Nanomolar effective report of tetra-cationic silver(II) porphyrins against non-tuberculous mycobacteria in antimicrobial photodynamic approaches

We report the photoinactivation evaluation of Ag(II) porphyrins (cationic AgTMeP and anionic AgTPPS) in the antimicrobial photodynamic therapy (aPDT) of rapidly growing mycobacterial strains. The aPDT assays in the Mycolicibacterium fortuitum, Mycobacteroides abscessus subs. abscessus, Mycobacteroides abscessus subsp. massiliense, and Mycolicibacterium smegmatis strains conducted without aggregating photosensitizers (PS) under irradiation for 90 min (270 J/cm(2)) showed that the most effective PS (nanomolar range) significantly reduced the concentration of viable mycobacteria. Structural damage on the Mycolicibacterium smegmatis non-pathogenic model was observed using atomic force microscopy, revealing that Ag(II)-porphyrin induced extensive changes in its electrical and adhesive forces, demonstrating changes in topography that may be linked to the action of different fractions of reactive oxygen species. The results presented in this paper provide solid evidence for using cationic porphyrin AgTMeP as an alternative to the conventional treatment of cutaneous mycobacteriosis and the disinfection of prosthetic devices and hospital equipment.

Automated summary

In this study, the photoinactivation evaluation of Ag(II) porphyrins in the antimicrobial photodynamic therapy of rapidly growing mycobacterial strains was reported. The results showed that Ag(II) porphyrins significantly reduced the concentration of viable mycobacteria and induced potential structural damage.