Multiclawed SiO2 Nano-Antibacterial Agent Based on Charge Inversed Ce6 Ionic Liquid Polymers for Combating Oral Biofilm Infection

Photodynamic antimicrobial chemotherapy (PACT) is a promising therapy against biofilm infection. However, due to the saliva clearance and obstacle of biofilm, the photosensitizer is difficult to concentrate in the infection site; then, the PACT is less effective on oral biofilm infection. In this article, we report a special nano-antibacterial agent (SiO2-PCe6-IL) to solve the bottleneck problem of PACT in treatment of oral biofilm infections. The SiO2-PCe6-IL was composed of SiO2 and poly ionic liquid photosensitizer (PCe6-IL) and had tri-fold features of eliminate biofilm infection: high binding ability, breaking biofilm barriers, and enrichment photosensitizer in infection site. In oral biofilm, the SiO2-PCe6-IL changed to SiO2-PIL+ like claws of octopus that could hold tightly with biofilm. Then, the poly-dodecyl on the SiO2-PIL+ broke down the barrier of biofilm. The results of HR-MS and zeta potential indicated that SiO2-PCe6-IL could change to positive (SiO2-PIL+) in acidic environment. The interaction forces and morphology results proved that the SiO2-PIL+ had a higher affinity to biofilm and could destroy the biofilm structure. Then, the photosensitizer was enriched in biofilm at sites of infection. The in vitro and in vivo experiments showed that SiO2-PCe6-IL could effectively eradicate oral biofilm infections and control of dental caries.

Tetramic Acids Mutanocyclin and Reutericyclin A, Produced by Streptococcus mutans Strain B04Sm5 Modulate the Ecology of an in vitro Oral Biofilm

The human oral microbiome consists of diverse microbes actively communicating and interacting through a variety of biochemical mechanisms. Dental caries is a major public health issue caused by fermentable carbohydrate consumption that leads to dysbiosis of the oral microbiome. Streptococcus mutans is a known major contributor to caries pathogenesis, due to its exceptional ability to form biofilms in the presence of sucrose, as well as to its acidophilic lifestyle. S. mutans can also kill competing bacteria, which are typically health associated, through the production of bacteriocins and other small molecules. A subset of S. mutans strains encode the muc biosynthetic gene cluster (BGC), which was recently shown to produce the tetramic acids, mutanocyclin and reutericyclins A, B, and C. Reutericyclin A displayed strong antimicrobial activity and mutanocyclin appeared to be anti-inflammatory; however the effect of these compounds, and the carriage of muc by S. mutans, on the ecology of the oral microbiota is not known, and was examined here using a previously developed in vitro biofilm model derived from human saliva. While reutericyclin significantly inhibited in vitro biofilm formation and acid production at sub-nanomolar concentrations, mutanocyclin did not present any activity until the high micromolar range. 16S rRNA gene sequencing revealed that reutericyclin drastically altered the biofilm community composition, while mutanocyclin showed a more specific effect, reducing the relative abundance of cariogenic Limosilactobacillus fermentum. Mutanocyclin or reutericyclin produced by the S. mutans strains amended to the community did not appear to affect the community in the same way as the purified compounds, although the results were somewhat confounded by the differing growth rates of the S. mutans strains. Regardless of the strain added, the addition of S. mutans to the in vitro community significantly increased the abundance of S. mutans and Veillonella infantium, only. Overall, this study illustrates that reutericyclin A and mutanocyclin do impact the ecology of a complex in vitro oral biofilm; however, further research is needed to determine the extent to which the production of these compounds affects the virulence of S. mutans.

Antibacterial potential of strawberries and basil extracts combination against Streptococcus sanguinis (ATCC 10556)

Introduction: Streptococcus sanguinis is a commensal microorganism as well as a pioneer colony in forming dental plaque. Oral biofilm formation can be prevented by a mechanical cleaning procedure followed by the use of mouthwash. The current gold standard for mouthwash is chlorhexidine. Nevertheless, it has side effects that are not recommended for long-term use. Previous studies had proven that herbal-based mouthwashes such as basil leaves (Ocimum basilicum) and strawberry fruit (Fragaria x ananassa) have been shown to have antibacterial properties. The effectivity of antibacterial activity phenomenon in combined extracts has been reported in other studies. This research aims to observe the antibacterial potential of the F. x ananassa and O. basilicum extract combinations against S. sanguinis (ATCC 10556). Methods: The sample of this study was a combination of F. x ananassa and O. basilicum extract, which initially screened for their antibacterial activities. Antibacterial activities of F. x ananassa and O. basilicum extracts against S. sanguinis were observed using Kirby Bauer method, while Minimum Inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) by serial microdilution method. The 2% concentration from each extract was combined in 1:1, 1:2, and 2:1 volume ratio variations then tested for inhibitory zones, MIC, and MBC. Results: F. x ananassa extract had 0.125% and 0.25% for MIC and MBC respectively, while O. basilicum extract showed the value of MIC and MBC as 0.031% and 0.063% against S. sanguinis (ATCC 10556). The extract combinations in 1:1, 1:2, and 2:1 volume ratio variations showed 0.016% for MIC and 0.031% for MBC. Conclusions: It was concluded that combining extracts of 2 % F. x ananassa and 2% O. basilicum in various ratios were observably to have the antibacterial potential against S. sanguinis (ATCC 10556).

Matrix-Bound Zolzoledronate Enhances the Biofilm Colonization of Hydroxyapatite: Effects on Osteonecrosis

(1) Background: The aim of this study was to test whether matrix-bound zoledronate (zol) molecules enhanced the oral biofilm colonization of a mineralized matrix, rendering the alveolar bone more susceptible to medication-related osteonecrosis of the jaw (MRONJ) following invasive dental procedures. (2) Methods: We tested the effect of matrix-bound zol on the growth and attachment of Porphyromonas gingivalis (Pg), Fusobacterium nucleatum (Fn) and Actinomyces israelii (Ai), and whether the nitrogen-containing component of zol contributed to such effect. The role of oral bacteria in the induction of osteonecrosis was then tested using an extra-oral bone defect model. (3) Results: The attachment of biofilm to hydroxyapatite discs increased when the discs were pre-treated with zol. Bacterial proliferation was not affected. Matrix-bound zol was more potent than non-nitrogen-containing etidronate in enhancing the colonization. Stimulation was dampened by pre-treating the bacteria with histidine. The delivery of oral biofilm to a tibial defect caused osteonecrosis in zol-treated rats. (4) Conclusions: We conclude that matrix-bound zol enhances the oral biofilm colonization of hydroxyapatite. This enhancement depended on the presence of the nitrogen-containing group. The oral biofilm rendered the extra-oral bone susceptible to medication-related osteonecrosis, suggesting that it has an important role in the induction of MRONJ.

Bullet for periodontal disease in future: Chemically modified tetracyclines

Chronic periodontitis is nowadays popularly regarded as Dysbiosis, [1] which causes destruction of tissues rich in collagen like periodontal ligament, alveolar bone and gingival connective tissue. The oral biofilm comprises many periodontal pathogens better regarded as ‘triggers’ in causing chronic periodontitis. Since, not everyone will be affected in the same manner due to periodontal pathogens. Some might not elicit a host response while, the others might have exaggerated response. So, host modulation therapy came into existence to counteract the exaggerated host response. The chemically modified tetracyclines (CMTs) have emerged to inhibit the inflammatory response or to reduce the collagenolytic activity of host. Though a derivative of tetracyclines, it still lacks an antimicrobial action and hence, can be used for periodontitis for longer duration with no adverse effects of gastrointestinal toxicity which parent tetracyclines have.

Veillonellae: Beyond Bridging Species in Oral Biofilm Ecology

The genus Veillonella comprises 16 characterized species, among which eight are commonly found in the human oral cavity. The high abundance of Veillonella species in the microbiome of both supra- and sub-gingival biofilms, and their interdependent relationship with a multitude of other bacterial species, suggest veillonellae to play an important role in oral biofilm ecology. Development of oral biofilms relies on an incremental coaggregation process between early, bridging and later bacterial colonizers, ultimately forming multispecies communities. As early colonizer and bridging species, veillonellae are critical in guiding the development of multispecies communities in the human oral microenvironment. Their ability to establish mutualistic relationships with other members of the oral microbiome has emerged as a crucial factor that may contribute to health equilibrium. Here, we review the general characteristics, taxonomy, physiology, genomic and genetics of veillonellae, as well as their bridging role in the development of oral biofilms. We further discuss the role of Veillonella spp. as potential “accessory pathogens” in the human oral cavity, capable of supporting colonization by other, more pathogenic species. The relationship between Veillonella spp. and dental caries, periodontitis, and peri-implantitis is also recapitulated in this review. We finally highlight areas of future research required to better understand the intergeneric signaling employed by veillonellae during their bridging activities and interspecies mutualism. With the recent discoveries of large species and strain-specific variation within the genus in biological and virulence characteristics, the study of Veillonella as an example of highly adaptive microorganisms that indirectly participates in dysbiosis holds great promise for broadening our understanding of polymicrobial disease pathogenesis.

Establishment of novel in vitro culture system with the ability to reproduce oral biofilm formation on dental materials

Intensive research has been conducted with the aim of developing dental restorative/prosthetic materials with antibacterial and anti-biofilm effects that contribute to controlling bacterial infection in the oral cavity. In situ evaluations were performed to assess the clinical efficacy of these materials by exposing them to oral environments. However, it is difficult to recruit many participants to collect sufficient amount of data for scientific analysis. This study aimed to assemble an original flow-cell type bioreactor equipped with two flow routes and assess its usefulness by evaluating the ability to reproduce in situ oral biofilms formed on restorative materials. A drop of bacterial suspension collected from human saliva and 0.2% sucrose solution was introduced into the assembled bioreactor while maintaining the incubation conditions. The bioreactor was able to mimic the number of bacterial cells, live/dead bacterial volume, and volume fraction of live bacteria in the in situ oral biofilm formed on the surface of restorative materials. The usefulness of the established culture system was further validated by a clear demonstration of the anti-biofilm effects of a glass-ionomer cement incorporating zinc-releasing glasses when evaluated by this system.