Cationic heme-mimetic gallium porphyrin kills bacteria and disrupts biofilms

Abstract

The emergence of antimicrobial resistance in ESKAPE pathogens remains a clinical challenge and limits the utility of conventional antibiotics. Antimicrobial photodynamic inactivation (aPDI) using metal porphyrins is of interest, but the activity of heme-mimetic gallium porphyrins against structured biofilms has not been well defined. In this study, we evaluated a newly synthesized cationic heme-mimetic gallium porphyrin (GaCHP-2-3) activated with visible light against biofilms formed by ESKAPE representatives under static and flow conditions and on titanium surface. Light-activated GaCHP-2-3 reduced biofilm viable counts by up to 4 log10 CFU/mL. Prolonged serial passaging of planktonic bacteria in the presence of GaCHP-2-3 for 20 passages did not yield increases in MIC, indicating no detectable resistance development under these conditions. This work presents GaCHP-2-3 aPDI as a candidate approach for biofilm control and treatment of infections where antibiotic resistance limits the option.