How would you explain the differential nature of the snyder agar medium as used for the detection of dental caries?

Dental caries is the demineralization of hard tissues on teeth by acid produced by organisms that reside in the dental plaque such as Streptococcus mutants and lactobacilli.

The BCG Dextrose Agar, also known as Snyder Test Agar is a colorimetric analysis used for the estimation of Lactobacilli counts in saliva. In this test, glucose is used as the fermentable carbohydrate and Bromcresol Green as the pH indicator. If Lactobacillus spp. are present the glucose fermentation will cause the pH to drop to 4.4, changing the color from blue-green to yellow, this will confirm the susceptibility of a person to develop dental caries based on acid production.

A differential contains specific ingredients to distinguish a bacteria from another one through observation, in this case, the detection of acidity with the bromocresol green indicator will be the factor that will allow us to differentiate Lactobacilli from another organism.

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