Oral Streptococcus species in pre-term and full-term children - a longitudinal study

Int J Paediatr Dent. 2009 Nov;19(6):406-11. doi: 10.1111/j.1365-263X.2009.01003.x. Epub 2009 Sep 1.


Background: Despite high clinical significance, the microbiology of the dental biofilm in young children remains poorly understood.

Aim: The aim of this longitudinal study was to investigate five Streptoccocus species commonly found in the oral biofilm of children, namely Streptococcus mutans, Streptococcus sobrinus, Streptococcus mitis, Streptococcus sanguinis, and Streptococcus salivarius to determine their relative numbers in caries-free pre-term children, and age-matched full-term controls.

Design: Plaque and saliva samples were obtained from 15 pre-term children and 15 age-matched controls at ages 3, 6, 12, 18, and 24 months. A quantitative real-time PCR technique was used to determine the numbers of five species of Streptococcus using probes and primers specific for each bacterial species.

Results: All species of Streptococcus generally increased from ages 3 to 24 months. The relative ratios of the bacteria remained fairly constant at all ages studied (P > 0.1). There were no significant differences in numbers of all Streptococcus species between pre-term children and full-term controls at all the ages investigated between.

Conclusion: The results show that the relative numbers of S. mutans, S. sobrinus, S. mitis, S. sanguinis, and S. salivarius remain relatively constant from 3 to 24 months of age in caries-free pre- and full-term children.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Case-Control Studies
  • Child, Preschool
  • Colony Count, Microbial
  • DNA, Bacterial / analysis
  • Dental Plaque / microbiology*
  • Humans
  • Infant
  • Infant, Newborn
  • Infant, Premature*
  • Longitudinal Studies
  • Pilot Projects
  • Saliva / microbiology*
  • Streptococcus / isolation & purification*


  • DNA, Bacterial