title: Horizontal transmission of Streptococcus mutans in schoolchildren.
abstract: OBJECTIVE
  The aim of this study was to analyze possible horizontal transmission patterns of S. mutans among 6-7-yr-old schoolchildren from the same class, identifying genotypes and their diversity and relationship with caries disease status.
  
  
  METHODS
  Caries indexes and saliva mutans streptococci and lactobacilli counts were recorded in 42 schoolchildren. Mutans streptococci colonies were identified by means of biochemical tests and all S. mutans strains were genotyped by arbitrarily primed polymerase chain reaction. A child was considered free of S. mutans when it could not be isolated in 3 samples at 1-week intervals.
  
  
  RESULTS
  S. mutans was isolated in 30 schoolchildren: 20 having one genotype and 10 two genotypes. Higher mutans streptococci and caries index values were found in those with two genotypes. Five genotypes were isolated in more than 1 schoolchild and one of these was isolated in 3 schoolchildren. Our results suggest that horizontal transmission may take place.
  
  
  CONCLUSIONS
  Schoolchildren aged 6-7 yrs may be the source of mutual transmission of S. mutans.
authors.affiliation: Department of Preventive Dentistry, University of Granada, Spain. pbaca@ugr.es
authors.forename: Pilar
authors.initials: P
authors.lastname: Baca
authors.forename: Ana-M
authors.initials: AM
authors.lastname: Castillo
authors.forename: M-Julia
authors.initials: MJ
authors.lastname: Liébana
authors.forename: Francisca
authors.initials: F
authors.lastname: Castillo
authors.forename: Antonio
authors.initials: A
authors.lastname: Martín-Platero
authors.forename: José
authors.initials: J
authors.lastname: Liébana
mesh_terms: D002648:Child; D003430:Cross-Sectional Studies; D003731:Dental Caries / Q000453:epidemiology / Q000382:microbiology; D018562:Disease Transmission, Infectious / Q000706:statistics & numerical data*; D005260:Female; D005838:Genotype; D006801:Humans; D008297:Male; D013290:Streptococcal Infections / Q000635:transmission*; D013295:Streptococcus mutans / Q000235:genetics