What does a positive VP test look like?

What does a positive VP test look like?

ər/ or VP is a test used to detect acetoin in a bacterial broth culture. The test is performed by adding alpha-naphthol and potassium hydroxide to the Voges-Proskauer broth which has been inoculated with bacteria. A cherry red color indicates a positive result, while a yellow-brown color indicates a negative result.

What color is methyl red in the presence of acid?

Indicator	pH Range	Acid
22 Methyl orange	3.1-4.4	red
23 Methyl red	4.4-6.3	red
16 Methyl violet	0.15-3.2	yellow
17 Methyl yellow	2.9-4.0	red

Would a false negative result for the VP?

Would a false negative result for the VP test more likely be attributable to poor sensitivity or to poor specificity of the test system? A false negative on the VP test is likely due to a lack of sensitivity- there is not enough acetoin to react with the test reagents.

Which test would likely benefit most from a longer incubation time why?

VP test

Is of glucose broth selective or differential?

Glucose Broth with Durham Tubes This is a differential medium. It tests an organism’s ability to ferment the sugar glucose as well as its ability to convert the end product of glycolysis, pyruvic acid into gaseous byproducts.

Which sugar is used in the methyl red test?

glucose

What is the difference between E coli and Staphylococcus?

E. coli was shown to have a more negatively charged and less soft surface than that of S. aureus. It is suggested that electrophoretic mobility measurements can be used to detect the difference in surface structure between gram-positive and gram-negative bacteria.

Why is it important to know if bacteria is Gram positive or negative?

If bacteria are present, this test can also help your doctor learn if the bacteria are gram negative or gram positive. The difference between gram-negative and gram-positive bacteria can affect their recommended treatment plan. Gram stains can be performed on various types of specimens, including: blood.