MEDIA AND BIOCHEMICAL TESTS Flashcards
How do you perform Indole test?
Inoculation of Tryptone broth with inoculating loop
Indole test is usually performed to differentiate species of _____.
Enterobacteriaceae
In indole test, bacteria species are examined if they have the ability to produce?
Indole
In indole test, bacteria use an enzyme _____ to break down the amino acid tryptophan.
tryptophanase
What are the reagents used in indole test?
- Tryptone broth
- Kovac’s reagent (HCl, dimethylaminobenzaldehyde)
How do you perform MRVP test?
- Inoculate 2 glucose broth with an inoculating loop.
- After 48 hrs incubation, add few drops of Methyl Red to one tube, and Voges Proskauer reagents to the other tube
In MRVP test, it is performed to differentiate species of ?
Enterobacteriaceae
In MRVP test, MR is for testing?
Acid end products from glucose fermentation
In VP test, VP is for testing?
Acetoin production from glucose fermentation
Describe the positive and negative results in Indole test.
Negative: 3 layers; orange, clear, thin brown layer
Positive: 3 layers; cloudy orange, “cloudish clear”, red top layer
What are the reagents used in MRVP test?
- Glucose broth
- Methyl red
- 5% alpha-naphtol
- Ethanol
- KOH
- Deionized water
Describe the positive and negative results for MRVP test.
MR: positive result in coloration of red indicates pH below 6; a negative results in coloration of yellow (no acid production)
VP: positive result becomes red after adding reagents indicating presence of acetoin; negative result has no changes in color
How do you perform Citrate test?
Inoculate slant with inoculating loop
Citrate test is performed to differentiate species of ?
Enterobacteriaceae
Citrate test is selective for bacteria that has the ability to consume citrate as its sole source of _____ and _____ as sole _____ source.
carbon; ammonium; nitrogen
What are the reagents used in Citrate test?
- Simmon’s Citrate Agar (Sodium Citrate)
- Ammonium ion (nitrogen source)
- Bromothymol blue (pH indicator
Describe the positive and negative results of Citrate test.
Positive result is blue w/c indicates that bacteria metabolize citrate and produce an acid end product. Negative result remains green
How do you perform SIM test?
Stab SIM media w/ inoculating needle.
SIM test is performed to differentiate species of ?
Enterobacteriaceae
SIM test is used to determine the ability of bacteria to reduce the _____ into _____.
sulfure; H2S
What are the reagents used in SIM test?
- Sulfur w/ amino acid
- Cysteine
- Sodium thiosulfate
- Peptonized iron or ferrous sulfate
Describe the positive and negative results for SIM test.
H2S will react w/ iron and produce a black precipitate. Positive result has a black precipitate. Negative has no black precipitate.
How do you perform Urea hydrolysis test?
Inoculate Urea broth with inoculating loop
Urea hydrolysis test is performed to determine a bacteria’s ability to hydrolyze _____ to make ______ using the enzyme _____.
urea; ammonia; Urease
What are the reagents used in Urea hydrolysis test?
- Urea broth (contains yeast extract)
- Monopotassium phosphate
- Disodium
- Urea
- Phenol red indicator
Describe the positive and negative results for Urea hydrolysis test.
Urea broth is a yellow-orange color. The enzyme urease will be used to hydrolyze urea to make ammonia. If ammonia is made, the broth turns a bright pink color and is positive.
Negative test has no changes in coloration and no ammonia is produced
How do you perform Motility test?
Stab motility media with inoculating needle
What are the reagents used in Motility test?
- Tryptose
- Sodium Chloride
- Agar
- Color indicator
Describe the positive and negative results for Motility test.
If bacteria is motile, there will be growth going out away from from the stab line, and test is positive. If bacteria is not motile, there will only be growth along the stab line. A colored indicator should be used to make the results more visible
How do you perform Lactose fermentation test?
Inoculate lactose broth with inoculating loop
What are the reagents used in Lactose fermentation test?
- Lactose broth contains beef extract
- Gelatin, peptone, and lactose
- Phenol red indicator (indication of acid production)
Describe the positive and negative results for Lactose fermentation test.
Positive result is yellow after indicator is added w/c indicates lactose fermentation
Negative result will have no color change or will be reddish
How do you perform Sucrose fermentation test?
Inoculate sucrose broth with inoculating loop
Sucrose fermentation test is performed to differentiate the species of ? Apart from sucrose fermentation, what is another component that is test?
Enterobacteriaceae; acid-end products
Describe the positive and negative results for Sucrose fermentation test.
Positive result is yellow after indicator is added w/c indicates lactose fermentation
Negative result will have no color change or will be reddish
How do you perform Glucose fermentation and Gas production test?
Inoculate glucose broth with inoculating loop
What are the reagents used in Glucose fermentation and Gas production?
- Lactose broth contains beef extract
- Gelatin, peptone, and lactose
- Phenol red indicator (indication of acid production)
Describe the positive and negative result for Glucose fermentation and Gas production test.
Positive result is yellow after indicator is added w/c indicates lactose fermentation
Positive result for gas is a bubble in the durham tube
How do you perform Blood agar plate w/ Novobiocin Test?
Inoculate BAP plate using streak plate method and incubate 24-48 hrs. Place a novobiocin disk in the first quadrant of streak
BAP with Novobiocin determines if the organism ?
- Resistant to Novobiocin
- Can lyse RBC
What are the reagents used in BPA w/ Novobiocin test?
- Nutrient agar w/ 5% sheep’s blood
- Novobiocin antibiotic disk
Describe the positive results for BPA w/ Novobiocin test.
Positive result is hemolysis, indicated by colonies turning translucent/green
Possible result is novobiocin resistance, indicated by zone of inhibition around the disk
How do you perform MSA test?
Inoculate MSA plate using streak plate and incubate for 24-48 hrs.
MSA test is performed to determine ?
- Test for bacteria’s ability to tolerate 7.5% salt concentration and ferment mannitol
- Media is selective and differential because is selects salt tolerant bacteria
What are the reagents used in MSA test?
- MSA contains nutrient agar
- Mannitol
- 7% NaCl
- Phenol red indicator
Describe the positive and negative results for MSA test.
Positive result is the growth of organism
If salt tolerant organism cannot ferment mannitol, the media will remain pink
How do you perform M staph broth test?
Inoculate broth and incubate for 24-48 hrs.
M staph broth test is used to determine ?
- Test for bacteria’s ability to tolerate 7% salt concentration and ferment mannitol
- Media is selective for salt tolerant Staphylococcus
What are the reagents used in M staph Broth test?
- Media contains nutrients for Staphylococcus
- 7.5% salt
Describe the positive result for M staph Broth test.
Positive result is the growth of the organism is indicated by turbidity.
How do you perform Coagulase test?
Inoculate rabbit plasma with one single colony. Break up colony and stir until blended in plasma. Incubate at 37 degrees for 24 hrs.
Coagulase test is used to determine ?
For bacteria’s ability to clot blood plasma using enzyme coagulase
What are the reagents used in Coagulase test?
Rabbit plasma in buffer solution
Describe the positive result for Coagulase test.
Positive result shows clumping of plasma indicating presence of coagulase
