lab practical Flashcards
1
Q
What rapid tests are used in the lab?
A
Immuno-based assays
2
Q
What are rapid strep tests for?
A
Diagnosis of Strep. Pyogenes
3
Q
what type of antigens do strep tests look for?
A
group A strepococcal antigens
4
Q
what binds to an antigen when it has dye attached?
A
antibodies
5
Q
what is being detected in an immuno-based assay test?
A
a protein that is specific to a pathogen or a condition
6
Q
what is the most common point-of-care testing format?
A
rapid immunoassays that employ test strips
7
Q
what are point-of-care tests?
A
tests that are conducted by healthcare workers or patient without the need for any other lab equiptment
8
Q
if the specimen being tested contains Group A strep bacteria, the strep antigens extracted from the throat swab will what?
A
bind to these antibodies
9
Q
what is the “test” region for the strep test?
A
retention of the dye-colored antigen/antibody complexes
10
Q
what indicates that the sample is positive for Group A strep?
A
colored line at the test line region
11
Q
what does the test region also contain in the strep A test?
A
fixed antibodies that will bind directly to dye-labeled antibodies
12
Q
what does a strep test positive result look like?
A
2 lines running through the test region and control region
13
Q
what does a strep negative result look like?
A
one line in the control region
14
Q
what does an invalid result look like in a strep test?
A
one line in the test region
15
Q
are rapid strep tests foolproof?
A
no
16
Q
what is involved in a rapid staph test?
A
latex bead agglutination tests
17
Q
how is a rapid staph test done?
A
coated latex beads are mixed with the test organism and allows to interact
18
Q
what does a positive rapid staph test look like?
A
beads will appear and clump up
19
Q
what does a negative rapid staph test look like?
A
the beads will reman in a a homogenous suspension
20
Q
what type of species is the rapid staph test specific to?
A
staph. aureus
21
Q
what do all pathogenic strains of S. aureus produce?
A
a bound coagulase and contain Protein A on their cell surface
22
Q
what are the latex particles in a rapid staph test coated with?
A
human fibrinogen and IgG
23
Q
what are the steps of a rapid strep test?
A
- add 4 drops of regeant A to the tube
- add 4 drops of reagent B to the tube
- place throat swab in the tube
- squeeze the swab against the tube
- remove group A test strip and put into tube
- read results
24
Q
what color will the solution be after adding reagent A in a rapid strep test?
A
light red
25
what color will the solution be after adding the reagent B in a rapid strep test?
will turn a pale yellow
26
how many times do you agitate the swab in the tube for the rapid strep test?
10 times
27
how long is the throat swab left in the tube of the strep test?
1 minute
28
what is the correct end of the group A test strip?
wavy lines
29
how long does it take to read the results of a rapid strep test? when do you not read the results?
- 5 min
| - 10 min
30
what are the steps of a rapid staph test?
1. make sure the card is flat
2. dispense 1 drop of test latex onto both of the circles on the reaction card
3. dispense 1 drop of negative control solution onto one circle on the reaction card
4. use a sterile loop and smear a colony onto the other test-latex-containing circle
5. pick up a hand rock card
6. dispose of the card
31
how long should you hand rock the rapid staph test card?
20 seconds
32
should the control latex agglutinate?
no
33
why is the test region placed before the control region on the rapid strep test?
so the antibodies can reach the test region but not reach the control region
34
what is critical throughout the unknown project?
to use appropriate aseptic technique to prevent introducing environmental organisms into your cultures
35
what is the initial step of the unknown isolation?
gram staining
36
what is an essential step for most microbial identification strategies?
obtaining pure cultures
37
what are the steps of part 1 of the unknown project?
1. observation of mixed culture by gram staining
2. obtaining isolated colonies
3. identify isolated colonies that are pure by observing gram stains
4. inoculate stock slants with bacteria from a isolated and pure colony
5. confirm the purity of your stock slants
38
why do we gram stain our unknown project in the beginning?
to confirm mixed culture and assess arrangement
39
what are the 3 types of agars we use in our isolation streaks?
1. nutrient/ TSA
2. PEA
3. MacConkey
40
is the TSA gram positive, negative or both?
both
41
is the PEA gram positive, negative or both?
gram positive
42
do we use the MacConkey agar to identify pure colonies?
no
43
what type of test did we do to properly classify gram positive organisms?
catalase test
44
what is the catalase test used to do?
differentiate staphlyococcal species from strep/enterococcal species
45
what is the catalase test based on?
how these organisms detoxify hydrogen peroxide
46
what exactly is catalase?
an enzyme that converts hydrogen peroxide into water and molecular oxygen
47
what is the catalase test's first step?
collect a sample of gram positive organism
48
what is the catalase test's 2nd step?
place 2 drops of 3% hydrogen peroxide into end of swab
49
what is the last step in the catalase test?
immediately look for bubbling reaction and record results
50
what is the presence of bubbles mean in the catalase test?
indicates the presence of catalase and positive test result
51
is the novobiovin sensitivity and growth characteristics on MH agar s catalase positive or catalase negative test?
catalase positive
52
what plate is divided in two sections in the Novobiocin sensitivity test?
Muller-hinton plate
53
what does college gram positive culture create?
a bacterial lawn on top portion
54
what do you put on the top half of the MH plate?
Novobiocin
55
is the DNAse agar plate preformed for a catalase positive or negative test?
catalase positive
56
how is the DNAse agar plate test done?
1. collect gram positive and inoculate the DNAse agar plate
| 2. tape the plate closed and incubate at 37C
57
what are the steps in the Mannitol salt agar plate?
1. label
2. inoculate the MSA with a straight line streak
3. tape plate closed
58
what are the steps in the PYR broth?
1. label
2. inoculate the broth
3. incubate
59
what are catalase positive tests?
- Novobiocin sensivity
- DNAse agar streak
- MSA agar
- PYR broth
60
what does the PYR broth test for?
aminopeptidase PYR
61
what does the MSA agar plate test for?
Mannitol Fermentation
62
what does the DNAse agar test for/
DNAse activity
63
what does the MH agar plate test for?
Novobiocin sensitivity or resistance
64
what are the types of catalase negative tests?
- STX sensitivity test
- BEA slant streak
- PYR broth
65
what type of bactrim STX grow on?
blood agar
66
what type of media is blood agar?
differential and enriched
67
what is beta hemolysis?
complete lysis of red blood cells
68
what is alpha hemolysis?
partial hemolysis of red blood cells
69
what are the three types of hemolysis in bacterium STX test?
1. beta
2. alpha
3. none
70
what type of medium is BEA?
selective and differential
71
what does the BEA test focus on?
positive or negative for esculin hydrolysis
72
what is considered a positive test in the BEA slant?
50% of slant should be grey/black
73
is the PYR broth a test in both gram positive cocci tests?
yes
74
what does a positive result look like in the PYR broth?
a red color will be produced
75
what does a negative result look like in the PYR test?
light orange color
76
what does a positive novobiocin sensitivity test?
zone of inhibition > 16mm
77
what is a negative novobiocin sensitivity test?
less than 16mm it is resistant
78
what is a positive DNAse agar test results look like?
a clear zone is observed
79
what is a positive MSA result look like?
zone of inhibitation >20mm
80
what is a negative blood agar plate result look like?
less than 20mm is resistant
81
what type of media is MSA?
selective and dfferential
82
what does the MSA contain?
7.5% NaCl
83
what is a positive result of MSA test?
phenol red turns yellow
84
colonies that are >3mm are considered?
large
85
colonies that are <1mm are considered?
small
86
what is the universal virulence factor in all gram-negative bacteria?
LPS in outer membrane
87
what does the universal virulence factor cause?
morbidity and mortality
88
what is the collection of biochemical tests called that we did on gram negatives?
microgen GNA-ID system
89
what species of gram negatives did the collection of biochemicals test identify?
enterobacteriaceae species
90
how many wells were there in the microgen GNA-ID system?
12 wells
91
what did each well contain?
- dehydration substrates
| - indicators in saline
92
what is the purpose of well 1?
to determine if the organism is able to carry out lysine decarboxylation
93
why was well 1 overlaid with mineral oil?
to generate an anaerobic environment
94
what is the purpose of well 2?
to determine if the organism is able to carry out ornthine decarboxylation
95
why was well 2 overlaid with mineral oil?
well 2 is anaerobic
96
what is the purpose of well 3?
to see which organisms produce the enzyme thiosulfate reductase
97
Does Well 3 need an anaerobic or aerobic environment? How is this solved?
- anaerobic
| - overlaying mineral oil
98
what do wells 4,5,6 test for?
the organisms ability to metabolize various carbohydrates
99
what does well 7 contain?
- ONPG
| - nitrate
100
how many tests does well 7 provide?
2 tests
101
what does well 7 test for/
first is the apperance of Beta-galactosidase activity
102
how is the nitrate reduction test preformed in well 7?
- second test after ONPG
- nitrate reagent A added first
- nitrate reagent B added
103
what happens if no color appears in the nitrate reduction test in well 7?
add a pinch of zinc and it is negative
104
what is the purpose of well 9?
to detect urease activity
105
what is the purpose of well 10?
to detect bacteria that ferment glucose but only produce one acid end produce
106
what test is done in well 10?
VP test
108
how long does the VP test in well 10 take?
15-30 min
109
what does well 8 test for?
- presence of tryptophanase
| - indole production
110
what is added to well 8?
kovac's reagent
111
what does well 11 test for?
citrate utilization
112
what does well 12 test for?
trypotphan deaminase activity
113
define bioinformatics
the use of computational tools to address biological questions
114
what is our primary collections of bioinformatics tools?
NCBI
115
what is the NCBI a division of?
the national library of medicine
116
what does the NCBI serve as?
a gateway for researchers to access informatio
117
what does BLAST stand for?
basic local alignment search tool
118
define BLASTn
uses a neucleotide sequence and searches a nucleotide database
119
define BLASTp
A nucleotide or amino-acid sequence information
120
what sequence should the Query sequence be entered in?
FASTA format
121
define electrophoresis
- a technique that separates molecules
| - based on size
122
define PCR
a technique that can exponentially amplify a fragment of DNA in a test tube
123
what type of PCR reaction will we preform on our unknown?
in silico
124
how is the amplicon determined in the PCR reaction?
by primers
125
define sanger sequencing
technique to sequence DNA
126
what is important when running a PCR test?
dispense the master mix back into PCR tube
127
what electrodes should be properly connected?
black and red
128
When the dark blue running dye has travelled ___ of the length of the gel, turn the power supply off and disconnect the _____
- 3/4
| - electrodes
129
what is fermentation?
a collection of bacterial metabolic processes that engage when respiration (aerobic or anaerobic) is not possible
130
what does fermentation result in?
the production of acidic waste products
131
What does the production of acidic products such as lactic acid, propionic acid, and acetic acid through fermentation result in?
conditions that alter the characteristics of the raw food product
132
Fermentation not only increases the concentration of _____ or _______ (SCFAs), but also the diversity of ______ products
- lactate
- short-chain fatty acids
- metabolic
133
what are the most commonly comsumed fermented products?
diary
134
what does adding salt do in vegetable ferments?
support the production of a brine
135
what illness continue to be a significant source of bacterial disease in he US?
foodborne
136
what are S&S agar plates selective for?
enteric gram negative organisms
137
Escherichia species are ____ ____ and appear as ____ colonies on S&S Agar
- lactose positive
| - red
138
Both Salmonella and Shigella species are _____ ___ and appear as __________ colonies on S&S Agar
- lactose negative
| - clear/tan
139
Foodborne Pathogens Lab steps
1. Take a ________ __ plate and divide the plate in ___.
2. Using a ____, roll over the _____ sample to collect organisms. Then swab the ____ portion of the S&S plate.
3. Using a sterilize ____ to collect some bacteria from the ____ of the plate and streak them out across the _____ half of the plate to obtain _______ _____
4. Using ______, securely close the plate prior to incubating at 37oC for 48 hours
- S&S agar, half
- swab, meat, loop-loop, top, lower, isolated colonies
- parafilm
