Exploiting endogenous Protoporphyrin IX for Photodynamic inactivation of Pseudomonas aeruginosa
摘要
Pseudomonas aeruginosa is a common cause of wound and soft tissue infection related to surgical sites. The formation of biofilms by this bacterium results in increasing resistance against conventional antibiotics and causes delayed recovery and prolonged hospital stays. This issue has driven interest toward alternate therapies; among them antimicrobial photodynamic therapy is gaining concern. In this research article, five absorption bands 405, 505, 542, 580 and 631 nm of Protoporphyrin IX (PpIX), an endogenously produced photosensitizer along pathway of heme synthesis inside Pseudomonas aeruginosa (PA), has been exploited to produce antimicrobial photodynamic effect for its inactivation. This was achieved by exciting PpIX through five excitation wavelengths emitting from three LEDs emitted at 418, 522 and 630 and two laser diodes with emission bands at 405 and 635 nm. Fluorescence spectroscopy and Plate count method have been employed for the assessment of inactivation rate of PA as a function of light doses at corresponding wavelengths. Experimental results illustrated that blue LED (FWHM ~ 16.9 nm) centered at 418 nm produces most prominent antimicrobial photodynamic effect, followed by green LED at 522 nm (FWHM ~ 68 nm), red LED at 630 nm (FWHM ~ 72 nm), blue laser diode at 405 nm (FWHM ~ 1.9 nm) and red laser diode at 635 nm (FWHM ~ 2 nm). The reason behind these observations might be the overlapping of emission bands of light sources with the absorption bands of PpIX. In conclusion, it was found that the development of a light source, of whom emission bands completely overlap the absorption bands of PpIX, might come up with an efficient modality for the disinfection of wounds infected by multidrug-resistant strain of Pseudomonas aeruginosa.