Detection and characterization of Streptococcus downei, a rare bacterial species of mutans streptococci from caries-active patients

Background: The oral bacteria, mutans streptococci (MS), are an etiological agent of dental caries. Of MS, Streptococcus downei are rarely isolated bacteria. Aim: The aim of this study was to isolate and characterize S. downei from caries-active subjects. Materials and Methods: In all, 65 dental plaque samples were collected from dental caries-active subjects. All the isolates were further identified and characterized using 16S rDNA sequencing, biochemical tests, antibiogram, and minimum inhibitory concentration (MIC). Results: Five isolates have been identified as S. downei using 16S rDNA sequencing. Phylogenetic analysis showed that S. downei was closely related to S. sobrinus. The biotype traits of these five isolates were IV (n = 3), V (n = 1), and variants (n = 2). The study proposed one new biotype, classified as biotype VIII for the variant strain. The antibiogram tests revealed that all the strains of S. downei were susceptible to all the antibiotics used in the study with higher sensitivity to penicillin and ampicillin. The MIC of ampicillin and erythromycin against S. downei was 0.047 and 0.39 μg/mL, respectively. Conclusion: The study reports the prevalence of S. downei in caries-active subjects and recommends further investigations to determine its role in the disease.

Antibacterial effect of different concentrations of garlic (Allium sativum) extract on dental plaque bacteria.

Background: Allium sativum, commonly known as garlic, exhibits antibacterial effects against a wide range of bacteria. Aim: The objective of this in vitro study was to assess the antibacterial effect of different concentrations of garlic extract against human dental plaque microbiota. Materials and Methods: Antibacterial activities of four different concentrations of garlic extract (5%, 10%, 20%, and 100%) were evaluated against Streptococcus mutans, Streptococcus sanguis, Streptococcus salivarius, Pseudomonas aeruginosa, and lactobacillus spp. using the disk diffusion method. Papers soaked in 0.2% concentration chlorhexidine gluconate and saline were used as positive and negative controls, respectively. The data were subjected to one-way ANOVA and the Tukey multiple comparisons test at a 5% significance level. Results: All bacterial strains were inhibited by all test materials. The inhibition zones of the different concentrations of garlic extract were not significantly different for S. mutans, S. sanguis, and S. salivarius. For P. aeruginosa and lactobacillus spp. the inhibition zones of 5%, 10% and 20% concentrations were not significantly different from one another, but they were significantly more than that of the 100% extract. Conclusion: The 5%, 10%, 20%, and 100% concentrations of garlic extract had similar effects, so further studies seem to be indicated on the usefulness of the 5% extract.

Antibacterial efficacy of triphala against oral streptococci: An in vivo study.

Background: Triphala is a botanical preparation consisting of equal parts of three herbal fruits. Much revered in Ayurveda, triphala has been proven to have antibacterial, antiviral, antifungal actions. Aims and Objectives: The objective of this study was to investigate the effect of 6% triphala in a mouthwash formulation on the salivary streptococci levels at the end of 48 h and 7 days, of twice a day usage, and to compare the same with 0.2% chlorhexidine. Materials and Methods: Sixty undergraduate student volunteers aged between 18 and 25 years were randomly allocated into three study groups. (a) 6% triphala mouthwash, 15 ml twice a day; (b) 0.2% chlorhexidine mouthwash, 15 ml twice a day (active control group); (c) passive control group asked to rinse with plain water, twice a day. The oral streptococci colony forming units/ml (CFUs/ml) was assessed by inoculating blood agar with saliva samples at the end of 48 h and at 7 days. Results: The triphala group showed a 17% and 44% reduction, while the chlorhexidine group showed 16% and 45% reduction at the end of 48 h and 7 days (P < 0.001). The reduction in CFUs/ml seen in triphala group closely paralleled that of chlorhexidine group. Conclusion: Triphala has been used in Ayurveda from time immemorial and has many potential systemic benefits. The promising results shown by Triphala call for further investigations of its antimicrobial effects against the numerous oral microorganisms.

Detection of oral streptococci in dental biofilm from caries-active and caries-free children / Detecção de estreptococos orais em biofilme dental de crianças cárie-ativas e livres de cárie

This work correlated the presence of oral streptococci in dental biofilm with clinical indexes of caries and oral hygiene in caries-active and caries-free children. S. mutans and/or S. sobrinus in the dental biofilm does not indicate a direct risk for developing dental caries.

Este trabalho correlacionou a presença de estreptococos orais no biofilme dental com índices clínicos de cárie dentária e higiene oral em crianças com alta e baixa atividade de cárie. S. mutans e/ou S. sobrinus no biofilme dental não significa o imediato desenvolvimento de lesões cariosas