Antibacterial Efficiency of Antibiotic-Impregnated Biomaterials in an In Vitro and In Vivo Study. Summary of the Doctoral Thesis

Abstract

Nowaday, biomaterials are used more frequently and are becoming increasingly important as biomaterials are used in all medical fields, and often the use of biomaterials are of life saving importance. Due to the extensive use and applications of biomaterials, and different types of biomaterials associated infections which are a significant medical problem. Depending on the type of infection, it may increase the patient’s risk of mortality, and increase the total cost of treatment due to necessary replacement of biomaterial. To prevent infection of biomaterials, it is necessary to reduce bacterial adhesion and biofilm formation on the biomaterial. This can be achieved with the use of antimicrobial substances. Local antibiotic substances released from the biomaterial is an advantage compared with most systemic antibiotic which are given to the patients before and after implantation surgery. The aim of this work is to exam the antibacterial efficiency of hydroxyapatite biomaterials with antibiotics (gentamicin or ciprofloxacin) and biodegradable polymer against the most common post-operative causative agents – Pseudomonas aeruginosa (P. aeruginosa) and Staphylococcus epidermidis (S. epidermidis). This work also compares the antimicrobial properties of composite materials with biodegradable polymers and without biodegradable polymers. Antibacterial properties of biomaterials were investigated against S. epidermidis and P. aeruginosa by using a standardized disc diffusion method in an agar medium, and in the bacterial suspension. The intensity of Inflammatory cytokines (TNF-α a IL-10) and antibacterial peptides (β-defensīna-2) were tested in an in vivo study after a biomaterial sample implantation in the rabbits subcutaneous pocket and wound contamination with S. epidermidis or P. aeruginosa. The results showed that the biomaterials with biodegradable polymer and antibiotic substances have statistically significantly longer antibacterial time than the biomaterials with antibiotic substances without the biodegradable polymer. The method which was used doesn’t influence the antibacterial properties of biomaterials. The porosity level of biomaterials influences on antibacterial time, the biomaterials with lower porosity level have statistically significantly shorter antibacterial time than biomaterials with higher porosity levels. In vivo study results showed that after composite material implantation with antibiotic substances, levels of inflammatory cytokines and antimicrobial peptides doesn’t increase in the surrounding tissues around biomaterials. Increased levels inflammatory cytokines and antibacterial peptides are in the tissue around biomaterials, after an implantation of biomaterials without antibiotic substances.