Abstract: A test kit and method is disclosed for the semi-quantitative detection of Streptococcus mutans from the oral cavity of a patient. Saliva from a patient is introduced into a diluent solution to which has been added just before the saliva a predetermined powdered amount of bacitracin. Then the diluent solution is contacted with a sterile media-coated paddle, the media-coated paddle containing the diluent and test saliva is incubated, and Streptococcus mutans in the test saliva is semi-quantitively determined by comparing the percent of colony density with a standard Streptococcus mutan colony density chart.