Explain what is meant by IMViC.
IMViC is an acronym that stands for four different diagnostic tests for the identification of members of family enterobacteriaceae. Each of these letters stands for one test. I is for indole test, M is for methyl red test, V is for Voges-Proskauer test and C is for citrate test. i is added in between for the ease of pronunciation. For these tests to perform, three test tubes are inoculated: tryptone broth for indole test, methyl red- Voges Proskauer broth and citrate.
Cultures of bacteria are grown for 24-48 hours at 37°C and and the tests are performed thereafter.
INDOLE TEST:
This test is performed in tryptophan broth or on sulfide-indole-motility(SIM) medium and then Kovac's reagent is added to read the result.
Red layer at the top of the tube after the addition of the reagent indicates positive result and lack of color change after the addition of the reagent inidcates negative result.
METHYL RED TEST:
This test is performed in methyl red-Voges Proskauer (MR-VP) broth. After the addition of methyl red reagent, if red color develops it indicates positive result and if no color change is seen then it indicates negative result.
VOGES-PROSKAUER TEST:
This test is performedin methyl red-Voges-Proskauer broth. Barritt's A and Barritt's B reagents are added and if red-brown color appears it inidcates positive result and if there is lack of color change, it indicates negative result.
CITRATE TEST:
This test is performed on Simmons citrate agar and if growth of bacteria is seen then a blue color change is seen and if there is lack of growth then no color change is seen in the tube.
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