Effect of Photodynamic Therapy on Skin Microbiome. Single Center Study (PHOMIC-II)
Condition: Postoperative Wound Infection Deep Incisional Surgical Site; Prosthesis and Implants; Surgical Site Infection; Prosthetic Joint Infection
MeSH terms: Infections; Communicable Diseases; Surgical Wound Infection; Wound Infection
Study type: Interventional

Summary: 
      The overarching aim of this research project is to prevent orthopedic implant-associated
      infections. This study aims to investigate if PDT has an effect on bacterial skin
      colonization in order to improve skin antisepsis strategies for the prevention of surgical
      site infections.
    

Detailed description: 
      Background: Periprosthetic joint infections are a feared complication after orthopedic
      surgery in particular in our increasing elderly population. These infections are usually
      difficult to treat, because microorganisms persist in biofilms on the orthopedic implant
      surface. Therefore, it would be desirable to prevent these infections. It is hypothesized
      that bacteria from the skin surface or dermis - such as Staphylococcus aureus,
      coagulase-negative staphylococci, or Cutibacterium sp. - are transmitted into the periimplant
      tissue during surgery. In an ongoing interdisciplinary study with the Orthopedic University
      Hospital Balgrist (data in preparation for publication), the investigators see that common
      skin antisepsis preparation is not effective to eliminate skin bacteria before surgery
      because they persist in sebaceous or sweat glands. Photodynamic therapy (PDT) has recently
      gained attention in the treatment of acne, a disease of the pilosebaceous unit, in which also
      Cutibacterium acnes is implicated. The PDT works here on the one hand through a long-lasting
      destruction of the sebaceous glands, and on the other hand due to anti-inflammatory and
      antimicrobial effects.

      In a previous pilot study, the investigators tested if skin antisepsis is improved with
      previous PDT with the photosensitizer-inducing prodrug 5% topical methyl aminolevulinate
      (MAL) on inguinal skin in 10 participants. The induced photosensitizer was protoporphyrin IX
      (Pp IX, 635 nm) activated by red light. The investigators showed a complete sterilization of
      colonizing skin bacteria at the same day after this treatment However, orthopedic surgeons
      are hesitant to perform an arthroplasty surgery after such a treatment due to skin erythema
      for a few days.

      The investigators are entirely convinced about this novel prevention concept but need to
      identify the photosensitizer with the ideal balance of antibactericidal effect versus skin
      irritation. Building upon the data they gathered, they will explore PDT with the
      Protoporphyrin IX inducing prodrug photosensitizer MAL and the photosensitizer Methylene blue
      with potentially less local side-effects (skin erythema).

      Primary outcome:

      Effect of photodynamic treatment with the photosensitizers Pp IX (MAL) and Methylene blue in
      combination with surgical antisepsis on bacterial skin colonization on the day of application
      and on day 1, 3, and 5 after PDT.

      Secondary outcome:

      Effect of PDT on the skin microbiome using molecular techniques.
    

Intervention name(s): Photodynamic Therapy
Intervention type(s): Other
Intervention description(s): PDT with two different photosensitizers
Allocation: Non-Randomized
Intervention model: Parallel Assignment
Intervention model description: Intervention group with PDT
Arm A will receive the photosensitizer MAL
Arm B will receive Methylene blue as photosensitizer for the PDT.
Masking: None (Open Label)
Primary purpose: Other