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Prosthetic joint infections (PJIs) can have disastrous consequences for patient health, including removal of the device, and placement of cemented implants is often required during surgery to eradicate PJIs. In translational research, in vivo models are widely used to assess the biocompatibility and antimicrobial efficacy of antimicrobial coatings and compounds. Here, we aim to utilize Galleria mellonella implant infection models to assess the antimicrobial activity of antibiotic-loaded bone cement (ALBC) implants. Therefore, we used commercially available bone cement loaded with either gentamicin alone (PALACOS R+G) or with a combination of gentamicin and vancomycin (COPAL G+V), compared to bone cement without antibiotics (PALACOS R). Firstly, the in vitro antimicrobial activity of ALBC was determined against Staphylococcus aureus. Next, the efficacy of ALBC implants was analyzed in both the G. mellonella hematogenous and early-stage biofilm implant infection model, by monitoring the survival of larvae over time. After 24 h, the number of bacteria on the implant surface and in the tissue was determined. Larvae receiving dual-loaded COPAL G+V implants showed higher survival rates compared to implants loaded with only gentamicin (PALACOS R+G) and the control implants without antibiotics (PALACOS R). In conclusion, G. mellonella larvae infection models with antibiotic-loaded bone cements are an excellent option to study (novel) antimicrobial approaches. [ABSTRACT FROM AUTHOR]

Antimicrobial photodynamic therapy (aPDT) depends on a variety of characteristics of the photosensitizers (PSs) used, the pathogens to target and the involved environment. In a recent study using a series of Ruthenium(II) polypyridyl complexes ([Ru(II)]), we reported on the importance of the chemical structure of aPDT compounds on both their photo-physical/physico-chemical properties and their aPDT efficacy [1]. Under standard in vitro conditions, effective [Ru(II)]-mediated aPDT was demonstrated against planktonic cultures of Pseudomonas aeruginosa and Staphylococcus aureus strains that were isolated from the airways of Cystic Fibrosis (CF) patients. CF lung disease is characterized with many patho-physiological disorders that can compromise the effectiveness of antimicrobials. The presentation will expand significantly on our previously reported work [1], with the aim to further investigate [Ru(II)]-mediated aPDT under in vitro experimental settings, approaching the conditions of infected airways in CF patients. Thus, the isolated influence of a series of parameters (including increased osmotic strength, acidic pH, lower oxygen availability, etc.) on the properties of two selected [Ru(II)] complexes will be discussed [2]. Furthermore, these compounds were used to evaluate the possibility to photo-inactivate P. aeruginosa, while preserving an underlying epithelium of human bronchial epithelial cells. Altogether, our results provide substantial evidence for the relevance of [Ru(II)]-based aPDT in CF lung airways. Besides optimized nano-complexes, this study also highlights the various needs for translating such a challenging perspective into clinical practice. [ABSTRACT FROM AUTHOR]