title: Colonization of mutans streptococci in Costa Rican children from a high-risk population.
abstract: OBJECTIVE
  The aim of the study was to determine the colonization of mutans streptococci (MS) in dental biofilm and saliva of children from a high-risk population with low socioeconomic status from San José, Costa Rica.
  
  
  METHODS
  A total of 68 healthy babies from 8 to 20 months of age (mean age=13 months), with caries-free status and cariogenic feeding habits (eg, nursing bottle- or breast-feeding on demand) were examined. Children divided in two groups (<13 months and 14-20 months). Samples from dental biofilm and saliva from each subject were processed and plated in blood agar (BA) and Mitis-Salivarius-Bacitracin agar (MSB) to determine MS percentage. Statistical analysis included the analysis of variance test, and stratification by age of MS levels.
  
  
  RESULTS
  Detectable MS levels in dental biofilm and saliva were found in 75% and 72% of children, respectively. Counts higher than 20000 colony forming units (CFU) per ml were found in 4% of saliva and in 35% of biofilm samples. The two groups showed significant differences in MS levels for dental biofilm (P=.036) and saliva (P=.009). Children older than 17 months presented higher MS levels (P<.05). Analysis by MS levels (<0.1%; 0.1-1.0%;>1.0% of MS) The two groups showed an insignificant association with increasing mean age. MS density was associated with mean number of erupted primary molars.
  
  
  CONCLUSIONS
  Mutans streptococci colonization of dental biofilm and saliva from high caries risk infants is associated with age and dental development.
authors.affiliation: Department of Pediatric Dentistry, School of Dentistry, University of Costa Rica, San Jose, Costa Rica. sgudino@racsa.co.cr
authors.forename: Sylvia
authors.initials: S
authors.lastname: Gudiño
authors.forename: Norman
authors.initials: N
authors.lastname: Rojas
authors.forename: Cristina
authors.initials: C
authors.lastname: Castro
authors.forename: Marianela
authors.initials: M
authors.lastname: Rodríguez
authors.forename: Maritza
authors.initials: M
authors.lastname: Vega
authors.forename: Lydia M
authors.initials: LM
authors.lastname: López
mesh_terms: D000367:Age Factors; D000704:Analysis of Variance; D015169:Colony Count, Microbial; D003364:Costa Rica / Q000453:epidemiology; D003731:Dental Caries / Q000209:etiology; D003773:Dental Plaque / Q000382:microbiology*; D004037:Diet, Cariogenic; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D012307:Risk Factors; D012463:Saliva / Q000382:microbiology*; D012923:Social Class; D013290:Streptococcal Infections / Q000453:epidemiology*; D013295:Streptococcus mutans / Q000302:isolation & purification*; D014078:Tooth Eruption