Sterile Implants Research Articles

Modifikacije površine zubnih implantata i njihov uticaj na proces oseointegracije

Introduction: Dental implantation is a process of implanting dental implants into the bone of a patient, in places where one or more teeth are missing. For successful implantation, the process of osteointegration has to happen, which means that the dental implant placed in the bone should create a connection with it. The success of the osteointegration process depends on several factors, one of which is a biological modification of the material from which the implant is made. As a failure, it can occur during periimplantitis. Aim: The present study aimed to prove the influence of the foreign body on osteointegration during dental implantation, that is, the cause of peri-implantitis. The subject of our research was the analysis of new, sterile implants and their comparison with fallen, lost implants Materials and methods: For this scientific research we used a scanning electron microscope, which allows a detailed analysis of the implant surface. The analysis was performed on brand new, as well as on failed implants. A Scanning Electron Microscope (SEM) is a type of electron microscope that produces images of a sample by scanning its surface with a focused beam of electrons. Results: As a consequence of the deposition of many minerals (like Mg, and P), a higher wear resistance occurs on the implant surface. Traces of contaminant Na along with carbon, N, Ca, Al and O were also detected on the Ti surface of the failed implants, which are fallen implants. All these elements negatively affect the implantation success and are the cause of unsuccessful implant treatment. Conclusion: Dental implant contamination is a key factor for the success/failure of implantation. Traces of organic and inorganic contaminants can be found, despite the implant cleaning process and surface treatment of Ti, substances such as acid and sand.

Ozonated Water Promotes in vitro Decontamination of Dental Implants Surface

ABSTRACT Although studies have shown high survival rates of dental implants, complications may occur mainly due to peri-implant infections. These highlight the importance of establishing protocols for implant decontamination using adjuvant therapies, such as ozone. This study aimed to evaluate the potential for in vitro decontamination of ozonated water on implants surface. Sixteen titanium implants were used, distributed into the groups (n = 4): group E – sterile implants; group C – contaminated implants; group O40 – contaminated implants treated with ozonated water 40 mg/L; and group O60 – contaminated implants treated with ozonated water 60 mg/L. The implants of groups C, O40, and O60 were contaminated in vitro with biofilm. Groups O40 and O60 were decontaminated with ozonated water for 1 minute. Microbiologic analysis was performed by counting colony-forming units (CFUs). Experimental group comparisons were done using a one-way ANOVA test with Tukey’s posttest; a comparison between groups O40 and O60 was done using an independent t-test (p < 0.05). There was a difference among all experimental groups (p = 0.000), with a more significant reduction in CFUs in group O60 (0.83 × 107 ± 0.06) compared to group C (3.41 × 107 ± 0.41). It was concluded that ozonated water 60 mg/L has shown good potential for in vitro decontamination of implants surface.

Bioactive glass air-abrasion promotes healing around contaminated implant surfaces surrounded by circumferential bone defects: An experimental study in the rat.

The present study aimed to evaluate the healing of experimentally induced bone defects around contaminated dental implants after air-abrasion using 45S5 or zinc oxide (ZnO)-containing bioactive glasses (BAGs). One maxillary first molar was extracted from each Sprague-Dawley rat (n=30). After 4-week healing, a titanium implant was placed in the extraction site with a circumferential bone defect. The rats were randomized into five different groups: (1) implants with Fusobacterium nucleatum and Porphyromonas gingivalis dual-species biofilm (IB); (2) implants with biofilm subjected to inert glass air-abrasion (inert); (3) sterile implants (S); (4) implants with biofilm subjected to 45S5 BAG air-abrasion (45S5); and (5) implants with biofilm subjected to ZnO-containing BAG air-abrasion (Zn4). After 8-week healing, maxillae were dissected, and histomorphometric analyses were performed. The first bone-to-implant contact was significantly shorter for the inert (1.58 ± 1.16 mm; p=0.016), S (0.28 ± 0.13 mm; p < 0.001), 45S5 (0.41 ± 0.28 mm; p < 0.001), and Zn4 (0.26 ± 0.16 mm; p < 0.001) groups compared to IB group. Also, significantly more bone-to-implant contact was seen for S (72.35% ± 8.32%; p < 0.001), 45S5 (57.91% ± 24.10%; p=0.002), and Zn4 (70.49% ± 12.74%; p < 0.001) groups than the IB group. The bone volume with the threads demonstrated significantly higher value for S (69.32% ± 9.15%; p < 0.001), 45S5 (58.93% ± 23.53%; p=0.001), and Zn4 (68.65% ± 12.41%; p < 0.001) groups compared to the IB group. The bone volume within the defects was significantly higher for S (68.79% ± 11.77%; p < 0.001), 45S5 (62.51% ± 20.51%; p=0.002), and Zn4 (73.81% ± 15.07%; p < 0.001) groups compared to the IB group. This study suggests that air-abrasion of contaminated moderately rough implant surfaces with either 45S5 or ZnO-containing BAGs enhances osseointegration and bone defect regeneration.

Spatially and Temporally Controllable BMP-2 and TGF-β3 Double Release From Polycaprolactone Fiber Scaffolds via Chitosan-Based Polyelectrolyte Coatings.

Temporally and spatially controlled growth factor release from a polycaprolactone fiber mat, which also provides a matrix for directional cell colonization and infiltration, could be a promising regenerative approach for degenerated tendon-bone junctions. For this purpose, polycaprolactone fiber mats were coated with tailored chitosan-based nanogels to bind and release the growth factors bone morphogenetic protein 2 (BMP-2) and transforming growth factor-β3 (TGF-β3), respectively. In this work we provide meaningful in vitro data for the understanding of the drug delivery performance and sterilizability of novel implant prototypes in order to lay the foundation for in vivo testing. ELISA-based in vitro release studies were used to investigate the spatial and temporal control of release, as well as the influence of radiation sterilization on protein activity and release behavior. Layer-by-layer coatings based on BMP-2-containing chitosan tripolyphosphate nanogel particles and negatively charged alginate showed a good sustainment of BMP-2 release from chemically modified polycaprolactone fiber mats. Release control improved with increasing layer numbers. The approach of controlling the release via a barrier of cross-linked chitosan azide proved less promising. By using a simple, partial immersion-based dip-coating process, it was possible to apply opposing gradients of the growth factors BMP-2 and TGF-β3. Final radiation sterilization of the growth factor-loaded implant prototypes resulted in a radiation dose-correlated degradation of the growth factors, which could be prevented by lyophilization into protective matrices. For the manufacture of sterile implants, the growth factor loading step must probably be carried out under aseptic conditions. The layer-by-layer coated implant prototypes provided sustained release from opposing gradients of the growth factors BMP-2 and TGF-β3 and thus represent a promising approach for the restoration of tendon-bone defects.

Learnings from a Cutibacterium acnes pseudo-outbreak in pediatric neurosurgical patients

Background:Cutibacterium acnes is normal skin flora as well as a common culture contaminant. It can cause infections in the setting of sterile implants, although clinical presentations can be subtle. Differentiating true infection from sample contamination is challenging and has implications for patient care. We describe an investigation of a cluster of 7 hospitalized pediatric patients with C. acnes isolated from anaerobic cultures of cerebrospinal fluid (CSF) over 3 weeks at a quaternary-care children’s hospital. Methods: An outbreak response was coordinated between the infection prevention and control (IPC), microbiology, and neurosurgery teams. We defined a case as a hospitalized patient with C. acnes isolated from a CSF culture beginning in November 2020. We reviewed charts of all cases and CSF culture collection on all case units, transport to and processing at the microbiology laboratory, and the IPC team measured adherence for all processes. Results: There were 8 positive cultures in 7 cases from November 10 to 27, 2020. The median case age was 2 months (range, 0–119). Cases occurred on 4 different units. All positive patients had at least 1 implanted neurosurgical device used for CSF drainage. There were no clear commonalities in surgeon responsible for device placement, hardware type placed, or staff collecting CSF samples. A standard protocol for CSF collection was followed for all cases. Overall, 3 patients cleared cultures without intervention, 2 received oral antibiotics, and 2 underwent surgical removal of their device. Specimen processing was unchanged, although due to supply issues, an alternative anaerobic culture media (Anaerobic Systems, Morgan Hills, CA) was used for 6 weeks, during which all cases were identified. Compared to routine media, the alternative is known to enhance organism detection. The company reported no concerns for media contamination or C. acnes outbreaks. Once routine media became available, CSF culture positivity for C. acnes returned to baseline (late November or early December) (Fig. 1). Conclusions: We identified a likely pseudo-outbreak related to temporary use of a more sensitive culture media. No direct patient harm was identified, although many had increased risk of harm by surgical intervention or prolonged length of stay. Technological advances may enhance organism identification but challenge existing paradigms of care. More studies are needed to better delineate the intersection of diagnostic advancements with patient care standards.Funding: NoneDisclosures: None

Sodium Bicarbonate Jet Reduces Contamination of Dental Implants In Vitro Without Causing Visible Surface Changes.

The increasing use of dental implants in oral rehabilitation has contributed to the increase of cases of peri-implantitis, a complex clinical condition that persists without an ideal treatment protocol. Therefore, this study aimed to verify the decontaminating action of the sodium bicarbonate jet in vitro, using different protocols, and the presence of visible changes on the surface of dental implants. Sixteen titanium implants (BioHE, Bioconnect) were used, divided into four groups (four implants per group): sterile implants (S)-negative control; implants contaminated with oral biofilm (C)-positive control; and implants contaminated with oral biofilm and decontaminated with a sodium bicarbonate jet for 30 seconds (J30) or 60 seconds (J60). The implants of groups C, J30, and J60 were contaminated in vitro with oral biofilm, then groups J30 and J60 received the respective decontamination treatments. Microbiologic analysis was performed by counting the colony-forming units (CFUs), and a qualitative descriptive analysis of the implant surface was performed after microbiologic analysis using scanning electron microscopy (SEM). Statistical analysis included one-way analysis of variance (ANOVA) and Tukey tests and the independent t test, with a .05 significance level. There was a significant reduction (P < .01) in the number of CFUs in groups J30 (3.63 × 106 ± 0.32) and J60 (2.74 × 106 ± 0.21) compared with group C (5.05 × 106 ± 0.43). Both decontaminated groups were statistically different from group S, which did not show bacterial growth (P < .01). When groups J30 and J60 were compared, there was also a significant difference between them (P < .01), and the group J60 showed greater decontaminating potential. The descriptive qualitative analysis did not show any visible changes on the surface of the implants. The sodium bicarbonate jet was effective in decontaminating titanium implants in vitro, causing no visible damage to the implant surface.

Staphylococcus aureus and Acinetobacter baumannii Inhibit Osseointegration of Orthopedic Implants.

Bacterial infections routinely cause inflammation and thereby impair osseointegration of orthopedic implants. Acinetobacter spp., which cause osteomyelitis following trauma, on or off the battlefield, were, however, reported to cause neither osteomyelitis nor osteolysis in rodents. We therefore compared the effects of Acinetobacter strain M2 to those of Staphylococcus aureus in a murine implant infection model. Sterile implants and implants with adherent bacteria were inserted in the femur of mice. Bacterial burden, levels of proinflammatory cytokines, and osseointegration were measured. All infections were localized to the implant site. Infection with either S. aureus or Acinetobacter strain M2 increased the levels of proinflammatory cytokines and the chemokine CCL2 in the surrounding femurs, inhibited bone formation around the implant, and caused loss of the surrounding cortical bone, leading to decreases in both histomorphometric and biomechanical measures of osseointegration. Genetic deletion of TLR2 and TLR4 from the mice partially reduced the effects of Acinetobacter strain M2 on osseointegration but did not alter the effects of S. aureus. This is the first report that Acinetobacter spp. impair osseointegration of orthopedic implants in mice, and the murine model developed for this study will be useful for future efforts to clarify the mechanism of implant failure due to Acinetobacter spp. and to assess novel diagnostic tools or therapeutic agents.

Bacterial-Specific Induction of Inflammatory Cytokines Significantly Decreases upon Dual Species Infections of Implant Materials with Periodontal Pathogens in a Mouse Model.

Cytokine profiles are often perturbed after infections of medical implants. With a non-invasive in vivo imaging system, we report in a mouse model that interferon expression after infection of subcutaneous implants with Streptococcus oralis, Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, and Treponema denticola (alone or as a combination) was species-specific, persisted longer in the presence of implants, and notably decreased upon dual species infections. This type I interferon expression disappeared within two weeks; however, histology of implant–tissue interface indicated high recruitment of immune cells even after three weeks. This was suggestive that biomaterial-associated infections could have prolonged effects, including the systemic stimulation of inflammatory cytokines. The present study investigated the systemic impact of this chronic peri-implant inflammation on the systemic expression of inflammatory cytokines (23) using a multiplex assay. Initially, the cytokine measurement in murine fibroblasts exposed to periodontal pathogens remained limited to the expression of five cytokines, namely, IL-6, G-CSF, CXCL-1/KC, MCP-1 (MCAF), and IL-12 (p40). The systemic determination of cytokines in mice increased to 19 cytokines (IL-1α, IL-2, IL-3, IL-5, IL-6, IL-9, IL-12 (p40), IL-12 (p70), IL-13, IL-17A, CCL-11/Eotaxin, G-CSF, IFN-γ, CXCL1/KC, MCP-1 (MCAF), MIP-1α/CCL3, MIP-1β/CCL4, CCL5/RANTES, and TNF-α). Systemic induction of cytokines was species-specific in the mouse model. The cytokine induction from infected implants differed significantly from sole tissue infections and sterile implants. Notably, systemic cytokine induction decreased after infections with dual species compared to single species infections. These findings describe the systemic effect of chronic peri-implant inflammation on the systemic induction of inflammatory cytokines, and this effect was strongly correlated to the type and composition of initial infection. Systemic modulations in cytokine expression upon dual species infections exhibit an exciting pattern that might explain the complications associated with biomaterial-related infection in patients. Moreover, these findings validate the requirement of multispecies infections for pre-clinical studies involving animal models.

Introducing a Novel Experimental Model for Osseo-Disintegration of Titanium Dental Implants Induced by Monobacterial Contamination: An In-Vivo Feasibility Study.

Background and Objectives: The aim of the current study was to establish an osseo-disintegration model initiated with a single microorganism in mini-pigs. Materials and Methods: A total of 36 titanium dental implants (3.5 mm in diameter, 9.5 mm in length) was inserted into frontal bone (n: 12) and the basis of the corpus mandible (n: 24). Eighteen implants were contaminated via inoculation of Enterococcus faecalis. Six weeks after implant insertion, bone-to-implant contact (BIC) ratio, interthread bone density (ITBD), and peri-implant bone density (PIBD) were examined. In addition to that, new bone formation was assessed via fluorescence microscopy, histomorphometry, and light microscopical examinations. Results: Compared to the sterile implants, the contaminated implants showed significantly reduced BIC (p < 0.001), ITBD (p < 0.001), and PBD (p < 0.001) values. Around the sterile implants, the green and red fluorophores were overlapping and surrounding the implant without gaps, indicating healthy bone growth on the implant surface, whereas contaminated implants were surrounded by connective tissue. Conclusions: The current experimental model could be a feasible option to realize a significant alteration of dental-implant osseointegration and examine novel surface decontamination techniques without impairing local and systemic inflammatory complications.

Dental Implants Surface in vitro Decontamination Protocols.

Objective The number of patients rehabilitated with dental implants has contributed to increased incidence of peri-implant diseases. Due to complex and difficult treatment, peri-implantitis is a challenge and an efficient clinical protocol is not yet established. Aim of this study was to evaluate the efficacy of two protocols for in vitro decontamination of dental implants surface. Materials and Methods Twenty titanium implants (BioHE-Bioconect) were used. Implants were divided into five groups ( n = 4). NC group (negative control): sterile implants; PC group (positive control): biofilm contaminated implants; S group: biofilm contaminated implants, brushed with sterile saline; SB group: biofilm contaminated implants, brushed with sterile saline and treated with air-powder abrasive system with sodium bicarbonate (1 minute); and antimicrobial photodynamic therapy (aPDT) group: biofilm contaminated implants, brushed with sterile saline and treated with antimicrobial photodynamic therapy (red laser + toluidine blue O). The implants were contaminated in vitro with subgingival biofilm and distributed in groups PC, S, SB, and aPDT. Each group received the respective decontamination treatment, except groups NC and PC. Then, all implants were placed in tubes containing culture medium for later sowing and counting of colony-forming units (CFUs). Statistical Analysis One-way analysis of variance and Tukey tests were performed, at 5% significance level. Results Significantly fewer CFUs were observed in the aPDT group (19.38 × 10 5 ) when compared with groups SB (26.88 × 10 5 ), S (47.75 × 10 5 ), and PC (59.88 × 10 5 ) ( p < 0.01). Both the aPDT and SB groups were statistically different from the NC group ( p < 0.01). Conclusion Proposed protocols, using air-powder abrasive system with sodium bicarbonate and aPDT, showed to be efficacious in the decontamination of dental implants surface in vitro .

Phama Sci Preparation, In Vitro and In Vivo Studies of Vitamin B12 Loaded Implants Al-Rasheed University College, Iraq

Vitamin B12 is an important water-soluble vitamin which is found in a variety of food such as fish, shellfish, meat, and dairy products. It helps maintain healthy nerve cells and red blood cells, as well as aid in rapid DNA production during cell division. The daily requirement of vitamin B12 for the human body is approximately 1-25 µg . In 1960 introduced long-acting depot antipsychotic drug as the first long acting medications. Depot formulations providing further reductions in morbidity and mortality. Because they bypass the gastrointestinal tract, Depot treatments decrease the amount of medication needed and reduce certain peripheral side effects. Understanding the clinical and compliance of patients from the use of single dose with multiple and consecutive treatment of B12, we have developed long-term implantable medication delivery loaded with vitamin B12. The proposed method of controlled drug delivery uses sterile implants processed with a Poly (lactic-co-glycolic acid) (PLGA) polymer with a delivery interval of up to one month depending on polymer composition, and drug loading. In this study, 3 goals were addressed: 1: To formulate six different batches of biodegradable polymer implants loaded with vitamin 12 and target profile shown in Tables 1. 2: To characterize the formulated implants and establish an in vitro release for the B12 as a function of time. 3: Perform in vivo study and measure the serum concentration of B12 released from implants subcutaneously inserted into rats. Accomplishment of these three goals could provide the feasibility of controlled release vitamin B12 implants for human treatment for vitamin deficiency.

LC-QTOF-MS and 1H NMR Metabolomics Verifies Potential Use of Greater Omentum for Klebsiella pneumoniae Biofilm Eradication in Rats.

Bacterial wound infections are a common problem associated with surgical interventions. In particular, biofilm-forming bacteria are hard to eradicate, and alternative methods of treatment based on covering wounds with vascularized flaps of tissue are being developed. The greater omentum is a complex organ covering the intestines in the abdomen, which support wound recovery following surgical procedures and exhibit natural antimicrobial activity that could improve biofilm eradication. We investigated changes in rats’ metabolome following Klebsiella pneumoniae infections, as well as the greater omentum’s ability for Klebsiella pneumoniae biofilm eradication. Rats received either sterile implants or implants covered with Klebsiella pneumoniae biofilm (placed in the peritoneum or greater omentum). Metabolic profiles were monitored at days 0, 2, and 5 after surgery using combined proton nuclear magnetic resonance (1H NMR) and high performance liquid chromatography quadrupole time-of-flight tandem mass spectrometry (LC–QTOF-MS) measurements of urine samples followed by chemometric analysis. Obtained results indicated that grafting of the sterile implant to the greater omentum did not cause major disturbances in rats’ metabolism, whereas the sterile implant located in the peritoneum triggered metabolic perturbations related to tricarboxylic acid (TCA) cycle, as well as choline, tryptophan, and hippurate metabolism. Presence of implants colonized with Klebsiella pneumoniae biofilm resulted in similar levels of metabolic perturbations in both locations. Our findings confirmed that surgical procedures utilizing the greater omentum may have a practical use in wound healing and tissue regeneration in the future.

Capsular contracture around silicone miniimplants following bacterial contamination: an in vivo comparative experimental study between textured and polyurethane implants

Capsular contracture remains a problem following breast implant surgery. Although impact of biofilm and implant surface on capsule formation has been demonstrated, interaction of microorganisms with different surface types has not been clarified yet. We aimed to compare the ability of biofilm formation of implants with different surfaces, under standard conditions and to demonstrate its impact on capsular contracture. Twenty-four rats were divided into four groups. Mini-implants with three different surfaces (fine-textured, rough-textured and polyurethane) were placed on the dorsum of each rat. In Group-1, sterile implants were placed in submuscular pockets. In Group-2, implants were incubated in Staphylococcus epidermidis medium before implantation. In Group-3, before implantation, implants were immersed in Rifamycin solution following bacterial contamination. In Group-4, sterile implants were immersed in Rifamycin solution before implantation, and served as the control group. Rats were sacrificed at three months. Clinical, microbiological, histological and immunohistochemical evaluations were performed. Capsule contracture developed only on infected rough-textured implants. Rough-textured and polyurethane implants showed more biofilm formation than fine-textured implants. Capsule thickness and inflammatory cell density were higher on rough-textured implants compared to fine-textured implants (p = 0.004). Actin sequence was parallel and concentric on fine-textured and rough-textured implants; but was in irregular array on polyurethane implants. In presence of bacterial contamination, rough-textured implants have the most propensity of developing capsular contracture comparing to fine-textured and polyurethane implants at three months after implantation. Despite high bacterial load and biofilm formation, polyurethane implants are resistant to capsule contracture due to surface characteristics.

CSA-90 reduces periprosthetic joint infection in a novel rat model challenged with local and systemic Staphylococcus aureus.

Infection of orthopedic implants is a growing clinical challenge to manage due to the proliferation of drug-resistant bacterial strains. In this study, we aimed to investigate whether the treatment of implants with ceragenin-90 (CSA-90), a synthetic compound based on endogenous antibacterial peptides, could prevent infection in a novel rat model of periprosthetic joint infection (PJI) challenged with either local or systemic Staphylococcus aureus. A novel preclinical model of PJI was created using press-fit porous titanium implants in the distal femur of male Wistar rats. Sterile implants were pre-treated with 500 μg CSA-90 in saline. S. aureus was applied either directly at the time of surgery or administered via tail vein injection immediately afterward. Animals were monitored daily for clinical and radiographic evidence of infection for a total of 6 weeks. Post-study microbiological, radiographic, and histological analysis were performed to determine the incidence of PJI and assess osseointegration. CSA-90 treated groups demonstrated a reduced rate of PJI as confirmed by deep tissue swab culture at the time of cull compared with untreated groups with both local (33% vs 100%; P = .009) and systemic (10% vs 90%; P < .0001) S. aureus inoculation. Median survival time also increased from 8 to 17 days and from 8 to 42 days, respectively. In conclusion, this study describes a novel preclinical model of local and hematogenous PJI using a porous metal implant. CSA-90 reduced the incidence of PJI in this model supporting its further development as an antimicrobial coating for orthopedic implants.

Galleria mellonella as an alternative in vivo model to study bacterial biofilms on stainless steel and titanium implants

The purpose of this study was to establish an infection model of Galleria mellonella larvae as an alternative in vivo model for biofilm-associated infections on stainless steel and titanium implants. First, the model was established with sterile implants to evaluate biocompatibility. Titanium or stainless steel implants were implanted without adverse effects over the entire observation period of 5 days compared to controls and even up to the pupae and moth stage. Then, stainless steel and titanium implants contaminated with Staphylococcus aureus were implanted into larvae to mimic biofilm-associated infection. For both materials, pre-incubation of the implant with S. aureus led to significantly reduced survival of the larvae compared to sterile implants. Larvae could not be rescued by gentamicin, whereas gentamicin significantly improved the survival of the larvae in case of planktonic infection with S. aureus without an implant, confirming the typical character­istics of reduced antibiotic susceptibility of biofilm infections. Biofilm formation and various stages of biofilm maturation were confirmed by surface electron microscopy and by measuring bacterial gene expression of biofilm-related genes on contaminated implants, which confirmed biofilm formation and upregulation of autolysin (atl ) and sarA genes. In con­clusion, G. mellonella can be used as an alternative in vivo model to study biofilm-associated infections on stainless steel and titanium implants, which may help to reduce animal infection experiments with vertebrates in the future.

Galleria mellonella as an alternative in vivo model to study bacterial biofilms on stainless steel and titanium implants_suppl2

The purpose of this study was to establish an infection model of Galleria mellonella larvae as an alternative in vivo model for biofilm-associated infections on stainless steel and titanium implants. First, the model was established with sterile implants to evaluate biocompatibility. Titanium or stainless steel implants were implanted without adverse effects over the entire observation period of 5 days compared to controls and even up to the pupae and moth stage. Then, stainless steel and titanium implants contaminated with Staphylococcus aureus were implanted into larvae to mimic biofilm-associated infection. For both materials, pre-incubation of the implant with S. aureus led to significantly reduced survival of the larvae compared to sterile implants. Larvae could not be rescued by gentamicin, whereas gentamicin significantly improved the survival of the larvae in case of planktonic infection with S. aureus without an implant, confirming the typical character­istics of reduced antibiotic susceptibility of biofilm infections. Biofilm formation and various stages of biofilm maturation were confirmed by surface electron microscopy and by measuring bacterial gene expression of biofilm-related genes on contaminated implants, which confirmed biofilm formation and upregulation of autolysin (atl ) and sarA genes. In con­clusion, G. mellonella can be used as an alternative in vivo model to study biofilm-associated infections on stainless steel and titanium implants, which may help to reduce animal infection experiments with vertebrates in the future.

Galleria mellonella as an alternative in vivo model to study bacterial biofilms on stainless steel and titanium implants_suppl1

The purpose of this study was to establish an infection model of Galleria mellonella larvae as an alternative in vivo model for biofilm-associated infections on stainless steel and titanium implants. First, the model was established with sterile implants to evaluate biocompatibility. Titanium or stainless steel implants were implanted without adverse effects over the entire observation period of 5 days compared to controls and even up to the pupae and moth stage. Then, stainless steel and titanium implants contaminated with Staphylococcus aureus were implanted into larvae to mimic biofilm-associated infection. For both materials, pre-incubation of the implant with S. aureus led to significantly reduced survival of the larvae compared to sterile implants. Larvae could not be rescued by gentamicin, whereas gentamicin significantly improved the survival of the larvae in case of planktonic infection with S. aureus without an implant, confirming the typical character­istics of reduced antibiotic susceptibility of biofilm infections. Biofilm formation and various stages of biofilm maturation were confirmed by surface electron microscopy and by measuring bacterial gene expression of biofilm-related genes on contaminated implants, which confirmed biofilm formation and upregulation of autolysin (atl ) and sarA genes. In con­clusion, G. mellonella can be used as an alternative in vivo model to study biofilm-associated infections on stainless steel and titanium implants, which may help to reduce animal infection experiments with vertebrates in the future.

Q-Switch Nd:YAG Laser-Assisted Decontamination of Implant Surface.

Peri-implantitis (PI) is an inflammatory disease of peri-implant tissues, it represents the most frequent complication of dental implants. Evidence revealed that microorganisms play the chief role in causing PI. The purpose of our study is to evaluate the cleaning of contaminated dental implant surfaces by means of the Q-switch Nd:YAG (Neodymium-doped Yttrium Aluminum Garnet) laser and an increase in temperature at lased implant surfaces during the cleaning process. Seventy-eight implants (titanium grade 4) were used (Euroteknika, Sallanches, France). Thirty-six sterile implants and forty-two contaminated implants were collected from failed clinical implants for different reasons, independent from the study. Thirty-six contaminated implants were partially irradiated by Q-switch Nd:YAG laser (1064 nm). Six other contaminated implants were used for temperature rise evaluation. All laser irradiations were calibrated by means of a powermetter in order to evaluate the effective delivered energy. The irradiation conditions delivered per pulse on the target were effectively: energy density per pulse of 0.597 J/cm2, pick powers density of 56 mW/cm2, 270 mW per pulse with a spot diameter of 2.4 mm, and with repetition rate of 10 Hz for pulse duration of 6 ns. Irradiation was performed during a total time of 2 s in a non-contact mode at a distance of 0.5 mm from implant surfaces. The parameters were chosen according to the results of a theoretical modeling calculation of the Nd:YAG laser fluency on implant surface. Evaluation of contaminants removal showed that the cleaning of the irradiated implant surfaces was statistically similar to those of sterile implants (p-value ≤ 0.05). SEM analysis confirmed that our parameters did not alter the lased surfaces. The increase in temperature generated at lased implant surfaces during cleaning was below 1 °C. According to our findings, Q-switch Nd:YAG laser with short pulse duration in nanoseconds is able to significantly clean contaminated implant surfaces. Irradiation parameters used in our study can be considered safe for periodontal tissue.

Experimental model of peri-prosthetic infection of the knee caused by Staphylococcus aureus using biomaterials representative of modern TKA.

ABSTRACTProsthetic joint infection (PJI) following total knee arthroplasty (TKA) remains the leading cause for revision surgery, with Staphylococcus aureus the bacterium most frequently responsible. We describe a novel rat model of implant-associated S. aureus infection of the knee using orthopaedic materials relevant to modern TKA. Male Sprague-Dawley rats underwent unilateral knee implant surgery, which involved placement of a cementless, porous titanium implant into the femur, and an ultra-highly cross-linked polyethyelene (UHXLPE) implant into the proximal tibia within a mantle of gentamicin-laden bone cement. S. aureus biofilms were established on the surface of titanium implants prior to implantation into the femur of infected animals, whilst control animals received sterile implants. Compared to controls, the time taken to full weight-bear and recover pre-surgical body weight was greater in the infected group. Neutrophils and C-reactive protein levels were significantly higher in infected compared to control animals at day 5 post surgery, returning to baseline levels for the remainder of the 28-day experimental period. Blood cultures remained negative and additional plasma inflammatory markers were comparable for control and infected animals, consistent with the clinical presentation of delayed-onset PJI. S. aureus was recovered from joint tissue and implants at day 28 post surgery from all animals that received pre-seeded titanium implants, despite the use of antibiotic-laden cement. Persistent localised infection was associated with increased inflammatory responses and radiological changes in peri-implant tissue. The availability of a preclinical model that is reproducible based on the use of current TKA materials and consistent with clinical features of delayed-onset PJI will be valuable for evaluation of innovative therapeutic approaches.

Research: Recovery of Microorganisms in Nonsterile, Reusable, Loaned Orthopedic Implants.

Currently, there are two orthopedic implant types: (1) Sterile implants (e.g., joint prostheses) are distributed in a ready-for-use sterile fashion, and (2) nonsterile implants (e.g., plates, screws, Schanz pins, intramedullary rods) are processed by a healthcare facility's central sterile service department (CSSD). The current study evaluated processed implants for presence of coagulase-negative staphylococci, which was observed in 30% of the cortical screws, spongy screws, and Schanz pins (37 total samples) processed by a CSSD. Some samples were resistant to antimicrobial agents, thereby demonstrating that risk exists in the current methods used in the processing of nonsterile implants. Also of important note, nonsterile implants are commonly loaned worldwide. Loaned implantable materials should not be processed in the same manner as materials routinely prepared in the CSSD, as it is not possible to know the quality of the cleaning performed before the materials are returned to the loaning company. It is not uncommon for hospitals to receive loaned materials with organic residues.