title: Distribution of Streptococcus mutans and Streptococcus sobrinus in saliva of Mexican preschool caries-free and caries-active children by microbial and molecular (PCR) assays.
abstract: The aim of the study was to investigate the distribution of mutans streptococci (MS) infection of caries-free (CF) and caries-active (CA) preschool Mexican children by microbial and molecular assays. Eighty preschool children were divided into two groups, 40 CF and 40 CA children. Saliva samples were inoculated onto MSB to identify CFU and DNA extractions were tested by PCR. Our results indicated that there was no statistical difference (p > 0.05) between groups either in age, weight, height or sex. S. sobrinus was detected by PCR twice as much in the CA group, the difference being statistically significant (p < 0.05). dmfs index was positive correlated with S. mutans (r = 0.2941, p = 0.0081), S. sobrinus (r = 0.3384, p = 0.0021) and S. mutans-S. sobrinus (r = 0.3978, p = 0.0003). ANCOVA revealed that dmfs index had a significant effect on the distribution of CFU of S. mutans (p = 0.0118) and S. sobrinus (p = 0.03). When MSB was compared with PCR to identify MS, there was no statistical difference (p > 0.05). We conclude that S. mutans and S. sobrinus were isolated in higher numbers from CA children and those harbouring both bacteria had higher dmfs scores. PCR is a useful tool in molecular epidemiology for dental caries studies; it was effective in detecting and identifying MS from saliva in children.
authors.affiliation: San Luis Potosi University, Mexico. jloyola@uaslp.mx
authors.forename: Juan Pablo
authors.initials: JP
authors.lastname: Loyola-Rodriguez
authors.forename: Rita Elizabeth
authors.initials: RE
authors.lastname: Martinez-Martinez
authors.forename: Blanca Irma
authors.initials: BI
authors.lastname: Flores-Ferreyra
authors.forename: Nuria
authors.initials: N
authors.lastname: Patiño-Marin
authors.forename: Angel Gabriel
authors.initials: AG
authors.lastname: Alpuche-Solis
authors.forename: Juan Francisco
authors.initials: JF
authors.lastname: Reyes-Macias
mesh_terms: D017677:Age Distribution; D015373:Bacterial Typing Techniques / Q000379:methods*; D016022:Case-Control Studies; D002675:Child, Preschool; D015169:Colony Count, Microbial / Q000379:methods; D003430:Cross-Sectional Studies; D004245:DMF Index; D003731:Dental Caries / Q000453:epidemiology / Q000382:microbiology*; D005260:Female; D006801:Humans; D008297:Male; D008800:Mexico / Q000453:epidemiology; D016133:Polymerase Chain Reaction / Q000379:methods; D012016:Reference Values; D015203:Reproducibility of Results; D012463:Saliva / Q000382:microbiology*; D017678:Sex Distribution; D013295:Streptococcus mutans / Q000302:isolation & purification*; D016986:Streptococcus sobrinus / Q000302:isolation & purification*