Curcumin-mediated antimicrobial photodynamic therapy for inactivating Mycobacterium abscessus: a promising approach for non-tuberculous mycobacterial skin infections

Non-tuberculous mycobacterial skin infection lead to complex and lengthy treatment cycles. Antimicrobial photodynamic therapy (aPDT) is an emerging promising approach for treating infections. This study aims to assess the effects of aPDT using curcumin as a photosensitizer (PS) on non-tuberculous mycobacteria, Mycobacterium abscessus, a subtype that has become common in dermatology in recent years. The antimicrobial efficacy of curcumin-mediated aPDT against M.abscessus ATCC19977 was evaluated using the colony-forming unit (CFU) assay. Reactive oxygen species (ROS) production and cell membrane integrity were assessed using H₂DCFDA and propidium iodide staining, respectively. Cellular damage was further examined through transmission electron microscopy (TEM). Curcumin-mediated aPDT showed significant antimicrobial effects on M.abscessus in a concentration- and light-dose-dependent manner. Complete inactivation of M.abscessus was achieved with 100 μM curcumin and 48 J cm^-2 light exposure. ROS levels and cell membrane damage increased with higher curcumin concentrations, with fluorescence intensities of ROS and damaged cells increasing by 5.32 and 9.53 times, respectively, compared to untreated controls. TEM confirmed extensive cell wall and cytoplasmic damage in treated cells. This study demonstrates that M.abscessus could be effectively inactivated by curcumin in the presence of light. Therefore, curcumin-mediated aPDT shows promise as a treatment for M.abscessus.