title: Phenotypic and molecular methods used for identification of oral streptococci and related microorganisms.
abstract: The oral cavity contains the greatest biodiversity, over 70 species being isolated from mouth mucosa, saliva, denture surfaces and/or dental-plaque. The oral streptococci, representing over 80% of the mouth micro flora, are able to synthesize glucosyl-transferases, enzymes involved in glucans production. Glucans are involved in production of an extracellular slime layer promoting adhesion and formation of a dental plaque biofilm. The 43 isolates studied obtained from partially and/or totally edentulous, were identified by VITEK system using gram-positive identification cards. Species-specific regions within the genes coding for glucosyl-transferases (gtf genes) were targeted for PCR identification of isolates. Sequencing of 16S rRNA was used as gold standard for strain confirmation. VITEK system identified a number of 11 strains as S. mitis/oralis, 12 strains as S. anginosus/gordonii, 12 strains as S. sanguinis/parasanguinis, 3 strains as S. salivarius, 3 strains as S. plurianimalium, 1 strain as S. cristatus and 1 strain as S. alactolyticus, respectively. The PCR system targeting gtf genes was able to identify S. oralis, S. salivarius and S. gordonii strains. Sequence of 16S rRNA discriminated among streptococci species and revealed 16 strains of Leuconostoc mesenteroides. Many studies are needed in order to select the most reliable phenotypic and genotypic methods in order to improve the identification algorithm for oral streptococci used by clinical laboratories. Their accurate identification is mandatory for better understanding their role in human infections.
authors.affiliation: National Institute of Research-Development for Microbiology and Immunology Cantacuzino, Bucharest, Romania. mdamian@cantacuzino.ro
authors.forename: Maria
authors.initials: M
authors.lastname: Damian
authors.forename: Andi Marian
authors.initials: AM
authors.lastname: Palade
authors.forename: Mădălina
authors.initials: M
authors.lastname: Băltoiu
authors.forename: Anca
authors.initials: A
authors.lastname: Petrini
authors.forename: Mihaela
authors.initials: M
authors.lastname: Păuna
authors.forename: Anca
authors.initials: A
authors.lastname: Roseanu
mesh_terms: D006801:Humans; D009055:Mouth / Q000382:microbiology*; D010641:Phenotype; D016133:Polymerase Chain Reaction; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D013291:Streptococcus / Q000235:genetics / Q000302:isolation & purification*
chemical_list: D012336:RNA, Ribosomal, 16S