Infections caused by microbes, particularly Staphylococcus aureus (S. aureus) and Pseudomonas aeruginosa (P. aeruginosa), pose a significant challenge in orthopaedic surgery, especially with bone implants. Furthermore, antibiotic resistance has been deemed a significant risk to public health. Despite the potential of Baghdadite (BAG), a synthetic bone substitute made from zirconium-incorporated calcium silicate, its limited antibacterial activity is a concern in medical applications. This study explores a solution to this problem by enhancing the antibacterial efficacy of BAG. We introduced biocompatible metals, specifically magnesium (Mg), into BAG (Mg-BAG). This modified bioceramic aims to offer improved antibacterial properties against key pathogens while maintaining its inherent biocompatibility. This addresses the urgent need for bone repair materials that resist infection. The results showed that Mg-BAG bioceramics exhibited significant antibacterial activity against the Gram-negative P. aeruginosa and Gram-positive S. aureus. The addition of Mg triggered a multifaceted antimicrobial response, including the generation of reactive oxygen species within bacterial cells, disruption of membrane electron transport, and cell membrane damage leading to leakage of cytosolic contents. A notable aspect of our research is the utilization of synchrotron macro ATR-FTIR microspectrosopy to investigate the alterations in lipids, proteins, and nucleic acids of bacteria following exposure to the Mg-BAG. This advanced analytical technique provided insights into the molecular interactions and structural changes in bacterial cells upon contact with Mg-BAG, offering a deeper understanding of the antimicrobial action at the molecular level. Importantly, these antimicrobial mechanisms could potentially prevent the development of bacterial resistance. Furthermore, these composites retained their biocompatibility, making them suitable for orthopaedic applications. Our study demonstrates that Mg-BAG bioceramics are promising next-generation bioceramics for orthopaedic applications. Their dual functionality - promoting bone cell growth and exhibiting effective antimicrobial properties against significant pathogens - positions them as innovative solutions for infection control in bone implant surgeries.
Keywords: calcium-silicate-based ceramics, baghdadite, implant infection, magnesium, orthopaedic, Staphylococcus aureus, Pseudomonas aeruginosa.