA

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10
Q

what is gamma radiation used for

A

to sterilize items that can’t be put through an autoclave (ex: plastics)

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11
Q

what is involved in liquid filtration

A

sterilized liquids by passing them through a filter with 2 micrometers

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12
Q

when is liquid filtration used

A

when heating would kill something you wanted to preserve

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13
Q

how does a hemocytometer/Petroff-Hausser Counter with microscopy work to count bacteria

A

it uses a microscope slide with grids
the volume of each square is known so you can count the number of cells in each square and multiple to determine the number of bacteria in the liquid sample

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14
Q

how does spectrophotometry work

A

a line is shined though the liquid sample and the amount of light blocked is used to determine the number of bacteria in the sample by comparing it to McFarlands 0.5 standard

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15
Q

what are 2 limitations with spectrophotometry

A

production of biofilm increases bacteria size so you may be over-counting
can’t be used with samples that are too dark or too opaque

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16
Q

what is the concentration and number of bacteria in McFarlands standard

A

0.5
1x10^8 bacteria/mL

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17
Q

how many bacterial colonies must be present on a plate to count

A

30-300

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18
Q

what are 2 limitations to counting bacteria on a plate

A

biofilm causes bacteria to stick together so each colony may represent more than 1 bacteria
having more than 300 colonies is likely that some colonies represent more than 1 bacteria leading to undercounting

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19
Q

what is the dilution standard for antibody/antigen samples

A

1:2

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20
Q

in titers, the __ the second number, the more antibody present (higher or lower)
ex: is 1:16 or 1:64 a greater titer

A

higher
1:64

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21
Q

what causes zeta potential in RBC

A

sialic acid on the RBC surface creates a net - charge that IgG is too small to overcome, therefore IgM must be used for crosslinking

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22
Q

what antibody does blood typing use

A

anti-RBC IgM

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23
Q

what is the question asked for the indirect Coomb’s test

A

is there IgG that binds to the RBC
*used maternal serum

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24
Q

what is the question asked for the direct Coomb’s test

A

does the RBC have IgG stuck to it
*uses fetal RBC

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25
how does radial immunodiffusion differ from double immunodiffusion
radial determines the amount of antigen in the sample double immunodiffusion tells us if the antigen is present or not
26
do immunoassays use monoclonal or polyclonal antibodies
mono
27
what is ELISA used for
to detect protein/antigen in serum using antibodies *can be used to determine titer
28
what does ELISPOT TSpot test for
how many cells dump out the protein of interest *more spots on plate= more cells that released the protein/cytokine ex: if T cells make IFN gamma "is IFN gamma released in response to tuberculosis antigen?"
29
what is the function of immunohistochemistry
used to access tissue location a protein localizes in
30
what results does fluorescence activated cell sorting (FACS) give is
percent of cells that express a specific marker and level of expression (flow cytometry)
31
what does neutrophil functional assay tell us
if oxidative burst is functioning and NADPH oxidase is made (shift in flow cytometry= working)
32
what is the function of leukocyte function assay
determine if B and T cells have normal activity by using something you know will activate all B or all T cells
33
what 2 things can be used to stimulate T cells in leukocyte function assay
PHA antibodies against CD3 and CD28
34
what is used to stimulate B cells in leukocyte function assay
antibody against antibody (ex: antibody against IgG)
35
how do you measure T cell proliferation
used fluorescence based assay, dye the cytoplasm, stimulate T cells, notice degree of decreasing fluorescence
36
how would you perform a functional assay for apoptosis
isolate monocytes/T/B cells treat with PHA to stimulate T cells culture with IL-2 for T cell proliferation add anti-FAS antibody to trigger apoptosis use TUNEL assay to detect fragmented DNA *undergoing apoptosis= cell will fluoresce
37
how can you test for T cell maturation
if cells are actively undergoing VDJ recombination in the thymus, the T cell receptor excision circles will be detected in the blood if they are absent, there is no VDJ recombination= no T cells= can be used to detect SCIDs
38
what is the function of CH50 test (complement hemolysis 50%)
test if complement is working or if it has been used up less complement= CH50 closed to 1:2
39
what is the Cr51 release assay used to test for
CD8+ T cell function
40
when should modified acid-fast staining be performed
for actinomyces, fungi, and some parasites
41
if everything turns pink, what happened with the gram stain
too much decolorizer
42
if everything is purple, what happened with the gram stain
not enough decolorizer
43
what bacteria does MacConkey agar select against
gram + and bacteria that can't grow in the presence of bile
44
what does it mean if MacConkey agar turned pink
bacteria ferments lactose
45
what does eosin methylene blue agar select against
gram +
46
what does if mean if the eosin methylene blue agar turned dark green/black
the bacteria ferments lactose
47
what does mannitol salt agar select against
bacteria that need high water activity to grow
48
what does it mean if mannitol salt agar turns yellow
the bacteria ferments mannitol
49
what bacteria show on ESBL agar
e.coli O157.H7 is pink MRSA is blue all other bacteria are white
50
TSI slants are used as a differential for what 3 characteristics
acid production (fermentation) gas production precipitation of metal
51
what 2 media allow for precipitation of a metal
Hektoen enteric agar tellurite containing blood/chocolate agar
52
what is charcoal buffered yeast agar used for
charcoal absorbs toxic metabolites generated by growing bacteria
53
what is chocolate agar used for
to grow bacteria that need components or RBC to grow but don't have the enzymes to break down RBC on their own
54
what is the function of PCR
look for presence or absence of 1 specific gene (ex: antibiotic resistance or virulence factor gene)
55
what is the function of rt-PCR
determine viral load of a virus with an RNA genome
56
what is the function of western blot what infection is it often used for
looks for the amount of one protein made HIV
57
what is pulse field gel electrophoresis (PFGE) used for
determine whether the organism is of the same strain (used to identify foodborne illness outbreaks)
58
what is multi-locus sequence typing used for
to measure evolutionary relatedness by identifying point mutations *more detailed than PFGE
59
what is ribosomal RNA sequencing used for
identify organisms at the species level
60
what are the steps to determine if molecular Kochs postulates have been met
mutate isolate to knockout the gene perform artificial transformation to reintroduce a plasmid containing the gene if reintroduction of the gene into the bacteria leads to the bacteria causing symptoms again, the pathogenic gene has been identified and postulates have been satisfied
61
how much blood should be collected for culture in adults vs children vs neonates
adults: at least 20mL children: at least 10mL neonates: 2mL
62
how can culturing be used to determine if meningitis is caused by bacterial or fungal infection
compare the glucose concentration in the blood vs in CSF Viral= normal glucose Bacterial or fungal= low glucose
63
once blood is collected, how is it distributed in vials
half in a viral for anerobic organisms half in a vial for aerobic organisms
64
when is a broncho-alveolar lavage used
if a sample needs to be taken but no sputum is being produced for collection
65
how does ViTEK identify organisms
based on culture characteristis
66
how does MALDI-ToF identify organisms
based on molecular signatures of different bacteria/fungi/parasites
67
how does BioFire identify an organism
by testing for the presence or absence of multiple genes simultaneously
68
why is MALDI-ToF not often used in hospital
it is expensive for the machine and subscription to databases
69
what is the main advantages of MALDI-ToF to identify an organism
results within 2 hrs= faster diagnosis
70
what are the 2 main advantages of BioFire to identify an organism
organisms don't have to be grown (uses the direct sample) primers cover the most common pathogens with the symptoms present
71
what agar is used for the Kirby Bauer test
Mueller Hinton
72
how does minimum inhibitory concentration differ from minimum bacterial concentration
MIC- lowest concentration to prevent bacterial growth MBC- lowest concentration to kill bacteria
73
what is the difference between primary cell culture vs diploid cell strain vs continuous cell line
primary- cells taken from a living animal, keep alive as long as possible diploid- cells of single cell type can be cultured approx. 50 times continuous- malignant cells can be cultured an infinite number of times
74
what is the cytopathic effect with viruses
even if we can't see visible virus, we know there was infections based on changes in the cell that the virus made
75
if a virus is a DNA viral, inclusion bodies will be found in __. If RNA, they will be found in __
DNA- nucleus RNA- cytoplasm
76
what is used to determine the number of viruses in a sample
viral plaque assay more virus= more cells killed= more plaques
77
for viruses, samples need to be collected within __ days of symptoms
3-7
78
viral samples for nucleic acid detection must be kept at __C or frozen at __
4C -70C
79
for detection of various viral strains, what are primers used to detect
hemagglutinin and neuramidase (each are strain specific)
80
for use of ELISA to detect viral proteins, how is it performed
add specific antibodies to blood antigen will bind to antibody add a secondary antibody to visualized bound antigens
81
what question is hemagglutination answering
how much virus is there
82
how is hemagglutination interpreted
the more virus, the more hemagglutinin, the more clumping (seen fuzzy in well plate)
83
what question is hemagglutinin inhibition answering
is there antibody that binds to the virus
84
how is hemagglutination inhibition results interpreted
higher hemagglutinin inhibition= more antibody= less clumping (seen as a button on well plate)
85
what method of identification would not be used to identify a virus
electron microscopy
86
how do cassette based tests work
viral proteins are bound to a nitrocellulose membrane antibodies bind to these proteins the control line is loaded with IgG so it will always show since the sample will always have IgG the test line has the peptide of interest so the patient's antibodies will stick to the antigen protein A colloid gold conjugated binds to the Fc portion of the antibody allowing for a visible colored time for test results
87
ELISA and flow cytometry (FACS) both measure protein expression. how do they differ in their measurement
ELISA- protein in serum/culture flow cytometry (FACS)- protein expression on cells
88
is fluoride always toxic
no, it depends on the concentration
89
what would we use to filter bacteria from solution containing it's toxin
liquid filtration
90
what size of filtration will not allow bacteria to pass
0.2micrometers
91
what would we use to check a bacteria sample in saline that is MRSA after inoculation on a plate
McFarland
92
what agar would be used to isolate intestinal bacteria that are gram -
MacConkey
93
what does the color change on eosin methylene blue agar indicate about the bacteria
lactose fermenting
94
what culture method should be used to see if something from a pond can grow on skin
Mannitol salt agar
95
what culture method would you use to test if an organism can live on human skin
mannitol salt agar
96
if a bacteria that is beta hemolytic when near bacteria that lyse RBC is grown on its own, what type of agar is needed
chocolate
97
what test would you use to compare 2 types of pathogens based on 1 gene
PCR
98
if an adult is suspected of having bacteremia, how would you diagnose it
draw 20mL blood and divide half and half into an anaerobic tube and an aerobic tube
99
why would a urine sample contain erythrocytes and gram positive and negative bacteria, but no leukocytes
contamination by normal vaginal flora and menstrual blood
100
why would we use a monoclonal antibody
it has high specificity
101
what benefits does immunohistochemistry provide
it allows us to visualize specific locations of cells and tissues that were targeted
102
what would be the secondary reagent in an indirect fluorescent antibody test
fluorochrome bound to an anti-human Ig

IDR (3 decks)

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