Development of bacteriophage treatment against antibiotic resistant bacteria in orthopaedic implant related infections

Joint replacement surgery is increasingly performed as a result of increasing life expectancy, improvements in surgical techniques, and the increased rates of obesity. Prosthetic joint infection (PJI) is a possible post-operative complication and its rate has remained steady throughout the years, at 1.4–3.3%, depending on the joint being replaced. A majority of PJIs are caused by staphylococci (>50%), streptococci, enterococci, aerobic gram-negative bacilli, and anaerobic bacteria with leading Cutibacterium acnes. Once in contact with the surface of the implant, the microorganisms colonize it and form bacterial biofilms, which complicate treatment. Bacterial biofilms are associated with significantly decreased antimicrobial susceptibility. Bacteria in biofilms grow slowly, which makes growth dependent antimicrobials particularly ineffective. In addition, implant sites are often poorly vascularized which decreases the ability of antimicrobial agents to reach the site of biofilms, while also impeding host defences. Treatment of prosthetic joint infection can be time-consuming, expensive and arduous. Various therapies have been used, including surgical removal of all the infected tissue and implant, and a combination of débridement with implant retention and long-term antimicrobial therapy that is active against biofilm microorganisms. Ideally, the antimicrobial agent for treatment of PJI should have bactericidal activity against surface-adhering, slow-growing, and biofilm-producing microorganisms. Such effect is typically achieved with combination of antibiotics. Increased antibiotic resistance of bacteria causing PJI, biofilm barrier and long term treatments dictate a need for further optimization of antibacterial therapy which could result in more implant retention in chronic infections, thus reducing the increased morbidity and delayed return to function associated with the two stage exchange. Bacteriophages, viruses that specifically recognize and lyse bacteria are promising candidates for antibacterial therapy. In comparison with antibiotics, they specifically target a bacterium, have a minimal effect on normal microbiota, and amplify themselves on the site of infection. There are already some sporadic applications of bacteriophage therapy for treatment of PJI but to demonstrate efficacy and safety systematic, FDA and EMA compliant approach is needed. Therefore, the project will evaluate bacteriophage efficacy against staphylococci in PJI in mice model and address issues not being evaluated until today: mode of application (systemic vs local), bacteriophage distribution in the animal body (basic bacteriophage pharmacokinetics) and development of bacteria resistance against bacteriophages. COBIK, a leading project partner, has an extensive collection of different clinically relevant bacteria isolated from PJI, and bacteriophages, specific for these bacteria. COBIK has already demonstrated bacteriophage efficacy in vitro on cell culture model and in order to proceed towards clinical application needed by Orthopaedic hospital Valdoltra patients, we need to test bacteriophage efficacy on the mice model, mastered by Centre for Laboratory animals. Bacteriophage formulation will be produced and formulated by technology developed by BIA Separations. The main goal of the project is to evaluate efficacy of bacteriophage treatment against Staphylococcus epidermidis in orthopaedic implant related infections in mice model. In the frame of the project we will: · prepare and evaluate in vitro efficacy of an innovative bacteriophage formulation · optimize bacteriophage GMP-like manufacturing process · determine bacteriophage distribution in mice organs after systemic and local application · evaluate bacteriophage treatment efficacy in mice model · evaluate combined antibiotic and bacteriophage treatment efficacy in mice model · determine bacteria resistance development against bacteriophages after bacteriophage therapy.