Comparative screening of porphyrins and chitosan-porphyrin composites as potential antibacterial photodynamic inactivation photosensitizers against multidrug-resistant ESKAPE pathogens

The increasing prevalence of MDR-ESKAPE pathogens, due to their resistance to conventional antibiotics, has become a serious challenge; thus, a need to explore the potential of chitosan-porphyrin composites as an alternative biomedical material. In this study, different porphyrin derivatives, including TPP, THPP, TMePP, TPPS, TCPP, and TMPyP, their metallated (Ag, Zn, and Sn) series, and chitosan-modified derivatives were evaluated for antibacterial photodynamic inactivation (aPDI) activities against some MDR bacterial pathogens under visible light irradiation using the agar well diffusion method. These MDR pathogens include Pseudomonas aeruginosa ( P. aeruginosa ), Acinetobacter baumannii ( A. baumannii ), Klebsiella pneumoniae ( K. pneumoniae ), Enterococcus faecium ( E. faecium ), and Staphylococcus aureus ( S. aureus ). In our results, the metallated derivatives AgTCPP, SnTHPP, and SnTMPyP showed strong aPDI activity against Gram-negative bacteria ( P. aeruginosa , A. baumannii , K. pneumoniae ). Also, AgTMPyP, SnTMPyP, and ZnTCPP inhibited E. faecium and S. aureus . For the CPCs, several CPCs exhibited antibacterial activity against P. aeruginosa 1 (C-AgTHPP, C-AgTMePP), P. aeruginosa 2 (C-AgTMePP, C-AgTMPyP), A. baumannii (C-ZnTHPP, C-SnTHPP, C-AgTMePP, C-ZnTPPS), K. pneumoniae (C-AgTHPP, C-ZnTHPP, C-AgTMePP), E. faecium (C-ZnTHPP, C-AgTMePP), and S. aureus (C-AgTPP, C-AgTMePP, C-ZnTPPS, C-AgTMPyP). Among the CPCs, C-AgTMePP and C-AgTMPyP demonstrated extended antibacterial activity against all test isolates. This comprehensive in vitro screening suggests the potential of CPCs as an aPDI agent against MDR-ESKAPE pathogens. Their clinical applications may offer an alternative therapeutic route to reducing the global threat of antimicrobial resistance.