Influence of hydrogen peroxide or gold nanoparticles in protoporphyrin IX mediated antimicrobial photodynamic therapy on Staphylococcus aureus

Abstract

Antimicrobial photodynamic therapy (APDT) has been considered to treat skin diseases infected by drug resistant microorganisms. In this work, attempts were made to study the effectiveness of APDT with protoporphyrin IX (PPIX) in the presence of gold nanoparticles (GNPs) or hydrogen peroxide (H 2 O 2 ) against the human bacterial pathogen, Staphylococcus aureus. To photoactivate the PPIX, xenon light source was used at 626 nm. The bactericidal effect was analyzed by standard plate counting method. Attempts were also made to study whether fluorescence spectroscopy can be used to characterize the damage at protein level. Results of the study revealed that PPIX with H 2 O 2 has showed higher bactericidal effect than that of PPIX alone and PPIX with GNPs. From fluorescence spectroscopic characterization it was found that protein damage is one of the reasons of bactericidal effect as there is a considerable change in the intensity of emission and fluorescence lifetime of tryptophan present in the microorganism between pre and post APDT.

Raman spectroscopy for the characterization of antimicrobial photodynamic therapy against Staphylococcus epidermidis

“…The increase in antibiotic resistance among different classes of gram‐positive and gram‐negative bacteria has led to research for substitute antimicrobial therapies. Many reports showed that antibiotic resistant pathogenic bacteria can be inactivated successfully with photodynamic therapy (PDT), which is known as antimicrobial photodynamic therapy (APDT) …”

“…Although PDT has been used for treatment of certain cancers, it is also considered for the treatment of some oral diseases such as root canal infections and oral candidiasis. Some applications of PDT at a less developed stage include treatments for arthritis, restenosis, psoriasis, Barretts's esophagus, and atherosclerosis . In addition, PDT is being used in dermatology for a broadrange of neoplastic, inflammatory, and infectious cutaneous conditions …”

In vitro Photodynamic Antimicrobial Activity of Protoporphyrin IX in the Presence of Hydrogen Peroxide against Staphylococcus aureus and Pseudomonas aeruginosa

“…The overall fluorescence from post-treated S.aureus and P. aeruginosa exhibited a significant reduction (P<0.005) in the intensity. The emission peak at 340 nm is attributed to the key amino acid, tryptophan which is present in the bacteria[43]. From the inset of Figs.…”