The antibacterial activity of photodynamic agents against multidrug resistant bacteria causing wound infection

Critical colonization or infection of wound are a widespread problem. In addition to delaying tissue healing, infection also progresses to deep tissues leading to the development of serious complications such as osteomyelitis, bacteremia, and sepsis. In this study, it was aimed to investigate the antibacterial activity of photodynamic agents against multidrug-resistant (MDR) bacteria which affect wound infection. MDR clinical isolates of methicillin-resistant S.aureus (MRSA), P.aeruginosa, E. coli, A.baumannii and K.pneumoniae were used in the study. In the research, novel cationic porphyrin derivatives (CPD) named PM, PE, PPN and PPL as photosensitizer which are synthesized by us and not included in the literature; a diode laser with a computer controlled 655-nm wavelength output power of 41.5 mW as the light source were used. In the study, aPDT experiments with combinations of the different concentrations CPD (3,125-650 μM) and different energy doses (25-150 J/cm2) a survival reduction of up to ≥99.9999 values in each MDR clinical isolate was detected. In the study has been determined that the efficacy of photoinactivation parallel to the increase in energy dose increased and the best effect is seen at the energy dose of 150 J/cm2. The best antimicrobial effect against MDR clinical isolates was seen in the aPDTs using PPL, while the lowest antimicrobial activity of the photosensitizer derivative was found to be PM. In our study, aPDT performed with CPD derivatives at concentrations below the minimum inhibitory concentration (MIC) values have the potential to show a strong antimicrobial activity against MDR wound infection agents. It is recommended in this study, further investigation is needed to investigate the differences in the susceptibility of MDR isolates according to type of CPD, and in vivo conditions of the toxicity on living cells of the aPDT parameters showing maximal antimicrobial effect. Keywords: Wound infections; multidrug resistant; antimicrobial photodynamic therapy; cationic porphyrin derivatives