Bacterial biofilm formation on ceramics of various composition used for orthopedic endoprosthetics

Aim. To assess the intensity and characteristics of bacterial biofilms formed by non-fermenting gram-negative bacteria Pseudomonas aeruginosa and Acinetobacter baumannii on ceramic biocomposite samples based on wollastonite and zirconia, including those modified with the bioactive phase of hydroxyapatite (HA).Materials and methods. Biofilms formed on bioceramic samples, prepared according to the author’s original method, were examined by scanning electron microscopy (SEM). The studied samples included non-composite ceramics based on wollastonite (CaSiO3); composite ceramics based on wollastonite with HA (CaSiO3-HA); non-composite ceramics based on zirconium dioxide ZrO2; ceramics based on zirconia with HA 15 wt% (ZrO2-(15 wt % HA); ceramics based on zirconia with (ZrO2-(50 wt% HA). Biofilms were obtained by placing the samples in a nutrient medium with P. aeruginosa and A. baumannii. Cultivation was carried out at 37 °С for 24 and 48 h, respectively. The dynamics of bacterial growth of the surface of the studied samples was assessed by analyzing SEM images using an LBP classifier.Results. A noticeable difference was observed in the activity and structure of bacterial biofilm formation on all studied samples. The intensity of biofilm formation (surface coverage of ZrO2-based samples) determined using an LBP-based classifier was as follows: ZrO2 ceramics without HA – 28.13%; ZrO2 + 15 wt% HA – 28.33%; and ZrO2 + 50 wt% HA – 88.46%. All samples with HA addition demonstrated higher susceptibility to biofilm formation.Conclusion. The presence of HA in the composition of bioceramics increases the intensity of biofilm formation. This also indicates a higher biocompatibility of such materials. When selecting bioceramic materials for bone defect repair, preference should be given to materials containing no more than 15 wt% HA in the view of reducing the risk of infection.