An efficient formulation based on cationic porphyrins to photoinactivate Staphylococcus aureus and Escherichia coli

Antibiotic resistance is an increasingly serious worldwide problem that needs to be addressed with alternative tools. Antimicrobial photodynamic therapy seems a promising approach but in some cases the synthesis of highly efficient photosensitizers requires laborious processes burdened by extensive chromatographic purifications. In this study, we evaluate the suitability of a formulation (Form-1) containing porphyrins bearing different charges, obtained during the synthesis of the highly efficient photosensitizer 5,10,15-tris(1-methylpyridinium-4-yl)-20-(pentafluorophenyl)porphyrin tri-iodide.

Form-1 was equally effective in the photoinactivation of Escherichia coli and Staphylococcus aureus (reductions >5 log) as the best stand-alone photosensitizer.

The effective reduction of bacteria with Form-1 provided promising indications supporting its use, leading to a substantial decrease in costs and production time.