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Microbiome Around A Percutaneous Osseointegrated Prosthesis

其他書名	A Longitudinal Prospective Study
出版	Morressier, 2017
URL	http://books.google.com.hk/books?id=SnCyzQEACAAJ&hl=&source=gbs_api

註釋INTRODUCTION: The benefits of percutaneous osseointegrated skeletally docked artificial limbs (POSD) are well recognized in multiple European trials. These systems differ in implant design, device materials, surface methods of osseointegration, means of skin attachment, surgical techniques, time to full ambulation, modes of mechanical failure, aseptic loosening, and stress shielded bone resorption. These systems, however, share a single commonality in that they all require an opening in the skin, the stoma, through which an artificial limb is connected to the appendicular skeleton. Any permanent percutaneous interface is at risk of superficial or deep infection from the bacterial populations normally colonizing the stoma. Clinical reports indicate that most of these devices become infected one or more times during their lifetime, and these infections are usually superficial and readily treated with the appropriate oral antibiotics. Bacteria that are native to the surrounding skin and external environment unavoidably colonize all stomas, and this colonizing microbiota can change over time. Fortunately, colonization does not always induce infection, and commensal and mutualistic skin bacteria likely provide some protection against catastrophic infection. Whether or not the stoma becomes infected depends upon a mechanically and/or biologically stable seal between the skin and the exiting device. Ideally, the interface should be impervious to the entrance of pathogenic bacteria into the subcutaneous soft tissues and prevent further penetration into the more vulnerable bone implant interface. If there is a failure of osseointegration or surgical technique and the device is loose in the medullary canal, motion at the interface uniformly allows infection to rapidly intervene in both the experimental and clinical situation. Device removal is necessary to cure the infection. The ultimate question is why some stomata become infected while others do not. The answer might be found in the bacterial ecology of the patient and the stomal site. To test this theory, a longitudinal study of 10 transfemoral amputees implanted with POSD devices was undertaken with the intent to determine the changes in the microbiome over the year following primary implantation. METHODS: In an FDA approved EFS Trial (NCT 02720159), and adhering to a joint University of Utah/Veterans Administration approved Institutional Review Board (IRB), the Utah POSD device (manufacturer of record, DJO-Surgical, Austin, TX) was implanted in 10 Veterans Administration patients with unilateral transfemoral amputations. The implant, made of grit-blasted medical grade Titanium (Ti) alloy with the distal 3 cm coated with a porous Ti surface, caps the end of the transected femur and is connected via Morse tapers and a ceramic (titanium oxynitride) coated cylinder to a Ferrier-coupler, to which, the prosthetic limb is attached. Six to eight weeks later, a second surgery establishes a shallow stoma and docking of the patientu2019s own artificial limb. The evolution of each patientu2019s skin and stomal flora was determined from the initial surgery to 1 year following the second stage. During each follow-up visit, three swab samplesstomal, ipsilaterial thigh and contralateral thighwere obtained. DNA was extracted from swabs, and bacterial 16S ribosomal RNA (rRNA) genes were amplified with primers to variable regions 1-3 and sequenced using the Illumina MiSeq platform with 2x300 bp chemistry. Sequences were processed using the HmmUFOtu workflow and the following R packages: vegan, DESeq2, phyloseq. RESULTS: Figure 1 shows Shannon Diversity Index (a), non-metric multidimensional scaling of Bray-Curtis dissimilarities (b) and principal component analysis (c) and (d), which shows diversity differences between the stomal bacterial ecology and the surrounding tissues. Most importantly, Figure 2 shows that Staphylococcus aureus is significantly more abundant in the stoma. Figure 3 depicts the relative abundances of bacterial taxa within the stomal environment and skin flora of the same thigh. DISCUSSION: Each patient served as their own control and there was significant variability in microbial speciation in each individual patient and the 10-patient group over the 12 months following the second surgery. There were, however, some commonalities found within these 10 patients. It is known that high values of Shannon Diversity Index would be representative of more diverse communities and a community with only a few species would have a value close to zero. Thus, the Shannon Diversity Index value allows us to know not only the number of species, but also how the abundance of the species is distributed among all the species in the community. Overall, the Shannon index data showed that the stomal bacterial community is distinct and diverse from the surrounding skin communities, and also, it takes approximately 12 months for the bacterial ecology to approach an equilibrium in each patient and in the patient group. Bray-Curtis dissimilarities index and principal component analyses (Figure 1) indicated that differences in community composition were statistically significant between skin and stomal sites when testing Bray-Curtis distances (P