title: Real-time quantitative polymerase chain reaction for enumeration of Streptococcus mutans from oral samples.
abstract: This study compared SYBR Green real-time quantitative PCR (qPCR) with standard plate counting for the enumeration of Streptococcus mutans in oral samples. Oral samples (n = 710) were collected from high-caries-risk children for quantification of S. mutans by qPCR using primer pairs. The S. mutans copy number was calculated with reference to a qPCR quantification cycle (Cq) standard curve and compared with the absorbance value at 600 nm of a standard suspension of S. mutans UA159. The S. mutans copy number results were evaluated in relation to standard plate count (SPC) results obtained from each sample following culture on Petri plates containing S. mutans selective media and reported as colony-forming units (CFUs). The mean S. mutans copy number calculated from qPCR was higher than the SPC CFUs (1.3 × 10(6) and 1.5 × 10(5) CFUs, respectively). The qPCR values were usually higher in individual samples and qPCR detected the presence of S. mutans 84% (231/276) of the time that the SPC did not, compared with 33% (4/12) of the time when qPCR failed to detect S. mutans and the SPC did. The qPCR technique was found to be more sensitive for detection of S. mutans from oral samples, a method that is not dependent on the viability of the sample taken and therefore is proposed as a more reliable and efficient means of quantification of S. mutans.
authors: Department of Pediatric Dentistry, School of Dentistry, University of Alabama at Birmingham, Birmingham, AL 35294-0007, USA. nkc@uab.edu
authors: Noel K
authors: NK
authors: Childers
authors: Robert C
authors: RC
authors: Osgood
authors: Kuei-Ling
authors: KL
authors: Hsu
authors: Chanika
authors: C
authors: Manmontri
authors: Stephanie S
authors: SS
authors: Momeni
authors: Harry K
authors: HK
authors: Mahtani
authors: Gary R
authors: GR
authors: Cutter
authors: John D
authors: JD
authors: Ruby
mesh_terms: D015373:Bacterial Typing Techniques / Q000379:methods*; D002648:Child; D002675:Child, Preschool; D015169:Colony Count, Microbial; D003731:Dental Caries / Q000382:microbiology* / Q000517:prevention & control; D003733:Dental Caries Susceptibility; D006801:Humans; D007223:Infant; D060888:Real-Time Polymerase Chain Reaction; D012463:Saliva / Q000382:microbiology*; D012680:Sensitivity and Specificity; D013295:Streptococcus mutans / Q000302:isolation & purification*