IADR Abstract Archives
Genomic, Acidogenic and Aciduric Variability of Streptococcus mutans Serotype c
Objectives: To assess the genomic, acidogenic and aciduric variability of Streptococcus mutans (S. mutans) serotype c from saliva of schoolchildren.
Methods: A descriptive study was undertaken under the approval of the institutional ethical committee. Previous informed consent and assent, non-stimulated saliva samples were taken from 29 children from 8-10 years old with and without caries. S. mutans and its serotypes were identified by PCR. 50 isolates corresponding to serotype c were genotyped by pulsed field gel electrophoresis (PFGE). A Dice coefficient >80% indicated similarity among genotypes. Subsequently, genotypes were tested for their ability to produce and resist acid. The Chi-square test was used to determine the association between the distribution of the serotypes in the groups.
Results: Serotype c is distributed similarly in children with and without caries. Three specific genotypes were found for the caries group and only one for the without caries group. Isolates were similarly acidogenic. However, an exclusive caries genotype had the greatest glycolytic activity. Although isolates survived at pH 5.0 after 90 minutes of incubation, they exhibited variable aciduricity and only survived up to 30 minutes after exposure to pH 2.8, and three caries genotypes were the least aciduric.
Conclusions: Despite the genetic variability found, acid production was similar; suggesting that the acidogenicity of S. mutans serotype c does not appear to be the differential virulence factor among the isolates. In addition, although a variable resistance to acid was evident, aciduricity does not appear to be a distinctive virulence factor either. Therefore, the pathogenic potential of serotype c could not be explained exclusively based on the differential genetic content of clinical isolates. It is important to evaluate other phenotypic characteristics that explain the establishment and colonization of specific genotypes of children with caries.
Methods: A descriptive study was undertaken under the approval of the institutional ethical committee. Previous informed consent and assent, non-stimulated saliva samples were taken from 29 children from 8-10 years old with and without caries. S. mutans and its serotypes were identified by PCR. 50 isolates corresponding to serotype c were genotyped by pulsed field gel electrophoresis (PFGE). A Dice coefficient >80% indicated similarity among genotypes. Subsequently, genotypes were tested for their ability to produce and resist acid. The Chi-square test was used to determine the association between the distribution of the serotypes in the groups.
Results: Serotype c is distributed similarly in children with and without caries. Three specific genotypes were found for the caries group and only one for the without caries group. Isolates were similarly acidogenic. However, an exclusive caries genotype had the greatest glycolytic activity. Although isolates survived at pH 5.0 after 90 minutes of incubation, they exhibited variable aciduricity and only survived up to 30 minutes after exposure to pH 2.8, and three caries genotypes were the least aciduric.
Conclusions: Despite the genetic variability found, acid production was similar; suggesting that the acidogenicity of S. mutans serotype c does not appear to be the differential virulence factor among the isolates. In addition, although a variable resistance to acid was evident, aciduricity does not appear to be a distinctive virulence factor either. Therefore, the pathogenic potential of serotype c could not be explained exclusively based on the differential genetic content of clinical isolates. It is important to evaluate other phenotypic characteristics that explain the establishment and colonization of specific genotypes of children with caries.
