A call for action to the biomaterial community to tackle antimicrobial resistance

The global surge of antimicrobial resistance (AMR) is a major concern for public health and proving to be a key challenge in modern disease treatment, requiring action plans at all levels. Microorganisms regularly and rapidly acquire resistance to antibiotic treatments and new drugs are continuously required. However, the inherent cost and risk to develop such molecules has resulted in a drying of the pipeline with very few compounds currently in development. Over the last two decades, efforts have been made to tackle the main sources of AMR. Nevertheless, these require the involvement of large governmental bodies, further increasing the complexity of the problem. As a group with a long innovation history, the biomaterials community is perfectly situated to push forward novel antimicrobial technologies to combat AMR. Although this involvement has been felt, it is necessary to ensure that the field offers a united front with special focus in areas that will facilitate the development and implementation of such systems. This paper reviews state of the art biomaterials strategies striving to limit AMR. Promising broad-spectrum antimicrobials and device modifications are showcased through two case studies for different applications, namely topical and implantables, demonstrating the potential for a highly efficacious physical and chemical approach. Finally, a critical review on barriers and limitations of these methods has been developed to provide a list of short and long-term focus areas in order to ensure the full potential of the biomaterials community is directed to helping tackle the AMR pandemic

Plant-based oral care product exhibits antibacterial effects on different stages of oral multispecies biofilm development in vitro

Background!#!Excessive biofilm formation on surfaces in the oral cavity is amongst the main reasons for severe infection development like periodontitis and peri-implantitis. Mechanical biofilm removal as well as the use of adjuvant antiseptics supports the prevention of pathogenic biofilm formation. Recently, the antibacterial effect of the oral care product REPHA-OS!##!Methods!#!An established in vitro oral multispecies biofilm, composed of Streptococcus oralis, Actinomyces naeslundii, Veillonella dispar and Porphyromonas gingivalis, was used to analyze the antibacterial effect of different REPHA-OS!##!Results!#!REPHA-OS!##!Conclusion!#!The strong antibacterial effect of REPHA-O

Development and characterization of an oral multispecies biofilm implant flow chamber model

<div><p>Peri-implant infections are the most common cause of implant failure in modern dental implantology. These are caused by the formation of biofilms on the implant surface and consist of oral commensal and pathogenic bacteria, which harm adjacent soft and hard tissues and may ultimately lead to implant loss. In order to improve the clinical situation, there has to be a better understanding of biofilm formation on abiotic surfaces. Therefore, we successfully developed a system to cultivate an oral multispecies biofilm model in a flow chamber system, optimized for the evaluation of biofilm formation on solid materials by direct microscopic investigation. The model contains four relevant oral bacterial species: <i>Streptococcus oralis</i>, <i>Actinomyces naeslundii</i>, <i>Veillonella dispar</i> and <i>Porphyromonas gingivalis</i> in ratios similar to the native situation. The reliability of the developed “Hanoverian Oral Multispecies Biofilm Implant Flow Chamber” (HOBIC) model was verified. Biofilm volume and live/dead distribution within biofilms were determined by fluorescence staining and confocal laser scanning microcopy (CLSM). The individual species distribution was analyzed using quantitative real time PCR with propidium monoazide pretreatment (PMA-qRT-PCR) and by urea-NaCl fluorescence <i>in situ</i> hybridization (urea-NaCl-FISH). This <i>in vitro</i> model may be used to analyze biofilm formation on dental implants in more detail and to develop future implant systems with improved material properties.</p></div

An In Vitro Study of Local Oxygen Therapy as Adjunctive Antimicrobial Therapeutic Option for Patients with Periodontitis

Periodontitis is a common global disease caused by bacterial dysbiosis leading to tissue destruction, and it is strongly associated with anaerobic bacterial colonization. Therapeutic strategies such as oxygen therapy have been developed to positively influence the dysbiotic microbiota, and the use of oxygen-releasing substances may offer an added benefit of avoiding systemic effects commonly associated with antibiotics taken orally or hyperbaric oxygen therapy. Therefore, the oxygen release of calcium peroxide (CaO2) was measured using a dissolved oxygen meter, and CaO2 solutions were prepared by dissolving autoclaved CaO2 in sterile filtered and deionized water. The effects of CaO2 on planktonic bacterial growth and metabolic activity, as well as on biofilms of Streptococcus oralis and Porphyromonas gingivalis, were investigated through experiments conducted under anaerobic conditions. The objective of this study was to investigate the potential of CaO2 as an antimicrobial agent for the treatment of periodontitis. Results showed that CaO2 selectively inhibited the growth and viability of P. gingivalis (p S. oralis (p 2 has the potential to selectively affect both planktonic bacteria and mono-species biofilms of P. gingivalis. The results of this study suggest that CaO2 could be a promising antimicrobial agent with selective activity for the treatment of periodontitis

Viable species distribution within the 24 hour biofilms on titanium specimens in the flow chamber system.

<p>Tukey box plots of biofilm content of viable species distribution in three independent biological replicates (1.–3.) containing three technical replicates (three chambers) each, after 24 h growth on titanium specimens in the flow chamber system. PMA-qRT-PCR was run in duplicate for each biofilm sample. Statistically equivalent results are indicated with “equ”.</p

CLSM image of the FISH-stained 24 h four species biofilm on titanium specimen.

<p>Individual images with a z-step size of 2 μm of the 24 h four-species biofilm stained with species-specific 16S rRNA FISH probes for <i>S</i>. <i>oralis</i> (MIT-588-Alexa-405; blue), <i>A</i>. <i>naeslundii</i> (ANA-103-Alexa-488; green), <i>V</i>. <i>dispar</i> (VEI-217-Alexa-568; yellow) and <i>P</i>. <i>gingivalis</i> (POGI-Alexa-647; red) were overlaid to one image. (a)–(d) shows the individual color channels for the four individual species, (e) shows the overlay of the four color channels. Scale bars: 30μm.</p

Quantification of biofilm volume and live/dead distribution.

<p>(a) 3D reconstruction of live/dead fluorescent stained 24 hours four species biofilm on titanium specimens grown in the flow chamber system. Viable bacteria are visualized in green and dead cells are visualized in red/orange. (b) Tukey box plots of the total biofilm volume per 1.2 x 1.2 mm² and (c) mean ± standard deviation of live/dead distribution of total biofilm of three biological replicates after 24 h growth on titanium specimens in the flow chamber system. Statistically equivalent results are indicated with “equ”.</p

Effects of commensal biofilms on a peri-implant mucosa in a three dimensional model

A symbiotic microbial community of commensals exists during oral health. Pathogenic bacteria are able to induce dysregulation of hostmicrobiota homeostasis and a dysbiotic biofilm formation can cause peri-implantitis, a chronic infection. Little is known about the role of commensal and pathogenic bacteria in the regulation of the balance between host tolerance and inflammation. Previous studies have indicated that commensal bacteria are related to disease prevention, but details about the modulatory effects are still missing. Moreover, knowledge about the influence of implant material on host-microbe interaction is limited. Thus, our aim was to investigate the effects of a commensal monospecies Streptoccocus oralis biofilm and a commensal four-species biofilm (S. oralis, Actinomyces naeslundii, Veillonella dispar, Porphyromonas gingivalis) in our novel implant-mucosa model. The three dimensional in vitro model combines the three components oral mucosa, implant material and oral biofilm. After S. oralis challenge, a morphological difference at the implant area was observed in comparison to the farther or unchallenged mucosa. In addition, culture with S. oralis biofilm led to an altered cytokine/chemokine secretion. This indicates a hyporesponsiveness of the tissue which can protect it from inflammatory destruction. However, in the in vivo situation a multispecies biofilm is present. Therefore, we integrated a commensal four-species biofilm in our model to reduce the gap to the in vivo situation. The four-species biofilm challenged mucosa showed no morphological difference to the unchallenged mucosa. This illustrates that the effects of commensal mono- or multispecies biofilms are different and the interaction of bacteria species can be important regarding tissue response. The novel 3D implant-mucosa model opens the opportunity for various in vitro studies of host-microbe interactions for implant improvement

Four species growth in the bioreactor.

<p>(a) Mean ± standard deviation of the optical density at 600 nm (OD₆₀₀) growth curve of <i>S</i>.<i>oralis</i>, <i>A</i>. <i>naeslundii</i>, <i>V</i>. <i>dispar</i> and <i>P</i>. <i>gingivalis</i> in the bioreactor for 24 hours. (b) Tukey box plots of viable species distribution in planktonic samples before inoculation (0 hours) and taken from the bioreactor after 4 and 24 hours analyzed by PMA-qRT-PCR.</p

Evaluation of biofilm colonization on multi-part dental implants in a rat model

Abstract Background Peri-implant mucositis and peri-implantitis are highly prevalent biofilm-associated diseases affecting the tissues surrounding dental implants. As antibiotic treatment is ineffective to fully cure biofilm mediated infections, antimicrobial modifications of implants to reduce or prevent bacterial colonization are called for. Preclinical in vivo evaluation of the functionality of new or modified implant materials concerning bacterial colonization and peri-implant health is needed to allow progress in this research field. For this purpose reliable animal models are needed. Methods Custom made endosseous dental implants were installed in female Sprague Dawley rats following a newly established three-step implantation procedure. After healing of the bone and soft tissue, the animals were assigned to two groups. Group A received a continuous antibiotic treatment for 7 weeks, while group B was repeatedly orally inoculated with human-derived strains of Streptococcus oralis, Fusobacterium nucleatum and Porphyromonas gingivalis for six weeks, followed by 1 week without inoculation. At the end of the experiment, implantation sites were clinically assessed and biofilm colonization was quantified via confocal laser scanning microscopy. Biofilm samples were tested for presence of the administered bacteria via PCR analysis. Results The inner part of the custom made implant screw could be identified as a site of reliable biofilm formation in vivo. S. oralis and F. nucleatum were detectable only in the biofilm samples from group B animals. P. gingivalis was not detectable in samples from either group. Quantification of the biofilm volume on the implant material revealed no statistically significant differences between the treatment groups. Clinical inspection of implants in group B animals showed signs of mild to moderate peri-implant mucositis (4 out of 6) whereas the mucosa of group A animals appeared healthy (8/8). The difference in the mucosa health status between the treatment groups was statistically significant (p = 0.015). Conclusions We developed a new rodent model for the preclinical evaluation of dental implant materials with a special focus on the early biofilm colonization including human-derived oral bacteria. Reliable biofilm quantification on the implant surface and the symptoms of peri-implant mucositis of the bacterially inoculated animals will serve as a readout for experimental evaluation of biofilm-reducing modifications of implant materials