Genetic diversity of Streptococcus mutans serotype c isolated from white spot and cavitated caries lesions from schoolchildren

Insight into the Relationship between Oral Microbiota and the Inflammatory Bowel Disease

Inflammatory bowel disease has been a growing concern of lots of people globally, including both adults and children. As a chronic inflammatory disease of the intestine, even though the etiology of inflammatory bowel disease is still unclear, the available evidence from clinic observations has suggested a close association with microorganisms. The oral microbiota possesses the characteristics of a large number and abundant species, second only to the intestinal microbiota in the human body; as a result, it successfully attracts the attention of researchers. The highly diverse commensal oral microbiota is not only a normal part of the oral cavity but also has a pronounced impact on the pathophysiology of general health. Numerous studies have shown the potential associations between the oral microbiota and inflammatory bowel disease. Inflammatory bowel disease can affect the composition of the oral microbiota and lead to a range of oral pathologies. In turn, there are a variety of oral microorganisms involved in the development and progression of inflammatory bowel disease, including Streptococcus spp., Fusobacterium nucleatum, Porphyromonas gingivalis, Campylobacter concisus, Klebsiella pneumoniae, Saccharibacteria (TM7), and Candida albicans. Based on the above analysis, the purpose of this review is to summarize this relationship of mutual influence and give further insight into the detection of flora as a target for the diagnosis and treatment of inflammatory bowel disease to open up a novel approach in future clinical practice.

Acidogenic and aciduric properties of Streptococcus mutans serotype c according to its genomic variability

Streptococcus mutans (S. mutans) has a wide genetic diversity that contributes to its phenotypic heterogeneity, and may be related to attributes associated with acidogenicity and aciduricity. The aim of this study was to evaluate the acidogenic and aciduric properties of S. mutans serotype c isolates from saliva of schoolchildren according to the genomic variability. S. mutans isolates were identified by polymerase chain reaction. Fifty S. mutans serotype c isolates were genotyped by pulsed field gel electrophoresis and tested for their ability to produce and resist acid. Three specific genotypes were identified in the caries-active group and only one in the caries-free group. Although isolates were similarly acidogenic, an exclusive caries-active genotype had the greatest glycolytic activity. In contrast, isolates exhibited variable aciduricity, and three caries-active genotypes were the least aciduric. We concluded that there is genetic variability within serotype c. Acid production was similar regardless of the caries status but correlated with the number of genotypes. In addition, resistance to acid could be an important characteristic for the establishment and colonisation of specific genotypes in children with caries. However, it is important to evaluate children's intrinsic characteristics and other phenotypic properties to explain the physiopathological behaviour of the different genotypes.

Assessment of cytotoxic and antimicrobial activities of two components of Cymbopogon citratus essential oil

Background

There is a continuing search for compuounds to improve the chemical plaque inhibitory action of oral hygiene products. Although the antibacterial effects of chlorhexidine (CHX) and essential oils components, citral/myrcene, have been described, there is contradictory information regarding their cytotoxic effects in host tissues. This study aimed to evaluate the cytotoxic activity of the major components of the oil C. citratus, citral and myrcene on human periodontal ligament fibroblast (HPLF) cultures and their antimicrobial effect on different bacterial species present in supragingival biofilm.

Material and Methods

Cytotoxicity of the compounds to HPLF was determined by MTT assay. Antimicrobial activity was tested against reference strains of Enterococcus faecalis, Streptococcus mutans and Lactobacillus rhamnosus and for S. mutans clinical strains by broth microdilution assay. One-way analysis of variance (ANOVA) with Games-Howell post-hoc multiple comparison or unpaired t tests were used for inter- and intragroup comparisons.

Results

Overall, all of the compounds under study showed a cytotoxic effect to HPLF which varied in a dose-dependant manner. Whilst myrcene did not show bacteriostatic activity at tested concentrations, both citral and CHX exhibited bacteriostatic/bactericidal effects to all strains at specific concentrations, being CHX most effective to inhibit bacterial growth at lower concentrations than what observed for citral.

Conclusions

Based on these findings, it would possible to conclude that whereas myrcene might be ineffective to control bacterial growth, citral could have a promising antimicrobial activity against dental colonizers with low cytotoxicity, and may be useful for preventing the onset and progression of oral diseases. Key words:Antimicrobial activity, citral, cytotoxicity, chlorhexidine, myrcene.