[Typing of Streptococcus mutans (serotype C) by arbitrarily primed polymerase chain reaction].
OBJECTIVE
To study the relationship between genetic diversity within Streptococcus mutans (C), and dental caries.


METHODS
One reference strain (GS5) was used to establish the suitability of primers and the initial AP-PCR conditions. Isolates of Streptococcus mutans (C) were obtained from 19 caries-free and 40 caries-active patients, and were originally isolated on mitis-salivarius-bacitracin agar. Totally 278 isolates were biochemically and serologically confirmed as Streptococcus mutans (C). Chromosomal DNA was extracted from those isolates by Chelex. One random primer, OPA-05 was used as a template in PCR reaction. All amplification reactions were conducted in a volume of 20 microliters containing 2 microliters of 10 x reaction buffer, 200 mumol/L each of dATP, dCTP, dGTP and dTTP and 2.5 units of Taq DNA polymerase. We varied the concentrations of MgCl2 (1.5-4.5 mmol/L), template DNA (2-40 ng), and primer (0.3-0.5 mumol/L) to determine the optical conditions for AP-PCR. The temperature profile in a thermocycler was 35 cycles as follows: 94 degrees C for 1 min, at 36 degrees C for 2 min, at 72 degrees C for 2 min. The initial denaturation was at 94 degrees C for 5 min and the final extension at 72 degrees C for 5 min.


RESULTS
The MgCl2 concentration in 4 mmol/L and the primer concentration in 0.5 mumol/L produced clearly distinct and reproducible fingerprints. We found 105 different patterns among the 278 isolates. In high-caries persons more than one genotype isolates of Streptococcus mutans (C) were colonized.


CONCLUSIONS
Isolates of Streptococcus mutans (C) exist apparent genetic diversity. The genotypes of isolates might relate to differences in caries susceptibility.
Huang
X
X
Department of Operative Dentistry and Endodontics, Hospital for Stomatology, Fujian University of Medical Sciences, Fuzhou 350001, China.
Liu
T
T
Chen
G
G
D004269:DNA, Bacterial / Q000032:analysis*; D003731:Dental Caries / Q000382:microbiology*; D003733:Dental Caries Susceptibility / Q000502:physiology; D014644:Genetic Variation; D005838:Genotype; D006801:Humans; D016133:Polymerase Chain Reaction; D012703:Serotyping; D013295:Streptococcus mutans / Q000145:classification / Q000235:genetics*
D004269:DNA, Bacterial