Genotypic diversity and phenotypic traits of Streptococcus mutans isolates and their relation to severity of early childhood caries

Remberto Marcelo Argandoña Valdez,Rodrigo Alex Arthur,Marcelo Fabiano Gomes Boriollo,Vanessa Rodrigues Dos Santos,Natalia Helena Colombo,Alberto Carlos Botazzo Delbem,Cristiane Duque,Thais De Cássia Negrini,Maria Luiza De Aguiar Loesch,Karina Sampaio Caiaffa

doi:10.1186/s12903-017-0406-1

Abstract

BackgroundEarly childhood caries (ECC) is an aggressive condition that can affect teeth of young children. This study aimed to evaluate genotypic diversity and phenotypic traits of S. mutans isolated from dental biofilms of children with different caries status in comparison with caries free (CF) children.MethodsStreptococcus mutans strains were isolated from supragingival biofilm samples of CF, ECC and severe-ECC (S-ECC) children and genotyped by arbitrary-primer polymerase chain reaction - AP-PCR. S. mutans genotypes were tested for their ability to reduce the suspension pH through glycolysis, to tolerate extreme acid challenge and by their ability to form biofilm. Response variables were analyzed by ANOVA/Tukey or Kruskal-Wallis/Mann-Whitney tests at a 5% of significance.ResultsThere was an increase in the prevalence of Streptococcus mutans in biofilms with the severity of dental caries. No differences in genotypic diversity and in acidogenicity of genotypes were found among CF, ECC and S-ECC children. S mutans strains with genotypes more characteristic for ECC and S-ECC children formed more biofilms than those identified in CF children. The strains isolated from S-ECC children were highly acid tolerant.ConclusionAlthough S. mutans genotypic diversity was similar among the groups of children, phenotypic traits of S. mutans, especially the acid tolerance response, could explain the severity of early childhood caries.

Highlights

Childhood caries (ECC) is an aggressive condition that can affect teeth of young children
S-Early childhood caries (ECC) children presented the highest percentage of S. mutans isolates compared with caries free (CF) and ECC children, which were not different between them (Table 1)
severe ECC (S-ECC) children seems to harbor lesser genotypes compared to other groups, the number of genotypes found in biofilms was not statistically different among CF, ECC and S-ECC children (Table 1)

Summary

Introduction

Childhood caries (ECC) is an aggressive condition that can affect teeth of young children. Dental caries is a biofilm-associated disease caused by frequent intake of dietary sugars. Fermentation of these sugars by biofilm microbiota leads to acid production, which disrupt microbial homeostasis and cause dissolution of tooth minerals [1]. Mainly Streptococcus mutans, have been considered as the most important bacteria implicated in dental caries etiology and progression. Childhood caries (ECC) is an aggressive condition of dental caries that affects young children. ECC disease has rampant, acute and progressive characteristics and lead to destruction of the primary dentition affecting negatively children’s physical and mental health in addition to increase the risk of new caries lesions in the permanent dentition [5]

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