Research progress on the structure and function of the type IX secretion system of Porphyromonas gingivalis / 口腔疾病防治

@#The Porphyromonas gingivalis type IX secretion system (T9SS) is a recently discovered protein secretion system that is widely distributed in Bacillus cereus. The T9SS is structurally complex and powerful. More than 20 T9SS components have been verified, and more than 30 virulence factors can be secreted by Porphyromonas gingivalis alone, which contributes significant to the pathogenicity of Porphyromonas gingivalis. T9SS is a large protein complex spanning the inner cell membrane, periplasm, and outer cell membrane. Through the structural and functional connections among its components, it forms a sophisticated functional complex that includes power provision, energy transduction, inner and outer membrane translocation, outer membrane modification, and regulatory systems to recognize, translocate, shear, and modify cargo proteins and translocate bacterial intracellular cargo proteins to the cell surface. In recent years, with advancements in X-ray diffraction and in situ cryoelectron microscopy, the exploration of T9SS has evolved from the functional study of single components to the in situ structural study of multiprotein complexes. Still, the structural resolution of the protein still has shortcomings such as low resolution and an inability to capture dynamic functional structures. Future research directions should focus more on exploring how T9SS interacts and functions with cargo proteins. In this paper, we review the research progress on Porphyromonas gingivalis T9SS on X-ray diffraction and cryoelectron microscopy structure resolution in order to gain a deeper understanding of the transport mechanism of T9SS.

Oral bacteria detection among children with cancer in a tertiary teaching hospital in Kuala Lumpur, Malaysia

@# This study sought to determine the prevalence of pathogenic and non-pathogenic bacteria in the oral cavities of children with cancer. There were 68 paediatric patients with cancer who were included in this study. Oral swab samples from the dorsum of tongues and mouth floors of these patients were subjected to culture, staining, and molecular methods to detect the bacteria. The overall prevalence of gram-positive and gram-negative bacteria was 79.4% (54/68; 95% CI = 68.4 – 87.3) and 25% (17/68; 95% CI = 16.2 – 36.4), respectively. Streptococcus salivarius and Streptococcus parasanguinis were the predominant pathogenic grampositive bacteria, while Neisseria subflava and Neisseria perflava were the most common pathogenic gram-negative bacteria. The results revealed that the number of bacteria isolates recovered in patients receiving cancer treatment was higher (55.9%) than those who had not received treatment (16.2%). Therefore, more isolated pathogenic bacteria were observed post-therapy (54.4%). Pathogenic organisms can have significant implications on patient health. Awareness of the types of bacteria inhabiting the oral cavity is essential to predict and prevent dental problems, and their associated systemic complications. Findings on the diversity of oral microflora can also provide a better understanding of the aetiology of oral diseases in paediatric patients receiving cancer treatment.

Relação entre periodontite e doenças pulmonares: revisão de literatura / Relationship between periodontitis and pulmonary diseases: literature review

A doença periodontal é uma doença infecciosa que atinge os tecidos de sustentação e proteção do dente e tem como principal determinante o biofilme dental. Recentemente foram feitas pesquisas que indicam a doença periodontal como um provável fator de risco para doenças cardiovasculares, incluindo aterosclerose, infarto do miocárdio, acidente vascular cerebral, diabetes, partos prematuros e distúrbios respiratórios. O presente trabalho tem como objetivo revisar na literatura a partir das influências da doença periodontal no desenvolvimento e potencialização de patologias pulmonares, compreendendo o processo infeccioso no trato respiratório ocasionado por bactérias bucais. Para tanto, foi realizada uma busca eletrônica de artigos científicos indexados em bases de dados, como: Pubmed, Scielo e Lilacs. Os critérios de inclusão adotados, foram: a) Idioma: Línguas Portuguesa e Inglesa; b) Período: De 2007 a 2018; c) Método de pesquisa: Estudos observacionais e ensaios clínicos. Os estudos que buscam investigar o vínculo existente entre as doenças periodontais e patologias pulmonares, bem como os fatores facilitadores e predisponentes são fundamentais à elaboração de estratégias no que concerne aos setores da saúde, em virtude de estarem relacionados a altos índices de morbidade e mortalidade. Os achados da literatura acima apresentadas neste trabalho, demonstram que a higienização bucal é o mecanismo mais eficaz à prevenção de origem e exacerbação de patologias respiratórias, provenientes do contato com agentes patógenos oriundos do biofilme oral.(AU)

The periodontal disease isaninfectious disease that reaches the tissues of support and protection of the tooth, its main determinant is the dental biofilm. Research has recently be end one that indicate periodontal disease as a likely risk factor for cardiovascular disease, including at herosclerosis, myocardial linfarction, stroke, diabetes, preterm delivery, and respiratory disorders. The present work aim store view in the literature from the influences of periodontal disease on the development and potentiation of pulmonary pathologies, including the infectious process in the respiratory tractcaused by oral bacteria. To do so an electronic search of scientific articles indexed in data bases was performed, such as Pubmed, Scielo and Lilacs. The inclusion criteria adopted were: a) Language: Portuguese and English; b) Period: From 2007 to 2018; c) Research method: Observational studies and clinical trials. Studies that seek to investigate the link between periodontal diseases and pulmonary pathologies, as well as the facilitating and predisposing factors are fundamental to the development of strategies in the health sectors, because they are related to high morbidit yandmortality rates. The literature findings presented in this study, demonstrated that oral hygiene is the most effective mechanism for the prevention of origin and exacerbation of respiratory pathologies, arising from contact with pathogenic agents originating from oral biofilm (AU)

Assessment of the endodontic microbiota of abscessed primary teeth using microarray technology

Knowledge of the microbial composition of abscessed primary tooth is limited. Aim: The aim was to investigate the presence of 10 oral bacterial species in samples from abscessed primary tooth root canals using microarray technology and to determine their association with clinical findings. Subjects and Methods: The samples were collected from root canals of 20 primary molars with acute primer infection. The bacterial composition of the samples was semi-quantitatively defined using a microarray system (ParoCheck®). Clinical parameters included the presence of spontaneous pain, mobility, percussion sensitivity and swelling. Statistical Analysis: Data were statistically analyzed by Student' t-test, Fisher's exact Chi-square test, Freeman–Halton–Fisher's exact test, and Spearman's rho correlation analysis. Results: All the tested species were detected in the samples. Fusobacterium nucleatum was the most frequent bacterium (100%), followed by Parvimonas micra (65%), Provetella intermedia (45%), and Treponema denticola (45%). According to paired bacterial combinations, F. nucleatum was significantly positively correlated with P. intermedia and P. micra (P < 0.05). T. denticola was significantly positively correlated with Porphyromonas gingivalis, Tannerella forsythia, Campylobacter rectus, and P. micra, while it was negatively correlated with Eikenella corrodens (P < 0.05). No statistically significant relationships were found between the presence of any bacteria and clinical findings. Conclusion: Microarray technology used in this study has demonstrated the presence of various bacteria with varying proportions in the root canals of abscessed primary teeth. The results regarding the high rate of certain bacterial combinations suggest the enhanced pathogenicity due to additive or synergistic effects of these microbial combinations.

Antimicrobial Effect of Acanthopanax sessiliflorum Fruit Extracts against Selected Oral Bacteria / 치위생과학회지

This study aimed to evaluate the antimicrobial effects of Acanthopanax sessiliflorum fruit (ASF; Ogaza) extracts on Streptococcus mutans and Streptococcus sobrinus, which are agents that cause dental caries, and on Streptococcus mitis and Streptococcus salivarius, the microbial flora of the oral cavity. The ASF extracts obtained using 70% ethanol were fractionated in the order of ethyl acetate and n-Butanol, concentrated under reduced pressure, and lyophilized to give powdery solvent extracts. The antimicrobial activity of ASF extracts from each solvent was examined using the disk diffusion method. As a result, only those extracts obtained using an ethyl acetate solvent showed antimicrobial activity. These extracts were selected, and the minimum inhibitory concentration was measured by disk diffusion method at various extract concentrations. Results showed a minimum inhibitory concentration of 32 mg/ml. The viable cell count was measured to confirm the minimum bactericidal concentration. Results showed a minimum bactericidal concentration of 64 mg/ml. In the cytotoxicity test using normal human dermal fibroblast cells, the absorbance value of the test group was similar to that of the control group at 0.64, 1.28, and 6.4 mg/ml. The bacteria and their colonies were examined using a scanning electron microscope. Boundaries between the antimicrobial activity region and non-antimicrobial activity region were observed around the paper disk, which was immersed in the extract with 32 mg/ml concentration. Bacterial colonization was not observed in the area with antimicrobial activity. This finding suggests that ASF extracts can inhibit the growth of some microorganisms in the oral cavity, in addition to the effects of these extracts known to date. In particular, ASF extracts may be used as a preparation for preventing dental caries by adding the extract to the toothpaste or oral mouthwash.

Screening of Antibiotics that Selectively Inhibit a Bacterial Species Associated with a Recurrent Aphthous Stomatitis Risk

Recurrent aphthous stomatitis (RAS) is a common oral mucosal disorder for which no curative treatment is available. We previously reported that decreased Streptococcus salivarius and increased Acinetobacter johnsonii on the oral mucosa are associated with RAS risk. The purpose of this study was to identify antibiotics that selectively inhibit A. johnsonii but minimally inhibit oral mucosal commensals. S. salivarius KCTC 5512, S. salivarius KCTC 3960, A. johnsonii KCTC 12405, Rothia mucilaginosa KCTC 19862, and Veillonella dispar KCOM 1864 were subjected to antibiotic susceptibility test using amoxicillin, cefotaxime, gentamicin, clindamycin, and metronidazole in liquid culture. The minimal inhibitory concentration (MIC) was defined as the concentration that inhibits 90% of growth. Only gentamicin presented a higher MIC for A. johnsonii than MICs for S. salivarius and several oral mucosal commensals. Interestingly, the growth of S. salivarius increased 10~200% in the presence of sub-MIC concentrations of gentamicin, which was independent of development of resistance to gentamicin. In conclusion, gentamicin may be useful to restore RAS-associated imbalance in oral microbiota by selectively inhibiting the growth of A. johnsonii but enhancing the growth of S. salivarius.

The oral microbiome community variations associated with normal, potentially malignant disorders and malignant lesions of the oral cavity

The human oral microbiome has been known to show strong association with various oral diseases including oral cancer. This study attempts to characterize the community variations between normal, oral potentially malignant disorders (OPMD) and cancer associated microbiota using 16S rDNA sequencing. Swab samples were collected from three groups (normal, OPMD and oral cancer) with nine subjects from each group. Bacteria genomic DNA was isolated in which full length 16S rDNA were amplified and used for cloned library sequencing. 16S rDNA sequences were processed and analysed with MOTHUR. A core oral microbiome was identified consisting of Firmicutes, Proteobacteria, Fusobacteria, Bacteroidetes and Actinobacteria at the phylum level while Streptococcus, Veillonella, Gemella, Granulicatella, Neisseria, Haemophilus, Selenomonas, Fusobacterium, Leptotrichia, Prevotella, Porphyromonas and Lachnoanaerobaculum were detected at the genus level. Firmicutes and Streptococcus were the predominant phylum and genus respectively. Potential oral microbiome memberships unique to normal, OPMD and oral cancer oral cavities were also identified. Analysis of Molecular Variance (AMOVA) showed a significant difference between the normal and the cancer associated oral microbiota but not between the OPMD and the other two groups. However, 2D NMDS showed an overlapping of the OPMD associated oral microbiome between the normal and cancer groups. These findings indicated that oral microbes could be potential biomarkers to distinguish between normal, OPMD and cancer subjects.

THE EFFECT OF OIL-PULLING AGAINST ON ORAL BACTERIA / Шинэ санаа Шинэ нээлт

@#BACKGROUND In recent years, the new treatment and technology developing quickly however, the disease prevention therapy necessary investigate in preventive dentistry. Oil pulling is a traditional Indian folk remedy and Researchers et al previously first time investigated this method. Asokan S, Emmadi P, Chamundeswari et al have indicated the antibacterial activity of sesame oil against on oral microorganisms and found the bacterial growth decreased 20%. In our country, this has not been investigated thus . AIM The aim of this study to assess the antimicrobial efficacy of sunflower oil for reducing micro bacterial count in the oral cavity. METHODS The present study was a parallel design, double-blind, randomized clinical trial with two groups which collected from 162 dental students at the MNUMS, School of Dentistry. The participants rinsed a mouth by 10 ml oil 5 min twice a day after meal and all participants used the same teeth paste during the study period. Oral health status and plaque index were obtained and assessed at baseline and after 30 days of oil therapy . RESULTS However, the Oral health status index not reduced after 30 days. The baseline bacterial count mean of treatment group: a) 0-15 colons subgroup increased from 40.4% to 55.4%, b) 16-200 colons subgroup reduced from 33.3% to 28.6% and c) >201 colons subgroup reduced from 26,3% to 16.1%. In the control group no differences the bacterial count means on baseline and after therapy. CONCLUSION The oil rinse therapy can be used as valuable preventive agents in maintaining and improving oral health furthermore reduced plaque formation and bacterial colonization 15%.

Antimicrobial efficacy of the combinations of Acacia nilotica, Murraya koenigii (Linn.) Sprengel, Eucalyptus, and Psidium guajava on primary plaque colonizers: An in vitro study.

Background: The rise in disease incidence, increased resistance of pathogenic bacteria to currently used antibiotics and chemotherapeutics, opportunistic infections in immunocompromised individuals, and financial considerations in developing countries necessitates alternate preventive and treatment strategies for oral diseases. Objective: The objective of the study is to assess the antimicrobial efficacy of triple and quadruple combinations of Acacia nilotica (AN), Murraya koenigii (Linn.) (MKL) Sprengel, Eucalyptus (Euca), and Psidium guajava (PS) on primary plaque colonizers. Materials and Methods: The phytochemicals in four plants were extracted using Soxhlet apparatus. The dried extracts were diluted with dimethyl sulfoxide (DMSO) to prepare stock solutions (100 mg/ml) of each plant. The triple and quadruple combinations were prepared after mixing equal quantities of stock solutions from each plant extracts. The antimicrobial efficacy testing was done on Streptococcus mutans, Streptococcus sanguis, and Streptococcus salivarius using agar well diffusion method. Chlorhexidine of 0.2% composition and DMSO were used as positive and negative controls, respectively. The mean diameter of inhibition zone between different categories was compared using one‑way analysis of variance. Results: The combination of AN + MKL Sprengel + Euca + PS produced the highest mean diameter of inhibition zone (23.5 ± 2.17 mm) against S. mutans. The combination of AN + MKL Sprengel + Euca produced the maximum antimicrobial efficacy against S. sanguis (19.83 ± 1.33). Conclusion: All the triple and quadruple combinations of the plant extracts offered antimicrobial benefits either superior or comparable to 0.2% chlorhexidine against S. mutans, S. sanguis, and S. salivarius.

Effect of Sub-minimal Inhibitory Concentration of Chlorhexidine on Biofilm Formation and Coaggregation of Early Colonizers, Streptococci and Actinomycetes

Chlorhexidine has long been used in mouth washes for the control of dental caries, gingivitis and dental plaque. Minimal inhibitory concentration (MIC) is the lowest concentration of an antimicrobial substance to inhibit the growth of bacteria. Concentrations lower than the MIC are called sub minimal inhibitory concentrations (sub-MICs). Many studies have reported that sub-MICs of antimicrobial substances can affect the virulence of bacteria. The aim of this study was to investigate the effect of sub-MIC chlorhexidine on biofilm formation and coaggregation of oral early colonizers, such as Streptococcus gordonii, Actinomyces naeslundii and Actinomyces odontolyticus. The biofilm formation of S. gordonii, A. naeslundii and A. odontolyticus was not affected by sub-MIC chlorhexidine. However, the biofilm formation of S. mutans increased after incubation with sub-MIC chlorhexidine. In addition, cell surface hydrophobicity of S. mutans treated with sub-MIC of chlorhexidine, decreased when compared with the group not treated with chlorhexidine. However, significant differences were seen with other bacteria. Coaggregation of A. naeslundii with A. odontolyticus reduced by sub-MIC chlorhexidine, whereas the coaggreagation of A. naeslundii with S. gordonii remained unaffected. These results indicate that sub-MIC chlorhexidine could influence the binding properties, such as biofilm formation, hydrophobicity and coaggregation, in early colonizing streptococci and actinomycetes.

Expression of Inflammasome Complex Following Various Oral Bacterial Infection in THP-1 Cells

Interleukin-1b (IL-1β), a proinflammatory cytokine, regulates the innate immune responses against bacterial infection. Mature IL-1β is produced from pro-IL-1β by activated caspase-1, which in turn is activated by the inflammasome complex formation. In this study, we compared the inflammasome mRNA expression induced by S. sanguinis, S. oralis, F. nucleatum and P. intermedia. Among the tested bacteria, S. sanguinis induced the highest IL-1β secretion. S. oralis, F. nucleatum and P. intermedia induced very weak IL-1β secretion. S. sanguinis mostly induced the NLRP3 mRNA expressions. Although F. nucleatum did not induce high IL-1β secretion, it induced high expression levels of AIM2, NLRP2, and NLRP3. No specific inflammasomes were induced by S. oralis and P.intermedia. Studying the inflammasome complex activation induced by oral bacteria may thus enhance our understanding of the pathogenesis of oral diseases.

Effect of roselle calyx extract on in vitro viability and biofilm formation ability of oral pathogenic bacteria

OBJECTIVE@#To investigate the effect of the roselle calyx extract (RCE) (Hibiscus sabdariffa L.) on the in vitro viability and biofilm formation ability of oral pathogenic bacteria.@*METHODS@#RCE was prepared by soaking roselle calyx powder with ethyl alcohol for 24 h at room temperature. After centrifugation, the extract was lyophilized. Then, the extract was dissolved in phosphate-buffered saline, the pH was adjusted, and the extract was aseptically filtered. We used Streptococcus mutans, Streptococcus sanguinis, Lactobacillus casei, Actinomyces naeslundii, Aggregatibacter actinomycetemcomitans, Fusobacterium nucleatum, Porphyromonas gingivalis and Prevotella intermedia in this study. The antibacterial activity of the RCE was determined by treating the cells of these bacteria with the extract for 10 or 20 min at room temperature. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration was determined using the microdilution method, and the effect of the RCE on the ability to form biofilm was determined using a polystyrene micro plate assay. In addition, we used the WST-1 assay to determine the cytotoxicity of the RCE on HGF, Ca9-22 and KB cells.@*RESULTS@#The RCE had antibacterial activity against oral bacteria used in this study. In particular, most significant antibacterial activity was observed against Fusobacterium nucleatum, Prevotella intermedia and Porphyromonas gingivalis. The MIC and minimum bactericidal concentration were 7.2 mg/mL-28.8 mg/mL and 14.4 to >57.6 mg/mL. The RCE had an inhibitory effect on biofilm formation at the MIC and sub-MIC levels. In addition, the RCE had low cytotoxic effects on HGF, Ca9-22 and KB cells.@*CONCLUSIONS@#Thus, our results indicate that the RCE may be used for preventing oral diseases.

Effect of roselle calyx extract on in vitro viability and biofilm formation ability of oral pathogenic bacteria

Objective: To investigate the effect of the roselle calyx extract (RCE) (Hibiscus sabdariffa L.) on the in vitro viability and biofilm formation ability of oral pathogenic bacteria. Methods: RCE was prepared by soaking roselle calyx powder with ethyl alcohol for 24 h at room temperature. After centrifugation, the extract was lyophilized. Then, the extract was dissolved in phosphate-buffered saline, the pH was adjusted, and the extract was aseptically filtered. We used Streptococcus mutans, Streptococcus sanguinis, Lactobacillus casei, Actinomyces naeslundii, Aggregatibacter actinomycetemcomitans, Fusobacterium nucleatum, Porphyromonas gingivalis and Prevotella intermedia in this study. The antibacterial activity of the RCE was determined by treating the cells of these bacteria with the extract for 10 or 20 min at room temperature. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration was determined using the microdilution method, and the effect of the RCE on the ability to form biofilm was determined using a polystyrene micro plate assay. In addition, we used the WST-1 assay to determine the cytotoxicity of the RCE on HGF, Ca9-22 and KB cells. Results: The RCE had antibacterial activity against oral bacteria used in this study. In particular, most significant antibacterial activity was observed against Fusobacterium nucleatum, Prevotella intermedia and Porphyromonas gingivalis. The MIC and minimum bactericidal concentration were 7.2 mg/mL-28.8 mg/mL and 14.4 to >57.6 mg/mL. The RCE had an inhibitory effect on biofilm formation at the MIC and sub-MIC levels. In addition, the RCE had low cytotoxic effects on HGF, Ca9-22 and KB cells. Conclusions: Thus, our results indicate that the RCE may be used for preventing oral diseases.

Detection of Bacterial Species in Chronic Periodontitis Tissues at Different Stages of Disease Severity

The goal of this research was to determine the relationship between the stage of chronic periodontitis and the presence of six bacterial pathogens (Aggregatibacter actinomycetemcomitans: AA, Fusobacterium nucleatum: FN, Porphyromonas gingivalis: PG, Prevotella intermedia: PI, Enterococcus faecalis: EF, and Parvimonas micra: PM). Forty-six chronic periodontitis patients visiting a dental hospital were included in this investigation. They were classified into four chronic periodontitis stages based on the sulcus bleeding index value and the probing depth. The tissue samples from the periodontal surgery were used for a direct PCR detection assay. A total of 49 samples from 46 patients were collected and classified into four chronic periodontitis groups (N: 6, P1: 13, P2: 18, P3: 12). The PCR assay showed that FN, PI, and PM were involved from the beginning of chronic periodontitis (P1), while AA and PG existed regardless of the disease stages. EF was strongly linked to the P3 stage of the disease. In order to assess the effect of dental treatments on patients with chronic periodontitis, EF should be a critical marker for P3 patients, while FN, PI, and PM would be good indicators for chronic periodontitis.

Identification of the Bacteria Isolated from Oral Cavities in Korea

The aim of this study was to identify bacteria isolated from the oral cavities and to determine their antimicrobial susceptibility against eight antibiotics. The bacterial strains were obtained from the Korean Collection for Oral Microbiology (KCOM). The bacteria were identified by comparing 16S rDNA sequences at the species level. The data showed that 77 bacterial strains were predominantly identified as streptococci (49.4%) and staphylococci (14.3%). Minimum inhibitory concentrations (MIC) were determined using a broth dilution assay to test the sensitivity of the bacterial strains. The MIC values of the oral bacterial strains against antibiotics were different. Streptococci were sensitive to clindamycin, cefuroxime axetil, and vancomycin, and they were resistant to tetracycline. Staphylococci also were sensitive to clindamycin, cefuroxime axetil, and vancomycin, and they were resistant to penicillin antibiotics. Gram-negative bacterial strains were sensitive to tetracycline and were resistant to clindamycin. These results suggest that the antimicrobial susceptibility test is necessary in deciding the prescription for antibiotics, to prevent the misuse or abuse of antibiotics.

Effect of Sub-Minimal Inhibitory Concentrations of Antibiotics on Biofilm Formation and Coaggregation of Streptococci and Actinomycetes

Minimal inhibitory concentration (MIC) is the lowest antibiotic concentration that inhibits the visible growth of bacteria. Sub-minimal inhibitory concentration (Sub-MIC) is defined as the concentration of an antimicrobial agent that does not have an effect on bacterial growth but can alter bacterial biochemistry, thus reducing bacterial virulence. Many studies have confirmed that sub-MICs of antibiotics can inhibit bacterial virulence factors. However, most studies were focused on Gram-negative bacteria, while few studies on the effect of sub-MICs of antibiotics on Gram-positive bacteria. In this study, we examined the influence of sub-MICs of doxycycline, tetracycline, penicillin and amoxicillin on biofilm formation and coaggregation of Streptococcus gordonii, Streptococcus mutans, Actinomyces naeslundii, and Actinomyces odontolyticus. In this study, incubation with sub-MIC of antibiotics had no effect on the biofilm formation of S. gordonii and A. naeslundii. However, S. mutans showed increased biofilm formation after incubation with sub-MIC amoxicillin and penicillin. Also, the biofilm formation of A. odontolyticus was increased after incubating with sub-MIC penicillin. Coaggregation of A. naeslundii with S. gordonii and A. odontolyticus was diminished by sub-MIC amoxicillin. These observations indicated that sub-MICs of antibiotics could affect variable virulence properties such as biofilm formation and coaggregation in Gram-positive oral bacteria.

Xylitol Sensitivity among Oral Streptococci

Xylitol is a five-carbon sugar alcohol that inhibits the growth of oral streptococci, including Streptococcus mutans. In this study, we tested xylitol sensitivity among the oral streptococci. We also compared nucleotide homology of putative fructose phosphotransferase system (PTS) and xylitol sensitivity, since xylitol is transported via the fructose PTS. Among the tested Streptococci, S. pneumonia showed the highest resistance to xylitol while S. gordonii and S. sanguinis showed the most sensitive growth inhibition. These streptococci could be grouped according to their xylitol sensitivity. S. mutans and S. salivarius showed similar bacterial growth inhibition by xylitol. S. mitis, S. oralis, S. pneumonia, S. intermedius and S. anginosus showed relatively low sensitivity to xylitol. When the genetic homologies of five fructose PTSs were compared among the tested streptococci, closely related streptococci showed similar sensitivity to xylitol. Taken together, fructose PTSs may mediate the sensitivity to xylitol in oral streptococci.

Antibacterial Activity of Hydrogen-rich Water Against Oral Bacteria

There are estimated to be about 700 species of bacteria in the oral cavity. Based on epidemiological investigations, some of these strains have been proposed as the pathogens responsible for oral diseases such as dental caries, gingivitis and periodontitis. Since electrolyzed hydrogen-rich water has been shown to have beneficial effects on human immunity, its use has increased. In our study, the antibacterial activity of hydrogen-rich water for oralagainst bacteria associated with oral disease was evaluated. The bacterial strains Streptococcus mutans, Fusobacterium nucleatum, Porphyromonas gingivalis and Tannerella forsythia were cultured in specific growth medium. S. mutans, F. nucleatum and P. gingivalis were soaked to thein both hydrogen water and tap water for 30 sec and then inoculated onto mitis-salivarius agar and brain heart infusion agar including supplemented withvitamin K and hemin, respectively. The numbers of bacterial colonies were then measured after cultivation for 48 hours. In the case of T. forsythia, which does not grow well on agar plates, inoculations into modified new oral spirochete (NOS) broth were performed and growth curve analysis was undertaken every day with a spectrophotometer. Hydrogen water showed antibacterial activity against all four bacterial strains in comparison with tap-water. We conclude from this that hydrogen water may have a positive impact on oral hygiene by helping to remove cariogenic bacteria and periodontopathogens.

Effect of Xylitol on various Oral bacteria

Xylitol is a five-carbon sugar alcohol that reduces the incidence of caries by inhibiting the growth of oral streptococci, including Streptococcus mutans. Since xylitol is transported via the fructose phosphotransferase system, we hypothesized that it could also affect the growth of other oral bacteria strains. We tested the effects of xylitol against non-periodontopathogenic oral bacteria frequently found in healthy subjects as well as periodontopathogens including Porphyromonas gingivalis, Treponema denticola, and Tannerella forsythia. With 5% xylitol, Streptococcus vestibularis and Gemella morbillorum showed marked growth inhibition. With 10% xylitol, all of the tested periodontopathogens and Actinomyces naeslundii showed marked growth inhibition, whereas the growth inhibition of Neisseria mucosa, Neisseria sicca and Veillonella parvula was mild only. Xylitol is a widely used sweetener and the concentration used in our experiment is easily achieved in the oral cavity. If xylitol reduces the growth of periodontopathogens more preferentially, it could also reduce the prevalence of these pathogens and have clinical utility in the prevention or treatment of periodontal disease.

Chemical Composition and Antimicrobial Activity of the Essential Oil of Chrysanthemum indicum Against Oral Bacteria

The chemical components of the essential oil obtained from Chrysanthemum indicum L. were analyzed by GC-MS. Seventy-three compounds accounting for 96.65% of the extracted essential oil were identified. The main compounds in the oil were alpha-pinene (4.4%), 1,8-cineole (10.4%), alpha-thujone (6.05%), camphor (10.12%), terpinen-4-ol (3.4%), bornyl acetate (6.1%), borneol (3.6%), cis-chrysanthenol (3.4%), beta-caryophyllene (5.1%), germacrene D (10.6%), and alpha-cadinol (3.0%). The essential oil of C. indicum exhibited stronger antibacterial activity against all oral bacteria tested (MICs, 0.1 to 1.6 mg/ml; MBCs, 0.2 to 3.2 mg/ml) than their major compounds. Furthermore, the MICs/MBCs were reduced to one half ~ one sixteenth as a result of the combinations included the essential oil with ampicillin or gentamicin for all oral bacteria. A strong bactericidal effect was exerted in drug combinations. The in vitro data suggest that the essential oil of C. indicum with other antibiotics may be microbiologically beneficial and synergistic.