Evaluation of a micromethod for determination of Streptococcus mutans and Lactobacillus infection

A micromethod was developed for quantitative estimation in saliva of Streptococcus mutans and lactobacilli. With a semiautomatic pipette, 25 microliter of diluted saliva was spotted on the surface of an agar plate containing a selective medium. This volume gave a spot with a diameter of about 10 mm in which separate colonies could be counted. The results obtained with the spotting technique showed excellent agreement with those obtained with conventional agar plating. The method is convenient and results in a substantial saving of culture media.