Antimicrobial treatment in bone and joint infections

Calcium phosphates enhanced with liposomes - the future of bone regeneration and drug delivery

Effective healing and regeneration of various bone defects is still a major challenge and concern in modern medicine. Calcium phosphates have emerged as extensively studied bone substitute materials due to their structural and chemical resemblance to the mineral phase of bone, along with their versatile properties. Calcium phosphates present promising biological characteristics that make them suitable for bone substitution, but a critical limitation lies in their low osteoinductivity. To supplement these materials with properties that promote bone regeneration, prevent infections, and cure bone diseases locally, calcium phosphates can be biologically and therapeutically modified. A promising approach involves combining calcium phosphates with drug-containing liposomes, renowned for their high biocompatibility and ability to provide controlled and sustained drug delivery. Surprisingly, there is a lack of research focused on liposome-calcium phosphate composites, where liposomes are dispersed within a calcium phosphate matrix. This raises the question of why such studies are limited. In order to provide a comprehensive overview of existing liposome and calcium phosphate composites as bioactive substance delivery systems, the authors review the literature exploring the interactions between calcium phosphates and liposomes. Additionally, it seeks to identify potential interactions between calcium ions and liposomes, which may impact the feasibility of developing liposome-containing calcium phosphate composite materials. Liposome capacity to protect bioactive compounds and facilitate localized treatment can be particularly valuable in scenarios involving bone regeneration, infection prevention, and the management of bone diseases. This review explores the implications of liposomes and calcium phosphate material containing liposomes on drug delivery, bioavailability, and stability, offering insights into their advantages.

Antimicrobial Stewardship for Outpatients with Chronic Bone and Joint Infections in the Orthopaedic Clinic of an Academic Tertiary Hospital, South Africa

Bone and joint infections are associated with prolonged hospitalizations, high morbidity and complexity of care. They are difficult to treat, and successful therapy requires organism-specific antimicrobial therapy at high doses for a prolonged duration as recommended in standard treatment guidelines (STGs). Adherence to the treatment plan is equally important, which is enhanced with knowledge of the condition as well as appropriate antibiotics. Consequently, the aim of this study was to provide antimicrobial stewardship (AMS) services to outpatients with chronic bone and joint infections presenting to the orthopaedic clinic at a public South African tertiary hospital. A total of 44 patients participated in this study. Chronic osteomyelitis was diagnosed in 39 (89%) patients and septic arthritis in 5 (11%). The majority (43%) of infections were caused by Staphylococcus aureus followed by Pseudomonas aeruginosa (14%). Seventy-one antibiotics were prescribed at baseline with rifampicin prescribed the most (39%), followed by ciprofloxacin (23%). The majority (96%) of the antibiotics were not prescribed according to the South African STG; however, interventions were only needed in 31% of prescribed antibiotics (n = 71) since the STG only recommends empiric therapy directed against Staphylococcus aureus. Seventy-seven percent of the patients obtained a high self-reported adherence score at baseline. Consequently, there is a need to improve AMS in bone and joint infections to improve future care.

Exploring Nanotechnology as a Strategy to Circumvent Antimicrobial Resistance in Bone and Joint Infections

Bone and joint infections (BJIs) are difficult to treat, necessitating antimicrobial therapy at high doses for an extended period of time, in some cases different from our local guidelines. As a consequence of the rise in antimicrobial-resistant organisms, drugs that were previously reserved for last-line defense are now being used as first line treatment, and the pill burden and adverse effects on patients are leading to nonadherence, encouraging antimicrobial resistance (AMR) to these last-resort medicines. Nanodrug delivery is the field of pharmaceutical sciences and drug delivery which combines nanotechnology with chemotherapy and/or diagnostics to improve treatment and diagnostic outcomes by targeting specific cells or tissues affected. Delivery systems based on lipids, polymers, metals, and sugars have been used in an attempt to provide a way around AMR. This technology has the potential to improve drug delivery by targeting the site of infection and using the appropriate amount of antibiotics to treat BJIs caused by highly resistant organisms. This Review aims to provide an in-depth examination of various nanodrug delivery systems used to target the causative agents in BJI.

Synthesis and characterization of lysozyme-conjugated Ag.ZnO@HA nanocomposite: A redox and pH-responsive antimicrobial agent with photocatalytic activity

Hydroxyapatite (HA) is extensively used for implantable device coating; however, it lacks antibacterial property, leading to potential bacterial infection during orthopedic implantation surgery. Herein, to enhance the antibacterial activity of HA, a redox- and pH-responsive HA nanocomposite with photocatalytic activity was designed. A photosensitive heterostructure, zinc oxide/hydroxyapatite (ZnO.HA), was coated with Ag nanoparticles (AgNPs) with assisted gallic acid using the UV-irradiation method. An antibacterial enzyme, lysozyme, was then conjugated on the surface of the nanocomposite by a cleavable disulfide linker, resulting in a redox-sensitive nanoplatform. In comparison with bare HA, the designed nanocomposites as Lyso.CAGZ@HA displayed much higher antibacterial activity (> 5-fold) toward Escherichia coli (E. coli) owing to the synergistic antibacterial effects of ZnONPs, AgNPs, gallic acid, and lysozyme on the surface of the nanocomposite. However, antibacterial and antifouling effects are much more enhanced in Lyso.CAGZ@HA-treated bacteria as they were subjected to UVA irradiation. Moreover, the cellular uptake of nanocomposite and intracellular glutathione depletion enhanced in the presence of UVA light, resulting in reactive oxygen specious generation enhancement. Further, in vitro cytotoxicity experiments on mammalian cells (human foreskin fibroblast) revealed that nanocomposite has no cytotoxic effects. Hence, this study demonstrated that Lyso.CAGZ@HA could be considered as a potential therapeutic approach against bacterial infectious diseases.