ANTIBACTERIAL PHOTODYNAMIC THERAPEUTIC STUDIES OF METALLATED PORPHYRIN AGAINST CHRONIC WOUND COLONISING BACTERIAL ISOLATES

Abstract

Wound infections have become life threatening as a result of treatment failures caused by multi-drug resistant pathogens. The search for newer compounds potent against antibiotic resistant bacteria associated with wounds is crucial. Hence this study investigated the application of antibacterial photodynamic therapy using meso tetra-(4-phenyl) porphyrin (TPP), metallated with zinc, tin and silver (ZnTPP, SnTPP and AgTPP), meso tetra-(4-sulphonatephenyl) porphyrin (TPPS) and the corresponding metallo meso tetra-(4-sulphonatephenyl) porphyrin (MTPPS) as photosensitizers. The in-vitro toxicity and photo-toxicity properties on four chronic wound colonizing multi-drug resistant bacterial strains: Staphylococcus aureus, Klebsiella sp., Proteus sp., and Escherichia coli were assessed using agar well diffusion method. Photo-toxicity of the compounds was investigated using 100 Watt tungsten lamp. Inhibitory activity of porphyrins tested against these bacterial strains showed Staphylococcus aureus to have both lowest (11±0.0 mm) and highest (33±1.1 mm) susceptibility to SnTPPS and ZnTPPS respectively. The sequence of data also showed appreciable improvement in the antimicrobial activities of five metalloporphyrins (SnTPP, AgTPP, ZnTPPS, SnTPPS and AgTPPS) exposed to light rays than when tested against bacterial strains in dark condition. ZnTPPS exhibited the best activity with improved photo-toxic activities against all bacterial strains (Staphylococcus aureus 33±1.1 mm, Klebsiella sp. 32±0.7 mm, Proteus sp. 28±0.7 mm and Escherichia coli 30±1.4 mm) examined in this study.