title: [A novel TaqMan® MGB probe for specifically detecting Streptococcus mutans].
abstract: OBJECTIVE
  To design a new TaqMan® MGB probe for improving the specificity of Streptococcus mutans's detection.
  
  
  METHODS
  We extracted six DNA samples from different streptococcal strains for PCR reaction. Conventional nested PCR and TaqMan® MGB real-time PCR were applied independently. The first round of nested PCR was carried out with the bacterial universal primers, while a second PCR was conducted by using primers specific for the 16S rRNA gene of Streptococcus mutans. The TaqMan® MGB probe for Streptococcus mutans was designed from sequence analyses, and the primers were the same as nested PCR. Streptococcus mutans DNA with 2.5 mg/L was sequentially diluted at 5-fold intervals to 0.16 μg/L. Standard DNA samples were used to generate standard curves by TaqMan® MGB real-time PCR.
  
  
  RESULTS
  In the nested PCR, the primers specific for Streptococcus mutans also detected Streptococcus gordonii with visible band of 282 bp, giving false-positive results. In the TaqMan® MGB real-time PCR reaction, only Streptococcus mutans was detected. The detection limitation of TaqMan® MGB real-time PCR for Streptococcus mutans 16S rRNA gene was 20 μg/L.
  
  
  CONCLUSIONS
  We designed a new TaqMan® MGB probe, and successfully set up a PCR based method for detecting oral Streptococcus mutans. TaqMan® MGB real-time PCR is a both specific and sensitive bacterial detection method.
authors.affiliation: Department of Orthodontics, Peking University School and Hospital of Stomatology, Beijing 100081, China.
authors.forename: Hui
authors.initials: H
authors.lastname: Zheng
authors.forename: Jiu-Xiang
authors.initials: JX
authors.lastname: Lin
authors.forename: Ning
authors.initials: N
authors.lastname: DU
authors.forename: Feng
authors.initials: F
authors.lastname: Chen
mesh_terms: D001483:Base Sequence; D017931:DNA Primers; D015342:DNA Probes; D004269:DNA, Bacterial / Q000235:genetics; D016133:Polymerase Chain Reaction / Q000379:methods*; D012336:RNA, Ribosomal, 16S / Q000032:analysis*; D016415:Sequence Alignment; D013291:Streptococcus / Q000145:classification / Q000235:genetics / Q000302:isolation & purification; D013295:Streptococcus mutans / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*
chemical_list: D017931:DNA Primers; D015342:DNA Probes; D004269:DNA, Bacterial; D012336:RNA, Ribosomal, 16S