Virulence of Streptococcus mutans: An intrafamilial cohort study on transmission of genotypes

A Cota,V Silva,S Da Silva

doi:10.4317/jced.56038

Abstract

BackgroundThe main aims of this cohort study were to measure the intrafamilial risk of transmission, sharing and stability of the most virulent S. mutans genotypes. Material and Methods A total of 392 clinical isolates of S. mutans obtained from caries-active adults and genotyped to evaluate their transmissibility over time. After extraction of the chromosomal DNA, PCR were performed to detect the genes involved in the production of GbpA (gbpA) and mutacin types I, II, III and IV (mutAI, mutAII, mutAIII and mutAIV). Results The gbpA, mutAI, mutAII, mutAIII and mutAIV genes were detected in 77.3, 12.5, 51, 16.6 and 89.8% of S. mutans isolates, respectively. The virulence of S. mutans was associated with its transmission (P< 0.01) and stability (P = 0.01), with the most virulent genotypes having higher transmissibility (RR = 1.83, 95% CI 1.44 to 2.32) and higher stability in the oral cavity (RR = 1.52, 95% CI 1.06 to 2.19). Conclusions Genotypes with the genetic information to synthesize GbpA and mutacins present an important ecological advantage in the process of colonization by S. mutans; they remain stable among the oral microbiota of the host and favor intrafamilial transmission. Key words:Streptococcus mutans, virulence factors, transmission, dental caries.

Highlights

Due to its virulence factors, Streptococcus mutans (S. mutans) is considered the most cariogenic microorganism to colonize the human oral cavity (1)
glucan-binding proteins (GBPs) are known to influence the maintenance of the dental biofilm architecture by joining bacteria to extracellular glucan molecules (4), which contribute to plaque formation and to the subsequent development of dental caries (5)
A systematic review (10) showed that caries risk assessment in children generally is based in case-control or cross-sectional and, cohort studies with adequate follow-up are needed. The aims of this cohort study were 1) to determine the frequencies of genes involved in the production of GbpA and mutacin types I, II, III and IV in S. mutans and 2) to measure the intrafamilial risk of transmission, sharing and stability of genotypes of virulent S. mutans genotypes

Summary

Introduction

Due to its virulence factors, Streptococcus mutans (S. mutans) is considered the most cariogenic microorganism to colonize the human oral cavity (1). The aims of this cohort study were 1) to determine the frequencies of genes involved in the production of GbpA (gbpA) and mutacin types I, II, III and IV (mutAI, mutAII, mutAIII and mutAIV) in S. mutans and 2) to measure the intrafamilial risk of transmission, sharing and stability of genotypes of virulent S. mutans genotypes.

Results

Conclusion