Discriminant ability for caries risk of modified colorimetric tests.

OBJECTIVE: The aim of this study was to evaluate the relationship between the caries risk in children over a two-year period and their baseline caries status, salivary levels of mutans streptococci and lactobacilli, and results of the Alban test and modifications thereof using different substrates. STUDY DESIGN: Ninety-five children aged 6-7 were examined in Granada (southern Spain) for dental caries at baseline and every six months. Stimulated saliva was sampled and inoculated in 7 colorimetric tests based on Snyder's medium with different sugars and polyalcohols. A mutans streptococci and lactobacilli count was performed (Dentocult SM strip® and Dentocult LB®). Caries risk proportions were contrasted against the potential predictor variables, i.e., basal caries history and salivary tests, by means of the Mantel Haenszel test for linear association, based on a chi-square distribution with 1 degree of freedom (df). RESULTS: Caries index, lactobacillus count and colorimetric tests showed significant, but limited, and non-different discriminant abilities. Increasing values of all predictor variables, except for Dentocult SM®, were related to increasing caries risk proportions. CONCLUSION: Colorimetric test results and caries history showed similar correlation values as caries predictors.

In vitro activity of macrolides and lincosamides against oral streptococci: a therapeutic alternative in prophylaxis for infective endocarditis.

Susceptibility to macrolides and lincosamides was tested in a total of 446 strains of oral streptococci belonging to eleven species, all isolated from dental plaque and/or saliva in 1991. Minimum inhibitory concentrations (MIC) were determined by the double serial dilutions method in agar. Clindamycin was the most effective antibiotic against all species tested. The results of nearly all parameters (range, mean, MIC(50), MIC(90)) in all species showed erythromycin to be less effective than josamycin, making the latter antibiotic a possible alternative to erythromycin in prophylaxis for infective endocarditis caused by oral streptococci, not only in patients allergic to penicillin, but also in all patients with low-risk lesions, who will be treated with low-risk dental procedures. In these latter patients, antibiotic prophylaxis may be indicated if, after careful evaluation of the individual's situation, no other alternatives are available.

Phenotypic characterization of oral streptococci by classical methods.

The phenotypic characteristics of 215 strains of oral streptococci were compared on the basis of the results of sorbitol, raffinose and trehalose fermentation, ammonium from arginine production, aesculin hydrolysis, H2O2 production, susceptibility to 2 U bacitracin, and growth in 4% NaCl solution. Eleven different species were identified. Among the most noteworthy findings were the low number of H2O2-producing strains of Streptococcus sobrinus, the effective discrimination between Streptococcus sanguis and Streptococcus mitis on the basis of raffinose fermentation, and the phenotypic similarity between Streptococcus oralis and the former mutans group. To avoid the creation of new species, the term biotype is proposed to designate phenotypically distinct organisms which do not qualify as different species.