A Method for Estimating the Bacterial Content of the Mouth by Direct Count

An accurate quantitative method of estimating bacteria in the mouth is of great value in following the progress of pathological conditions and the effect of antiseptics as well as the changes due to certain diets. Cultural methods have been unsatisfactory because many different kinds of media under aerobic and anaero-bic conditions are necessary in order to cultivate the numerous types of organisms which inhabit the mouth. The danger of out-diluting organisms in attempts to produce suitable plates for counting must also be borne in mind. The methods of making direct counts have many realized defects. They have, however, given consistently higher values than the plate method. Kligler (1915), in comparing the two methods, found that the microscope count was about five to six times greater than the plate count. One of the major difficulties in the direct-count method has been the clumping of bacteria, due to mucin and epithelial cells in the saliva and to the thread forms which entangle masses of bacteria. It was with the aim of separating these clumps of bacteria, so as to have a uniform distribution of organisms in a smear, that the following method was worked out. In general, the procedure followed was similar to that used by Breed and Brew (1933) for making direct bacterial counts of milk, with the exception that an atomizer was employed to break up the larger masses and a very dilute sodium hydroxide solution was used as a diluent to dissolve the mucin