A MEDIUM FOR THE DIFFERENTIATION OF STRONGLY ACIDOGENIC FROM WEAKLY ACIDOGENIC ORGANISMS OF HUMAN SALIVA

A PRELIMINARY REPORT

¹ Department of Bacteriology, Northwestern University Dental School, Chicago, Ill.

A preliminary report is presented on a new medium for the estimation of acidogenic bacteria in saliva. It appears to have certain advantages over media previously used for the purpose because it supports the growth of many different types of bacteria but permits the quantitative differentiation of strongly acidogenic organisms from those which are weakly acidogenic, non-acidogenic, or alkali-producing. The differentiation is clear cut, and the colonies may be recognized by naked-eye examination.

As a test for caries susceptibility, this procedure, in common with all in vitro tests, shows only the relative numbers of organisms capable of producing acid of a sufficiently low pH to decalcify enamel in the presence of a suitable substrate. If the preliminary work here reported is supported by further clinical and laboratory investigation, and the results of the tests can be correlated with the factors responsible for the rate of neutralization in the mouth of the patient concerned, it appears that this medium may have a place as an adjunct to diagnosis preparatory to and during the institution of a program of preventive dentistry. Since the oral flora is known to fluctuate with the rise and fall of the intake of carbohydrates, a series of tests at regular intervals will be found to be of more significance than a single test.