RESUMEN
Mutans streptococci (MS) are key organisms associated with the etiology of dental caries. Using probabilities that were tested by oversampling, we designed this study to determine the minimal number of MS isolates from an individual required to evaluate diversity of genotypes. MS isolates were genotyped by repetitive extragenic palindromic-polymerase chain-reaction (rep-PCR). Analysis of 20 isolates from individuals resulted in a mean of 1.6 and 2.4 genotypes in children (N = 12) and adults (N = 10), respectively. In a follow-up study, reducing the number of isolates to 7-10 resulted in a theoretical probability of up to 78% for detecting up to 4 genotypes. A mean of 1.5 genotypes was found in 35 children and 10 adults. These findings provide evidence for the design of studies of MS genotyping that can serve as a model for the analysis of genotypes within individuals.
Asunto(s)
Placa Dental/microbiología , Reacción en Cadena de la Polimerasa/métodos , Streptococcus mutans/genética , Adulto , Técnicas de Tipificación Bacteriana , Niño , Preescolar , Dermatoglifia del ADN/métodos , ADN Bacteriano/genética , ADN Bacteriano/aislamiento & purificación , Biblioteca de Genes , Variación Genética , Genotipo , Humanos , Modelos Genéticos , Análisis de Secuencia por Matrices de Oligonucleótidos , Probabilidad , Secuencias Repetitivas de Ácidos Nucleicos/genéticaRESUMEN
The aim of this study was to determine the reproducibility of individual versus pooled plaque sampling of permanent first molars (PFM) to quantitate Streptococcus mutans (SM)/total streptococci (TS). Ten individual and pooled plaque samples were collected from 35 subjects, randomly assigned to individual-first or pooled-first group. Plaque samples were processed and quantified for SM and TS. SM/TS ratio was used to determine the reproducibility within two group samples. Mean percentage of SM/TS in both methods were not significantly different. However, within subject detection of SM was found to be significantly more sensitive for individual sampling method. Despite the lack of a difference between both methods for SM/TS quantitation, the difference in SM detection suggests that individual sampling is more sensitive.
Asunto(s)
Placa Dental/microbiología , Streptococcus mutans/aislamiento & purificación , Adolescente , Adulto , Niño , Recuento de Colonia Microbiana/métodos , Femenino , Humanos , Masculino , Persona de Mediana Edad , Diente Molar/microbiología , Streptococcus/aislamiento & purificación , Adulto JovenRESUMEN
Pulsed-field gel electrophoresis (PFGE) is considered the "gold standard" for molecular epidemiological study. Repetitive extragenic palindromic PCR (rep-PCR) is less time-consuming and more suitable for analyzing large numbers of bacterial strains in human populations. PFGE and rep-PCR provide comparable genotyping results for investigating Streptococcus mutans diversity and transmission.