Exploration of Caries and Microbial Status in American Indian Children

Objectives: Streptococcus mutans (SM), Streptococcus sobrinus (SS), and Lactobacillus (LB) species have been shown to play a role in the development of dental caries. Children from low socioeconomic families have a greater incidence and prevalence of early childhood caries. Our current study is looking at mutans streptococci (SM and SS) colonization and transmission and prevalence of Lactobacilli in a Northern Plains American Indian Tribe. We report here on SM, SS, and LB and species colonization profiles and detection frequency in a subset of children from this population (n=64) and the relationship to caries status (caries-free/caries-active).
Methods: Whole mouth plaque samples were collected 8 times between the child’s birth and 36 months of age. Samples were spiral plated onto MSKB (Mitis salivarius-Kanamycin-Bacitracin) agar for mutans streptococci (MS) counts and isolation and Rogosa agar for LB counts. MS isolates were identified as SM or SS by sugar fermentation profiles and PCR. Scores based on the number of visits each species was detected (detection frequency) along with a three species colonization profile were recorded for each subject. Detection frequencies were compared using the Wilcoxon rank sum test. The distribution of colonization profiles were compared using Fisher’s Exact test. Analyses were performed using SAS 9.4 (Cary, NC).
Results: Statistically significant differences were seen in species detection frequency between groups for SM (p=0.0025), SS (p=0.0004), and LB (p<0.001). The colonization profiles observed were different for both groups. (p<0.0001).
Conclusions: We observed differences in SM, SS, and LB colonization profiles and detection frequency of each species in caries-free versus caries-active children. Ongoing investigation includes genotyping of SM, SS, and LB isolates from this subject set by arbitrarily primed PCR to further explore the link between these microbial species and the rampant caries observed in this population.