title: Identification of non-streptococcal organisms from human dental plaque grown on the Streptococcus-selective medium mitis-salivarius agar.
abstract: OBJECTIVE
  Mitis-salivarius (MS) agar has been used widely in microbial epidemiological studies because oral viridans streptococci can be selectively grown on this medium. Even though the previous findings reported the limited selecting power of MS agar for streptococcus strains, the identities of non-streptococcal strains from human oral samples which can grow on this medium are not clear yet. In this study, we identified non-streptococcal organisms grown on MS agar plates by polymerase chain reaction (PCR) amplification and sequencing of the 16S ribosomal RNA (rRNA) gene.
  
  
  METHODS
  Eighty bacterial colonies on MS plates were isolated from plaque samples, and bacterial identification was achieved with the rapid ID 32 Strep system and mini API reader. The bacterial colonies identified as non-streptococci by the API system were selected for further identification. The 16S rRNA gene was amplified by PCR and verified using DNA sequencing analysis for identification. Sequences were compared with those of reference organisms in the genome database of the National Center for Biotechnology Information using the Basic Local Alignment Search Tool (BLAST).
  
  
  RESULTS
  Among the 11 isolated non-streptococcal strains on MS plates, 3 strains were identified as Actinomyces naeslundii, 7 strains were identified as Actinomyces oris and 1 strain were identified as Actinomyces sp. using Blastn.
  
  
  CONCLUSIONS
  In this study, we showed that some oral Actinomyces species can grow on Streptococcus-selective MS agar plates.
authors.affiliation: Department of Microbiology and Immunology, College of Dentistry, Research Institute of Oral Science, Gangneung-Wonju National University, Gangneung 210-702, Republic of Korea.
authors.forename: Yeon-Hee
authors.initials: YH
authors.lastname: Kim
authors.affiliation: Department of Microbiology and Immunology, College of Dentistry, Research Institute of Oral Science, Gangneung-Wonju National University, Gangneung 210-702, Republic of Korea. Electronic address: siyoung@gwnu.ac.kr.
authors.forename: Si Young
authors.initials: SY
authors.lastname: Lee
mesh_terms: D000190:Actinomyces / Q000302:isolation & purification*; D003470:Culture Media; D004269:DNA, Bacterial / Q000032:analysis; D003773:Dental Plaque / Q000382:microbiology*; D005260:Female; D006801:Humans; D008297:Male; D016133:Polymerase Chain Reaction; D013291:Streptococcus / Q000302:isolation & purification*
chemical_list: D003470:Culture Media; D004269:DNA, Bacterial
keywords: Actinomyces; Dental plaque; Mitis-salivarius agar; Streptococcus