J Korean Acad Oral Health.  2014 Dec;38(4):227-231. 10.11149/jkaoh.2014.38.4.227.

Photodynamic bactericidal effect against Enterococcus faecalis by erythrosine concentration and LED irradiation times

Affiliations
  • 1Department of Oral Microbiology, College of Dentistry, Gangneung-Wonju National University, Gangneung, Korea.
  • 2Department of Preventive and Public Health Dentistry, College of Dentistry, Gangneung-Wonju National University, Gangneung, Korea. mads@gwnu.ac.kr
  • 3Research Institute of Oral Science, Gangneung-Wonju National University, Gangneung, Korea.

Abstract

OBJECTIVES: The purpose
of this study was to provide photodynamic bactericidal effect against Enterococcus faecalis by erythrosine concentrations and LED irradiation times.
METHODS
Erythrosine was used as a photosensitizer and green LED (3 Watt, 520-530 nm) was used as light source. E. faecalis ATCC 1943 and E. faecalis ATCC 29212 were used in this study. Approximately 10(5) CFU of bacteria were added in wells of a 96-well microtitration plate. For examining the effects of concentrations of erythrosine, 0, 0.625, 1.25, 2.5, 5, and 10 microM of erythrosine were added in wells containing bacteria. The irradiation time with LED was 30 sec. In another set of experiment, the effect of irradiation time for killing of bacteria was investigated by increasing irradiation time from 0 to 30 s with 10 microM of erythrosine final concentration. After irradiation, each sample was serially diluted with PBS and 50 microl of diluents was spread on duplicate blood agar plates. The plates were incubated for 72 h at 37degrees C under aerobic conditions and the number of CFU was determined. The experiments were repeated four times. The results were analyzed using one-way ANOVA, and Tukey's multiple comparison at a significance level of 0.05.
RESULTS
When the erythrosine concentrations were more than 2.5 microM, E. faecalis ATCC 29212 was significantly decreased (P<0.05). The more erythrosine concentrations increased, the more E. faecalis ATCC 1943 decreased statistically significantly (P<0.05). In another set of experiment, when LED irradiation time was more than 20 s, E. faecalis ATCC 1943 decreased significantly (P<0.05), and if the irradiation times was more than 5 s, E. faecalis ATCC 29212 decreased significantly (P<0.05).
CONCLUSIONS
PDT using erythrosine and green LED was found to be an effective method in killing E. faecalis.

Keyword

Enterococcus faecalis; Erythrosine; LED; Photodynamic therapy
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