Real-time Quantitative PCR for Evaluation of Mutans Streptococci and Dental Caries PDF Download

Author: Chanika Manmontri
Publisher:
ISBN:
Category :
Languages : en
Pages : 53

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Book Description
Mutans streptococci (MS), e.g., Streptococcus mutans (Sm) and Streptococcus sobrinus (Ss), are associated with dental caries. Quantification of MS has been shown to predict caries risk. Traditional culture methods are problematic, especially because consistently maintaining the viability of bacteria is difficult. A new technology using PCR has the potential to streamline and improve MS quantification compared to traditional culture methods. Purpose: To use real-time quantitative PCR (qPCR) and standard plate counting (SPC) for detection and quantification of levels of Sm, Ss and total streptococci (TS) in clinical samples from high-caries-risk children (no regular access to dental care) and to evaluate the correlation of these results to caries prevalence. Methods: Saliva and plaque samples were collected from school-aged children for SYBR Green based qPCR using primers specific for Sm, Ss and TS from DNA extracted. UA159 genomic DNA was used as standard from which "copy number" (CN/ml) of MS and TS was computed. For comparison, samples were also processed and quantified for "colony forming unit" (CFU/ml) of MS and TS using SPC. Calibrated examiners performed oral examinations (DMFT/DMFS/dmft/dmfs). Pearson's analysis and T-test assessed correlations between level of Sm and ratio of Sm to TS to caries using SAS V9.2. Results: Fifty-eight subjects (mean age=9.8 years, DMFS/dmfs=7.0) had samples collected. By qPCR Sm was detected in 98.1% of samples while SPC was 72.9%. Ss was only found in 4 qPCR samples (none by SPC). Mean qPCR CN/ml of samples were: Sm (2.54x106), Ss (5.27x102) and TS (2.34x109). Mean SPC CFU/ml of samples were: Sm (9.4x105), Ss (0) and TS (1.0x107). Significant correlations were found between level of Sm and ratio of Sm/TS from oral samples to prevalence of dental caries. Conclusion: The levels of Sm and ratio of Sm/TS by qPCR and SPC were correlated to dental caries. Correlations between mean levels of Sm and ratio of Sm/TS to caries experience from qPCR are comparable to SPC. Given the similar correlations found, the more streamlined method of qPCR is a suitable outcome measure in epidemiological studies.