Polymerase chain reaction-based identification of various serotypes of Streptococcus mutans in adults with and without dental caries.

Background: Dental caries is a multistep process which initiates the development of plaque' defined as a structured biofilm containing microbial communities. Teeth provide unique surfaces for bacterial colonization. Serotypes of Streptococcus mutans implicate the development of dental caries. Aim: The aim of the study was to determine the prevalence and association of serotypes of S. mutans in groups with and without dental caries. Materials and Methods: One hundred and fifty adults aged between 18 and 35 years were included in the study. Supragingival plaque samples were collected, followed by deoxyribonucleic acid extraction. Polymerase chain reaction was performed to identify S. mutans and its serotypes. Proportions of S. mutans and its serotypes were correlated with caries-active (CA) and caries-free (CF) groups. Results: CA group showed 66.7% positivity for S. mutans and CF group showed only 42.7% of positivity. Serotype C showed a higher proportion followed by E' F, and K in the CA group, whereas in the CF group, higher proportion was observed with K followed by C' E, and F. 70.8% cases showed single serotype in the CA group and 83.3% in CF group. Multiple serotypes were seen in 29.2% in the CA group and 16.7% in the CF group. Conclusions: The study clearly established variation in proportions of S. mutans and its serotypes between CA and CF groups. Positive correlation was observed in the CA group for S. mutans and its serotypes.

Simultaneous detection and evaluation of Prevotella intermedia, Prevotella nigrescens, Prevotella loescheii, and Prevotella melaninogenica in subgingival plaque samples of chronic periodontitis and healthy individuals through multiplex polymerase chain reaction.

Background: Prevotella is a Gram-negative anaerobic bacilli. The phenotypic characteristics of the various species of Prevotella are similar, which often makes it difficult in routine differentiation and identification of all the species. Aim: The purpose of the study was to detect and compare presence of Prevotella intermedia, Prevotella nigrescens, Prevotella melaninogenica, and Prevotella loescheii in subgingival plaque samples of chronic periodontitis and healthy individuals. Materials and Methods: Two hundred and thirty-six subjects were considered consisting of chronic periodontitis (128) and healthy (108) individuals. Subgingival plaque sample was collected in reduced transport fluid and analyzed. DNA extraction and polymerase chain reaction (PCR) were performed for genus Prevotella followed by positive samples were considered for the detection of selected species through multiplex PCR using specific primers. Results: Out of 236 samples, 94.1% were positive for genus Prevotella. Out of 222 cases P. nigrescens showed the highest number of cases positive (59.5%) followed by P. melaninogenica (57.2%), P. intermedia (55.4%), and P. loescheii (40.1%). Species were analyzed individually between chronic periodontitis and healthy, P. intermedia, P. nigrescens, and P. loescheii showed greater positivity in healthy compared to chronic periodontitis. Positivity for P. melaninogenica was high in chronic periodontitis compared to healthy. Conclusion: The number of positive cases for species, when correlated with clinical parameters showed an increase in mean score for all clinical parameters assessed, suggesting the presence of variation in the prevalence of Prevotella species and geographic variation do exist in oral microflora. Findings suggest that they can be normal commensals and opportunistic.