CHL‑Fe PDT Shows Bactericidal Activity Against Drug‑Resistant C. acnes

Sodium iron chlorophyllin (CHL‑Fe) plus red-light CHL‑Fe photodynamic therapy demonstrated preclinical bactericidal activity against drug-resistant Cutibacterium acnes in laboratory testing. It highlights the dosing and red-light fluence conditions used for the in vitro work and presents the finding as preclinical rather than as a clinical outcome narrative.

In the experimental context described, the investigators tested the approach against 10 C. acnes strains spanning diverse antibiotic-resistance profiles, including pan-, extensively, multi-, and single-drug resistance, derived from patients with mild to severe acne vulgaris. Under the reported “optimal efficacy” conditions, the research cites bactericidal reductions of >3 log₁₀ CFU/mL using a fixed CHL‑Fe dose of 7.5 mg/dL combined with red light delivered at 3.5 J/cm². The research frames these observations as strain-spanning bactericidal activity achieved under a defined photosensitizer-and-light regimen.

The bactericidal effect was dependent on combining the photosensitizer with illumination. CHL‑Fe alone or red light exposure alone did not produce comparable bactericidal activity to the paired condition. Photodynamic therapy is presented in straightforward terms—CHL‑Fe as the photosensitizer and red light as the activating illumination—without additional mechanistic claims.

In interpretation, the authors characterized CHL‑Fe PDT as a potential nonantibiotic approach and situates it in the setting of drug‑resistant Cutibacterium acnes. They also note proposed applications beyond acne treatment itself, including eradicating C. acnes colonization and helping prevent infections in surgical and implant-related contexts.

Key Takeaways:

• Recent research describes in vitro bactericidal activity of CHL‑Fe PDT across multiple C. acnes strains with diverse antibiotic-resistance profiles.
• Activity was tied to a specific CHL‑Fe dose and red-light fluence, and the bactericidal effect was not comparable with CHL‑Fe alone or red light alone.
• The authors’ interpretation is presented as a potential nonantibiotic strategy with proposed applications that include colonization eradication and surgical/implant infection prevention.