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Background:Streptococcus mutans and Streptococcus sobrinus are main etiological agents of dental caries.Aim:The aim of the study was to isolate, identify, characterize, and determine the minimum inhibitory concentration (MIC) of S. mutans and S. sobrinus from caries-active subjects.Materials and Methods:Sixty-five plaque samples were collected from caries-active subjects aged between 35 and 44 years, processed and cultured on mitis salivarius bacitracin agar. All the bacterial isolates were subjected to morphotyping and the suspected colonies were identified by 16S rDNA sequencing. The S. mutans and S. sobrinus strains were characterized by biotyping and phylogenetic analysis. The MIC of ampicillin and erythromycin was determined by microtiter plate method.Results:Of the study population, 41 isolates displayed typical colony morphologies of S. mutans and S. sobrinus. The 16S rDNA sequencing results revealed that 36 isolates were S. mutans and 5 isolates were S. sobrinus. The biotyping of these isolates demonstrated three biotypes, namely, biotype I (n = 35), biotype III (n = 1), and biotype IV (n = 2). However, 3 isolates exhibited variant biotypes. The phylogenetic analysis revealed that the clinical strains of S. mutans and S. sobrinus clustered independently along with respective reference strains. The average MIC of ampicillin and erythromycin against S. mutans and S. sobrinus was 0.047 μg/ml and 0.39 μg/ml, respectively.Conclusion:The 16S rDNA sequencing was an impeccable method for S. mutans and S. sobrinus identification when compared with morphotyping and biotyping methods. The study also suggested that nonspecific bacteria might be involved in caries formation.

The chitosan-copper oxide (Chi-CuO) biopolymer nanocomposites were synthesized by a simple green chemistry method using ascorbic acid as a reducing and capping agent. The intense peak around 300 nm was observed in the UV-visible spectrum indicating the formation of CuO nanoparticles. The prepared Chi-CuO nanocomposites were characterized using energy-dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), X-ray diffraction spectroscopy (XRD), and Fourier transform-infrared spectroscopy (FT-IR). SEM and XRD pattern showed cubic shape for Chi-CuO nanocomposites with average crystalline size of 17 nm, as calculated using Debye-Scherrer's formula. The FT-IR spectral studies showed the Cu-O bond formation with chitosan to form nanocomposites. Synthesized nanocomposites showed significant anti-microbial activity against Bacillus subtilis, Pseudomonas aeruginosa, Escherichia coli and Penicillium notatum, assayed using the agar well diffusion method. It also showed sporicidal activity against B. subtilis and exhibited effective biofilminhibitory activity against B. subtilis (69%/100 μg/mL) and P. aeruginosa (63%/100 μg/mL).

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BACKGROUND:Ruta graveolens is one of the most used phytomedicines. To date, there is no report of determining the bioactivity of R. graveolens against cariogenic causing bacteria (Streptococcus mutans and Streptococcus sobrinus).OBJECTIVE:The objective of the present study was to determine the antibacterial activity and metabolite profile of R. graveolens against S. mutans and S. sobrinus.MATERIALS AND METHODS:R. graveolens plant material was collected and processed in the month of February. The plant material was extracted by Soxhlet apparatus using methanol solvent. Two strains of S. mutans and two strains of S. sobrinus were isolated from dental caries-active participants and cultured on mitis salivarius-bacitracin agar. The antibacterial susceptibility testing of methanolic extract of R. graveolens was performed by disc diffusion method. The metabolite profile of the plant extract was determined using electrospray ionization-tandem mass spectrometry.RESULTS:The methanolic extract of R. graveolens showed a promising antibacterial activity against S. mutans and S. sobrinus. Two compounds named γ-fagarine and kokusaginine were identified from the methanolic extract of R. graveolens.CONCLUSION:The study concluded that R. graveolens contains significant antibacterial activity. However, further investigations are suggested to understand the anticaries properties of these pure compounds.