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.

ß-TCP/S53P4 Scaffolds Obtained by Gel Casting: Synthesis, Properties, and Biomedical Applications.

The objective of this study was to investigate the osteogenic and antimicrobial effect of bioactive glass S53P4 incorporated into ß-tricalcium phosphate (ß-TCP) scaffolds in vitro and the bone neoformation in vivo. ß-TCP and ß-TCP/S53P4 scaffolds were prepared by the gel casting method. Samples were morphologically and physically characterized through X-ray diffraction (XRD) and scanning electron microscope (SEM). In vitro tests were performed using MG63 cells. American Type Culture Collection reference strains were used to determine the scaffold's antimicrobial potential. Defects were created in the tibia of New Zealand rabbits and filled with experimental scaffolds. The incorporation of S53P4 bioglass promotes significant changes in the crystalline phases formed and in the morphology of the surface of the scaffolds. The ß-TCP/S53P4 scaffolds did not demonstrate an in vitro cytotoxic effect, presented similar alkaline phosphatase activity, and induced a significantly higher protein amount when compared to ß-TCP. The expression of Itg ß1 in the ß-TCP scaffold was higher than in the ß-TCP/S53P4, and there was higher expression of Col-1 in the ß-TCP/S53P4 group. Higher bone formation and antimicrobial activity were observed in the ß-TCP/S53P4 group. The results confirm the osteogenic capacity of ß-TCP ceramics and suggest that, after bioactive glass S53P4 incorporation, it can prevent microbial infections, demonstrating to be an excellent biomaterial for application in bone tissue engineering.

S53P4 BIOACTIVE GLASS PUTTY IN THE LOCAL TREATMENT OF CAVITARY CHRONIC OSTEOMYELITIS.

Objective: Evaluating the clinical results of bioactive glass S53P4 putty for the treatment of cavitary chronic osteomyelitis. Methods: Retrospective observational study, including patients of any age with clinical and radiological diagnosis of chronic osteomyelitis, who underwent surgical debridement and implantation of bioactive glass S53P4 putty (BonAlive® Putty, Turku, Finland). Patients who underwent any plastic surgery on the soft tissues of the affected site or had segmental bone lesions or septic arthritis were excluded. Statistical analysis was performed using Excel®. Demographic data, as well as data on the lesion, treatment, and follow-up, were collected. Outcomes were classified as "disease-free survival," "failure," or "indefinite." Results: This study included 31 patients, of which 71% were men and had with a mean age of 53.6 years (SD ± 24.2). In total, 84% were followed-up for at least 12 months and 67.7% had comorbidities. We prescribed combination antibiotic therapy for 64.5% of patients. In 47.1%, Staphylococcus aureus was isolated. Finally, we classified 90.3% of cases as "disease-free survival" and 9.7% as "indefinite." Conclusion: Bioactive glass S53P4 putty is safe and effective to treat cavitary chronic osteomyelitis, including infections by resistant pathogens, such as methicillin-resistant S. aureus. Level of Evidence IV, Case Series.

Objetivo: Avaliar a atividade do vidro bioativo S53P4 em pasta no tratamento de osteomielite crônica. Métodos: Estudo observacional retrospectivo, com inclusão de indivíduos de qualquer idade com diagnóstico clínico e radiológico de osteomielite que realizaram tratamento cirúrgico com limpeza e desbridamento, seguido do preenchimento da cavidade com biovidro S53P4 em pasta (BonAlive ® Putty, Turku, Finland). Foram excluídos pacientes submetidos a procedimentos de cirurgia plástica nos tecidos moles do local afetado, com lesões ósseas segmentares e com presença de artrite séptica. A análise estatística foi realizada em Excel ® . Foram coletados dados demográficos, sobre a lesão, o tratamento e o acompanhamento. O desfecho foi classificado em "sobrevida livre de doença", "falha" ou "indeterminado". Resultados: Dos 31 pacientes analisados, 71% eram homens, com idade média de 53,6 anos (DP ± 24,26). Do total, 84% foram acompanhados por no mínimo 12 meses, e 67,7% apresentaram comorbidades. A terapia antibiótica combinada foi realizada em 64,5% dos pacientes, sendo o patógeno mais frequente o Staphylococcus aureus (47,1%). Ao final, 90,3% dos pacientes obtiveram "sobrevida livre de doenças" e 9,7% foram considerados "indeterminados". Conclusão: O vidro bioativo S53P4 em pasta é seguro e eficaz no tratamento da osteomielite cavitária e de infecções por patógenos resistentes, incluindo o S. aureus multirresistente. Nível de Evidência IV, Série de Casos.

S53p4 bioactive glass putty in the local treatment of cavitary chronic osteomyelitis / Biovidro ativo s53p4 em pasta no tratamento local da osteomielite crônica cavitária

ABSTRACT Objective: Evaluating the clinical results of bioactive glass S53P4 putty for the treatment of cavitary chronic osteomyelitis. Methods: Retrospective observational study, including patients of any age with clinical and radiological diagnosis of chronic osteomyelitis, who underwent surgical debridement and implantation of bioactive glass S53P4 putty (BonAlive® Putty, Turku, Finland). Patients who underwent any plastic surgery on the soft tissues of the affected site or had segmental bone lesions or septic arthritis were excluded. Statistical analysis was performed using Excel®. Demographic data, as well as data on the lesion, treatment, and follow-up, were collected. Outcomes were classified as "disease-free survival," "failure," or "indefinite." Results: This study included 31 patients, of which 71% were men and had with a mean age of 53.6 years (SD ± 24.2). In total, 84% were followed-up for at least 12 months and 67.7% had comorbidities. We prescribed combination antibiotic therapy for 64.5% of patients. In 47.1%, Staphylococcus aureus was isolated. Finally, we classified 90.3% of cases as "disease-free survival" and 9.7% as "indefinite." Conclusion: Bioactive glass S53P4 putty is safe and effective to treat cavitary chronic osteomyelitis, including infections by resistant pathogens, such as methicillin-resistant S. aureus. Level of Evidence IV, Case Series.

RESUMO Objetivo: Avaliar a atividade do vidro bioativo S53P4 em pasta no tratamento de osteomielite crônica. Métodos: Estudo observacional retrospectivo, com inclusão de indivíduos de qualquer idade com diagnóstico clínico e radiológico de osteomielite que realizaram tratamento cirúrgico com limpeza e desbridamento, seguido do preenchimento da cavidade com biovidro S53P4 em pasta (BonAlive ® Putty, Turku, Finland). Foram excluídos pacientes submetidos a procedimentos de cirurgia plástica nos tecidos moles do local afetado, com lesões ósseas segmentares e com presença de artrite séptica. A análise estatística foi realizada em Excel ® . Foram coletados dados demográficos, sobre a lesão, o tratamento e o acompanhamento. O desfecho foi classificado em "sobrevida livre de doença", "falha" ou "indeterminado". Resultados: Dos 31 pacientes analisados, 71% eram homens, com idade média de 53,6 anos (DP ± 24,26). Do total, 84% foram acompanhados por no mínimo 12 meses, e 67,7% apresentaram comorbidades. A terapia antibiótica combinada foi realizada em 64,5% dos pacientes, sendo o patógeno mais frequente o Staphylococcus aureus (47,1%). Ao final, 90,3% dos pacientes obtiveram "sobrevida livre de doenças" e 9,7% foram considerados "indeterminados". Conclusão: O vidro bioativo S53P4 em pasta é seguro e eficaz no tratamento da osteomielite cavitária e de infecções por patógenos resistentes, incluindo o S. aureus multirresistente. Nível de Evidência IV, Série de Casos.

Mastoid obliteration and external auditory canal reconstruction using 3D printed bioactive glass S53P4 /polycaprolactone scaffold loaded with bone morphogenetic protein-2: A simulation clinical study in rabbits.

Introduction: The lack of good prosthetic materials and objective standards has limited the promotion of mastoid obliteration and external auditory canal reconstruction, and the quality of the surgery varies. In this study, bioactive glass S53P4 (S53P4), the most popular artificial prosthetic material, was modified and combined with polycaprolactone (PCL) and bone morphogenetic protein-2 (BMP-2) to produce an individualized biological scaffold using 3D printing technology to explore a better material and method for mastoid obliteration and external auditory canal reconstruction. Methods: 3D-printed S53P4/PCL scaffolds were fabricated from 3D reconstruction data of bone defect areas in New Zealand rabbits simulating "Canal Wall Down Mastoidectomy". The water absorption, swelling rate, porosity, and Young's modulus of the scaffold were measured, and the morphology and pore size of the scaffold were observed using scanning electron microscopy. The cytotoxicity of the S53P4/PCL scaffolds was detected using the CCK8 assay, and the in vitro antibacterial activity of the S53P4/PCL scaffolds was detected using the inhibition circle method. The BMP-2-loaded S53P4/PCL scaffolds were prepared using the drop-in lyophilization method and implanted into animal models. The biocompatibility, osteogenic activity, and external auditory canal repair of the scaffolds were observed using endoscopy, micro-CT, and histological examination. Results: The S53P4/PCL scaffold was highly compatible with the defective area of the animal model, and its physicochemical properties met the requirements of bone tissue engineering. In vitro experiments showed that the S53P4/PCL scaffold was non-cytotoxic and exhibited better antibacterial activity than the same volume of the S53P4 powder. In vivo experiments showed that the S53P4/PCL scaffold had good biocompatibility and osteogenic activity, and could effectively repair bone defects and reconstruct the normal morphology of the external auditory canal in animal models. Furthermore, its osteogenic activity and repair ability were significantly improved after loading with BMP-2. Conclusions: The 3D printed S53P4/PCL scaffold has great potential for clinical mastoid obliteration and external auditory canal reconstruction.

Postoperative surgical site infection in cholesteatoma surgery with and without mastoid obliteration, what can we learn?

INTRODUCTION: This study aims to describe the occurrence of postoperative complications related to cholesteatoma surgery and to determine factors influencing the most common complication, i.e. postoperative surgical site infection (SSI) in cases with and without mastoid obliteration. MATERIALS AND METHODS: Retrospective analyses were performed on surgically treated cholesteatomas in our hospital between 2013 and 2019. Patient characteristics, peri- and postoperative management and complications were reviewed. The cases were divided into two groups based on whether mastoid obliteration was performed or not. RESULTS: A total of 336 cholesteatoma operations were performed, of which 248 cases received mastoid obliteration. In total 21 complications were observed, of which SSI was the most common (15/21). No difference in occurrence of any postoperative complication was seen between the obliteration and no-obliteration group (p = 0.798), especially not in the number of SSI (p = 0.520). Perioperative and/or postoperative prophylactic antibiotics were not associated to the development of an SSI in both groups. In the no-obliteration group a younger age (p = 0.015), as well as primary surgery (p = 0.022) increased the risk for SSI. In the obliteration group the use of bioactive glass (BAG) S53P4 was identified as independent predictor of SSI (p = 0.008, OR 5.940). DISCUSSION: SSI is the most common postoperative complication in cholesteatoma surgery. The causes of SSI are multifactorial, therefore further prospective research is needed to answer which factors can prevent the development of an SSI in cholesteatoma surgery.

Antimicrobial activity of bioactive glass S53P4 against representative microorganisms causing osteomyelitis - Real-time assessment by isothermal microcalorimetry.

Bioactive glass (BAG) is a synthetic bone substitute with intrinsic antimicrobial properties, used for bone defect filling. We evaluated the antimicrobial activity of two formulations of BAG S53P4 against representative pathogens of osteomyelitis: Staphylococcus aureus, Staphylococcus epidermidis, Enterococcus faecalis, Escherichia coli and Candida albicans. Antimicrobial activity of BAG S53P4 was assessed by isothermal microcalorimetry, a highly sensitive assay measuring metabolic-related microbial heat production in real-time. Standard CFUs-counting was performed in parallel. BAG granules (diameter 500-800 µm) and powder (<45 µm) were evaluated in two concentrations (400 and 800 mg/ml). Isothermal microcalorimetry was performed in glass ampoules containing growth medium, BAG and test microorganism, heat production was measured for 24 h. BAG S53P4 inhibited heat production of most-tested microorganisms with heat reduction of 60%-98% compared to positive control after 24 h of exposure to the highest-tested concentration (800 mg/ml). BAG S53P4 in powder formulation (<45 µm) inhibited more microbial growth than in granule formulation (500-800 µm), with the exception of C. albicans for which both formulations presented similar inhibition rates ranging between 87 % and 97 %. The BAG inhibitory ratios estimated from the variation in the growth rate constants of each microorganism compared to the growth control ranged between 2.55 % and 100 %. Comparable results were obtained by CFUs-counting, with complete reduction in cell viability of most microorganisms after ≤ 24 h of microbial exposure to BAG S53P4 powder. In summary, BAG S53P4 demonstrated efficient inhibition of microbial growth, especially in powder formulation.

S53P4 Bioactive Glass Inorganic Ions for Vascularized Bone Tissue Engineering by Dental Pulp Pluripotent-Like Stem Cell Cocultures.

IMPACT STATEMENT: In this study, we proposed for the first time the use of inorganic ions dissolved from BaG in a cell coculture system to induce vascularized bone formation in vitro. For that, we used dental pulp pluripotent-like stem cells from a single individual source obtained in a minimally invasive extraction manner. Moreover, we carried out all the experiments under xeno-free conditions, allowing the extrapolation of the results to the development of clinically orientated applications. Overall, these results would provide a new promising system to promote the success and survival of bone tissue engineering constructs after implantation.

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.

Bioactive Glass S53P4 versus Chlorhexidine Gluconate as Intracanal Medicament in Primary Teeth: An In-vivo Study Using Polymerase Chain Reaction Analysis.

BACKGROUND: Bacteria have long been recognized as the primary etiology for pulpal and periapical lesions, which necessitates the elimination of bacteria from the root canal system. In primary teeth, irrigation and debridement is the main protocol required to disinfect the canal. Biomechanical preparation cannot be vigorously done on the primary teeth due to anatomical barrier such as thin and flared roots. This calls for the use of an effective intracanal medication that will assist disinfection of root canal system. Aim of the study was to examine the in-vivo susceptibility of root canal bacteria to chlorhexidine (CHX) gluconate-1% gel and bioactive glass (BAG) S53P4 when used as intracanal medicaments using polymerase chain reaction (PCR). METHODOLOGY: PCR (analysis used oligonucleotide primers of Escherichia coli) was used to detect and compare the microbial load reduction after medication of 14 teeth for a week with either CHX gel - 1% or BAG S53P4. The pre and post microbial load was checked in the form of colony forming units. When analysis was done, a statistically significant difference was observed between the two groups. RESULTS: The study revealed that both medicaments caused a considerable amount of microbial load reduction. BAG S53P4 caused much more reduction than CHX 1% gel. Statistical analysis showed a significant difference between the two groups. CONCLUSION: BAG S53P4 has superior antibacterial property as compared to CHX 1% gel.

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.