A Small Amount of Singlet Oxygen Generated via Excited Methylene Blue by Photodynamic Therapy Induces the Sterilization of Enterococcus faecalis

Komine, Chiaki; Tsujimoto, Yasuhisa

doi:10.1016/j.joen.2012.11.051

Cited by 61 publications

(36 citation statements)

References 38 publications

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“…Absorption of the light triggers excitation of the photosensitizer that immediately produces highly reactive singlet oxygen or creates secondary reactive oxygen species (ROS) in presence of oxygen. There is evidence showing that ROS kill bacteria by damaging bacterial cell wall, membrane proteins and nucleic acids [4].…”

Section: Introductionmentioning

confidence: 99%

Repeated exposures to blue light-activated eosin Y enhance inactivation of E. faecalis biofilms, in vitro

Marinic

Manoil

Filieri

et al. 2015

Photodiagnosis and Photodynamic Therapy

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Background: In dentistry, antibacterial photodynamic therapy (a-PDT) has shown promising results for inactivating bacterial biofilms causing carious, endodontic and periodontal diseases. In the current study, we assessed the ability of eosin Y exposed to 3 irradiation protocols at inactivating Enterococcus faecalis biofilms, in vitro. Methods: E. faecalis biofilms formed on hydroxyapatite disks were incubated with eosin Y (10-80 M), then activated with blue light using different irradiation protocols. Biofilms exposed to continuous exposure were incubated for 40 min before being light-activated for 960 s. For the intermittent exposure, biofilms were exposed 4 times to the light/photosensitizer combination (960 s total) without renewing the photosensitizer. For repeated a-PDT, the same light dose was delivered in a series of 4 irradiation periods separated by dark periods; fresh photosensitizer was added between each light irradiation. After treatment, bacteria were immediately labeled with LIVE/DEAD BacLight Bacterial Viability kit and viability was assessed by flow cytometry (FCM). Results were statistically analyzed using one-way ANOVA and Tukey multiple comparison intervals (˛= 0.05). * Corresponding author. Results:The viability of E. faecalis biofilms exposed to 10 M eosin Y, was significantly reduced compared to controls (light only-eosin Y only). After a second exposure to blue light-activated eosin Y, viability significantly decreased from 58% to 12% whereas 6.5% of the bacterial biofilm remained live after a third exposure (p < 0.05). Only 3.5% of the bacterial population survived after the fourth exposure. Conclusions:The results of this study indicate that blue light-activated eosin Y can photoinactivate E. faecalis biofilms grown on hydroxyapatite disks. Also, repeated exposures to blue light-activated eosin Y were shown to significantly improve efficacy. Further studies seem warranted to optimize the antibacterial activity of blue light-activated eosin Y on major oral pathogens.

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Section: Introductionmentioning

confidence: 99%

Repeated exposures to blue light-activated eosin Y enhance inactivation of E. faecalis biofilms, in vitro

Marinic

Manoil

Filieri

et al. 2015

Photodiagnosis and Photodynamic Therapy

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“…It is a standard treatment option to eliminate microorganisms involved in periodontal and endodontic infection (7,11,13). Studies show that an effective PDT requires the modification of its parameters including PS and irradiation parameters (14). On the other hand, ICG was proposed as PS for its NIR wavelength absorbance at about 800 nm, considering the optical efficacy of laser at NIR wavelength (810 nm) to reduce the E. faecalis count in the RCS (32).…”

Section: Discussionmentioning

confidence: 99%

“…Numerous studies showed that the above methods only render 50% -70% of the infected canals free of microorganisms, depending on which method is used (11,12); therefore, a large number of teeth require retreatment and/or periradicular surgery to successfully treat persistent infections (11). Hence, new disinfection methods and standard endodontic antimicrobial procedures should be developed to increase the success rate of endodontic therapy (11,13) and preserve, and if possible enhance, the dentin chemical/mechanical stability through selective bactericidal properties (14). Photodynamic therapy (PDT) in combination with organic nanomaterials is a promising method to achieve such goals (8,11,15,16).…”

Section: Introductionmentioning

confidence: 99%

Improve ICG Based Photodynamic Properties Through Conjugation of ICG Into Nano-Graphene Oxide Against Enterococcus faecalis

Akbari¹,

Pourhajibagher²,

Chiniforush³

et al. 2018

Avicenna J Clin Microbiol Infect

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Background: Nowadays, a new technique such as photodynamic therapy (PDT) is used to achieve effective root canal disinfection and eliminate Enterococcus faecalis as the most prevalent species associated with secondary endodontic infections and treatment failures. Employment of an optimized nontoxic photosensitizer (PS) such as indocyanine green (ICG) is a crucial part of this technique; the current study aimed at improving ICG photodynamic properties through conjugation of ICG into nano-graphene oxide (nGO) as a new PS, to evaluate the antimicrobial effects of nGO/ICG against E. faecalis. Methods:The nGO was synthesized based on the modified Hummer method and then, direct loading of ICG onto its surface. The nGO formation was evaluated using the scanning electron microscope (SEM). The antimicrobial effect of nGO/ICG-PDT against E. faecalis was assessed by counting colony forming units (CFUs). Results and Conclusion:The SEM analysis confirmed successful synthesis of nGO. The nGO/ICG-PDT at an incorporated concentration of 400 µg/mL ICG with irradiation at an energy density of 31.2 J/cm 2 showed significant reduction in the number of E. faecalis higher than PDT based on ICG (1000 µg/mL) (P < 0.05). Since nGO-ICG-PDT showed a significant reduction in the count of E. faecalis at low concentration of ICG (400 µg/mL), it could be proposed as a new approach to treat endodontic infections, alone or in combination with conventional root canal treatment.

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“…Komine and Tsujimoto [47] correlated the amount of singlet oxygen generated by different concentrations of activated methylene blue during PDT with the bactericidal effect against E. faecalis cells. They concluded that methylene blue at a concentration of 0.01%, when activated by diode laser with a wavelength of 660 nm and 200 mW of power, was able to generate the greatest amount of singlet oxygen that consequently resulted in a reduction of 3 to 4 log 10 in the number of CFU cells.…”

Section: Discussionmentioning

confidence: 99%

Enterococcus faecium and Enterococcus faecalis in endodontic infections: antibiotic resistance profile and susceptibility to photodynamic therapy

et al. 2017

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Introduction Enterococcus faecium has become an important microorganism in nosocomial infections with great ability to acquire antibiotic resistance. However, little is known about their presence on the oral cavity. Therefore, our objective was to verify the presence of E. faecium and E. faecalis in endodontic infections and compare their susceptibility to conventional antibiotics and photodynamic therapy. Methods We performed 38 collections from the root canals of different patients. Positive Enterococcus agar samples were submitted to phenotypic and genotypic testing for speciesspecific confirmation. The isolates identified as E. faecium and E. faecalis were tested for susceptibility to antibiotics by the E-test method. After that, the isolates were evaluated for susceptibility to photodynamic therapy (PDT) using methylene blue and gallium arsenide aluminum laser with a wavelength of 660 nm and fluence of 39.5 J/cm 2 (energy of 15 J and time of 428 s).Results Cultures positive for E. faecalis were found in 22 patients (58%). Among these patients, only two had E. faecium in mixed infections with E. faecalis. In the isolates of E. faecalis, 27% were resistant to antibiotics, including tetracycline, ciprofloxacin, and azithromycin. The isolates of E. faecium showed no resistance to the antibiotics tested. Both the isolates of E. faecium and E. faecalis exhibit significant susceptibility to PDT, including the isolates resistant to antibiotics. The reductions achieved by PDT ranged of 2.76 to 4.31 log 10 for E. faecalis strains and of 3.93 to 4.33 log 10 for E. faecium strains. Conclusion E. faecium showed lower prevalence in endodontic infections and higher susceptibility to antibiotics when compared to E. faecalis. In in vitro assays, PDT had a significant antimicrobial activity for both strains.

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A Small Amount of Singlet Oxygen Generated via Excited Methylene Blue by Photodynamic Therapy Induces the Sterilization of Enterococcus faecalis

Cited by 61 publications

References 38 publications

Repeated exposures to blue light-activated eosin Y enhance inactivation of E. faecalis biofilms, in vitro

Repeated exposures to blue light-activated eosin Y enhance inactivation of E. faecalis biofilms, in vitro

Improve ICG Based Photodynamic Properties Through Conjugation of ICG Into Nano-Graphene Oxide Against Enterococcus faecalis

Enterococcus faecium and Enterococcus faecalis in endodontic infections: antibiotic resistance profile and susceptibility to photodynamic therapy

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