IMMUNIZATION OF HUMAN BEINGS WITH ORAL LACTOBACILLI

¹ Army Dental School, Army Medical Center, Washington 12, D. C.

1. Subcutaneous inoculation of human beings with both heat-killed and living vaccines, containing the strains of lactobacilli used in these tests, was accomplished 4 times at weekly intervals without inciting any severe local or general detrimental effects.

2. Vaccination increased the blood agglutinin titers for the strains used in the vaccines, the maximum being attained around 2 weeks after vaccination. The titers decreased after this period and were near the unvaccinated levels 5 months after the last injections. Controls showed no appreciable change in titer.

3. Salivary counts for lactobacilli over a period of 4 months demonstrated that 15 out of 20 persons (75%) in the immunized group had apparent reductions in average salivary counts. Statistical analysis indicated that only 5 out of the 20 (25%) could be regarded as having reductions greater than could be accounted for by chance. The average counts for lactobacilli in the controls showed changes which were within the limits of chance variation.

4. The average agglutinin titer levels were about the same for both sections of the immunized group, one with reductions in average counts within the limits of chance variation. No relationships could be established between the blood agglutinins and the changes in average counts.

5. The results seem to indicate that the immunization, as performed in this study, had no consistent effect on the numbers of lactobacilli cultivable from the oral cavity.