• Korean Journal of Microbiology
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• v.19 no.3
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• pp.137-141
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• 1981

Occurrence and distribution of sucrose metabolizing enzymes in oral streptococci had been studied. In these studies, the carbohydrate component of the culture medium had been glucose. I have extended these studies by analyzing bacterial culture supernatants for the relative content of hexosyltransferases, namely glucosyl and fructosyltransferase. As a carbohydrate, fructose was used. The growth measured for nine oral streptococci (Strptococcus mutans strains BHT, ING, AHT, 6715, LM-7, and SL-1 ; Streptococcus sanguis 903, 9811, and M-5) varied. The level of glucosyltansferase activity also varied among S. mutans strains, and its level in S. sanguis was relatively low. Fructosyltansferase activity of the various strains fluctuated more than of glucosyltransferase. S.mutans strain LM-7 had significantly higher level of both enzymes. As a whole, fructose-grown cultures had generally an agreeable trend of enzyme activity to those from glucose-grown cultures.

• International Journal of Oral Biology
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• v.39 no.4
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• pp.201-206
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• 2014

This study investigated the antimicrobial activity of methanol extract of mulberry leaf against 16 strains of mutans streptococci and four species of periodontopathogens: Porphyromonas gingivalis, Prevotella intermedia, Fusobacterium nucleatum, and Aggregatibacter actinomycetemcomitans. The antimicrobial activities of the crude extracts or silica gel chromatography fractions of methanol-extracted mulberry leaf were evaluated by determining minimal inhibitory concentrations using an established microdilution method. The cytotoxicity of the extracts of mulberry leaf on KB cells was tested by the methyl thiazolyl tetrazolium assay. Chromatography fraction 12 displayed the most potent antimicrobial activity against all 16 strains of mutans streptococci, P. gingivalis, and P. intermedia. No KB cell cytotoxicity was evident up to $128{\mu}g/ml$ of fraction 12. The methanol extract had no antimicrobial activity against F. nucleatum and A. actinomycetemcomitans. These results suggest chromatography fraction 12 methanol extract of mulberry leaf could be useful in the development of oral hygiene products, such as dentifrice and oral hygiene solution, for the prevention of dental caries.

• The korean journal of orthodontics
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• v.35 no.1 s.108
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• pp.51-59
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• 2005

The aim of this study was to compare the species and biotypes of mutans streptococci isolated from dental plaques sampled from the interfaces between the bracket aid tooth surface and smooth tooth surfaces In orthodontic patients. Dental plaque was collected from the interfaces between brackets aid teeth (test group), and from smooth tooth surfaces distant from brackets by more that 2mm (control group). The dental plaque collected by a sterilized curette was transferred into a vial of 1 X PBS. The sample in the vial was vigorously vortexed for 1 min and plated ou mitis-salivarius bacitracin (MSB) agar plate using cotton tips. The agar plates were incubated at $37^[\circ}C$ in a candle jar for 2 days, and again incubated for 1 more day at anambient temperature Individual colonies were cultured in TH broth at $37^[\circ}C\;CO_2$ incubator. The PCR-RFLP based on dextranase gene was performed for the identification of mutans streptococci at the species-level For biotyping of mutans streptococci, biochemical tests were performed There was no significant difference of the species of mutans streptococci isolated from both test and control groups However, the biotypes of the mutans streptococci isolated from test and control groups were different. These results may offer the basic data to verify the relationship between the mutans streptococci biotype and enamel decalcification or dental caries in orthodontic patients with fixed appliances.

• International Journal of Oral Biology
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• v.38 no.1
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• pp.29-36
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• 2013

Mitis group streptococci (MGS) were classified based on the nucleotide sequences 16S rRNA gene (16S rDNA) and comprised 13 Streptococcus species. However, 16S rDNA homogeneity among MGS was too high to discriminate between clinical strains at the species level, notably between Streptococcus mitis, Streptococcus oralis, Streptococcus pneumoniae, and Streptococcus pseudopneumoniae. The purpose of this study was to discriminate between 37 strains of MGS isolated from Korean oral cavities using phylogenetic analysis of the DNA-dependant RNA polymerase beta-subunit gene (rpoB). 16S rDNA and rpoB from clinical strains of MGS were sequenced using the dideoxy chain termination method and analyzed using MEGA version 5 software. The resulting phylogenetic data showed that the rpoB sequences could delineate clinical strains of MGS at the species level. Phylogenetic analysis of rpoB is therefore a useful approach for identifying MGS at the species level.

• International Journal of Oral Biology
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• v.38 no.2
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• pp.61-65
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• 2013

Erythromycin is a macrolide antibiotic and inhibits bacterial protein synthesis by stimulating the dissociation of the peptidyl-tRNA molecule from the ribosomes during elongation. The use of macrolides has increased dramatically over the last few years and has led to an increase in bacterial resistance to these antibiotics. Bacterial resistance to erythromycin is generally conferred by the ribosome methylation and/or transport (efflux) protein genes. Among the identified erythromycin-resistant genes, erm(B) (erythromycin methylation) and mef(A) (macrolide efflux) are generally detectable in erythromycin-resistant streptococcal species. The distribution of these genes in oral streptococcal isolates has been reported in studies from other countries but has not been previously examined in a Korean study. We here examined by PCR the presence of erm(B) and mef(A) in oral streptococci isolated from Korean dental plaques. Among the 57 erythromycin-resistant strains tested, 64.9% harbored erm(B) whereas 40.4% were positive for mef(A). Eleven isolates had both the erm(B) and mef(A) genes. Twenty six isolates had only erm(B) and 12 isolates had only mef(A). Eight of the 57 strains examined were negative for both genes.

• Korean Journal of Microbiology
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• v.27 no.3
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• pp.259-264
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• 1989

The adherence of $^{3}H$-labeled oral streptococcal cells to protein-coated hydroxyapatite (HA) beads was studied by a standard adherence assay. The adherence equilibrium for S. mutans 10449 occured in about 2 hrs. The cell numbers adhering to SHA was 50% less than those on bare HA. Sailva from different subjects had varying effect on bacterial adherence. The use of saliva adsorbed with homologouis bacteria decreased S. mutans adherence by 38% ; this indicates the presence of salivary agglutinin in acquired pellicle formed on HA. Animal sera and BSA decreased S. sanguis adherence. BSA concentration as high as 10mg/ml caused up to 87% adherence inhibition. The desorption experiment of adhered bacteria confirmed the previous reports that the adhesive sites on HA beads for S. mutans were different from those for S. sanguis and that S. mutans could enhance the adherence of S. sanguis but not vice versa.

• International Journal of Oral Biology
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• v.38 no.1
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• pp.21-27
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• 2013

Anginosus group streptococci (AGS) were classified based on the nucleotide sequences of the 16S rRNA gene (16S rDNA) and comprised Streptococcus anginosus, Streptococcus intermedius, and Streptococcus constellatus. It is known that AGS is a causative factor of oral and systematic diseases. The purpose of this study was to discriminate the 56 clinical strains of AGS isolated from Korean oral cavities using phylogenetic analysis of 16S rDNA and species-specific PCR at the species-level. The 16S rDNA of clinical strains of AGS was sequenced using the dideoxy chain termination method and analyzed using MEGA version 5 software. PCR was performed to identify the clinical strains using species-specific primers described in previous studies and S. intermedius-specific PCR primers developed in our laboratory. The resulting phylogenetic data showed that the 16S rDNA sequences can delineate the S. anginosus, S. intermedius, and S. constellatus strains even though the 16S rDNA sequence similarity between S. intermedius and S. constellatus is above 98%. The PCR data showed that each species-specific PCR primer pair could discriminate between clinical strains at the species-level through phylogenetic analysis of 16S rDNA nucleotide sequences. These results suggest that phylogenetic analysis of 16S rDNA and PCR are useful tools for discriminating between AGS strains at the species-level.

• The korean journal of orthodontics
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• v.33 no.5 s.100
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• pp.381-389
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• 2003

Mutans streptococci is the major causative factor in dental caries. Especially, orthodontic patients with fixed appliance are a risk group for dental caries. Because fixed appliances attached on teeth may change the environment of dental plaque, the enamel decalcification or dental caries around the bracket and band is a major side effect of orthodontic treatmet. The aim of this study was to search plant extracts that have antimicrobial effect on mutans streptococci. Seed-extract of Casia torn were prepared with ethanol and CHMC-2032, the leaf-extracts from Camellia sinensis extract, was obtained extract, 2 type strains and 20 clinical isolates of mutans streptococci isolated from the interface between orthodontic brackets and tooth surfaces in the orthodontic patients were used in this study. The minimal inhibitory concentration of CHMC-2032 was 5mg/ml on the S. mutans KCTC 3065, S. sobrinus KCTC 3088, and 8 clinical isolates of S. sobrinus. However, there was no antibacterial effect of seed-extract of C. tora on mutans streptococci. These data suggest that green tea nay be more effective than the tea Prepared from C tora In the prevention of enamel decalcification or dental caries around brackets.

• Journal of Microbiology
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• v.43 no.2
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• pp.204-208
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• 2005

The objective of this study was to both isolate and identify non-mutans streptococci organisms (non­MSO) from dental plaques recovered on mitis-salivarius sucrose bacitracin agar (MSB) plates. The dental plaque samples, which had been collected from 63 human subjects, were diluted and plated on MSB. The bacteria growing on the MSB plates were then identified with biochemical tests, as well as with 16S rDNA cloning and sequencing techniques. Our data indicated that bacteria from 30 subjects had been recovered on the MSB plates. Among the 21 typical colonies selected from the 30 subjects, 12 colonies, derived from 10 subjects, were identified as non-MSO. These 12 colonies were determined to be Streptococcus anginosus (8 colonies), S. sanguinis (1 colony), and Pantoea agglomerans (3 colonies). These results strongly suggest that a new selective medium will be required for the reliable isolation of mutans streptococci.

• Journal of Oral Medicine and Pain
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• v.21 no.1
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• pp.123-131
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• 1996

Bacteremia occurs in a wide variety of clinical procedures in oral cavity. Reduction of the number of causative microorganisms of infective endocarditis in oral cavity by local administration of antimicrobial agents decreases the magnitude of bacteremia and possibility of infective endocarditis. The effects of chlorhexidine on Streptococcus sanguis, Streptococcus mitis, Streptococcus mutans, Streptococcus oralis, Streptococcus gordonii, Staphylococcus aureus, and Staphylococcus epidermis were investigated by measurement of turbidity. The effects of 0.1% chlorhexidine gargling for 7 days on oral bacterial flora, total streptococci, S. mutans, S. aureus, and S. epidermis in whole saliv a of 7 healthy human subjects, were investigated by measurement of Colony Forming Units (CFU). The obtained results were as follows : 1. Chlorhexidine showed significant antimicrobial effects on Streptococcus snaguis, Streptococcus mitis, Streptococcus mutans, Streptococcus oralis, Streptococcus gordonii, Staphylococcus aureus, and Staphylococcus epidermis. However, the effects on S. sanguis and S. gordonii were not apparent compared with other microorganisms. 2. Oral gargling of 0.1% chlorhexidine decreased the CFU values of normal oral bacterial flora, total streptococci, S. mutans, S. aureus, and S. epidermis in whole saliva. The antimicrobial effects were significant after 4 days of chlorhexidine gargling. 3. Local antimicrobial administration in addition to systemic antibiotic prophylaxis can be highly recommended as an effective adjunct regimen for prevention of infective endocarditis.