Abstract
Purpose :
To evaluate the temporal effectiveness of photodynamic antimicrobial chemotherapy (PACT) on Pseudomonas aeruginosa (P. aeruginosa).
Methods :
PACT with porphyrin derivative (TONS504; Porphyrin Lab, Okayama, Japan) and a light-emitting diode (LED) device (CCS, Kyoto, Japan) that delivers light at a single wavelength (660nm) was applied onto 106 colony forming unit of P. aeruginosa in vitro. P. aeruginosa was exposed to TONS504 at concentration of 10µg/mL, irradiated at light energy of 30J/cm2, and cultured at 30°C. Bacterial viability was evaluated at 0 min, 30 min, 1 h, 3 h, 6 h, 9 h, 12 h and 24 h after LED irradiation by observation of colony formation after 36 hours incubation on agar plates. Furthermore, the second LED irradiation was performed three hours after the initial LED irradiation and was observed colony formation after 36 hours incubation on agar plates.
Results :
In single LED irradiation, the bacterial growth was inhibited remarkably after 3 to 9 hours of LED exposure. The maximum inhibition effect was shown after 3 hours. Furthermore, after the second LED radiation, the inhibition effect of the bacterial growth was higher and its effect was extended for longer time.
Conclusions :
The inhibitory effect of bacterial growth by PACT on P. aeruginosa appears in a time-dependent manner. Furthermore, an additional LED exposure has also highly inhibitory effect on bacterial growth. This result may help us to achieve in vivo application in infectious keratitis.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.