RESUMEN
INTRODUCTION: Genotypic analyses of Streptococcus mutans using fingerprinting methods depend on a few genetic loci being different but do not reveal the underlying genome-wide differences between strains. METHODS: We used comparative genomic hybridization (CGH) with 70-mer oligonucleotide microarrays containing open reading frames (ORFs) from S. mutans strain UA159 to examine the genetic diversity of 44 isolates from nine children selected from a local study population in Eastern Iowa. RESULTS: Unique strains (clones) within each child initially identified by arbitrary-priming polymerase chain reaction were confirmed by CGH. There was a wide range of variation in the hybridization patterns of the 1948 ORFs among the test isolates examined. Between 87 and 237 ORFs failed to give a positive signal among individual isolates. A total of 323 of the UA159 ORFs were absent from one or more of the test strains. These 323 variable genes seemed to be distributed across the entire UA159 genome and across all the predicted functional categories. CONCLUSION: This set of very close geographically and temporally collected S. mutans isolates had a degree of gene content variation as high as a previously examined global set of strains. Comparing the frequency of these variable genes, the majority of which have unknown function, among strains of different origins (i.e. different caries status) could help to determine their relevance in S. mutans cariogenicity.
Asunto(s)
Índice CPO , Caries Dental/microbiología , Genoma Bacteriano/genética , Streptococcus mutans/genética , Preescolar , Mapeo Cromosómico , Hibridación Genómica Comparativa , Dermatoglifia del ADN , Heterogeneidad Genética , Variación Genética/genética , Genotipo , Humanos , Iowa , Análisis de Secuencia por Matrices de Oligonucleótidos , Sistemas de Lectura Abierta/genética , Reacción en Cadena de la Polimerasa , Streptococcus mutans/patogenicidad , Virulencia/genéticaRESUMEN
Using data from the Center for Oral Health Research in Appalachia Study, we examined variability in susceptibility to dental caries among children and adolescents in rural Appalachia. Among 210 participants who were caries-free at the initial visit, age at the baseline visit can be used as a proxy for the degree of caries resistance; probability of caries development at the tooth level decreased as age at the baseline visit increased. Participants who stayed caries-free for a longer period during childhood and adolescence experienced less extensive caries, as measured by the number of carious teeth. However, the probability of becoming caries-positive did not correlate with age at the baseline visit. For children between 1 and 18 years of age, there was not a "threshold age" after which a caries-free child's risk of caries onset is significantly reduced.