The application of antimicrobial photodynamic therapy on pseudomonas aeuroginosa and enterococcus fecalis using heperecin and methylene blue photosensitizers

Abstract

The spread of multi-resistant bacterial strains is a fundamental threat to the public health and increases mortality rates and health care costs.Given that the main reason for resistance in bacteria is over use and misuse of antibiotic compounds. the photodynamic therapy has been introduced as new way to deal with resistant infections. In this empirical in vitro study, the strain of Enterococcus faecalis and the strain of Pseudomonas aeruginosa were prepared as standard strains. Two photosynthesizers of Methylene blue and hypericin as well as solutions of Enterococcus faecalis, and Pseudomonas aeruginosa were tested in 96-well plates. The irradiation process was conducted in the sterilized condition in the darkness as follows: First, they were irradiated for 30, 60 and 120 seconds using laser diodes with a wavelength of 630 nm. None of the colonies of bacteries grew in the presence of hypericin with and without laser irradiation and after 48 hours of incubation. The number of the colonies counted from Enterococcus bacteria in the presence of methylene blue and the radiation rate of both 2.5 and 5 mm Watt lasers were zero after 48 hours of incubation. However, the number of the colonies counted from the Enterococcus faecalis was 36 CFU/mL in the case of exposure to methylene blue with the concentration of 25 ?g/mL and without laser irradiation. The results showed that hypericin with and without laser therapy property has a bactericidal property against both Enterococcus faecalis and Pseudomonas aeruginosa.. Moreover, the use of methylene blue at a concentration of 25 ?g/mL in the presence of 5 mm-watt laser, has a bactericidal property against Enterococcus faecalis, and reduces the number of Pseudomonas aeruginosa bacteria.