Inhibition of Streptococcus gordonii Metabolic Activity in Biofilm by Cranberry Juice High-Molecular-Weight Component

Previous studies demonstrated that a cranberry high-molecular-mass, nondialyzable material (NDM) can inhibit adhesion of numerous species of bacteria and prevents bacterial coaggregation of bacterial pairs. Bacterial coaggregation leads to plaque formation leading to biofilm development on surfaces of oral cavity. In the present study, we evaluated the effect of low concentrations of NDM on Streptococcus gordonii metabolic activity and biofilm formation on restorative dental surfaces. We found that the NDM selectively inhibited metabolic activity of S. gordonii, without affecting bacterial viability. Inhibiting the metabolic activity of bacteria in biofilm may benefit the health of the oral cavity

Geranylgeraniol Reverses the Toxicity Induced by Clinical Doses of Zoledronic Acid on Gingival Epithelial Cells and Gingival Fibroblasts

BACKGROUND: Medication-related osteonecrosis of the jaw (MRONJ) is of considerable concern among clinicians and researchers, with no clear pathology mechanism, preventive, or treatment protocols. AIM: This study aimed to assess the effects of geranylgeraniol (GGOH) on the toxicity induced by clinical doses of zoledronic acid (ZOL) on gingival epithelial cells and gingival fibroblasts in vitro. METHODS: Human gingival fibroblasts and gingival epithelial cells were treated with 5, 25, or 50 μM ZOL ± 50 μM GGOH for 3 days. Viability of the cells was determined using the 3-[4, 5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide assay. Calculation of percentage of the control group, analysis of variance and Tukey post-hoc comparisons were performed to test the significance between groups, which was set at p = 0.05. Cell morphology was evaluated using light microscopy. RESULTS: ZOL significantly reduced the viability of both epithelial cells and fibroblasts at all concentrations (p < 0.05), with the exception of fibroblasts at concentration of 5 μM (p = 0.44). GGOH had positive effects on the viability of the cells treated with ZOL at all concentrations. However, statistically significant improvement was obtained only in epithelial cells at 5 and 25 μM ZOL. The cell morphology of both types of cells was improved after addition of GGOH. CONCLUSION: GGOH reverses the toxic effects of clinical doses of ZOL on gingival epithelial cells and has slightly positive, but not significant effects on gingival fibroblasts. This study suggests that GGOH may be effective in the prevention and treatment of MRONJ

New Type of Oxygenase Involved in the Metabolism of Propane and Isobutane

Nocardia paraffinicum (Rhodococcus rhodochrous), a hydrocarbon-degrading microorganism, was used in a study of propane and isobutane metabolism. The bacterium was able to utilize propane or isobutane as a sole source of carbon, and oxygen was found to be essential for its metabolism. Gas chromatographic analysis showed that n-propanol was the major compound recovered from the metabolism of propane by resting cells, although trace amounts of isopropanol and acetone were detected. When a mixture of propane and isobutane was used, drastic inhibition (72 to 88%) of hydrocarbon utilization by resting cells occurred. The ratio of hydrocarbon to oxygen consumed was found to be approximately 2:1 during the metabolism of propane or isobutane by resting cells when these substrates were provided individually to the organism. Gas chromatographic-mass spectrometric analysis of products formed from (18)O(2) confirmed that the initial oxidative step in the metabolism of these substrates involved molecular oxygen. The proportion of the alcohol containing (18)O was the same as that of (18)O(2) in the gas mixture. Only a negligible amount of (18)O was detected in the alcohol when H(2)(18)O was incorporated into the system. The observed 2:1 ratio of hydrocarbon to oxygen consumption suggests that the oxygenase in N. paraffinicum, unlike the conventional mono- or dioxygenases, requires two hydrocarbon-binding sites for each of the oxygen-binding sites and is therefore an intermolecular dioxygenase. The newly described oxygenase, which catalyzes the reaction of two molecules of propane with one molecule of oxygen to yield two molecules of a C(3) alcohol, is proposed as the initial oxidation step of the hydrocarbon substrate

Efficiency of nanotube surface-treated dental implants loaded with doxycycline on growth reduction of Porphyromonas gingivalis

© 2017 by Quintessence Publishing Co Inc. Purpose: The prevalence of peri-implant infection in patients with dental implants has been shown to range from 28% to 56%. A nanotube-modified implant surface can deliver antibiotics locally and suppress periodontal pathogenic bacterial growth. The aim of this study was to evaluate the deliverability of antibiotics via a nanotube-modified implant. Materials and Methods: Dental implants with a nanotube surface were fabricated and loaded with doxycycline. Afterward, each dental implant with a nanotube surface was placed into 2-mL tubes, removed from solution, and placed in a fresh solution daily for 28 days. Experimental samples from 1, 2, 4, 16, 24, and 28 days were used for this evaluation. The concentration of doxycycline was measured using spectrophotometric analysis at 273-nm absorbance. The antibacterial effect of doxycycline was evaluated by supplementing Porphyromonas gingivalis (P gingivalis) growth media with the solution collected from the dental implants at the aforementioned time intervals for a period of 48 hours under anaerobic conditions. A bacterial viability assay was used to evaluate P gingivalis growth at 550-nm absorbance. Results: Doxycycline concentration varied from 0.33 to 1.22 μg/mL from day 1 to day 28, respectively. A bacterial viability assay showed the highest P gingivalis growth at day 1 (2 nm) and the lowest at day 4 (0.17 nm), with a gradual reduction from day 1 to day 4 of approximately 87.5%. The subsequent growth pattern was maintained and slightly increased from baseline in approximately 48.3% from day 1 to day 24. The final P gingivalis growth measured at day 28 was 29.4% less than the baseline growth. Conclusion: P gingivalis growth was suppressed in media supplemented with solution collected from dental implants with a nanotube surface loaded with doxycycline during a 28-day time interval

Chitosan coatings deliver antimicrobials from titanium implants: A preliminary study

OBJECTIVE: Chitosan was investigated as a coating for local delivery of antimicrobials for prevention of acute implant infection. The objectives of this study were to (1) measure the release of 2 antimicrobials from chitosan coatings, (2) determine efficacy of eluted antimicrobials against bacteria, in vitro, and (3) evaluate toxicity of eluted drugs to host cells/tissues. METHODS: Chitosan coatings (80.7% deacetylated, 108 kDa) containing 20% tetracycline or 0.02% chlorhexidine digluconate were bonded to titanium via silane reactions. After elution in culture medium for 7 days, eluates were tested against model pathogens Actinobacillus actinomycetemcomitans and Staphylococcus epidermidis in turbidity tests and in 24-hour cytotoxicity tests using human osteoblasts and fibroblasts. Finally, antibiotic-loaded chitosan-coated titanium pins were implanted for 7 days in muscle of Sprague-Dawley rats to evaluate the initial tissue response. RESULTS: Coatings released 89% of tetracycline in 7 days and 100% chlorhexidine in 2 days. Released tetracycline inhibited growth (95%-99.9%) of pathogens for up to 7 days with no cytotoxicity to human cells. Released chlorhexidine was active against pathogens for 1 to 2 days (56%-99.5% inhibition) but was toxic to cells on the first day of elution. Typical acute inflammatory response was observed to antimicrobial-loaded chitosan coatings similar to unloaded coatings. CONCLUSION: These preliminary data support the hypothesis that chitosan coatings have the potential to locally deliver antimicrobials to inhibit bacteria without being toxic to host cells/tissues and warrant additional studies to evaluate the ability of the coatings to prevent/resist infection and promote osseointegration. © 2011 Lippincott Williams & Wilkins, Inc

Bacterial inhibition by chitosan coatings loaded with silver-decorated calcium phosphate microspheres

Porous calcium phosphate microspheres have been modified to contain nanoparticles of silver to provide both osteoconductive and antimicrobial components to implant coatings. These microspheres have been mixed with chitosan and bonded to titanium via alkyloxysilane reaction. Silver concentration on calcium phosphate microspheres was varied from 0 to 50% and microspheres were loaded at 30 wt.% within chitosan coatings. Increasing concentrations of silver loaded on calcium phosphate microspheres within the chemically bound coating reduces bacterial viability by up to 90% in both anaerobic and aerobic pathogenic microorganisms, including Staphylococcus aureus, Prevotella denticola, and Porphyromonas gingivalis. This novel coating could reduce the incidence of infection in orthopaedic and dental implant applications

Inhibitory Effects Of A Cured Antibacterial Bonding System On Viability And Metabolic Activity Of Oral Bacteria.

To evaluate the antimicrobial efficacy of Clearfil SE Protect (CP) and Clearfil SE Bond (CB) after curing and rinsed against five individual oral microorganisms as well as a mixture of bacterial culture prepared from the selected test organisms. Bacterial suspensions were prepared from single species of Streptococcus mutans, Streptococcus sobrinus, Streptococcus gordonii, Actinomyces viscosus and Lactobacillus lactis, as well as mixed bacterial suspensions from these organisms. Dentin bonding system discs (6 mm×2 mm) were prepared, cured, washed and placed on the bacterial suspension of single species or multispecies bacteria for 15, 30 and 60 min. MTT, Live/Dead bacterial viability (antibacterial effect), and XTT (metabolic activity) assays were used to test the two dentin system's antibacterial effect. All assays were done in triplicates and each experiment repeated at least three times. Data were submitted to ANOVA and Scheffe's f-test (5%). Greater than 40% bacteria killing was seen within 15 min, and the killing progressed with increasing time of incubation with CP discs. However, a longer (60 min) period of incubation was required by CP to achieve similar antimicrobial effect against mixed bacterial suspension. CB had no significant effect on the viability or metabolic activity of the test microorganisms when compared to the control bacterial culture. CP was significantly effective in reducing the viability and metabolic activity of the test organisms. The results demonstrated the antimicrobial efficacy of CP both on single and multispecies bacterial culture. CP may be beneficial in reducing bacterial infections in cavity preparations in clinical dentistry.30e238-4

Modified Polymeric Nanoparticles Exert In Vitro Antimicrobial Activity Against Oral Bacteria.

Polymeric nanoparticles were modified to exert antimicrobial activity against oral bacteria. Nanoparticles were loaded with calcium, zinc and doxycycline. Ions and doxycycline release were measured by inductively coupled plasma optical emission spectrometer and high performance liquid chromatography. Porphyromonas gingivalis, Lactobacillus lactis, Streptoccocus mutans, gordonii and sobrinus were grown and the number of bacteria was determined by optical density. Nanoparticles were suspended in PBS at 10, 1 and 0.1 mg/mL and incubated with 1.0 ml of each bacterial suspension for 3, 12, and 24 hours. The bacterial viability was assessed by determining their ability to cleave the tetrazolium salt to a formazan dye. Data were analyzed by ANOVA and Scheffe’s F (p<0.05). Doxycycline doping efficacy was 70%. A burst liberation effect was produced during the first 7 days. After 14 days, a sustained release above 6 µg/mL, was observed. Calcium and zinc liberation were about 1 and 0.02 µg/mL respectively. The most effective antibacterial were the Dox-Nanoparticles (60 to 99% reduction) followed by Ca-Nanoparticles or Zn-Nanoparticles (30 to 70% reduction) and finally the non-doped nanoparticles (7 to 35% reduction). P.gingivalis, S.mutans and L.lactis were the most susceptible bacteria, being S.gordonii and S.sobrinus the most resistant.The found of sourcing of the study was Project MAT2017-85999-P, supported by the Ministry of Economy and Competitiveness (MINECO) and European Regional Development Fund (FEDER). No funds were received to cover publication costs