Isolation and typing of Streptococcus mutans and Streptococcus sobrinus from caries-active subjects

Abstract

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.

Genotypic Variations of Mutans Streptococci Isolated from Dental Caries by REP-PCR

“…Ten clinical strains of S. mutans (H5, H17, H18, H19, H20, H23, H26, H35, H36 and H37), five clinical strains of S. sobrinus (H16, H21, H29, H43 and H65) and four clinical strains of S. downei (H45, H47, H50 and H62) were obtained from our previous studies (8,11).…”

“…An extensive and comprehensive National Health Survey performed throughout India revealed that 80 % of the population in the age group 35-44 years old affected by dental caries (6). Mutans streptococci (MS), Streptococcus mutans and Streptococcus sobrinus, are the principal causative agents of the formation of dental caries (7,8). S. mutans is considered as the solitary pioneer cariogenic determinant (7,9).…”

“…Genetic diversity referred as the number of genotypes present within an organism. The genotyping can illuminate the phenotypic diversity in microorganisms, such as antibiotic resistance, geographic dissemination, host specificity, pathogenicity, transmission and virulence factors (8,12). The genetic diversity can also study the heterogeneity of the MS (13,14) and the possibility to design a vaccine.…”

“…In the previous published studies, we have detected strains of S. mutans, S. sobrinus and S. downei isolated from dental caries active subjects aged between 35 to 44 years (8,11). Insight to this context, the objective of the existing study was focused to investigate the genetic diversity of those species using REP-PCR.…”

Determination of antibacterial activity and metabolite profile of Ruta graveolens against Streptococcus mutans and Streptococcus sobrinus

“…Among oral microbiome, Streptococcus mutans and Streptococcus sobrinus are the key agents of causing dental caries, which are belonging to acid-producing bacterial group called mutans streptococci (MS). [1,2] However, a rare species of MS, Streptococcus dentapri, has been recently isolated from human dental caries. [3] Due to the incremental cost of manufacturing of antibiotics and the rise of bacterial resistance to the presently available antimicrobial agents, new strategies of controlling the diseases such as the use of plant-derived extract were initiated.…”