lab tests Flashcards

1
Q

what type pH test is able to hydrolyze urea?

A

urease test

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2
Q

what is urea?

A

a product of the carboxylation of several amino acids

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3
Q

when you hydrolyze urea you get two products, what are they?

A

ammonia and CO2

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4
Q

what is used for the detection of urease-producing bacteria?

A

pH indicator (phenol red)

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5
Q

in a urease test, if the bacteria has a high pH this means it is_______ and the broth will turn______.

A

basic, hot pink

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6
Q

RAPID urease producers

A

media that have two buffers to resist alkalization

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7
Q

T/F you have to read the urease test within 24hrs.

A

True

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8
Q

why do you have to read the urease test within 24 hours?

A

So it doesn’t make a burst of ammonia to take over the system in a very lange concentration

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9
Q

Is the urease test able to be autoclaved?

A

No

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10
Q

How do you sterilize the urease test?

A

use filter sterilization (need to have pores of 0.2 uL)

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11
Q

DNAase test

A

Excoenzyme, Depolimerizes DNA

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12
Q

After the DNA is polimerized, can DNA associate with methyl green?

A

no

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13
Q

what kind of organism is the IMViC test mostly used for?

A

gram negative enteric organisms

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14
Q

what does IMViC stand for?

A

Indole, Methyl red, Voges-pros-Kaver, citrate

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15
Q

what does the Indole test look for?

A

looks for the expression of tryptophanase

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16
Q

what does tryptophanase do?

A

breaks down tryptophan

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17
Q

what 3 products are produced if tryptophanase is produced?

A

indole, pyruvate, ammonia

18
Q

In the indole test, what is the only product that sticks around?

A

indole (its the key target)

19
Q

what type of broth do you use during the indole test? what do you add to see the results?

A

1% tryptone broth, add kovacs reagent

20
Q

what does the kovacs reagent do?

A

adds a red ring on top of the media

21
Q

what does SIM media stand for?

A

sulfer reduction, indole, motility

22
Q

Both methyl red and voges pros kaver use________

A

MR-VP broth

23
Q

what is methyl red looking for?

A

looks for evidence of mixed acid fermentation (lactase succinate, formate, acetate)

24
Q

in the IMViC test does methyl red use a pH indicator?

A

yes, if red its an acidic pH which is a positive test

25
what is the voges pros kaver test looking for?
looking for evidence of butandiol fermentation, acetoin
26
what is acetoin?
precurser to butandiol
27
what two reagents do you add to the voges pros kaver test?
Barritts reagent A( alpha napthol) and Barritts reagent B (KOH)
28
Are you able to get an organism that is positive for mixed acid and butandiol fermentation?
No
29
what type of agar does the citrate test use?
simmons citrate agar (synthetic media)
30
all ______ ________ ________ bacteria can use citrate as an energy source
gram negative enteric
31
what does the citrate test look for?
looking for the expression of citrate permease
32
what is in simmons citrate agar?
mineral salts, sodium citrate, and ammonium ions
33
T/F if bacteria can grow in the simmons citrate agar they have citrate permease
true
34
in citrate test, if the broth uses _______ _____ and increase pH, this can be used as a definitive answer. (look for pH change)
ammonium ions
35
what is the pH indicator in the citrate test?
Bromthymol blue
36
if the pH _____ then the tube turns _____. green means _______
increases, blue, neutral
37
T/F Methyl green attaches to fragmented DNA to signify a positive DNase result
False
38
why are there two buffers that resist alkilization in the urease test?
so you can distinguish the RAPID urease producers
39
what three characteristics can be determied by inoculating SIM media?
sulfer reduction indole motility
40
the ___________________ test determines whether a bacteria can undergo butandiol fermentation by looking for the production of the butandiol precursor, _________, after incubation after the the addition of _____________.
voges pros kaver, acetoin, barritts reagents