In vitro antibiofilm activity of bioactive glass S53P4

Bacterial biofilm formation on headpieces of Cochlear implants

INTRODUCTION

Bacterial biofilm formation on medical devices, such as Cochlear implants (CI), can lead to chronic infections. Not only the inner parts of the implant but also the externally located headpiece might be associated with prolonged superficial skin eczema resulting in the inability of wearing the headpiece. In this study, the surface of three CI headpieces from different manufacturers were examined for bacterial biofilm formation.

MATERIALS AND METHODS

Two bacterial species associated with implant-related infections were tested: Pseudomonas aeruginosa (ATCC9027) and Staphylococcus aureus (ATCC6538). Biofilms were formed over 24 h in tryptic soy broth at 36 °C. Biofilm formation was detected in form of biomass measurement by crystal violet staining. CI headpiece dummies of three manufacturers were used.

RESULTS

Both tested bacterial species formed biofilms on the examined CI headpiece-surfaces in a species-dependent manner with higher biofilm formation of P. aeruginosa. For both, S. aureus and P. aeruginosa, biofilm formation on the CI components was comparable to a polystyrene control surface. Between the three manufacturers, no significant difference in biofilm formation was found.

DISCUSSION

The tested bacteria displayed biofilm formation on the CI headpieces in a species-specific manner with higher amount of biofilm formed by P. aeruginosa. The biofilm formation was comparable between the manufacturers. In this study, an enhanced biofilm formation on CI headpieces could not be demonstrated. These in vitro tests suggest a minor role of bacterial biofilm on the CI headpiece in skin infections under the CI headpiece.

Bioglass and nano bioglass: A next-generation biomaterial for therapeutic and regenerative medicine applications

Biomaterials are an indispensable component in tissue engineering that primarily functions to resemble the extracellular matrix of any tissue targeted for regeneration. In the last five decades, bioglass has been extensively used in the field of therapeutic and tissue engineering. The doping of metal components into bioglass and the synthesizing of nano bioglass particles have found remarkable implications, both in vivo and in vitro. These include various medical and biological applications such as rejuvenating tissues, facilitating regeneration, and delivering biomolecules into cells and therapy, etc. Therefore, the current review discusses the various techniques used in synthesizing bioglass particles, trends of various ion-doped nano bioglass, and their applications in therapy as well as in regenerative medicine, specifically in the fields of dentistry, cardiovascular, skin, nervous, and respiratory systems. Apart from these, this review also emphasizes the bioglass combined with diverse natural polymers (like collagen, chitosan, etc.) and their applications. Furthermore, we discuss the effectiveness of bioglass properties such as antibacterial effects, biomolecular delivery systems, tissue compatibility, and regenerative material. Finally, the prospects and limitations are elaborated.

Efficacy of different bioactive glass S53P4 formulations in biofilm eradication and the impact of pH and osmotic pressure

AIM

The challenging properties of biofilm-associated infections and the rise of multidrug-resistant bacteria are prompting the exploration of alternative treatment options. This study investigates the efficacy of different bioactive glass (BAG) formulations - alone or combined with vancomycin - to eradicate biofilm. Further, we study the influence of BAG on pH and osmotic pressure as important factors limiting bacterial growth.

METHOD

Different BAG S53P4 formulations were used for this study, including (a) powder (<45 μm), (b) granules (500-800 µm), (c) a cone-shaped scaffold and (d) two putty formulations containing granules with no powder (putty A) or with additional powder (putty B) bound together by a synthetic binder. Inert glass beads (1.0-1.3 mm) were included as control. All formulations were tested in a concentration of 1750 mg/ml in Müller-Hinton-Broth against methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-resistant Staphylococcus epidermidis (MRSE). Vancomycin was tested at the minimum-inhibitory concentration for each strain. Changes in pH and osmolality over time were assessed at 0 h, 24 h, 72 h and 168 h.

RESULTS

All tested BAG formulations showed antibiofilm activity against MRSA and MRSE. Powder and putty B were the most effective formulations suppressing biofilm leading to its complete eradication after up to 168 h of co-incubation, followed by granules, scaffold and putty A. In general, MRSE appeared to be more susceptible to bioactive glass compared to MRSA. The addition of vancomycin had no substantial impact on biofilm eradication. We observed a positive correlation between a higher pH and higher antibiofilm activity.

CONCLUSIONS

BAG S53P4 has demonstrated efficient biofilm antibiofilm activity against MRSA and MRSE, especially in powder-containing formulations, resulting in complete eradication of biofilm. Our data indicate neither remarkable increase nor decrease in antimicrobial efficacy with addition of vancomycin. Moreover, high pH appears to have a direct antimicrobial impact; the role of high osmolality needs further investigation.

Bioceramic micro-fillers reinforce antibiofilm and remineralization properties of clear aligner attachment materials

Introduction: Clear aligners, while offering a more hygienic alternative to fixed appliances, are still associated with challenges including plaque accumulation and enamel demineralization. The aim of the present study was to investigate the antibiofilm and remineralization effectiveness of innovative flowable composite attachments containing bioceramic micro-fillers. Methods: Four experimental attachments were formulated and bonded to human enamel specimens: 3M Filtek Supreme flowable composite (Filtek SF) + 10% bioactive glass 45S5 (BAG), Filtek SF + 30% BAG, Filtek SF + 10% Bredigite (BRT), Filtek SF + 30% BRT. Plaque biofilms were grown on the bonded enamel using a standardized protocol and the biofilm-killing effect was assessed by confocal laser scanning microscopy and scanning electron microscopy. Vickers microhardness was measured to evaluate the remineralization effect of the attachments containing bioceramic fillers after acid challenge. Shear bond test was performed to assess the bonding strength. Results: Attachments with bioceramic fillers significantly inhibited plaque biofilm growth in 3 weeks on enamel, contributing over 20% bacterial cell killing in 10% filler groups and over 30% killing in 30% filler groups. All four experimental groups demonstrated significantly higher microhardness values than the control group without fillers on the attachment side. The shear bonding strength was not compromised in the attachments with micro-fillers. Discussion: Proper incorporation of bioceramic micro-fillers in attachments provides an innovative approach for clear aligner therapy with reinforced antibiofilm and remineralization effects without weakening shear bonding strength.

Outcome and Predictors of Treatment Failure in Chronic Osteomyelitis Using Bioactive Glass Granules and Putty Formulations

BACKGROUND

The aim of this study is to evaluate the outcome of patients with cavitary chronic osteomyelitis undergoing adjuvant treatment with bioactive glass (BAG) S53P4 and identify the independent risk factors (RFs) for recurrence in 6- and 12-month patient follow-up.

METHODS

A retrospective, multicentre observational study conducted in tertiary specialised hospitals among patients undergoing the surgical treatment of chronic cavitary osteomyelitis using BAG-S53P4 in a granule and/or putty formulation to assess the clinical outcome and RFs for failure in 6- and 12-month patient follow-up.

RESULTS

Of the 92 and 78 patients with 6-month and 12-month follow-ups, infection was eradicated in 85.9% and 87.2%, respectively. In the 6-month follow-up, BAG-S53P4 in the granule formulation presented a greater risk of recurrence compared to the bioactive glass putty formulation or combined granules and putty (prevalence ratio (PR) = 3.04; confidence interval 95% [CI95%]: 1.13-10.52) and neoplasia (PR = 5.26; CI95%: 1.17-15.52). In the 12-month follow-up cohort of 78 patients, smoking (PR = 4.0; 95% CI: 1.03-15.52) and nonfermenting GNB infection (PR = 3.87; CI95%: 1.09-13.73) presented a greater risk of recurrence.

CONCLUSIONS

BAG-S53P4 is a viable option for bone-void filling and the treatment of chronic cavitary osteomyelitis. Formulations of BAG with putty or in combination with granules showed better results.

Effect of 20 μm thin ceramic coatings of hydroxyapatite, bioglass, GB14 and Beta-Tricalciumphosphate with copper on the biomechanical stability of femoral implants

In the present work, we test four thin coatings for titanium implants, namely, bioglass, GB14, Beta-Tricalciumphosphate (β-TCP) and hydroxyapatite (HA) with and without incorporated copper ions for their osteointegrative capacity. A rabbit drill hole model for time intervals up to 24 weeks was used in this study. Implant fixation was evaluated by measuring shear strength of the implant/bone interface. Quantitative histological analysis was performed for the measurements of bone contact area. Implants with and without copper ions were compared after 24 weeks. Thin coatings of GB14, HA or TCP on titanium implants demonstrated high shear strength during the entire test period of up to 24 weeks. Results confirmed osteointegrative properties of the coatings and did not reveal any negative effect of copper ions on osteointegration. The integration of copper in degradable osteoconductive coatings with a thickness of approx. 20 μm represents a promising method of achieving antibacterial shielding during the entire period of bone healing while at the same time improving osteointegration of the implants.

Gamma Radiation Induced Synthesis of Novel Chitosan/Gold/Bioactive Glass Nanocomposite for Promising Antimicrobial, and Antibiofilm Activities

In the present study we reported, for the first time, the gamma irradiation induced synthesis of chitosan/Au/bioactive glass (CS/Au/BG) nanocomposite. The bioactive glass (BG), with the composition 45% SiO2, 32.5% CaO, 15% Na2O, and 7.5% P2O5 wt% was synthesized through the sol–gel technique. XRD, SEM, EDX, and elemental mapping images were utilized to evaluate the structure of pure BG and CS/Au/BG nanocomposite. The antimicrobial efficacy was evaluated by zone of inhibition (ZOI), minimum inhibitory concentration (MIC), growth curve assay, and Ultraviolet irradiation effect. Investigation was carried on the antibiofilm effectiveness. Membrane leakage as well as SEM imaging were used to evaluate the antibacterial reaction mechanism. The crystallite size of CS/Au/BG nanocomposite was determined via Scherer equation as 22.83 nm. CS/Au/BG possessed the most ZOI activity against the tested microbes. The highest inhibition % of BG, and CS/Au/BG nanocomposite was investigated for S. aureus (15.65%, and 77.24%), followed by C. albicans (13.32%, and 64.75%). The quantity of protein leakage was directly-proportional after increasing the concentration of BG, and CS/Au/BG and counted to be 70.58, and 198.25 µg/mL, respectively (after applied 10 mg/mL). The promising results suggested the use of novel CS/Au/BG nanocomposite as an encourage candidate for wastewater treatment application against pathogenic microbes.

Antibiofilm Activity of Biocide Metal Ions Containing Bioactive Glasses (BGs): A Mini Review

One of the major clinical issues during the implantation procedure is the bacterial infections linked to biofilms. Due to their tissue localization and the type of bacteria involved, bacterial infections at implant sites are usually difficult to treat, which increases patient morbidity and even mortality. The difficulty of treating biofilm-associated infections and the emergence of multidrug-resistant bacteria are further challenges for the scientific community to develop novel biomaterials with excellent biocompatibility and antibacterial properties. Given their ability to stimulate bone formation and have antibacterial properties, metal ion-doped bioactive glasses (BGs) have received considerable research. This mini review aims to be successful in presenting the developments made about the role of biocide metal ions incorporated into BGs against the development of bacterial biofilms and the spread of nosocomial diseases.

Comparison of antibacterial and antibiofilm activity of bioactive glass compounds S53P4 and 45S5

Background

Bone loss and deformation due to damage caused by injury or recurrent invasive infections presents a major clinical obstacle. While bone substitute biomaterials promote osseous tissue regeneration, their application in sites complicated by microbial infections such as osteomyelitis, is limited. Bioactive glass biomaterials (Bioglass) have been shown to have efficient mechanisms of repairing the integrity of bone, while inhibiting growth of a range of bacterial strains. There are several commercially available bioactive glass compounds, each with a unique chemical composition. One compound in particular, S53P4, has demonstrated antimicrobial effects in previous studies but the antimicrobial activity of the parent compound 45S5 has not been investigated.

Results

To assess whether antimicrobial activity is common among bioglass compounds, 45S5-the parent compound, was evaluated in comparison to S53P4 for antibacterial and antibiofilm effects against multiple strains of aerobic and anaerobic bacteria associated with various types of osteomyelitis. Experiments of antimicrobial effects in liquid cultures demonstrated that both compounds were antimicrobial against various microbial genera including S. gordonii, V. parvula, P. aeruginosa and MRSA; particles of the smallest size (32–125 µm) invariably showed the most robust antimicrobial capabilities. When employed against biofilms ecological biofilms grown on hydroxyapatite, 45S5 particles produced a stronger reduction in biofilm mass compared to S53P4 particles when considering small particle ranges.

Conclusion

We found that 45S5 seems to be as effective as S53P4 and possibly even more capable of limiting bacterial infections. The efficacy of bioactive glass was not limited to inhibition of planktonic growth, as it also extended to bacterial biofilms. The increased antibacterial activity of 45S5 compared to S53P4 is true for a variety of size ranges.

Cell loaded hydrogel containing Ag-doped bioactive glass-ceramic nanoparticles as skin substitute: Antibacterial properties, immune response, and scarless cutaneous wound regeneration

An ideal tissue-engineered dermal substitute should possess angiogenesis potential to promote wound healing, antibacterial activity to relieve the bacterial burden on skin, as well as sufficient porosity for air and moisture exchange. In light of this, a glass-ceramic (GC) has been incorporated into chitosan and gelatin electrospun nanofibers (240-360 nm), which MEFs were loaded on it for healing acceleration. The GC was doped with silver to improve the antibacterial activity. The bioactive nanofibrous scaffolds demonstrated antibacterial and superior antibiofilm activities against Gram-negative and Gram-positive bacteria. The nanofibrous scaffolds were biocompatible, hemocompatible, and promoted cell attachment and proliferation. Nanofibrous skin substitutes with or without Ag-doped GC nanoparticles did not induce an inflammatory response and attenuated LPS-induced interleukin-6 release by dendritic cells. The rate of biodegradation of the nanocomposite was similar to the rate of skin regeneration under in vivo conditions. Histopathological evaluation of full-thickness excisional wounds in BALB/c mice treated with mouse embryonic fibroblasts-loaded nanofibrous scaffolds showed enhanced angiogenesis, and collagen synthesis as well as regeneration of the sebaceous glands and hair follicles in vivo.

Mid-term clinical results of chronic cavitary long bone osteomyelitis treatment using S53P4 bioactive glass: a multi-center study

Introduction: Chronic osteomyelitis is a challenging condition in the orthopedic practice and traditionally treated using local and systemic antibiotics in a two-stage surgical procedure. With the introduction of the antimicrobial biomaterial S53P4 bioactive glass (Bonalive^®), chronic osteomyelitis can be treated in a one-stage procedure. This study evaluated the mid-term clinical results of patients treated with S53P4 bioactive glass for long bone chronic osteomyelitis. Methods: In this prospective multi-center study, patients from two different university medical centers in the Netherlands were included. One-stage treatment consisted of debridement surgery, implantation of S53P4 bioactive glass, and treatment with culture-based systemic antibiotics. If required, wound closure by a plastic surgeon was performed. The primary outcome was the eradication of infection, and a secondary statistical analysis was performed on probable risk factors for treatment failure. Results: In total, 78 patients with chronic cavitary long bone osteomyelitis were included. Follow-up was at least 12 months (mean 46; standard deviation, SD, 20), and 69 patients were treated in a one-stage procedure. Overall infection eradication was 85 %, and 1-year infection-free survival was 89 %. Primary closure versus local/muscular flap coverage is the only risk factor for treatment failure. Conclusion: With 85 % eradication of infection, S53P4 bioactive glass is an effective biomaterial in the treatment of chronic osteomyelitis in a one-stage procedure. A major risk factor for treatment failure is the necessity for local/free muscle flap coverage. These results confirm earlier published data, and together with the fundamentally different antimicrobial pathways without antibiotic resistance, S53P4 bioactive glass is a recommendable biomaterial for chronic osteomyelitis treatment and might be beneficial over other biomaterials.

Bioactive glass, a new tool for the treatment in the diabetic foot recalcitrant osteomyelitis: A case series with 24-month follow-up

BACKGROUND

The bioactive glass (BAG) is a promising solution for the reconstruction of bone defects and the eradication of infection in patients with osteomyelitis, however references to the treatment of diabetic foot osteomyelitis are scarce in the literature.

METHODS

Our experience in patients with diabetic foot osteomyelitis, who required surgical debridement and void filling, in which we use bioactive glass (n = 6), was evaluated. During a minimum follow-up of 24 months, the presence of persistent infection and healing rate, post-surgical complications, surgical reinterventions, degree of osseointegration and BAG-related side effects was analyzed.

RESULTS

At the end of the follow-up, none of the patients showed signs of persistent infection and the healing rate was 66.6% (4/6). Postoperative complications were noted in 3 patients and two of the them required new surgical intervention, both due to skin coverage or vascular complications. A complete osseointegration in the 66.6% of the patients and no cases of local adverse effects were recorded.

CONCLUSIONS

The bioactive glass can be a useful tool in the treatment of certain cases of diabetic foot osteomyelitis, provided that a multidisciplinary approach and strict patient selection is in place.

LEVEL OF EVIDENCE

IV.

Effect of S53P4 bioactive glass and low-level laser therapy on calvarial bone repair in rats submitted to zoledronic acid therapy

PURPOSE

To evaluate the influence of bioactive glass and photobiomodulation therapy (PBMT) in calvarial bone repair process in rats submitted to zoledronic acid therapy.

METHODS

Twenty-four rats were selected and treated with the dose of 0.035 mg/kg of zoledronic acid every two weeks, totalizing eight weeks, to induce osteonecrosis. After the drug therapy, surgical procedure was performed to create 5-mm diameter parietal bone defects in the calvarial region. The rats were then randomly assigned to groups according to the following treatments: AZC: control group, treated with blood clot; AZBIO: bone defect filled with bioactive glass; AZL: treated with blood clot and submitted to PBMT; and AZBIOL: treated with bioactive glass S53P4 and submitted to PBMT. Tissue samples were collected and submitted to histomorphometric analysis after 14 and 28 days.

RESULTS

At 14 days, bone neoformation in the AZBIO (52.15 ± 9.77) and AZBIOL (49.77 ± 13.58) groups presented higher values (p ≤ 0.001) compared to the AZC (23.35 ± 10.15) and AZL groups (23.32 ± 8.75). At 28 days, AZBIO (80.24 ± 5.41)still presented significant higher bone recovery values when compared to AZC (59.59 ± 16.92)and AZL (45.25 ± 5.41) groups (p = 0.048). In the 28-day period, the AZBIOL group didn't show statistically significant difference with the other groups (71.79 ± 29.38).

CONCLUSIONS

The bioactive glass is an effective protocol to stimulate bone neoformation in critical defects surgically created in rats with drug induced osteonecrosis, in the studied periods of 14 and 28 days.

Polymer-Based Honeycomb Films on Bioactive Glass: Toward a Biphasic Material for Bone Tissue Engineering Applications

The development of innovative materials for bone tissue engineering to promote bone regeneration while avoiding fibrous tissue infiltration is of paramount importance. Here, we combined the known osteopromotive properties of bioactive glasses (BaGs) with the biodegradability, biocompatibility, and ease to shape/handle of poly-l-co-d,l-lactic acid (PLDLA) into a single biphasic material. The aim of this work was to unravel the role of the surface chemistry and topography of BaG surfaces on the stability of a PLDLA honeycomb membrane, in dry and wet conditions. The PLDLA honeycomb membrane was deposited using the breath figure method (BFM) on the surface of untreated BaG discs (S53P4 and 13-93B20), silanized with 3-aminopropyltriethoxysilane (APTES) or conditioned (immersed for 24 h in TRIS buffer solution). The PLDLA membranes deposited onto the BaG discs, regardless of their composition or surface treatments, exhibited a honeycomb-like structure with pore diameter ranging from 1 to 5 μm. The presence of positively charged amine groups (APTES grafting) or the precipitation of a CaP layer (conditioned) significantly improved the membrane resistance to shear as well as its stability upon immersion in the TRIS buffer solution. The obtained results demonstrated that the careful control of the substrate surface chemistry enabled the deposition of a stable honeycomb membrane at their surface. This constitutes a first step toward the development of new biphasic materials enabling osteostimulation (BaG) while preventing migration of fibrous tissue inside the bone defect (honeycomb polymer membrane).

Use of contemporary biomaterials in chronic osteomyelitis treatment: Clinical lessons learned and literature review

Chronic osteomyelitis has always been a therapeutic challenge for patient and surgeon due to the specific problems related with bone infection and bacterial biofilm eradication. Other than being the cause of infection or facilitating spread or persistence of infection, biomaterials are also becoming a tool in the treatment of infection. Certain novel biomaterials have unique and ideal properties that render them perfectly suited to combat infection and are therefore used more and more in the treatment of chronic bone infections. In case of infection treatment, there is still debate whether these properties should be focused on bone regeneration and/or their antimicrobial properties. These properties will be of even greater importance with the challenge of emerging antimicrobial resistance. This review highlights indications for use and specific material properties of some commonly used contemporary biomaterials for this indication as well as clinical experience and a literature overview.

Li-doped bioglass® 45S5 for potential treatment of prevalent oral diseases

OBJECTIVES

Despite the excellent properties of both pure bioglasses (BG) and BG doped with therapeutic ions (such as Li) in hard tissue applications, there is not enough information about their role in the remineralization and bacterial-growth in oral diseases. The aim of this contribution is to evaluate the effect of both pure BG and BG doped with 5-wt% of Li (BGLi) on both the remineralization of in vitro demineralized human-teeth and the antimicrobial behavior against strains from caries and periodontitis.

METHODS

Bioglass® 45S5 (BG) and BGLi were synthesized by the sol-gel method. The remineralization tests were carried out using in vitro demineralized enamel teeth and evaluated by Electron Microscopy (SEM) and Vickers micro-hardness (HV). The antimicrobial behavior of the particles was evaluated against S. mutans, A. actinomycetemcomitans, and P. gingivalis, representing pathogens from caries and periodontitis.

RESULTS

Enamel lesion was partially remineralized when both bioglasses (BG and BGLi) were applied on its surface with micro-hardness recoveries around 45 %. They further inhibited the growth of S. mutans and P. gingivalis, at 50 and 200 mg/mL, respectively. BGLi presented a higher toxicity against A. actinomycetemcomitans than BG, with inhibition concentrations of 20 mg/mL and 100 mg/mL, respectively.

CONCLUSIONS

Bioglasses could be used in the treatment of two of the most prevalent oral diseases: caries and periodontitis, promoting the remineralization of the teeth and killing the main pathogens. The presence of Li did not affect the bioactivity of the bioglass and improved the antibacterial effect over A. actinomycetemcomitans strain.

Bactericidal activity and biofilm inhibition of F18 bioactive glass against Staphylococcus aureus

Antimicrobial treatment failure has been increasing at alarming rates. In this context, the bactericidal properties of biocompatible antimicrobial agents have been widely studied. F18 is a recently developed bioactive glass that presents a much wider working range when compared to other bioactive glasses, a feature that allows it to be used for coating metallic implants, sintering scaffolds or manufacturing fibers for wound healing applications. The aim of this study was to investigate the in vitro bactericidal and anti-biofilm activity of F18 glass as a powder and as a coating on steel samples, and to explore the effects of its dissolution products at concentrations from 3 mg/mL to 50 mg/mL against the Staphylococcus aureus and methicillin-resistant Staphylococcus aureus (MRSA) biofilms. Furthermore, we intend to verify whether changes in the medium pH could influence the bactericidal activity of F18. The results indicated that F18 presented bactericidal activity in preformed S. aureus and MRSA biofilms, reducing more than 6 logs of the viable cells that remained in contact with 50 mg/mL for 24 h. Moreover, an anti-biofilm activity was observed after 12 h of direct contact, with a drop of more than 6 logs of the viable bacterial population. Neutralization of the F18 solution pH decreased its bactericidal efficacy. These results indicate that the F18 glass could be considered as an alternative material for controlling and treating infections by S. aureus.

[Advances in clinical diagnosis and treatment of chronic osteomyelitis in adults]

Objective

To review the progress of clinical diagnosis and treatment of chronic osteomyelitis in adults.

Methods

The literature related to chronic osteomyelitis in recent years was extensively reviewed, and the clinical diagnosis and treatment methods were summarized.

Results

Clinical characteristics and laboratory examination can help to diagnose chronic osteomyelitis in adults. Pathogenic identification is the basis for choosing antibiotics. Diagnostic imaging is specific. The treatment includes systemic treatment and local treatment, and the local treatment is the key to radical cure.

Conclusion

The diagnosis of chronic osteomyelitis in adults should be made as early as possible. According to the anatomical and physiological classification of the patients, the appropriate treatment plan should be made.

Management of tegmen defects with mastoid and epitympanic obliteration using S53P4 bioactive glass

OBJECTIVE

To evaluate the surgical results and complications in a cohort of patients operated on to repair a tegmen bony defect using either transmastoid approach with obliteration using S53P4 bioactive glass granules (TMA-O), or the classic middle cranial fossa approach (MCFA).

STUDY DESIGN

A retrospective monocentric study.

METHODS

Twenty-five cases (24 patients) were included. Data regarding patient demographics, etiology, intraoperative findings, complications, recurrences, audiometric data, and follow-up were analyzed.

RESULTS

Seven patients were operated with MCFA and 17 patients with TMA-O. One patient was operated on using a combined approach (MCFA + TMA-O). In the preoperative HRCT scan, the size of the defect was estimated to be 6 ± 3.8 mm in the TMA-O group and 6 ± 3.5 mm in the MCFA group (P = .969). Intraoperatively, in the MCFA group, the location of the defect was mostly anterior (86%) with an intact ossicular chain (86%). A discontinuous chain was observed in 15 patients (88%) in the TMA-O group. The mean follow-up time was 22 ± 14 months in the TMA-O group and 24 ± 15 months in the MCFA group (P = .762). In both groups, there were no early postoperative complications or recurrences during follow-up.

CONCLUSION

Repair of a tegmen bony defect with S53P4 bioactive glass granules seems to be safe and effective, limiting the use of the middle cranial fossa approach to cases with epitympanic defects and with an intact ossicular chain, and it could be used whatever the size of the defect and/or the presence of meningoencephalocele.

LEVEL OF EVIDENCE

4.

Bioactive glass as dead space management following debridement of type 3 chronic osteomyelitis

BACKGROUND

Chronic osteomyelitis is a challenging condition to treat and although no exact treatment guidelines exist, the surgical management strategy includes wide resection of necrotic and infected bone followed by dead space management. This study evaluates the use of bioactive glass as a single-stage procedure for dead space management following surgical debridement.

METHODS

A consecutive series of 24 patients with Cierny-Mader type 3 osteomyelitis, treated between March 2016 and June 2018, were identified and evaluated retrospectively. Patients were managed with bioactive glass as dead space management following surgical debridement.

RESULTS

Of the patients who completed more than 12 months follow-up, all fourteen (100%) showed complete resolution of symptoms. Of the remaining ten patients with less than 12 months follow-up, eight had complete resolution of symptoms. Therefore, a preliminary result of 22 out of 24 patients (91.65%) had resolution of symptoms following debridement and dead space management with bioactive glass. One patient experienced a complication related to the use of bioactive glass. This manifested as prolonged serous wound drainage that resolved with local wound care.

CONCLUSION

The use of bioactive glass appears to be effective for dead space management following debridement of anatomical type 3 chronic osteomyelitis of the appendicular skeleton.

Imaging studies of bacterial biofilms on cochlear implants-Bioactive glass (BAG) inhibits mature biofilm

The capability of Pseudomonas aeruginosa and Staphylococcus aureus to form biofilm on varying CI component materials differs in the presence and absence of bioactive glass (BAG). The application of BAG induces significant changes in biofilm morphology which can be visualized via scanning electron microscopy (SEM). Bacterial biofilm formation on medical devices, such as cochlear implants (CI), can lead to chronic infections. Interestingly, BAG of type S53P4 seems to be a promising tool for use in the reduction of biofilm development. Primarily, four bacterial species known to cause implant-related infections, P.aeruginosa (ATCC9027), S. aureus (ATCC6538), Staphylococcus epidermidis (ATCC12228) and Streptococcus pyogenes (ATCC19615) were analyzed regarding their capacity to form biofilm on CI components manufactured from three kinds of material: silicone, platinum and titanium. Subsequently, P. aeruginosa and S. aureus biofilms were visualized using scanning electron microscopy, comparing BAG-treated biofilm with non-treated biofilm. The four bacterial species presented biofilm-forming capabilities in a species and surface dependent manner. Metal CI components allowed for the greatest proliferation of biofilm. S. aureus and P. aeruginosa showed the highest rate of biofilm formation on polystyrene surfaces. For both species, SEM revealed altered biofilm morphology after treatment of S53P4 BAG. This study indicates that bacterial biofilm formation and structure on CI components is dependent on the surface composition, altering between metal and silicone surfaces. After application of BAG, changes in biofilm morphology on CI components were observed. These data highlight the impact of BAG on bacterial biofilm morphology.

Bioactive Glass Applications in Dentistry

At present, researchers in the field of biomaterials are focusing on the oral hard and soft tissue engineering with bioactive ingredients by activating body immune cells or different proteins of the body. By doing this natural ground substance, tissue component and long-lasting tissues grow. One of the current biomaterials is known as bioactive glass (BAG). The bioactive properties make BAG applicable to several clinical applications involving the regeneration of hard tissues in medicine and dentistry. In dentistry, its uses include dental restorative materials, mineralizing agents, as a coating material for dental implants, pulp capping, root canal treatment, and air-abrasion, and in medicine it has its applications from orthopedics to soft-tissue restoration. This review aims to provide an overview of promising and current uses of bioactive glasses in dentistry.

Structural and Functional Dynamics of Staphylococcus aureus Biofilms and Biofilm Matrix Proteins on Different Clinical Materials

Medical device-associated staphylococcal infections are a common and challenging problem. However, detailed knowledge of staphylococcal biofilm dynamics on clinically relevant surfaces is still limited. In the present study, biofilm formation of the Staphylococcus aureus ATCC 25923 strain was studied on clinically relevant materials-borosilicate glass, plexiglass, hydroxyapatite, titanium and polystyrene-at 18, 42 and 66 h. Materials with the highest surface roughness and porosity (hydroxyapatite and plexiglass) did not promote biofilm formation as efficiently as some other selected materials. Matrix-associated poly-N-acetyl-β-(1-6)-glucosamine (PNAG) was considered important in young (18 h) biofilms, whereas proteins appeared to play a more important role at later stages of biofilm development. A total of 460 proteins were identified from biofilm matrices formed on the indicated materials and time points-from which, 66 proteins were proposed to form the core surfaceome. At 18 h, the appearance of several r-proteins and glycolytic adhesive moonlighters, possibly via an autolysin (AtlA)-mediated release, was demonstrated in all materials, whereas classical surface adhesins, resistance- and virulence-associated proteins displayed greater variation in their abundances depending on the used material. Hydroxyapatite-associated biofilms were more susceptible to antibiotics than biofilms formed on titanium, but no clear correlation between the tolerance and biofilm age was observed. Thus, other factors, possibly the adhesive moonlighters, could have contributed to the observed chemotolerant phenotype. In addition, a protein-dependent matrix network was observed to be already well-established at the 18 h time point. To the best of our knowledge, this is among the first studies shedding light into matrix-associated surfaceomes of S. aureus biofilms grown on different clinically relevant materials and at different time points.

Bioactive Glass Granules Inhibit Mature Bacterial Biofilms on the Surfaces of Cochlear Implants

HYPOTHESIS

Biofilm formation on cochlear implant (CI) surfaces differs between bacterial species and can be reduced by the application of S53P4 bioactive glass.

BACKGROUND

The formation of bacterial biofilms on medical devices, such as cochlear implants, can lead to chronic infections resulting in the need for implant removal. In this study, various surfaces of three CI implant kits from different manufacturers were examined for bacterial biofilm formation and reduction of a pre-existing biofilm by the application of bioactive glass.

METHODS

Biofilm formations of 4 bacterial species causing implant-related infections were tested on 17 different surfaces: Pseudomonas aeruginosa (ATCC9027), Staphylococcus aureus (ATCC6538), Staphylococcus epidermidis (ATCC12228), and Streptococcus pyogenes (ATCC19615). For P. aeruginosa and S. aureus biofilm reduction after application of S53P4 bioactive glass was evaluated.

RESULTS

All tested microbial species formed biofilms on the examined CI surfaces in a strain-dependent manner. For S. aureus, a significantly higher biofilm formation on metal components compared with silicone was found whereas the other strains did not show a material specific biofilm formation. Application of S53P4 bioactive glass resulted in a significant reduction of P. aeruginosa and S. aureus mature biofilm.

CONCLUSION

The four bacteria species displayed biofilm formation on the CI surfaces in a species- and material-specific manner. The results show that bioactive glass can reduce biofilm formation on CI materials in vitro. Future studies are necessary to confirm the results in vivo.

Cost-Effectiveness Study of One-Stage Treatment of Chronic Osteomyelitis with Bioactive Glass S53P4

This study was set up to evaluate the costs of a one-stage treatment of chronic osteomyelitis using bioactive glass S53P4 versus a two-stage treatment using gentamicin-loaded PMMA beads. Furthermore, a cost-effectiveness analysis was performed from a hospital’s perspective together with the evaluation of clinical outcome. A treatment group (n = 25) receiving one-stage surgery with bioactive glass was retrospectively compared with a two-stage control group (n = 25). An assessment was made of all costs included from first outpatient visit until one year after treatment. Bootstrap simulation and sensitivity analyses were performed. The primary endpoint was cost-effectiveness with clinical outcome as the secondary endpoint. The base case analyses shows dominance of the one-stage treatment with bioactive glass S53P4 due to lower costs and a better clinical outcome. Sensitivity analyses confirm these findings. This study is the first in its kind to show one-stage treatment of chronic osteomyelitis with bioactive glass S53P4 to be cost-effective.

Resorption of the calcium phosphate layer on S53P4 bioactive glass by osteoclasts

Clinically, S53P4 bioactive glass (BAG) has shown very promising results in bone infection treatment, but it is also known to degrade very slowly in vivo. To evaluate which mechanisms (cellular or dissolution) can play a role in the degradation of S53P4 BAG and S53P4 BAG putty, in vitro degradation experiments at different pH (7.4 and 4.6) were performed. Micro computed tomography showed a rapid dissolution of the synthetic binder in the putty formulation, within 12 h is simulated body fluid (pH = 7.4), leaving behind only loose granules. Therefore the degradation of the loose granules was investigated further. Significant weight loss was observed and ion chromatography showed that Ca2+, Na+ and PO43- ions were released from S54P4 BAG granules in the two fluids. It was observed that the weight loss and ion release were increased when the pH of the fluid was decreased to 4.6. Osteoclasts are known to create such a low pH when resorbing bone and therefore their capacity to degrade S53P4 surfaces were studied as well. Scanning electron microscopy and energy-dispersive X-ray spectroscopy confirmed that osteoclasts were able to create resorption pits in the calcium phosphate layer on S53P4 BAG surfaces. The silica of the BAG, located underneath the calcium phosphate, seemed to hinder further osteclastic resorption of the material. To our knowledge we were the first to observe actively resorbing osteoclasts on S53P4 bioactive glass surfaces, in vitro. Future research is needed to define the specific role osteoclasts play in the degradation of BAG in vivo.

A Novel Silver Bioactive Glass Elicits Antimicrobial Efficacy Against Pseudomonas aeruginosa and Staphylococcus aureus in an ex Vivo Skin Wound Biofilm Model

Biofilm infection is now understood to be a potent contributor to the recalcitrant nature of chronic wounds. Bacterial biofilms evade the host immune response and show increased resistance to antibiotics. Along with improvements in antibiotic stewardship, effective new anti-biofilm therapies are urgently needed for effective wound management. Previous studies have shown that bioactive glass (Bg) is able to promote healing with moderate bactericidal activity. Here we tested the antimicrobial efficacy of a novel BG incorporating silver (BgAg), against both planktonic and biofilm forms of the wound-relevant bacteria Pseudomonas aeruginosa and Staphylococcus aureus. BgAg was stable, long lasting, and potently effective against planktonic bacteria in time-kill assays (6-log reduction in bacterial viability within 2 h) and in agar diffusion assays. BgAg reduced bacterial load in a physiologically relevant ex vivo porcine wound biofilm model; P. aeruginosa (2-log reduction) and S. aureus (3-log reduction). BgAg also conferred strong effects against P. aeruginosa biofilm virulence, reducing both protease activity and virulence gene expression. Co-culture biofilms appeared more resistant to BgAg, where a selective reduction in S. aureus was observed. Finally, BgAg was shown to benefit the host response to biofilm infection, directly reducing host tissue cell death. Taken together, the findings provide evidence that BgAg elicits potent antimicrobial effects against planktonic and single-species biofilms, with beneficial effects on the host tissue response. Further investigations are required to elucidate the specific consequences of BG administration on polymicrobial biofilms, and further explore the effects on host-microbe interactions.

In vitro antibacterial activity of bioactive glass S53P4 on multiresistant pathogens causing osteomyelitis and prosthetic joint infection

Background

Conventional local treatment for medullary osteomyelitis (OM) includes insertion of antibiotic-loaded polymethylmethacrylate (PMMA) cement. Nevertheless, PMMA may delivery irregular concentration of antibiotic to surrounding tissue. We aimed to compare the in vitro antibacterial activity of Bioactive Glass (BAG) S53P4, which is a compound showing local antibacterial activity, to that of antibiotic-loaded PMMA against multidrug resistant bacteria from OM isolates.

Methods

We studied convenience samples of multidrug resistant (MDR) microorganisms obtained from patients presenting OM and prosthetic joint infection (PJI). Mixtures containing tryptic soy broth (TSB) and inert glass beads (2 mm), BAG-S53P4 granules (0.5–0.8 mm and < 45 mm) and Gentamicin or Vancomycin-loaded PMMA beads were inoculated with methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-resistant coagulase-negative Staphylococcus (MR-CoNS), Pseudomonas aeruginosa or Klebsiella pneumoniae isolates. Glass beads (2.0 mm) were used as a control. Antibacterial activity was evaluated by means of time-kill curve, through seeding the strains on blood agar plates, and subsequently performing colony counts after 24, 48, 72, 96, 120 and 168 h of incubation. Differences between groups were evaluated by means of two-way analysis of variance (ANOVA) and Bonferroni’s t test.

Results

Inhibition of bacterial growth started soon after 48 h of incubation, reached zero CFU/ml between 120 and 168 h of incubation for both antibiotic-loaded PMMA and BAG S53P4 groups, in comparison with inert glass (p < 0.05). No difference regarding time-kill curves between antibiotic-loaded PMMA and BAG S53P4 was observed.

Conclusions

BAG S53P4 presented antibacterial properties as much as antibiotic-loaded PMMA for MDR bacteria producing OM and PJI.

Electronic supplementary material

The online version of this article (10.1186/s12879-018-3069-x) contains supplementary material, which is available to authorized users.

BAG-S53P4 as bone graft extender and antimicrobial activity against gentamicin- and vancomycin-resistant bacteria

AIM

To evaluate the suitability of bioactive glass (BAG)-S53P4 as a bone-graft extender for large bony defect filling in bone and joint infection.

MATERIALS & METHODS

Antimicrobial activity of BAG-S53P4 against clinically relevant strains isolated from bone and joint infections was evaluated by means of time-kill curves in presence of bone graft. Furthermore, the susceptibility to BAG of strains resistant to vancomycin and gentamicin was assessed.

RESULTS

Though attenuated, BAG maintains a good in vitro antimicrobial activity in presence of human body fluids and tissues contained in bone graft, with the exception of Enterococcus faecalis.

CONCLUSION

BAG-S53P4 is a suitable bone substitute that can be used as an extender with autologous bone graft to promote better fusion and healing.

Recent Evidence on Bioactive Glass Antimicrobial and Antibiofilm Activity: A Mini-Review

Bone defects caused by trauma or pathological events are major clinical and socioeconomic burdens. Thus, the efforts of regenerative medicine have been focused on the development of non-biodegradable materials resembling bone features. Consequently, the use of bioactive glass as a promising alternative to inert graft materials has been proposed. Bioactive glass is a synthetic silica-based material with excellent mechanical properties able to bond to the host bone tissue. Indeed, when immersed in physiological fluids, bioactive glass reacts, developing an apatite layer on the granule’s surface, playing a key role in the osteogenesis process. Moreover, the contact of bioactive glass with biological fluids results in the increase of osmotic pressure and pH due to the leaching of ions from granules’ surface, thus making the surrounding environment hostile to microbial growth. The bioactive glass antimicrobial activity is effective against a wide selection of aerobic and anaerobic bacteria, either in planktonic or sessile forms. Furthermore, bioglass is able to reduce pathogens’ biofilm production. For the aforementioned reasons, the use of bioactive glass might be a promising solution for the reconstruction of bone defects, as well as for the treatment and eradication of bone infections, characterized by bone necrosis and destruction of the bone structure.

Osteotomy Site Grafting in Bilateral Sagittal Split Surgery With Bioactive Glass S53P4 for Skeletal Stability

In orthognathic surgery, the aim of the treatment is to achieve a good occlusion and a satisfying aesthetic outcome. In large mandibular advancements insufficient healing at the mandibular inferior border may lead to loss of support for the overlaying tissue at the osteotomy site. Augmentation can be performed to improve stability, bone regeneration, and the aesthetic outcome. The purpose of this prospective clinical study was to evaluate the use of a novel material for this indication; granules of the antibacterial, osteoconductive, and slowly resorbing bioactive glass S53P4 as filling material in large mandibular advancement in bilateral sagittal split osteotomies. The authors treated 25 patients who underwent bilateral sagittal split osteotomies due to class II dentoskeletal deformities. The mandibular osteotomy site defects (8-15 mm) were augmented with bioactive glass S53P4. The average clinical follow-up was 33 months and the average radiological follow-up with cone beam computerized tomography was 24 months. The clinical and radiological results were good with regard to healing, bone regeneration, and stability of the osteotomy sites. The recontouring of the inferior mandibular border provided a good soft tissue support followed by an excellent aesthetic outcome in 96% of the osteotomy sites. The occlusion was stable in 88% of the patients. The authors' results show that bioactive glass S53P4 is a safe grafting material for osteotomy site defects in significant mandibular advancements with reliable bone regeneration, providing long-term stability at the osteotomy site and at the inferior mandibular border.

Development of fish collagen/bioactive glass/chitosan composite nanofibers as a GTR/GBR membrane for inducing periodontal tissue regeneration

The development of a guided tissue or bone regeneration (GTR/GBR) membrane with excellent performance has been a major challenge in the biomedical field. The present study was designed to prepare a biomimetic electrospun fish collagen/bioactive glass/chitosan (Col/BG/CS) composite nanofiber membrane and determine its structure, mechanical property, antibacterial activity, and biological effects on human periodontal ligament cells (HPDLCs). The effects of this composite membrane on inducing periodontal tissue regeneration were evaluated using a dog class II furcation defect model. It was found that the composite membrane had a biomimetic structure with good hydrophilicity (the contact angle was 12.83 ± 3°) and a tensile strength of 13.1 ± 0.43 Mpa. Compared to the pure fish collagen membrane, the composite membrane showed some degree of antibacterial activity on Streptococcus mutans. The composite membrane not only enhanced the cell viability and osteogenic gene expression of the HPDLCs, but also promoted the expression of RUNX-2 and OPN protein. Further animal experiments confirmed that the composite membrane was able to promote bone regeneration in the furcation defect of dogs. In conclusion, a biomimetic fish Col/BG/CS composite membrane has been developed in the present study, which can induce tissue regeneration with a certain degree antibacterial activity, providing a basis for potential application as a GTR/GBR membrane.

Mastoid obliteration with S53P4 bioactive glass in cholesteatoma surgery

CONCLUSION

Evaluation of the follow-up of 67 patients shows that S53P4 bioactive glass (BAG) granules are safe and effective as obliteration material in cholesteatoma surgery.

OBJECTIVES

To investigate the safety and efficacy of mastoid obliteration using S53P4 BAG in cholesteatoma surgery. Clinical outcomes were infection control (Merchant's grading), cholesteatoma recidivism, and audiometric performance.

METHODS

Retrospective follow-up study at the Diakonessenhuis, Utrecht, the Netherlands. Eighteen young (age <17 years) and 49 adult (age ≥17 years) patients treated for cholesteatoma underwent tympanomastoidectomy with mastoid obliteration using S53P4 BAG in the period 2012-2015. Outcome was monitored with clinical otoscopy, otorrhea incidence measurement (Merchant's grading), DW-MRI, and audiographic performance analyses (pure tone average and air bone gap).

RESULTS

During the follow-up period (mean = 22 months; range = 12-54 months) cholesteatoma recidivism was observed in 6% of the patients (four ears), mostly in young patients (three ears). An acceptably dry ear (Merchant grade 0-1) was achieved in 96% of all cases. The remaining 4% of cases scored a Merchant grade 2. Overall, both air conduction thresholds and air bone gap were slightly lowered when comparing post-operative values to pre-operative values and significantly in the case of ossicular reconstruction. In none of the patients (0%) did post-operative wound infections occur.

Regeneration of Cystic Bone Cavities and Bone Defects With Bioactive Glass S53P4 in the Upper and Lower Jaws

Cysts and tumors are common lesions in the jaws. To be able to retain a good volume of the alveolar ridge during healing as well as strengthening the angle and body of the mandible and provide an instant improved support for adjacent teeth, reliable long-term bone regeneration is needed. The purpose of this prospective study was to promote bone regeneration by filling bony defects in the upper or lower jaw with granules of the bioactive glass S53P4 (BAG), which have osteostimulative and antimicrobial properties.The authors treated 20 patients (21 defects) surgically; benign tumors, cysts, or infection related to impacted teeth in the maxilla or mandible. The tumor or cyst was removed or enucleated and thorough cleaning of the infected area was performed. The bone cavity was filled with granules of the BAG S53P4 despite signs of chronic infection in the area at the time of surgery. The patients were followed up for an average of 34 months clinically and with cone beam computerized tomography for 28 months. In 20 defects the final outcome was successful. Despite infection at the time of surgery in 65% of the patients, no material associated infection was seen during the follow-up. The BAG S53P4 granules were radiologically remodeled into bone after 2 years follow-up. The use of granules of the BAG S53P4 in the treatment of large bone defects provides infection-free reliable bone regeneration despite chronic infection at the time of surgery, which improves the prognosis of adjacent teeth.

Bioactive glasses as delivery systems for antimicrobial agents

Most biomaterial-associated infections are caused by opportunistic pathogens and bacteria that are regularly found within the microflora of the implant site. In addition, a biomaterial implant or device remains at risk of infection by hematogenous spread of bacteria disseminated from infections elsewhere in the body or from infected peri-implant tissue in revision surgery. The resulting infections are frequently accompanied by patient morbidity and discomfort and can lead to surgical replacement of the implant after lengthy, unsuccessful attempts to mitigate infections with antibiotic treatments. Therefore, extensive study is aiming to find new infection-resistant antimicrobial biomaterials and coatings for implants and devices to effectively reduce the incidence of biomaterial-associated infections. An overview of the in vitro and in vivo antimicrobial efficacies of the numerous biomaterials currently available is beyond the scope of this review. Herein, we provide a comprehensive review of bioactive glasses as biomaterial delivery systems for antimicrobial agents.

Multifunctional and biomimetic fish collagen/bioactive glass nanofibers: fabrication, antibacterial activity and inducing skin regeneration in vitro and in vivo

The development of skin wound dressings with excellent properties has always been an important challenge in the field of biomedicine. In this study, biomimetic electrospun fish collagen/bioactive glass (Col/BG) nanofibers were prepared. Their structure, tensile strength, antibacterial activity and biological effects on human keratinocytes, human dermal fibroblasts and human vascular endothelial cells were investigated. Furthermore, the Sprague Dawley rat skin defect model was used to validate their effect on wound healing. The results showed that compared with pure fish collagen nanofibers, the tensile strength of the Col/BG nanofibers increased to 21.87±0.21 Mpa, with a certain degree of antibacterial activity against Staphylococcus aureus. It was also found that the Col/BG nanofibers promoted the adhesion, proliferation and migration of human keratinocytes. Col/BG nanofibers induced the secretion of type one collagen and vascular endothelial growth factor by human dermal fibroblasts, which further stimulated the proliferation of human vascular endothelial cells. Animal experimentation indicated that the Col/BG nanofibers could accelerate rat skin wound healing. This study developed a type of multifunctional and biomimetic fish Col/BG nanofibers, which had the ability to induce skin regeneration with adequate tensile strength and antibacterial activity. The Col/BG nanofibers are also easily available and inexpensive, providing the possibility for using as a functional skin wound dressing.

Squamous cell carcinoma in chronic osteomyelitis: a case report and review of the literature

Background

Chronic osteomyelitis is a challenging problem, and malignant transformation is a rare occurrence. We report a case of a patient with squamous cell carcinoma arising from an osteomyelitic hotbed and discuss through a literature review the etiopathogenesis, diagnosis, and treatment of this lesion.

Case presentation

A 69-year-old Italian man had sustained an exposed tibial fracture 40 years ago during a road accident, for which he had undergone various surgical osteosynthesis treatments with multiple antibiotic therapies. He presented to our hospital because of recurrence of a fistula at the proximal third of the anterior region of the tibia. For 2 months, we treated the lesion with antibiotics, and local medication with curettage. We saw no evidence of lesion improvement, and we advised the patient to undergo a knee amputation, which he refused. The alternative we chose was a surgical toilet of the osteomyelitic hotbed and used bioglass as a bone substitute. After 2 months of follow-up, we noticed a fulminating, budding formation in the area of the surgical wound that turned out to be a squamous cell carcinoma on biopsy. The patient again refused the amputation and underwent a wide-margin surgical debridement. After 2 months, the carcinoma recurred, and an above-the-knee amputation was performed.

Conclusions

Our experience with this case indicates that amputation is the most appropriate treatment for squamous carcinoma occurring in patients with chronic osteomyelitis. To avoid risks of lymphonodular and organ metastasization, this radical surgical procedure should not be delayed. Early diagnosis and timely therapy can prevent amputation only in selected cases. Surgeons who treat osteomyelitis and chronic wounds should be aware of the risk of tumor degeneration. Squamous cell carcinoma associated with chronic osteomyelitis has a low-grade malignancy, but implications of lymphonodular involvement and organ metastasis should not be excluded.

Reconstruction of Vertebral Bone Defects using an Expandable Replacement Device and Bioactive Glass S53P4 in the Treatment of Vertebral Osteomyelitis: Three Patients and Three Pathogens

BACKGROUND AND AIMS

Bioactive glass S53P4 is an antibacterial bone substitute with bone-bonding and osteostimulative properties. The bone substitute has been successfully used clinically in spine; trauma; orthopedic; ear, nose, and throat; and cranio-maxillofacial surgeries. Bioactive glass S53P4 significantly reduces the amount of bacteria in vitro and possesses the capacity to kill both planktonic bacteria and bacteria in biofilm. Three patients with severe spondylodiscitis caused by Mycobacterium tuberculosis, Candida tropicalis, or Staphylococcus aureus were operatively treated due to failed conservative treatment. The vertebral defects were reconstructed using bioactive glass S53P4 and an expandable replacement device.

MATERIAL AND METHODS

Decompression and a posterolateral spondylodesis, using transpedicular fixation, were performed posteriorly in combination with an anterior decompression and reconstruction using an expandable vertebral body replacement device. For patients 1 and 2, the expander was covered with bioactive glass S53P4 only, and for patient 3, the glass was mixed with autograft bone.

RESULTS

The patients healed well with complete neurological recovery. Fusion was observed for all patients. The total follow-up was 4 years for patient 1, 1 year and 8 months for patient 2, and 2 years and 2 months for patient 3. No relapses or complications were observed.

CONCLUSION

The antibacterial properties of bioactive glass S53P4 also make it a suitable bone substitute in the treatment of severe spondylodiscitis.

Mechanical behaviour of Bioactive Glass granules and morselized cancellous bone allograft in load bearing defects

Bioactive Glass (BAG) granules are osteoconductive and possess unique antibacterial properties for a synthetic biomaterial. To assess the applicability of BAG granules in load-bearing defects, the aim was to compare mechanical behaviour of graft layers consisting of BAG granules and morselized cancellous bone allograft in different volume mixtures under clinically relevant conditions. The graft layers were mechanically tested, using two mechanical testing modalities with simulated physiological loading conditions: highly controllable confined compression tests (CCT) and more clinically realistic in situ compression tests (ISCT) in cadaveric porcine bone defects. Graft layer impaction strain, residual strain, aggregate modulus, and creep strain were determined in CCT. Graft layer porosity was determined using micro computed tomography. The ISCT was used to determine graft layer subsidence in bone environment. ANOVA showed significant differences (p<0.001) between different graft layer compositions. True strains absolutely decreased for increasing BAG content: impaction strain -0.92 (allograft) to -0.39 (BAG), residual strain -0.12 to -0.01, and creep strain -0.09 to 0.00 respectively. Aggregate modulus increased with increasing BAG content from 116 to 653MPa. Porosity ranged from 66% (pure allograft) to 15% (pure BAG). Subsidence was highest for allograft, and remarkably low for a 1:1 BAG-allograft volume mixture. Both BAG granules and allograft morsels as stand-alone materials exhibit suboptimal mechanical behaviour for load-bearing purpose. BAG granules are difficult to handle and less porous, whereas allograft subsides and creeps. A 1:1 volume mixture of BAG and allograft is therefore proposed as the best graft material in load-bearing defects.

Antibiofilm agents against MDR bacterial strains: is bioactive glass BAG-S53P4 also effective?

OBJECTIVES

The treatment of bone and joint infections is challenging due to the presence of bacterial biofilm and the increasing emergence of multiresistant strains. BAG-S53P4 is a bone substitute that is characterized by osteoconductive and antimicrobial properties. The aim of this study was to assess the effectiveness of BAG-S53P4 against biofilm produced in vitro by multiresistant bacterial strains.

METHODS

Multiresistant Staphylococcus epidermidis, Acinetobacter baumannii and Klebsiella pneumoniae isolated from bone and joint infections were used in this study. Titanium discs covered by bacterial biofilm were incubated with BAG-S53P4 or inert glass as a control. The amount of biofilm on each titanium disc was evaluated after 48 h of incubation by means of confocal laser scanning microscopy.

RESULTS

Significantly lower total biomass volumes were observed for all strains after treatment with BAG-S53P4 when compared with controls. Moreover, the percentage of dead cells was significantly higher in treated samples than in controls for all the tested strains.

CONCLUSIONS

BAG-S53P4 is able to reduce the biofilm produced by multiresistant S. epidermidis, A. baumannii and K. pneumoniae on titanium substrates in vitro, probably by interfering with cell viability. Owing to its osteoconductive, antibacterial and antibiofilm properties, the use of BAG-S53P4 may be a successful strategy for the treatment of bone and prosthetic joint infections.

Cutaneous and Labyrinthine Tolerance of Bioactive Glass S53P4 in Mastoid and Epitympanic Obliteration Surgery: Prospective Clinical Study

Objective. To evaluate the cutaneous and the inner ear tolerance of bioactive glass S53P4 when used in the mastoid and epitympanic obliteration for chronic otitis surgery. Material and Methods. Forty-one cases have been included in this prospective study. Cutaneous tolerance was clinically evaluated 1 week, 1 month, and 3 months after surgery with a physical examination of the retroauricular and external auditory canal (EAC) skin and the presence of otalgia; the inner ear tolerance was assessed by bone-conduction hearing threshold 1 day after surgery and by the presence of vertigo or imbalance. Results. All surgeries but 1 were uneventful: all patients maintained the preoperative bone-conduction hearing threshold except for one case in which the round window membrane was opened during the dissection of the cholesteatoma in the hypotympanum and this led to a dead ear. No dizziness or vertigo was reported. Three months after surgery, healing was achieved in all cases with a healthy painless skin. No cases of revision surgery for removal of the granules occurred in this study. Conclusion. The bioactive glass S53P4 is a well-tolerated biomaterial for primary or revision chronic otitis surgery, as shown by the local skin reaction which lasted less than 3 months and by the absence of labyrinthine complications.

Effect of S53P4 bone substitute on staphylococcal adhesion and biofilm formation on other implant materials in normal and hypoxic conditions

To study the effect of bioactive glass bone substitute granules (S53P4) on bacterial adhesion and biofilm formation on other simultaneously used implant materials and the role of the hypoxic conditions to the adhesion. Bacterial and biofilm formation were studied on materials used both in middle ear prostheses and in fracture fixtures (titanium, polytetrafluoroethylene, polydimethylsiloxane and bioactive glass plates) in the presence or absence of S53P4 granules. The experiments were done either in normal atmosphere or in hypoxia simulating atmospheric conditions of middle ear, mastoid cavity and sinuses. We used two collection strains of Staphylococcus aureus and Staphylococcus epidermidis. In the presence of bioglass and hypoxic conditions the adhesion of the planktonic bacterial cells was decreased for most of the materials. The biofilm formation was decreased for S. epidermidis on titanium and polydimethylsiloxane in both atmospheric conditions and on bioglass plates in normoxia. For S. aureus the biofilm formation was decreased on bioglass plates and polytetrafluoroethylene in normoxia. Hypoxia produces a decrease in the biofilm formation only for S. aureus on polytetrafluoroethylene and for S. epidermidis on bioglass plates. However, in none of the cases bioactive glass increased the bacterial or biofilm adhesion. The presence of bioglass in normoxic and hypoxic conditions prevents the bacterial and biofilm adhesion on surfaces of several typical prosthesis materials in vitro. This may lead to diminishing postoperative infections, however, further in vivo studies are needed.

Antimicrobial activity and resistance selection of different bioglass S53P4 formulations against multidrug resistant strains

AIMS

This study aimed to evaluate the antimicrobial activity of two different formulations of bioglass BAG-S53P4 against multiresistant microorganisms involved in bone infections, and the capability of bioglass to select for resistance.

METHODS

Antibacterial activity was evaluated by means of killing curves. The ability to select for resistant bacteria was evaluated by subculturing microorganisms in serial dilutions of bioglass. Scanning electron microscope acquisitions were conducted to evaluate bioglass-induced morphology changes.

RESULTS

BAG-S53P4 formulations display a high antimicrobial activity and do not seem to select for resistance. Scanning electron microscopy analysis showed cell shrinkage and membrane damage after exposure to bioglass.

CONCLUSIONS

BAG-S53P4 has a significant potential as bone substitute for the treatment of infections caused by multiresistant microorganisms.