Objectives

The surface of pure titanium (Ti) shows decreased histocompatibility over time; this phenomenon is known as biological ageing. UV irradiation enables the reversal of biological ageing through photofunctionalisation, a physicochemical alteration of the titanium surface. Ti implants are sterilised by UV irradiation in dental surgery. However, orthopaedic biomaterials are usually composed of the alloy Ti6Al4V, for which the antibacterial effects of UV irradiation are unconfirmed. Here we evaluated the bactericidal and antimicrobial effects of treating Ti and Ti6Al4V with UV irradiation of a lower and briefer dose than previously reported, for applications in implant surgery.

Aim. Prosthetic joint infections (PJI) remain a great challenge in orthopedic surgery with a high mortality rate. It is particularly complicated by biofilms and infections caused by Methicillin-resistant Staphylococcus aureus (MRSA). It concurrently shields bacteria from host immune responses and confers resistance to antibiotics. This study aims to investigate the efficacy of radioimmunotherapy as an innovative therapeutic modality to address the challenges posed by MRSA and its biofilm. Method. We induced specific monoclonal antibodies 4497-IgG1 as carriers, which target wall teichoic acids (WTA) existing on MRSA and its biofilm. Radionuclides actiniumr-225 (. 225. Ac, α-emitter) and lutetium-177 (. 177. Lu, β-emitter) were conjugated with mAbs using DOTA as chelator. Quality control was assessed using thin layer chromatography and immunoreactivity assays. . 225. Ac- and . 177. Lu-labelled 4497-IgG1 were employed to evaluate the susceptibility of MRSA and its biofilm to the radioimmunotherapy in vitro. Planktonic MRSA and biofilms, at concentrations of 10. 8. and 10. 7. CFU/mL, were incubated at 37°C for 60 minutes in PBS containing either . 225. Ac-mAb (0 - 14.8 kBq) or . 177. Lu-mAb (0 - 14.8 MBq). Radiolabelled dunituximab and free radionuclides serve as isotype-matched negative control. The bacterial viability and metabolic activity were subsequently quantified using CFU and XTT assays. Results. The radiochemical purity of the . 225. Ac-mAbs and . 177. Lu-mAbs complex were determined to be 95.4% and 96.16%. Immunoreactivity fractions of them were measured at 81.8% and 80.8%. . 225. Ac-mAbs and . 177. Lu-mAbs exhibited significant and dose-dependent antimicrobial effects on both planktonic MRSA and biofilm. . 225. Ac- and . 177. Lu-4497IgG1 at doses of 7.4 kBq and 7.4 MBq resulted in more than 4-log reduction in bacterial counts. In biofilms, 2-log reduction at the highest . 225. Ac radioactivity of 14,8kBq. The . 177. Lu complex showed a strong dose-dependent effect, with a reduction of up to 4-log. The XTT assay confirmed these findings, showing a decrease in metabolic activity corresponding to a decrease in bacterial counts, and a slight increase in metabolic activity at the lower dose. Conclusions. Our study demonstrates the efficacy of . 225. Ac and . 177. Lu-labelled 4497-IgG1 antibodies in mediating dose-dependent bactericidal effects against planktonic MRSA and biofilms in vitro. This indicates that radioimmunotherapy could be a potential targeted therapeutic strategy against MRSA and its biofilm. Further research in preclinical and clinical settings is warranted to validate and refine these findings on biofilm-associated implant infections

Bioactive glasses (BAGs) are bone substitutes with bone bonding, angiogenesis promoting and antibacterial properties. The bioactive process leading to bone bonding has been described as a sequence of reactions in the glass and at its surface. Implantation of the glass is followed by a rapid exchange of Na+ in the glass with H+ and H3O+ from the surrounding tissue, leading to the formation of silanol (SiOH) groups at the glass surface. Due to migration of Ca2+ and PO43− groups to the surface and cystallization, a CaO-P2O5 hydroxyapatite (HA) layer is formed on top of the Si-rich layer. Finally, cell interactions with the HA layer subsequently initiate the bone forming pathway. The rapid increase in pH and the subsequent osmotic effect caused by dissolution of the glass have been suggested to partly explain the antibacterial properties observed for BAGs. Comparing bactericidal effects of different BAGs, BAG-S53P4 has been shown to be the most effective, with the fastest killing or growth inhibitory effect. This antibacterial effect has been observed in vitro for all pathogens tested, including the most important aerobic and anaerobic pathogens, as well as very resistant bacteria. In a multicentre study in 2007–2009, BAG-S53P4 was used as bone graft substitute in treatment of osteomyelitis. Eleven patients (nine males, two females) with a radiologically diagnosed osteomyelitis in the lower extremity (N=10) and in the spine (N-1) participated. In the operation, the infected bone and the soft tissue were removed, and the cavitary bone defects were filled with BAG-S53P4 (BonAlive™, Bonalive Biomaterials Ltd., Finland). In four patients, muscle flaps were used as part of the treatment. Eight patients were treated in a one-stage procedure. Kanamycin granules were used in one patient and Garamycin granules (Septocol ®) in two patients. Patient data were obtained from hospital patient' records until August 2010, resulting in a mean follow-up period of 29 months (range 15–43). BAG-S53P4 was well tolerated; no BAG-related adverse effects were seen in any patient. The use of BAG-S53P4 as a bone graft substitute resulted in a fast recovery. Long-term clinical outcome was good or excellent in ten of eleven patients. These primary results indicate that BAG-S53P4 can be considered as a good and usable material in treatment of osteomyelitis. After this study BAG-S53P4 has been used in several other patients with very promising results

Aims

Biofilm-related infection is a major complication that occurs in orthopaedic surgery. Various treatments are available but efficacy to eradicate infections varies significantly. A systematic review was performed to evaluate therapeutic interventions combating biofilm-related infections on in vivo animal models.

Aims

To characterize the intracellular penetration of osteoblasts and osteoclasts by methicillin-resistant Staphylococcus aureus (MRSA) and the antibiotic and detergent susceptibility of MRSA in bone.

The June 2014 Research Roundup³⁶⁰ looks at:Intraoperative irrigation a balance of toxicities; Ibandronate effective in bone marrow oedema; Risk stratification in damage control surgery; Osteoblast like cells potentially safe; Better wear and antibacterial?; Assessing outcomes in hip fracture.