Isolation and identification of Streptococcus mutans strains with different genotype from clinical samples / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To identify Streptococcus mutans (S. mutans) strains from clinical samples.</p><p><b>METHODS</b>Plaque samples from caries-active and caries-free sites on enamel surfaces were obtained and cultivated for S. mutans isolation. Morphology, biochemistry, automatic microorganism analysis system and polymerase chain reaction using primers homologous to surface protein antigen I/II (spaP), glucosyltransferase B (gtfB) and dextranase (dexA) were used to identify S. mutans. Genotype of isolated S. mutans was determined by arbitrarily primed polymerase chain reaction.</p><p><b>RESULTS</b>Forty-six strains of S. mutans were obtained from the 32 subjects and were identified as S. mutans by biochemistry, automatic microorganism analysis system and polymerase chain reaction. Five identical genotypes were found by arbitrarily primed polymerase chain reaction.</p><p><b>CONCLUSION</b>Forty-one strains of S. mutans with different genotype were obtained from clinical samples.</p>

Preliminary screen of high cariogenicity Streptococcus mutans strains isolated from clinical specimens / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To screen of high cariogenicity Streptococcus mutans (S. mutans) strains isolated from clinical specimens preliminary.</p><p><b>METHODS</b>Acidogenicity, aciduricity, extracellular polysaccharide production and adhesion of 41 strains of S. mutans isolated from clinical specimens were investigated to screen high cariogenicity S. mutans strains.</p><p><b>RESULTS</b>There were different cariogenicity among 41 strains of S. mutans, in which 3 strains of S. mutans had all high ability to produce extracellular polysaccharide, adhere to the saliva-coated hydroxyapatite, produce acid and tolerate acid, indicated there were 3 strains with high cariogenicity S. mutans strains isolated from clinical specimens. Another 3 strains of S. mutans with all low ability to produce extracellular polysaccharide, adhere to the saliva-coated hydroxyapatite, produce acid and tolerate acid indicated they were low cariogenicity S. mutans strains isolated from clinical specimens.</p><p><b>CONCLUSION</b>We may have obtained high cariogenicity S. mutans strains isolated from clinical specimens.</p>

Selection and identification of ssDNA aptamers specific to clinical isolates of Streptococcus mutans strains with different cariogenicity / 南方医科大学学报

<p><b>OBJECTIVE</b>To select and identify ssDNA aptamers specific to Streptococcus mutans strains with different cariogenicity isolated from clinical specimens.</p><p><b>METHODS</b>Subtractive SELEX technology targeting the whole intact cells was used to screen for ssDNA aptamers specific to the clinical isolates Streptococcus mutans strains with different cariogenicity. Radioactive isotope, flow cytometry, gene cloning and sequencing, MEME online software and RNA structure analysis software were employed to analyze the first and secondary structures of the aptamers and identify the screened aptamers.</p><p><b>RESULTS</b>Detection by radioactive isotope showed sufficient pool enrichment after 9 rounds of subtractive SELEX. Flow cytometry showed that the selected aptamers H1, H16, H4, L1, L10 and H19 were capable of binding specifically with highly cariogenic Streptococcus mutans strains but not with strains with a low cariogenicity. The aptamer H19 had the strongest binding capacity to highly cariogenic Streptococcus mutans strains, with a dissociation constant of 69.45∓38.53 nmol/L.</p><p><b>CONCLUSION</b>We have obtained the ssDNA aptamers specific to the clinical isolates of highly cariogenic Streptococcus mutans strains.</p>