ABSTRACT
OBJECTIVE: The objective of this research was to determine the effectiveness of antimicrobial photodynamic therapy (aPDT) in the removal of mycoplasmas from contaminated cells. BACKGROUND DATA: Mycoplasmas often contaminate cell cultures. The cell-contaminating mycoplasmas are removed by antibiotics, but the use of antibiotics usually induces antibiotic-resistant bacteria. aPDT is expected to be a possible alternative to antibiotic treatments for suppressing infections. MATERIALS AND METHODS: Mycoplasma salivarium (Ms)-infected human embryonic kidney (HEK) 293 cells were irradiated using a red light-emitting diode (LED) in the presence of methylene blue (MB) as a photosensitizer. The Ms viable count was determined using culture on agar plates or using a mycoplasma detection kit. RESULTS: aPDT performed using red LED irradiation was effective in decreasing live Ms in the presence of MB without damaging the HEK293 cells. aPDT removed live Ms from the infected cells after washing the cells with sterilized phosphate-buffered saline (PBS) to decrease the initial number of live Ms before aPDT. CONCLUSIONS: This study suggests that aPDT could remove mycoplasmas from contaminated cells.
Subject(s)
Mycoplasma salivarium/drug effects , Photochemotherapy , Apoptosis/drug effects , Cells, Cultured , HEK293 Cells , Humans , Methylene Blue/pharmacology , Photosensitizing Agents/pharmacologyABSTRACT
AIM: Light-emitting diodes have been investigated as new light activators for photodynamic therapy. We investigated the bactericidal effects of high-power, red light-emitting diodes on two periodontopathic bacteria in vitro. METHODS: A light-emitting diode (intensity: 1100 mW/cm(2) , peak wavelength: 650 nm) was used to irradiate a bacterial solution for either 10 or 20 s. Bacterial solutions (Porphyromonas gingivalis or Aggregatibacter actinomycetemcomitans) at a concentration of 2.5 × 10(6) c.f.u./mL were mixed with an equal volume of either methylene blue or toluidine blue O (0-20 µg/mL) and added to titer plate wells. The plate wells were irradiated with red light-emitting diode light from a distance of 22 or 40 mm. The contents were diluted, and 50 µL was smeared onto blood agar plates. After 1 week of culturing, bacterial c.f.u. were counted. RESULTS: The light-emitting diode energy density was estimated to be approximately 4 and 8 J/cm(2) after 10 and 20 s of irradiation, respectively. Red light-emitting diode irradiation for 10 s from a distance of 22 mm, combined with methylene blue at concentrations >10 µg/mL, completely killed Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans. CONCLUSION: High-power, red light-emitting diode irradiation with a low concentration of dye showed effective bactericidal effects against two periodontopathic bacteria.
Subject(s)
Aggregatibacter actinomycetemcomitans/drug effects , Disinfection/instrumentation , Lighting/instrumentation , Photochemotherapy/instrumentation , Porphyromonas gingivalis/drug effects , Aggregatibacter actinomycetemcomitans/radiation effects , Bacterial Load/drug effects , Bacterial Load/radiation effects , Bacteriological Techniques , Humans , Methylene Blue/pharmacology , Photosensitizing Agents/pharmacology , Porphyromonas gingivalis/radiation effects , Radiation Dosage , Time Factors , Tolonium Chloride/pharmacologyABSTRACT
An Er:YAG laser light delivery system composed of a polymer-coated silver hollow waveguide and a quartz sealing cap has been developed for calculus fragmentation. Sealing caps with various distal-end geometries were fabricated, and the focusing effects of these caps for Er:YAG laser light were measured both in air and in water. Owing to the high power capability of the quartz a beam of sealing caps, Er:YAG laser light with an output energy of 200 mJ and a repetition rate of 10 Hz was successfully transmitted in saline solution by use of the system. Calculus fragmentation experiments conducted in vitro showed that the delivery system is suitable for medical applications in lithotripsy. We also found that the cap with a focusing effect is more effective in cutting calculi. The deterioration of the sealing caps after calculus fragmentation is also discussed.
