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Updated: May 31, 2025
An In Vitro Approach to Photodynamic Therapy
Published on: August 17, 2018
Photodynamic Therapy with Protoporphyrin IX Precursors Using Artificial Daylight Improves Skin Antisepsis for
Tiziano A Schweizer1, Julia S Würmli1, Julia Prinz1
1Department of Dermatology, University Hospital Zurich, University of Zurich, 8091 Zurich, Switzerland.
Abstract:
Classical preoperative skin antisepsis is insufficient in completely eliminating bacterial skin colonization for arthroplasty. In contrast, photodynamic therapy (PDT) with red light and methyl-aminolevulinate (MAL), combined with skin antisepsis, led to the absence of bacterial growth in healthy participants, though with local skin erythema, posing an obstacle for orthopedic surgery. Therefore, we explored whether artificial daylight PDT (PDT-DL) was superior to red light. Twenty healthy participants were allocated to either 5-aminolevulinic acid-(5-ALA) PDT-DL (n = 10) or MAL-PDT-DL (n = 10) before antisepsis with povidone-iodine/alcohol. Skin swabs from the groin were taken to cultivate bacteria at baseline, after PDT-DL, and after the subsequent antisepsis. Additional swabs were taken on day 4 before and after antisepsis without PDT. The contralateral groin of each participant and of ten additional healthy volunteers served as the control (n = 30). In selected participants, 16S rRNA-based amplicon deep sequencing was performed. All participants showed a baseline bacterial colonization. After a PDT-DL with skin antisepsis, bacterial growth occurred in three (30%) and in one (10%) participants with 5-ALA and MAL, respectively, compared to the sixteen (55%) participants in the control group. On day 4, three (30%) participants per group showed positive cultures post antisepsis. Adverse effects were reported in six (60%) and zero (0%) participants for 5-ALA- and MAL-PDT-DL, respectively. The skin bacteriome changes correlated with the bacterial culture results. The MAL-PDT-DL with skin antisepsis significantly increased bacterial reduction on the skin without adverse effects. This offers an opportunity to prevent infections in arthroplasty patients and reduce antibiotic use, thus contributing to antibiotic stewardship goals emphasized in the One Health approach.
Insights
Methyl-aminolevulinate-photodynamic daylight therapy (MAL-PDT-DL) combined with skin antisepsis effectively reduces skin bacteria before surgery. This approach offers a promising strategy for preventing arthroplasty infections and supporting antibiotic stewardship.
Area of Science:
- Photodynamic Therapy
- Dermatology
- Microbiology
- Orthopedic Surgery
Background:
- Standard preoperative skin antisepsis is insufficient for eliminating bacterial colonization in arthroplasty patients.
- Photodynamic therapy (PDT) with red light and methyl-aminolevulinate (MAL) reduces bacteria but causes skin erythema, hindering orthopedic procedures.
- Investigating artificial daylight PDT (PDT-DL) as a potentially superior alternative to red light PDT.
Purpose of the Study:
- To compare the efficacy of 5-aminolevulinic acid (5-ALA) PDT-DL versus MAL-PDT-DL in reducing skin bacterial colonization before antisepsis.
- To evaluate the safety and adverse effects of both PDT-DL protocols.
- To assess the impact of PDT-DL on the skin bacteriome and its correlation with bacterial culture results.
Main Methods:
- Twenty healthy participants received either 5-ALA-PDT-DL or MAL-PDT-DL, followed by povidone-iodine/alcohol antisepsis.
- Skin swabs were collected at baseline, post-PDT-DL, and post-antisepsis for bacterial culture.
- 16S rRNA-based amplicon deep sequencing was performed on selected samples to analyze the skin microbiome.
Main Results:
- MAL-PDT-DL combined with antisepsis resulted in significantly greater bacterial reduction compared to 5-ALA-PDT-DL and the control group.
- No adverse effects were reported with MAL-PDT-DL, whereas 60% of participants experienced adverse effects with 5-ALA-PDT-DL.
- Skin bacteriome changes correlated with bacterial culture findings, indicating PDT-DL's impact on microbial composition.
Conclusions:
- MAL-PDT-DL, when combined with standard skin antisepsis, significantly enhances bacterial reduction on the skin without adverse effects.
- This method presents a viable strategy for preventing surgical site infections in arthroplasty.
- The findings support the integration of MAL-PDT-DL into surgical protocols to improve patient outcomes and contribute to antibiotic stewardship within the One Health framework.
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