Sample, count, identify, and store the mutans streptococci

According to a new method for sampling mutans streptococci, "Strip mutans", a plastic strip is contaminated by human saliva and incubated in a selective broth. After growth the strip with adherent colonies may be dried and stored. We wanted to know for how long a time bacteria in the colonies were viable if the strips were stored under different conditions. The survival time is important if the bacteria need to be subjected to further analyses. The results showed that the viability of the bacteria after the incubation period was at least 1 yr when the strips were stored frozen or frozen in glycerine. Stored dried in room temperature the survival was about 8 wk. A second part of the study aimed at identifying the colonies on strips obtained from different countries. Dried strips were sent air mail to our laboratory for biochemical and immunological analyses and the results showed that serotype/biotype c/e/f of S. mutans were most frequent but d/g S. sobrinus was also present in the samples, which came from Brazil, Greece, and Sweden. Three colonies of 213 on these strips did not grow, possibly indicating non-mutans bacteria.