Effects of the antibacterial monomer 12-methacryloyloxydodecylpyridinium bromide (MDPB) on bacterial viability and metabolism

The antibacterial monomer 12-methacryloyloxydodecylpyridinium bromide (MDPB) is a strong bactericide when unpolymerized and has the potential to be utilized in various resinous biomaterials. To analyze the antibacterial characteristics of this monomer in detail, the ability of high concentrations of unpolymerized MDPB to kill Streptococcus mutans in planktonic or biofilm forms within a short time-period of contact, and the inhibitory effects of low concentrations of MDPB on the metabolic function of S. mutans, were examined. High concentrations of MDPB showed effective killing of planktonic and biofilm S. mutans cells within 60 s, and complete killing was obtained by contact with 1,000 μg ml(-1) of MDPB for 60 s. At a concentration of 4-8 μg ml(-1) , MDPB demonstrated growth inhibition, inducing elongation of the lag phase and of the doubling time, when the bacterial number was low. Inhibition of the production of acid from S. mutans by 8 μg ml(-1) of MDPB may have been caused by the inhibition of lactate dehydrogenase activity. At high concentrations, MDPB is lethal to both planktonic and biofilm forms of S. mutans in a short time-period, and at low concentrations, MDPB inhibits metabolic enzymatic activity.     

In vitro antibacterial effects of the dentin primer of Clearfil Protect Bond.

OBJECTIVES: This study aimed to investigate the antibacterial effects of the dentin primer of a commercially available self-etching adhesive system, Clearfil Protect Bond, which contains antibacterial monomer 12-methacryloyloxydodecylpyridinium bromide (MDPB). METHODS: Inhibitory effects against Streptococcus mutans, Lactobacillus casei, or Actinomyces naeslundii were examined by an agar-disc diffusion method using the Clearfil Protect Bond primer containing 5% MDPB and an acidic adhesion-promoting monomer MDP, the primer only with MDP, and the primer with 1% cetylpyridinium chloride. The minimum inhibitory/bactericidal concentrations (MIC/MBC) of each primer for the three bacterial species were determined by serial microdilution assays. For testing the bactericidal effects seen in dentin, the primer was applied to demineralized dentin blocks in which S. mutans had been impregnated, and numbers of viable bacteria were counted. RESULTS: For all three bacteria, the sizes of the inhibition zones produced by Clearfil Protect Bond primer were significantly greater than for the other primers (p<0.05, ANOVA and Scheffe's F-test). The MIC/MBC values of Clearfil Protect Bond primer were less than those of the primer without MDPB, and comparable to those of the primer containing cetylpyridinium chloride. No bacterial recovery was obtained after application of Clearfil Protect Bond primer to the bacteria-impregnated dentin, although the primer without MDPB showed some bactericidal effect. SIGNIFICANCE: Clearfil Protect Bond primer has strong antibacterial activity based upon MDPB against S. mutans, L. casei and A. naeslundii, and the capability to disinfect cavities containing residual bacteria.     

Antibacterial effects of three experimental quaternary ammonium salt (QAS) monomers on bacteria associated with oral infections

The aim of this study was to test the antibacterial effects of three experimental quaternary ammonium salt monomers in order to evaluate their potential applications as dental materials. In vitro susceptibility testing of the monomers was performed by the broth dilution method on bacteria associated with oral infections: Streptococcus mutans ATCC 25175, Actinomyces viscosus ATCC 15987, Staphylococcus aureus ATCC 29213 and Lactobacillus casei ATCC 393. The time-kill kinetics of the monomer with relatively higher antibacterial activity against S. mutans were also investigated. It was found that all the tested bacteria strains were susceptible to the three monomers, among which methacryloxylethyl cetyl ammonium chloride (DMAE-CB) exhibited the lowest minimal inhibitory concentrations, ranging from 1.2 to 4.8 microg/ml. The time-kill curve showed that DMAE-CB achieved 99.44% killing at 19.2 microg/ml (4 times the minimal bactericidal concentration) against S. mutans after 1 min and 100% killing within 10 min of contact. This result indicates that the quaternary ammonium salt monomer DMAE-CB may be a candidate antibacterial agent for incorporation into dental restorative materials.     

The effect of antibacterial monomer MDPB on the growth of organisms associated with root caries

MDPB, 12-methacryloyloxydodecylpyridinium bromide, was tested for its ability to inhibit the growth of organisms associated with active root caries lesions and to modify the growth characteristics of these organisms at sub-MICs. MICs and MBCs of MDPB for independent isolates (n=5) of the following taxa: Streptococcus mutans, Streptococcus oralis, Streptococcus salivarius, Actinomyces naeslundii, Actinomyces israelii, Actinomyces gerensceriae, Actinomyces odontolyticus, Lactobacillus spp., and Candida albicans were determined, and the effects at sub-MIC on microbial growth kinetics were assessed. All isolates were sensitive to inhibition by MDPB. The median MICs and MBCs of MDPB for these organisms were in the range of 3.13 to 25.0 microg/ml and 6.25 to 50.0 microg/ml, respectively. As for the influence of pH, inhibition was sensitive to acidic pH. Even at sub-MICs, the growth of all strains, measured as cell yield and doubling time, was significantly reduced. Based on the results of this study, MDPB exhibited the potential to inhibit the growth of microbiota associated with active root caries lesions.     

Assessment of bactericidal effects of quaternary ammonium-based antibacterial monomers in combination with colloidal platinum nanoparticles

Pretreatment of dentin using colloidal platinum nanoparticles (CPtN) can enhance the bond strength of dentin adhesives. However, the combination of CPtN, which is negatively charged, with cationic monomer-containing adhesive may reduce the antibacterial activity of the original material. Thus, the purpose of this study was to assess the effect of CPtN on the bactericidal activity of two cationic antibacterial monomers, 12-methacryloyloxydodecylpyridinium bromide (MDPB) and methacryloxylethyl cetyl dimethyl ammonium chloride (DMAE-CB). The rapid killing effects of the two monomers against planktonic or attached Streptococcus mutans in the presence or absence of CPtN were examined by viable cell counts. The measurement of minimum inhibitory and bactericidal concentrations demonstrated that CPtN up to 2.5 mM has no antibacterial activity. In the absence of CPtN, rapid killing of both planktonic and attached Streptococcus mutans were achieved by the two cationic monomers. Combination with 0.1 mM CPtN did not reduce the bactericidal effects of the two monomers, indicating that CPtN may be used as a pretreatment with antibacterial adhesives.     

Penetration of an antibacterial dentine-bonding system into demineralized human root dentine in vitro

In this study, the penetration of three proprietary dentine-bonding agents (Prime & Bond 2.1, Single Bond, Liner Bond 2) and experimental dentine-bonding systems incorporating an antibacterial monomer, 12-methacryloyloxydodecylpyridinium bromide (MDPB), into artificial root caries lesions was evaluated, and the bactericidal activity of each material against Streptococcus mutans or Lactobacillus casei impregnated into demineralized dentine blocks was assessed. All of the commercial dentine-bonding agents were capable of penetrating into the artificial carious lesions to more than 150 microm. The depth of penetration of the experimental systems, which were based on Liner Bond 2, was not significantly different from that of their parent product. Liner Bond 2 primer exhibited the greatest bactericidal effects among the three proprietary dentine-bonding agents tested. Bactericidal activities of experimental primers containing MDPB were greater than those of any other products, and the application of 4% MDPB-containing primer resulted in complete killing of bacteria in demineralized dentine. The results indicate that the penetration of dentine-bonding agents into extensively demineralized root dentine is possible in vitro, and the experimental dentine-bonding systems containing the antibacterial monomer MDPB are capable of killing bacteria within demineralized dentine. This could be of benefit when managing root caries lesions.     

Inhibitory effect of garlic extract on oral bacteria

Garlic (Allium sativum) has long been known to have antibacterial, antifungal and antiviral properties but there are few data on its effects against oral bacterial species particularly putative periodontal pathogens or their enzymes. Filter sterilised, aqueous extract of garlic was tested for ability to inhibit the growth of a range of oral species and to inhibit the trypsin-like and total protease activity Porphyromonas gingivalis. The garlic extract (57.1% (w/v), containing 220 microg/ml allicin) inhibited the growth and killed most of the organisms tested. In general, the minimal inhibitory and minimum bactericidal concentrations for the Gram-negative strains (garlic MIC range 35.7-1.1 mg/ml; allicin mean MIC 4.1 microg/ml; mean MBC 7.9 microg/ml) were lower than those for the Gram-positive strains tested (garlic MIC range 142.7-35.7 mg/ml; allicin mean MIC 27.5 microg/ml; mean MBC 91.9 microg/ml). Also, of the organisms tested, the putative periodontal pathogens had among the lowest MICs (17.8-1.1 mg/ml garlic) and MBCs (35.7-1.1 mg/ml garlic). Time-kill curves for Streptococcus mutans and P. ginigvalis, showed that killing of the latter started almost immediately, whereas there was a delay before S. mutans was killed. The garlic extract also inhibited the trypsin-like and total protease activity of P. gingivalis by 92.7% and 94.88%, respectively. These data indicate that garlic extract inhibits the growth of oral pathogens and certain proteases and so may have therapeutic value, particularly for periodontitis.     

激光选区熔化钛表面不同形貌对口腔链球菌黏附的影响

目的探讨激光选区熔化（SLM）制造的钛试件表面不同形貌对变异链球菌和血链球菌黏附的影响。 方法通过喷砂、碱处理和阳极氧化在SLM钛片表面制备纳米网（NN组）和纳米管（NT组）表面形貌,并与喷砂SLM钛片（SB组）及未处理SLM钛片（SLM组）进行对比,通过扫描电镜、表面形貌分析仪、表面接触角测试仪对各组钛片表面形貌、粗糙度和亲水性进行表征。将各组钛片与变异链球菌和血链球菌共同培养24 h。通过菌落形成单位计数及细菌荧光染色分析比较不同表面形貌SLM钛片上2种细菌在的黏附活、死菌量及活死菌总量,进而评价SLM钛表面不同形貌对口腔链球菌黏附的影响。 结果SLM组表面为波浪状起伏微米形貌,SB组表面为沟嵴状起伏微米形貌;NN组表面和NT组表面形成了纳米网和纳米管结构。经表面处理的SB组、NN组和NT组较SLM组表面粗糙度降低（Ra_SB= 2.87 μm,Ra_NN= 2.90 μm,Ra_NT= 2.65 μm,Ra_SLM= 7.19 μm）,亲水性提高（SLM组、SB组、NN组和NT组表面水接触角分别为76.90°、64.47°、23.17°和44.13°）。菌落形成单位计数结果显示,NT组表面变异链球菌和血链球菌的细菌密度为661.29和668.45 CFU/mm²,为各组最低,且与其余组差异具有统计学意义（P<0.05）;细菌荧光染色结果显示,NT组表面变异链球菌和血链球菌的活死菌总平均荧光强度为281.17和303.58,亦为各组最低,且与其余组差异具有统计学意义（P<0.05）;NN组表面变异链球菌和血链球菌死菌比例为0.47和0.62,均显著高于其余各组（P<0.05）。 结论在SLM起伏微米形貌基底上,阳极氧化纳米管具有较强的抗细菌黏附性能,碱处理纳米网抗细菌黏附性能弱于阳极氧化纳米管,但具有一定杀菌性能。     

Antibacterial activity and bonding characteristics of an adhesive resin containing antibacterial monomer MDPB.

OBJECTIVES: The aims of this study were to investigate the antibacterial activity of an adhesive resin incorporating the antibacterial monomer 12-methacryloyloxydodecylpyridinium bromide (MDPB) as well as its bonding characteristics in terms of bond strength into dentin and curing ability. METHODS: An experimental adhesive resin was prepared by incorporation of 2.5% MDPB into proprietary adhesive (LB Bond), and the inhibitory effect of cured specimen against the growth of Streptococcus mutans on its surface was determined. Bond strength to human dentin and degree of conversion of the experimental adhesive in combination with 1, 2, or 5% MDPB-containing primers, which were previously reported to possess bactericidal effect, were evaluated by conventional tensile bond strength test and Fourier transformation infrared spectroscopy. RESULTS: The cured experimental adhesive exhibited an inhibitory effect on S. mutans growth, reducing the number of bacteria to approximately 3% of control adhesive without MDPB. Tensile bond strength of experimental adhesive was not significantly different from that of the control (p>0.05), and use in combination with MDPB-containing primer did not show any adverse influence on bond strength. The degree of conversion of the bonding system was not different (p>0.05) between control and experimental adhesive irrespective of addition of MDPB into primer. SIGNIFICANCE: These results indicate that an adhesive resin with antibacterial activity after curing could be produced by incorporation of MDPB without influencing bond strength or curing performance, suggesting that the comprehensive bonding system including MDPB-containing primer and adhesive should be highly effective in its antibacterial effect before and after curing.     

新型抗菌单体DMAE-TB的抗菌活性及生物安全性研究

目的研究自行合成的一种季铵盐型抗菌甲基丙烯酰氧乙基-正十四烷基-二甲基氯化铵(DMAE-TB)对口腔常见致病菌的抗菌活性、抗菌动力学及细胞毒性。方法采用液体稀释法研究季铵盐单体对8种口腔常见致病菌的抗菌活性和杀菌动力学。并采用MTT法初步考察此单体的细胞毒性作用。结果季铵盐单体DMAE-TB对8种口腔致病菌均表现出较高的抗菌活性,最小抑菌浓度(MIC)值介于2.4～9.8μg/ml之间。该单体在浓度为79.2μg/ml时与变形链球菌接触1 min,能杀灭99%的细菌;接触5 min,即可杀灭所有细菌。细胞毒性实验表明DMAE-TB对细胞增殖的半数抑制浓度为8.21μg/ml。结论DMAE-TB对口腔常见致病菌具有强效、快速的抗菌活性,生物安全性较理想,具有应用于牙科抗菌修复材料的前景。     

Interaction of inflammatory cells and oral microorganisms

Polymorphonuclear leukocytes (PMNs) come in contact with plaque microorganisms in the gingival sulcus. However, little is known about the ability of PMNs to kill or inhibit the growth of plaque microorganisms. In this study, the bactericidal effects of human PMNs and serum against S. mutans 6715, S. sanguis M5, and A. viscosus T14 virulent and avirulent were examined. Plaque microorganisms grown to stationary phase were incubated with human PMNs and/or serum for 90 minutes at 37°C. The killing and growth inhibition of bacteria were determined by measurement of percent reduction in colony forming units and percent inhibition of ³H-uridine uptake by the microorganisms. A. viscosus T14 virulent was the only microorganism significantly killed by human PMNs in the absence of serum. In the presence of fresh but not heat-inactivated (56°C, 30 minutes) human serum, human PMNs had a significant bactericidal effect against all of the microorganisms tested. Exposure of S. mutans 6715, but not S. sanguis M5, to sucrose inhibited the bactericidal effect of human PMNs in the presence of fresh human serum but not in the presence of rabbit anti- S. mutans immunoglobulin. Cytochalasin B markedly inhibited phagocytosis of S. mutans 6715 by human PMNs in the presence of serum. However, cytochalasin B-treated PMNs still were significantly bactericidal for S. mutans 6715 in the presence of serum. The data suggests that human PMNs may kill or inhibit the growth of certain plaque microorganisms in the gingival crevice. The microbial killing may be influenced by bacterial extracellular polysaccharides and the presence of serum antibodies and complement, both resulting in phagocytosis and extracellular lysosomal release from PMNs.     

Bactericidal capacity of silver nanoparticles associated with Gantrez S-97 on Streptococcus mutans

Dental caries is a worldwide public health problem. S mutans plays an important role in the etiology of caries. There have been studies that showed the antimicrobial properties of silver nanoparticles are an effective agent to diminish S. mutans. The objective of this study was to evaluate the bactericidal and bacteriostatic effects of silver nanoparticles in addition to the Gantrez S-27 copolymer, on S mutans. METHOD: We performed an in vitro experimental study using the liquid microdilution method in order to find the minimum inhibitory concentrations (MICs) and the minimum bactericidal concentrations (MBCs) with the subcultures obtained. The mixture was obtained by preparing 98 microg/mL of silver nanoparticles (10(3)mol) with Gantrez S-27 2%, in distilled water The readings were performed 24 hours after incubation and on 3 consecutive days. The results showed an average MTC of 6.12 microg /mL and MBC of 6.12 microg /mL. CONCLUSION: The addition of Gantrez 2% to silver nanoparticles does not alter its antimicrobial effect.     

The effect of extracellular polysaccharides from Streptococcus mutans on the bactericidal activity of human neutrophils.

Extracellular polysaccharides (PS) synthesized by oral bacteria constitute one of their major virulence factors. The PS, synthesized from sucrose, facilitate adhesion and colonization by bacteria to tooth surfaces. The study was designed to test the effect of in situ production of extracellular PS by Streptococcus mutans on the bactericidal activity of human neutrophils. These effects were tested on bacteria pre-exposed to sucrose (PS-positive Strep. mutans) and compared to bacteria not exposed to sucrose (PS-negative Strep. mutans). The interactions between neutrophils and Strep. mutans were tested in suspension and on bacteria in an experimental model of dental plaque. Viability of Strep. mutans was measured by [3H]-thymidine incorporation into the bacteria. Degranulation of neutrophils was evaluated by the release of lysozyme, and the production of reactive oxygen products was measured by chemiluminescence. When neutrophils were incubated with suspended bacteria, the viability of PS-negative Strep. mutans was 20% of that of bacteria not incubated with neutrophils (control), while the viability of PS-positive Strep. mutans was 40% of the control. In the experimental dental-plaque model, 50% of the PS-negative Strep. mutans were killed by neutrophils while the viability of PS-positive Strep. mutans was not different than of the control. Degranulation of neutrophils was not affected by the presence of extracellular PS of Strep. mutans. Artificial stimulation of neutrophils with phorbol myristate acetate also did not enhance the bactericidal effect of neutrophils on PS-positive Strep. mutans. However, PS-positive Strep. mutans elicited oxygen-reactive products from neutrophils, 2-fold less than with PS-negative Strep. mutans. The results indicate that in situ production of bacterial extracellular polysaccharides might be a major virulence factor of Strep. mutans, enabling PS-positive Strep. mutans in the dental-plaque biofilm to evade killing by human neutrophils.     

Effect of Psidium cattleianum leaf extract on Streptococcus mutans viability, protein expression and acid production

Plants naturally produce secondary metabolites that can be used as antimicrobials. The aim of this study was to assess the effects of Psidium cattleianum leaf extract on Streptococcus mutans. The extract (100%) was obtained by decoction of 100 g of leaves in 600 ml of deionized water. To assess killing, S. mutans biofilms were treated with water (negative control) or various extract dilutions [100, 50, 25% (v/v) in water] for 5 or 60 min. To evaluate the effect on protein expression, biofilms were exposed to water or 1.6% (v/v) extract for 120 min, proteins were extracted and submitted to 2-dimensional difference gel electrophoresis. Differentially expressed proteins were identified by mass spectrometry. The effect of 1.6% (v/v) extract on acid production was determined by pH measurements and compared to a water control. Viability was similar after 5 min of treatment with the 100% extract or 60 min with the 50% extract (about 0.03% survival). There were no differences in viability between the biofilms exposed to the 25 or 50% extract after 60 min of treatment (about 0.02% survival). Treatment with the 1.6% extract significantly changed protein expression. The abundance of 24 spots was decreased compared to water (p < 0.05). The extract significantly inhibited acid production (p < 0.05). It is concluded that P. cattleianum leaf extract kills S. mutans grown in biofilms when applied at high concentrations. At low concentrations it inhibits S. mutans acid production and reduces the expression of proteins involved in general metabolism, glycolysis and lactic acid production.     

Increase of Candida cell virulence by anticancer drugs and irradiation

The influence of anticancer drugs and irradiation on Candida cell proliferation, adherence to HeLa cells and susceptibility to antifungal drugs (amphotericin B and miconazole) and neutrophils were examined using two Candida albicans strains. After treatment with 5-fluorouracil (25 microg/ml to 250 microg/ml), cis-diammine-dichloroplatinum (10 microg/ml to 100 microg/ml), peplomycin (0.5 microg/ml to 5 microg/ml) or 137Cs (20 Gy to 40 Gy) for 3 days or more, surviving Candida cells proliferated more rapidly than did untreated control cells. Anticancer agent-pretreated Candida cells revealed an increased adhesion to HeLa cells corresponding to an increase of binding to the lectins. The concentration of half limited colony formation (IC50) of amphotericin B and miconazole was increased to near two-fold that of the control by pretreatment of Candida cells with the anticancer agents, except peplomycin, which only weakly increased IC50. In addition, the enolase and Candida acid proteinase activities in the culture supernatants were increased by pretreatment with the drugs and irradiation. Correspondingly, surviving Candida cells after these treatments were resistant to neutrophils, with a reduction to half of the killing. These results indicate that anti-cancer drugs and irradiation potentiate the virulence of Candida cells, or they eliminate Candida cells with low virulence, thereby enhancing the risk of oral and systemic candidiasis.     

Clotrimazole and econazole inhibit Streptococcus mutans biofilm and virulence in vitro

Objective: The aim of this study was to determine the inhibitory effect of eight antifungal drugs on S. mutans growth, biofilm formation and virulence factors.MethodsThe actions of antifungal drugs on S. mutans were determined by recovery plates and survival kinetic curves. Biofilms were observed by scanning electron microscopy and the viable cells were recovered on BHI plates, meanwhile biofilms were stained by BacLight live/dead kit to investigate the biofilm viability. Bacteria/extracellular polysaccharides staining assays were performed to determine the EPS production of S. mutans biofilms. Acidogenicity and acidurity of S. mutans were determined using pH drop and acid tolerance assays, and the expression of ldh gene was evaluated using qPCR.ResultsWe found that clotrimazole (CTR) and econazole (ECO) showed antibacterial activities on S. mutans UA159 and S. mutans clinical isolates at 12.5 and 25 mg/L, respectively. CTR and ECO could also inhibit S. mutans biofilm formation and reduce the viability of preformed biofilm. CTR and ECO affected the live/dead ratio and the EPS/bacteria ratio of S. mutans biofilms. CTR and ECO also inhibited the pH drop, lactate acid production, and acid tolerance. The abilities of CTR and ECO to inhibit S. mutans ldh expression were also confirmed.ConclusionsWe found that two antifungal azoles, CTR and ECO, had the abilities to inhibit the growth and biofilm formation of S. mutans and more importantly, they could also inhibit the virulence factors of S. mutans.     

Antibacterial activity of yoghurt against viridans streptococci in vitro

OBJECTIVE: Yoghurt consumption leads to a selective decrease in the oral level of mutans streptococci. It is not clear whether this decrease is due to the bactericidal activity of yoghurt or other mechanisms. The present study investigated the differences in susceptibility to yoghurt between several strains of viridans streptococci. DESIGN: The sources of variation were minimised, at the expense of the external validity of the study, using culture collection strains. Each strain was tested separately on five occasions in planktonic form and logarithmic growth phase. Two strains of each of the following Streptococcus species were tested: mutans, sobrinus, gordonii, oralis, parasanguinis and sanguinis. One millilitre [10(8) colony-forming units (cfu)] of each strain was incubated (37 degrees C, 60min) with 9mL of fat-free plain yoghurt containing Streptococcus thermophilus and Lactobacillus bulgaricus (10(8) and 10(7)cfu/g, respectively) in gently vortexed tubes. Survival rates were calculated every 15min by dividing the number of viable cells, obtained using conventional laboratory procedures, by the baseline number. RESULTS: Survival rates were 8% (S. mutans 6519T), 12% (S. mutans 31738), 35% (S. oralis 25671) and >50% (all other species tested) after 15min, and 0.01% (S. mutans) and >10% (all other species tested) after 30min. Overall, S. parasanguinis and S. sobrinus were the most resistant species. When heat-treated yoghurt (<10cfu/g bacteria and inactivated bacteriocins) was used, this antibacterial activity was not found. CONCLUSION: In vitro, yoghurt with live bacteria showed selective anti-mutans activity, suggesting that the overall decrease in mutans streptococci in vivo could be due to a bactericidal effect on S. mutans but not on S. sobrinus.     

壳寡聚糖抑制变形链球菌的致龋能力

目的研究壳寡聚糖(chitooligosaccharide,COS)对变形链球菌生长、产酸及粘附能力的影响。方法选用变形链球菌标准株ATCC 25175,采用对倍稀释法测定COS对变形链球菌的最低抑菌浓度(minimum inhibitory concentration,MIC)和最低杀菌浓度(minimum bactericidal concentration,MBC);采用菌落计数法,通过时间—杀菌曲线的变化,分析COS对细菌生长速度的影响;将COS及变形链球菌菌悬液各1 m L接种于无菌试管内厌氧培养,使COS的终浓度分别达到1/2 MIC、1/4 MIC、1/8MIC,测定上清液p H变化并绘制p H曲线;采用液体闪烁计数法测定壳寡聚糖对变形链球菌粘附羟磷灰石能力的影响。结果 COS对变形链球菌的MIC和MBC分别为2.00 g/L和4.00 g/L;COS能有效抑制变形链球菌的生长,较高浓度时对细菌还具有杀菌作用。亚抑菌浓度的COS可显著影响变形链球菌的产酸性和粘附能力,并且这种抑制作用呈浓度依赖性。结论 COS对变形链球菌的生长、产酸和粘附能力均有抑制作用。     

In vitro inhibitory effects of Polygonum cuspidatum on bacterial viability and virulence factors of Streptococcus mutans and Streptococcus sobrinus

OBJECTIVES: Polygonum cuspidatum has been used in Korean folk medicine to improve oral hygiene. This study was performed to evaluate the effects of methanol extract from root of P. cuspidatum (MEP) on bacterial viability and the virulence factors of Streptococcus mutans and Streptococcus sobrinus. METHODS: To test the effects of MEP on bacterial viability, we determined the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) against 20 bacterial strains, including S. mutans and S. sobrinus, using a micro-dilution assay. In case of S. mutans and S. sobrinus, the assays for time-kill and bacterial growth rate at sub-MIC concentrations were also performed. To determine effects of the extract on the virulence factors of S. mutans and S. sobrinus, the assays for sucrose-dependent adherence, water-insoluble glucan formation, glycolytic acid production, and acid tolerance were performed at sub-MIC levels. Phytochemical analysis for constituents of MEP was carried out. RESULTS: MEP showed a broad antibacterial range (MIC 0.5-4 mg/ml). The MBC was two to four times higher than the MIC. The time-kill curves showed S. mutans and S. sobrinus were significantly killed after 1h of incubation. At sub-MIC levels, doubling times of S. mutans and S. sobrinus dose-dependently increased up to 211% and 123%, respectively. At sub-MIC levels, MEP also showed inhibitory effects on the virulence factors of S. mutans and S. sobrinus in a dose-dependent fashion. Phytochemical analysis revealed the presence of alkaloids, sterol/terpenes, tannins, flavonoids, and carbohydrates. CONCLUSION: These data indicate that MEP has inhibitory effects on bacterial viability at higher concentrations (> or =MIC) and the virulence factors of S. mutans and S. sobrinus at sub-MIC concentrations, suggesting that it might be useful for the control of dental plaque formation and subsequent dental caries formation.     

In vivo antibacterial effects of dentin primer incorporating MDPB

This study examined the hypothesis that experimental primer containing the antibacterial monomer 12-methacryloyloxydodecylpyridinium bromide (MDPB), which was previously reported to show bactericidal effects in vitro, inhibits bacteria in cavities under in vivo conditions. The number of bacteria resulting from applying primer solution to cavities in dog teeth infected with Streptococcus mutans was determined. The infected cavities were also restored using primer and the pulp response was histopathologically examined after 7, 30 and 75 days. No bacteria were recovered after applying the experimental primer, although the bactericidal effects of the proprietary primer were insignificant. Restoration with the experimental primer resulted in little or no pulpal inflammation for all periods; whereas, mild to moderate inflammatory response was observed when using proprietary primer. These results indicate that the experimental primer containing MDPB could exhibit in vivo antibacterial effects, suggesting its possible clinical benefit.