How is IMViC test performed?
Table of Contents
How is IMViC test performed?
Indole Test Procedure
- Take sterilized test tubes containing 4 ml of tryptophan broth.
- Inoculate the tube aseptically by taking the growth from 18 to 24 hrs culture.
- Incubate the tube at 37°C for 24-28 hours.
- Add 0.5 ml of Kovac’s reagent to the broth culture.
- Observe for the presence or absence of a ring.
What is the IMViC test?
The IMViC series is a group of four individual tests that are commonly used to identify bacterial species, especially coliforms. The capital letters in ‘IMViC’ each stand for one of the four tests: I for Indole test, M for Methyl Red test, V for Voges-Proskauer test, and C for Citrate test.
How many tests are in IMViC test?
four different tests
IMViC tests consist of four different tests each of the letters in “IMViC” stands for one of these tests. The letter “i” is only for rhyming purpose. The four reactions are: Indole test, Methyl Red test, Voges Proskauer test and Citrate utilization test.
Why is the IMViC test important?
When used alone, the IMViC tests are particularly useful for differentiating Escherichia coli, Enterobacter aerogenes, Enterobacter cloacae, and Klebsiella pneumoniae (although colonial morphology and the presence of capsules can also be used to differentiate Klebsiella).
What is IMViC full form?
IMViC stands for Indole, Methyl Red, Voges Proskauer and Citrate. Fecal coliforms like Escherichia coli are + + – – in the IMViC tests. Nonfecal coliforms like Enterobacter aerogenes are – – + + in these tests. Indole Methyl Red VP Citrate.
What reagent does IMViC use?
A variation on this test using Ehrlich’s reagent (using ethyl alcohol in place of isoamyl alcohol, developed by Paul Ehrlich) is used when performing the test on non-fermenters and anaerobes….
| Indole Spot Reagent: | |
|---|---|
| p-Dimethylaminocinnamaldehyde (DMACA) | 10.0 gm |
| Deionized Water | 900.0 ml |
What does Voges-Proskauer test for?
The Voges-Proskauer test detects the presence of acetoin, a precursor of 2,3 butanediol. If the culture is positive for acetoin, it will turn “brownish-red to pink” (tube on the left in the second picture).
Is IMViC a biochemical test?
Biochemical Test (IMViC) : It is a biochemical series of tests including the following tests: Indole, Methyl Red (MR), Voges-Proskauer (VP), and Citrate. All of the series was designed to differentiate among the Enterics (family Enterobacteriaceae). I = Test for production of indole from tryptophan.
Why is the IMViC test useful in identifying Enterobacteriaceae?
IMViC is useful for identifying enterobacteriaceae, because each separate substrate is able to identify a different type of enterobacteriaceae, also use serological tests and phage tests.
Why do we indole test?
The indole test screens for the ability of an organism to degrade the amino acid tryptophan and produce indole. It is used as part of the IMViC procedures, a battery of tests designed to distinguish among members of the family Enterobacteriaceae.
What is methyl red and Voges Proskauer test?
This test is used to determine which fermentation pathway is used to utilize glucose. In the mixed acid fermentation pathway, glucose is fermented and produces several organic acids (lactic, acetic, succinic, and formic acids).
Is E coli Voges-Proskauer positive?
For example, Escherichia coli shows positive results in methyl red test and negative results in Voges Proskauer test.
Which family of organisms is differentiated by the IMViC tests?
family Enterobacteriaceae
IMViC tests are employed in the identification/differentiation of members of the family Enterobacteriaceae.
Which reagent is used in indole test?
To test for indole production, add 5 drops of Kovács reagent directly to the tube (3, 5). A positive indole test is indicated by the formation of a pink to red color (“cherry-red ring”) in the reagent layer on top of the medium within seconds of adding the reagent (Fig. 1b).
Which media is used for indole test?
The main requirement for a suitable indole test medium is that it contains a sufficient amount of tryptophan (Tryptone broth, indole-free peptone water medium, Urea-indole medium, Tryptophan peptone broth, Sulfide-indole motility medium ( SIM) …).
What is the difference between MR and VP test?
MR: If the tube turns red, the test is positive for mixed acid fermentation (one or more organic acids formed during the fermentation of glucose). VP: If the tube (or interface) turns pink or red, the test is positive for acetoin, a precursor of 2,3-butanediol.
What is methyl red used for?
The methyl red test is used to detect the ability of an organism to produce and maintain acid end products from glucose fermentation.
What is methyl red and Voges-Proskauer test?
Voges Proskauer test helps in the detection of acetoin (neutral-reacting end products ) producing bacteria when cultivated in specific media. Basically, the MRVP test (Methyl red and Voges Proskauer test) is used for the detection of which fermentation pathway is used by the bacteria to utilize glucose.
Why Voges-Proskauer test is done?
The Voges-Proskauer (VP) test is used to determine if an organism produces acetylmethyl carbinol from glucose fermentation. If present, acetylmethyl carbinol is converted to diacetyl in the presence of ∝- naphthol, strong alkali (40% KOH), and atmospheric oxygen.
How do you prepare for an IMViC test?
Procedure
- (a) Preparation of MRVP medium or glucose phosphate broth:
- Inoculate the tubes with the bacterial culture.
- Incubate for 48 hours at 37°C.
- Pipette 1 mL from each culture tube into clean separate tubes.
- Add 18 drops (0.5 mL) of Barrit’s solution A (a-naphthol) to each tube that contains the media.
