A Simple Colorimetric Method for the Estimation of Relative Numbers of Lactobacilli in the Saliva

Abstract

This paper includes the results of an attempt to develop a simple colorimetric method for the estimation of the relative numbers of lactobacilli in the saliva as a supplementary procedure for the quantitative techniques (1, 2) used in the study of dental caries. The test was based on the assumption that since caries activity is closely correlated with the numerical rise and fall of lactobacilli in the saliva, it should be possible to demonstrate a corresponding increase and decrease in the amount of acid produced in a selective carbohydrate medium inoculated with definite amounts of saliva. Thus, significant color changes in selected time intervals could be interpreted roughly in terms of lactobacilli per c.c. of saliva as established by an adequate number of control plate counts. The present data embodies a large series of tests on specimens of saliva sent to the School of Dentistry of the University of Michigan for estimation of numbers of lactobacilli. METHOD AND MATERIALThe essential requirement for such a method was a medium selective for the acidogenic organisms, especially the lactobacilli, in the saliva and so colored that shifts in the indicator could easily be detected. Beef infusion agar to which glucose or lactose and an indicator were added was found to be very satisfactory since acid tomato-peptone agar (2) masked the color of the indicators used. Since the medium to be sufficiently selective must have an initial acidity of at least pH 5.0, the number of indicators was at once limited.After many trials with brom-cresol-green (pH 3.8-5A), brom-phenol-blue (pH 3.0-4.6), benzene-azo-a-naphthylamine (pH 3.7-5.0), and a-naphthylamine-azo-sulfanilic acid (pH 3.5-5.7), it was found that brom-cresol-green was the most satisfactory because the color changes were easy to follow and the indicator was stable at sterilizing temperatures.

Caries Risk Tests and Salivary Levels of Immunoglobulins to <i>Streptococcus mutans</i> and <i>Candida albicans </i>in Mouthbreathing Syndrome Patients

“…These findings were not in accordance to those obtained by Fabris et al [1968] and Fiorentini [1969], who found raised caries risk in MBS patients using Snyder's test. Considering that a relationship between the results obtained by Snyder's test and the concentration of lactobacilli in the saliva sample has been described [Snyder, 1940], the similar lactobacilli counts observed for the studied groups confirm the Snyder's test results obtained.…”

“…This test was performed according to Snyder [1940] and the results were classified as follows: negative, small (test positive after 72 h), moderate (test positive after 48 h) and high caries activity (test positive after 24 h).…”

Cultural methods for the identification and quantitation of Streptocococcus mutans and lactobacilli in oral samples

“…Early observations on the associatioti between oral lactobacilli and dental caries led Snyder (50) to develop a simple coloritnctric test for estitnation of relative nutnbers of lactobacilli in saliva. The Snyder Test was based on the color change in selected time intervals of brotn-cresol-green, glucose or lactose infusion agar (pH 5,0) in shake tubes after inoculation with saliva.…”

The relationship between the caries activity test (Snyder) and salivary IgA level.

“…Such activity is more frequent when both organisms are present and more infrequent when both are absent. The Snyder test is a means of estimating viable lactobacilli in a given volume of saliva (SNYDER [14]). The rapidity of color change in the Snyder test is indicative of the magnitude of the potential for producing dental caries.…”