Background: The aim of the present study was to undertake a systematic review exploring the relationship between childhood obesity and fecal microorganisms, to answer the following question: “Are Firmicutes and Bacteroidetes a significant risk indicator/factor for obesity in children?” The main search terms were “child” and “obesity” together with “gut microbiota” (PubMed: 2005–2017). The minimal requirements for inclusion were the evaluation of gut microbiota composition and BMI in children between 0 and 13 years of age. Methods: Assessed articles were carefully classified according to a predetermined criterion, and the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) were considered. Seven articles were critically appraised and used as a basis for conclusions. Results: Three studies showed a positive association between Bacteroides fragilis and obesity. In addition, a high value of evidence indicated that a decrease in the Bacteroidetes phylum and in Bacteroides/Prevotella groups was related to high BMI. For the Firmicutes phylum, one high-quality study highlighted that it was positively correlated with weight gain. With regard to Firmicutes species, Clostridium leptum , Eubacterium hallii , and Lactobacillus spp. indicated adipose tissue storage, while Clostridium difficile and the Staphylococcus genus were correlated with low BMI. Despite the fact that only one study did not perform real-time polymerase chain reaction to quantify the microorganisms, its results corroborated those of the studies that did. Conclusions: Changes in Firmicutes and Bacteroidetes phyla/species levels might in fact be significant indicators/factors for childhood obesity. However, given the small number of articles appraising these entire phyla and the heterogeneity among the species assessed, further well-designed studies are required to improve the knowledge.

We explored the association between caries development, colonization with caries-associated microflora, and immunity as children begin the transition to mixed dentition. Forty children received dental examinations at 3–4 years of age, repeated a year later. Children were grouped into caries-free (n = 23; CF) and caries-active (n = 17; CA ≧3 new lesions on follow-up). Salivary IgA and IgA antibody to Streptococcus mutans virulence epitopes were measured by Luminex assay. Mutans streptococci (MS), lactobacilli and total microorganisms were enumerated on selective media from plaque samples. There was no significant difference in baseline levels of MS or lactobacilli between CF and CA groups. However, both MS and lactobacilli levels were higher at follow-up in the CA group. Furthermore, children with detectable lactobacilli at baseline had significantly higher caries risk. Salivary IgA concentrations increased significantly in both groups during the study. Both CF and CA groups also displayed significant increases in salivary IgA antibody levels to glucosyltransferase, glucan-binding protein (Gbp) and antigen I/II salivary binding region. CF antibody levels to seven peptides associated with domains of biological importance increased at follow-up, in contrast to increases to only three peptides in CA saliva samples. Multivariate modeling showed that a lower baseline level of salivary IgA anti-GbpB was associated with higher caries risk. These data indicate that MS and lactobacilli are associated with caries in this population, that the secretory immune system is undergoing significant maturation during this period, and that the breadth of mucosal IgA response to epitopes of S. mutans virulence components may influence the degree to which these cariogenic microorganisms can cause disease.

This study aimed to determine the activity of carbonic anhydrase isoenzyme VI (CAVI) in the saliva of preschool children with caries and to investigate the relationship between caries and salivary CAVI activity, salivary flow rate and biofilm pH before and after a 20% sucrose rinse. Thirty preschool children aged 45.3–80.3 months were divided into two groups: a caries-free group and a caries group. Clinical examinations were conducted by one examiner (ĸ = 0.95) according to WHO criteria (dmfs) and early caries lesions. From each subject, CAVI activity, salivary flow rate and plaque pH were determined before and after a sucrose rinse. The results were submitted to Wilcoxon, Mann-Whitney and Spearman correlation tests (α = 0.05). The results showed that prerinse CAVI activity and its variation were higher in the saliva from caries children than from caries-free children. No difference was found between the two groups in postrinse salivary CAVI activity. After rinsing, biofilm pH differences were lower in both groups (p = 0.0012 and p = 0.0037 for the caries and caries-free groups, respectively). Also, after the sucrose rinse, salivary flow rate significantly increased in caries and caries-free groups (p = 0.0003, p = 0.0037). The variation of salivary CAVI activity was negatively correlated with caries (r = –0.501, p = 0.005). Child’s age showed a positive correlation with caries (r = 0.456, p = 0.011). These results suggest that variation of salivary CAVI activity and child’s age are associated with dental caries in preschool children.