title: Establishment of Streptococcus mutans in infants induces decrease in the proportion of salivary α-haemolytic bacteria.
abstract: OBJECTIVE
  For paediatric dentists, an indicator to assess caries risk of infants is very important. Conventionally, the number and/or proportions of Streptococcus mutans have been employed as risk indicator; however, because such figures reflect the existing situation, they are not suitable for assessing caries risk of infants that have not yet been infected with S. mutans. Thus, we searched for an indicator for the establishment of S. mutans.
  
  
  METHODS
  To evaluate the changes caused by the establishment of S. mutans in the microbiota of the infant oral cavity, we monitored changes in the oral microbiota of two pre-dentate infants over a 3-year period and in a cross-sectional study of 40 nursery school-aged children by cultivation of saliva on nonselective blood agar, Mitis-Salivarius agar, and Mitis-Salivarius agar supplemented with bacitracin combined with identification of selected isolates.
  
  
  RESULTS
  Two longitudinal observations suggested that the establishment of S. mutans would induce a decrease in α-haemolytic bacteria in the microbial population of the oral cavity. This suggestion was compensated with the results of cross-sectional study, and it was revealed that the establishment of 10(3)  CFU/mL of mutans streptococci in saliva might be predicted by a microbiota comprising less than approximately 55% of α-haemolytic.
  
  
  CONCLUSIONS
  Decrease in the proportion of α-haemolytic bacteria in saliva of infant was found to be applicable as an indicator to predict the establishment of S. mutans and to assess dental caries risk as a background for planning of dental care and treatment in the infants before infection with S. mutans.
authors.affiliation: Department of Pediatric Dentistry, Osaka University Graduate School of Dentistry, Osaka, Japan.
authors.forename: Mamoru
authors.initials: M
authors.lastname: Kawaguchi
authors.forename: Tomonori
authors.initials: T
authors.lastname: Hoshino
authors.forename: Takashi
authors.initials: T
authors.lastname: Ooshima
authors.forename: Taku
authors.initials: T
authors.lastname: Fujiwara
mesh_terms: D001419:Bacteria / Q000145:classification / Q000378:metabolism; D002675:Child, Preschool; D015169:Colony Count, Microbial; D003430:Cross-Sectional Studies; D006460:Hemolysin Proteins / Q000378:metabolism; D006801:Humans; D007223:Infant; D059013:Microbial Consortia / Q000502:physiology*; D056265:Microbial Interactions / Q000502:physiology*; D009055:Mouth / Q000382:microbiology*; D012016:Reference Values; D012463:Saliva / Q000382:microbiology*; D013295:Streptococcus mutans / Q000502:physiology*
chemical_list: D006460:Hemolysin Proteins