Determination of antibiotic resistance in oral bacteria grown on selective media.

Over fifty percent of oral microbes have not been cultured in the laboratory (Harper-Owen, 1999). Oral microbes are pathogens of periodontal disease and systemic diseases such as atherosclerosis. Oral microbes may become more resistant to antibiotics as humans age due to antibiotic usage over a person's life span. New culture media was developed for this study to identify possible novel species of oral microbes. Nine modifications from a published recipe of Facultative Anaerobe Media, known to grow oral pathogens, were used. After Human Subjects approval, 27 extracted human teeth of which age and sex were known were added to a modified broth and incubated for 24 hours. Organisms grown in the modified broth were serially diluted and replica plated onto the published media to easily identify possible novel species. Each inoculated modified plate was incubated under aerobic, anaerobic, and CO2 conditions. Isolates were chosen for further study based on gram stain results, and Triple Sugar Iron and bile esculin biochemical tests. Antibiotic sensitivity testing was carried out on at least 54 colonies grown over three age groups (18-39, 40-59, and 60+) to test the hypothesis that antibiotic resistance increases with human age. Isolates were cryopreserved in broth containing 10% glycerol for future studies. Suspected novel species will be confirmed by 16S rDNA sequencing. This research will lead to new methods of identifying and controlling chronic oral conditions. This research was supported by Sigma Xi and Central Missouri State University.

Claxton, J.L. and A.R. Oller *. Department of Biology and Earth Science, Central Missouri State University.