2292 Streptococcus mutans Phenotypes in Head Start Children
B. RAND, B. OLSON, and D. DRAKE, University of Iowa, College of Dentistry, Iowa City, USA

Objectives: We conducted a 1-year clinical trial to assess the efficacy of a novel, alcohol-free, flavored 1% Chlorhexidine (CHX) gel on levels of Streptococcus mutans (SM) in Head Start preschool children. A component of this study was to create a cryolibrary of well-characterized SM isolates from each subject, and perform DNA fingerprinting via AP-PCR to determine clonal type profiles in children over time receiving the CHX or placebo gels. Methods: Plaque samples in transport media were initially plated on MSKB (Mitis-Salivarius agar with kanamycin and bacitracin) via a spread plating system. Candidate SM isolates were subjected to standard biochemical tests to confirm their identity. Determination of phenotypes was done on colonies plated again on MSKB agar. Cryolibraries of 1-10 isolates per subject were prepared for future DNA fingerprinting depending upon the level of SM colonization. Results: Initial studies were done on isolates from caries-free and caries-active subjects in the placebo group. Subjects that harbored >10^6 SM and were caries-active had a minimum of 2-3 distinct SM phenotypes seen on MSKB plates. In contrast, caries-free subjects that harbored lower SM counts (<10^4) had only one distinct SM phenotype. Conclusion: We observed more distinct colonial phenotypes in isolates from caries-active subjects than caries-free subjects. Studies determining clonal types via DNA fingerprinting are in progress to determine if clonal type profiles differ in caries-free and caries-active subjects, and the potential effect of CHX gel treatment.

Seq #237 - Gram-positive Cocci B
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