[Isolation and biotyping of Streptococcus mutans among preschool children in Kaohsiung city].

Strains of streptococcus mutans were isolated from the saliva of preschool children in Kaohsiung City. The unstimulated whole saliva samples were inoculated onto modified Gold's agar plates and incubated for 24-48 hours anaerobically at 37 degrees C. Strains of S. mutans were classified according to Shklair and Keene's biochemical methods and biotyped according to the methods of Farghaly et al. S. mutans could be detected in 102 (89.5%) of 114 preschool children. The most common biotype of S. mutans in single isolation was biotype I (72.9%). The percentages of the other biotypes are as follows: biotype II (5.2%), biotype III (7.3%), biotype IV (7.3%) and biotype V (7.3%). Our study revealed that the deft index was significantly higher in children who were biotype I carriers than in those who were nonbiotype I carriers. This observation suggests that biotype I may be related to the higher incidence of dental caries in our preschool children.