Microbiome and Metagenome in Percutaneous Osseointegrated Prostheses (MMPOP)
Condition: Transfemoral Amputation
Study type: Observational

Summary: 
      The purpose of this study is to investigate the clinical implementation of a new percutaneous
      prosthetic attachment system by determining the resident microbial ecology of the implant
      exit site and to simultaneously study the systemic and local stomal immune responses. This
      study will follow 10 patients implanted with percutaneous osseointegrated prosthetics (POPs)
      for a period of one year. Two state-of-the-art, pre- and post-surgery bacterial monitoring
      technologies will be used; these procedures are intended to facilitate the early prediction,
      detection, and treatment of infection, as well as to provide follow-up data that can
      potentially be used to advantageously manipulate the stomal microbial environment in future
      clinical trials.

      Commensal skin bacteria colonize all stomas. Colonization does not necessarily result in
      infection. Over time, the presence of this skin penetrating foreign object (implant) will
      cause measurable changes in the bacterial population (microbiota) at and around the POP exit
      site. It is anticipated that the evolving microbiota, in concert with measurable changes in
      the local and systemic cytokine responses, will reveal patterns associated with
      mutualistic-commensal bacteria and/or pathogenic bacteria related to the stages of chronic
      wound healing. These patterns could be used to determine the presence of a stable uninfected
      stoma or the progression of a stomal infection. Hopefully, this information will allow timely
      intervention to prevent infection, i.e. by detecting early stages of infection or discerning
      common patterns of stable mutualistic-commensal bacterial strains, effective intervention
      protocols (antibiotics, probiotics or manipulation of the stomal and skin microbiota) may be
      developed to avoid patient morbidity and assure implant survival.
    

Detailed description: 
      Percutaneous osseointegrated prosthetic (POP) attachment (i.e., the direct skeletal
      attachment of artificial limbs) is a rapidly evolving technology. This follows over a decade
      of successful European trials that largely involved transfemoral amputees. This information
      together with the translational animal studies have made it possible to commence an Early
      Feasibility Device Exemption (IDE) Pilot Program under the direction of the Federal Drug
      Administration (FDA). Ten transfemoral amputees, selected from the Veteran and active
      military populations will receive a novel POP device. The objective of this study is to
      follow 10 patients implanted with a POP for a period of one year.

      All stomas are colonized by local skin bacteria; colonization does not necessarily result in
      infection. Over time, the presence of this skin penetrating foreign object (implant) will
      cause measurable changes in the bacterial population (microbiota) at and around the POP exit
      site.

      It is anticipated that the evolving microbiota, in concert with measurable changes in the
      local and systemic cytokine responses, will reveal patterns associated with
      mutualistic-commensal bacteria and/or pathogenic bacteria related to the stages of chronic
      wound healing. These patterns could be used to determine the presence of a stable uninfected
      stoma or the progression of a stomal infection. Hopefully, this information will allow timely
      intervention to prevent infection, i.e. by detecting early stages of infection or discerning
      common patterns of stable mutualistic-commensal bacterial strains, effective intervention
      protocols (antibiotics, probiotics or manipulation of the stomal and skin microbiota) may be
      developed to avoid patient morbidity and assure implant survival.

      The study aims will test the following:

      Aim 1: Determine and characterize the microbiota in the region surrounding the skin/implant
      interface. Sampling will take place over all stages of wound healing and stomal maturation
      and will begin with Stage 1 and Stage 2 surgeries, as well as at defined time points, and
      collection sites (i.e., the stoma, ipsilateral and contralateral thigh skin) for up to one
      year post surgery. This will be carried-out by using a specific swabbing technique to collect
      bacterial and fungal deoxyribonucleic acid (DNA) and to amplify and sequence bacterial 16
      Svedberg units ribosomal ribonucleic acid (16S rRNA) and fungal 18 Svedberg units ribosomal
      ribonucleic acid (18S rRNA) genes.

      AIM 2: Compare the expression patterns of the local and systemic inflammatory biomarkers over
      time and determine if there is a correlation with the microbiota pattern to diagnose the
      state of wound healing at the skin/implant interface and the systemic response to a
      potentially life-long chronic wound. The measurements of the pro-inflammatory cytokines,
      found in the stomal exudate (local biomarkers) and blood serum (systemic biomarkers), along
      with evolving microbiota profiles (Aim #1) will help to better characterize the homeostatic
      state of the stoma and subsequent optimum wound care therapies.

      The ability to predict infection and to avoid it without the use of antibiotics would be of
      great value to future clinical trials. Assuming the success of this feasibility pilot trial,
      it is anticipated that the trial will be expanded to include 200 patients.
    

Observational model: Cohort
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        10 transfemoral amputees selected from Veteran and active military populations
      
Biospecimen description: 
      Stomal and skin swab samples for bacterial 16S ribosomal RNA and fungal 18S ribosomal RNA.
      Blood samples to detect messenger ribonucleic acid (mRNA) of genes regulating production of
      immune proteins. Serous drainage from the stoma to determine wound healing cytokine
      expression.
    
Keywords: amputee