A Mouse Model of Post-Arthroplasty Staphylococcus aureus Joint Infection to Evaluate In Vivo the Efficacy of Antimicrobial Implant Coatings

Background

Post-arthroplasty infections represent a devastating complication of total joint replacement surgery, resulting in multiple reoperations, prolonged antibiotic use, extended disability and worse clinical outcomes. As the number of arthroplasties in the U.S. will exceed 3.8 million surgeries per year by 2030, the number of post-arthroplasty infections is projected to increase to over 266,000 infections annually. The treatment of these infections will exhaust healthcare resources and dramatically increase medical costs.

Methodology/Principal Findings

To evaluate novel preventative therapeutic strategies against post-arthroplasty infections, a mouse model was developed in which a bioluminescent Staphylococcus aureus strain was inoculated into a knee joint containing an orthopaedic implant and advanced in vivo imaging was used to measure the bacterial burden in real-time. Mice inoculated with 5×10³ and 5×10⁴ CFUs developed increased bacterial counts with marked swelling of the affected leg, consistent with an acute joint infection. In contrast, mice inoculated with 5×10² CFUs developed a low-grade infection, resembling a more chronic infection. Ex vivo bacterial counts highly correlated with in vivo bioluminescence signals and EGFP-neutrophil fluorescence of LysEGFP mice was used to measure the infection-induced inflammation. Furthermore, biofilm formation on the implants was visualized at 7 and 14 postoperative days by variable-pressure scanning electron microscopy (VP-SEM). Using this model, a minocycline/rifampin-impregnated bioresorbable polymer implant coating was effective in reducing the infection, decreasing inflammation and preventing biofilm formation.

Conclusions/Significance

Taken together, this mouse model may represent an alternative pre-clinical screening tool to evaluate novel in vivo therapeutic strategies before studies in larger animals and in human subjects. Furthermore, the antibiotic-polymer implant coating evaluated in this study was clinically effective, suggesting the potential for this strategy as a therapeutic intervention to combat post-arthroplasty infections.     

Using home gardens to decipher health and healing in the Andes

Home gardens are a pervasive component of Andean agricultural systems, but have been ignored in anthropological and agronomic research. Recent research in the indigenous community of Saraguro, Ecuador, employed a combination of in-depth interviews, free-listing, videotaped walk-throughs, and mapping to explore the role of home gardens, which are established and controlled by women. Findings reveal that, although gardens offer multiple benefits, they are overwhelmingly devoted to the cultivation of medicinal plants, operating as de facto medicine cabinets that supply women with most of the resources they need to treat family illnesses. Results also suggest that the natural history of home gardens mirrors transformations within the family, and that Saraguro women study the contents of their neighbors' gardens, using this knowledge as a foundation for deciphering the owners' economic and health status. New threats to the sustainability of home gardens threaten the foundation of Saraguro's ethnomedical system and women's authority in the home and community.     

New Advances in Bone Research

An edited summary of an Interdepartmental Conference arranged by the Department of Medicine, UCLA School of Medicine, Los Angeles. William M. Pardridge, MD, Associate Professor of Medicine, is Director of Conferences.     

Challenges faced by research ethics committees in El Salvador: results from a focus group study

Objective:  To identify perceived barriers to capacity building for local research ethics oversight in El Salvador, and to set an agenda for international collaborative capacity building.
Methods:  Focus groups were formed in El Salvador which included 17 local clinical investigators and members of newly formed research ethics committees. Information about the proposed research was presented to participants during an international bioethics colloquium sponsored and organized by the St. Jude Children's Research Hospital in collaboration with the National Ethics Committee of El Salvador and the University of El Salvador. Interviews with the focus group participants were qualitatively analyzed.
Results:  Participants expressed the need to tailor the informed consent process and documentation to the local culture; for example, allowing family members to participate in decision-making, and employing shorter consent forms. Participants indicated that economic barriers often impede efforts in local capacity building. Participants valued international collaboration for mutual capacity building in research ethics oversight.
Conclusions:  Research ethics committees in El Salvador possess a basic knowledge of locally relevant ethical principles, though they need more training to optimize the application of bioethical principles and models to their particular contexts. Challenges increase the value of collaborative exchanges with ethics committee members in the United States. Further research on facilitating communication between host country and sponsor country ethics committees can maximize local research ethics expertise, and thus raise the standard of protecting human participants involved in international research.