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Sinclair LG, Anderson JG, MacGregor SJ, Maclean M. Enhanced antimicrobial efficacy and energy efficiency of low irradiance 405-nm light for bacterial decontamination. Arch Microbiol 2024; 206:276. [PMID: 38777923 PMCID: PMC11111507 DOI: 10.1007/s00203-024-03999-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2024] [Revised: 04/28/2024] [Accepted: 05/10/2024] [Indexed: 05/25/2024]
Abstract
Due to its increased safety over ultraviolet light, there is interest in the development of antimicrobial violet-blue light technologies for infection control applications. To ensure compatibility with exposed materials and tissue, the light irradiances and dose regimes used must be suitable for the target application. This study investigates the antimicrobial dose responses and germicidal efficiency of 405 nm violet-blue light when applied at a range of irradiance levels, for inactivation of surface-seeded and suspended bacteria. Bacteria were seeded onto agar surfaces (101-108 CFUplate-1) or suspended in PBS (103-109 CFUmL-1) and exposed to increasing doses of 405-nm light (≤ 288 Jcm-2) using various irradiances (0.5-150 mWcm-2), with susceptibility at equivalent light doses compared. Bacterial reductions ≥ 96% were demonstrated in all cases for lower irradiance (≤ 5 mWcm-2) exposures. Comparisons indicated, on a per unit dose basis, that significantly lower doses were required for significant reductions of all species when exposed at lower irradiances: 3-30 Jcm-2/0.5 mWcm-2 compared to 9-75 Jcm-2/50 mWcm-2 for low cell density (102 CFUplate-1) surface exposures and 22.5 Jcm-2/5 mWcm-2 compared to 67.5 Jcm-2/150 mWcm-2 for low density (103 CFUmL-1) liquid exposures (P ≤ 0.05). Similar patterns were observed at higher densities, excluding S. aureus exposed at 109 CFUmL-1, suggesting bacterial density at predictable levels has minimal influence on decontamination efficacy. This study provides fundamental evidence of the greater energy efficacy of 405-nm light for inactivation of clinically-significant pathogens when lower irradiances are employed, further supporting its relevance for practical decontamination applications.
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Affiliation(s)
- Lucy G Sinclair
- The Robertson Trust Laboratory for Electronic Sterilisation Technologies (ROLEST), Department of Electronic & Electrical Engineering, University of Strathclyde, Glasgow, UK
| | - John G Anderson
- The Robertson Trust Laboratory for Electronic Sterilisation Technologies (ROLEST), Department of Electronic & Electrical Engineering, University of Strathclyde, Glasgow, UK
| | - Scott J MacGregor
- The Robertson Trust Laboratory for Electronic Sterilisation Technologies (ROLEST), Department of Electronic & Electrical Engineering, University of Strathclyde, Glasgow, UK
| | - Michelle Maclean
- The Robertson Trust Laboratory for Electronic Sterilisation Technologies (ROLEST), Department of Electronic & Electrical Engineering, University of Strathclyde, Glasgow, UK.
- Department of Biomedical Engineering, University of Strathclyde, Glasgow, UK.
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2
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Hygiene requirements for cleaning and disinfection of surfaces: recommendation of the Commission for Hospital Hygiene and Infection Prevention (KRINKO) at the Robert Koch Institute. GMS HYGIENE AND INFECTION CONTROL 2024; 19:Doc13. [PMID: 38655122 PMCID: PMC11035912 DOI: 10.3205/dgkh000468] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Subscribe] [Scholar Register] [Indexed: 04/26/2024]
Abstract
This recommendation of the Commission for Hospital Hygiene and Infection Prevention (KRINKO) addresses not only hospitals, but also outpatient health care facilities and compiles current evidence. The following criteria are the basis for the indications for cleaning and disinfection: Infectious bioburden and tenacity of potential pathogens on surfaces and their transmission routes, influence of disinfecting surface cleaning on the rate of nosocomial infections, interruption of cross infections due to multidrug-resistant organisms, and outbreak control by disinfecting cleaning within bundles. The criteria for the selection of disinfectants are determined by the requirements for effectiveness, the efficacy spectrum, the compatibility for humans and the environment, as well as the risk potential for the development of tolerance and resistance. Detailed instructions on the organization and implementation of cleaning and disinfection measures, including structural and equipment requirements, serve as the basis for their implementation. Since the agents for surface disinfection and disinfecting surface cleaning have been classified as biocides in Europe since 2013, the regulatory consequences are explained. As possible addition to surface disinfection, probiotic cleaning, is pointed out. In an informative appendix (only in German), the pathogen characteristics for their acquisition of surfaces, such as tenacity, infectious dose and biofilm formation, and the toxicological and ecotoxicological characteristics of microbicidal agents as the basis for their selection are explained, and methods for the evaluation of the resulting quality of cleaning or disinfecting surface cleaning are presented.
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3
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Das A, Sil A, Kumar P, Khan I. Blue light and skin: what is the intriguing link? Clin Exp Dermatol 2023; 48:968-977. [PMID: 37097168 DOI: 10.1093/ced/llad150] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2023] [Accepted: 04/20/2023] [Indexed: 04/26/2023]
Abstract
Blue light has garnered attention because of its ability to penetrate more deeply into the skin layers, and induce cellular dysfunction and DNA damage. Photoageing, hyperpigmentation and melasma are some of the cutaneous changes that develop on exposure to blue light. To date, the therapeutic roles of blue light have been evaluated in dermatological conditions like psoriasis, eczema, acne vulgaris, actinic keratosis and cutaneous malignancies, among others. In this review, we have attempted to present an evidence-based compilation of the effects of blue light on the skin.
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Affiliation(s)
- Anupam Das
- Department of Dermatology, KPC Medical College and Hospital, Kolkata, West Bengal, India
| | - Abheek Sil
- Department of Dermatology, Venereology and Leprosy, R.G. Kar Medical College and Hospital, Kolkata, West Bengal, India
| | - Piyush Kumar
- Department of Dermatology, Madhubani Medical College & Hospital, Madhubani, Bihar, India
| | - Ismat Khan
- Department of Dermatology, Medical College and Hospital Kolkata, Kolkata, West Bengal, India
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Anforderungen an die Hygiene bei der Reinigung und Desinfektion von Flächen. Bundesgesundheitsblatt Gesundheitsforschung Gesundheitsschutz 2022; 65:1074-1115. [PMID: 36173419 PMCID: PMC9521013 DOI: 10.1007/s00103-022-03576-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
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5
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Metzger M, Hacobian A, Karner L, Krausgruber L, Grillari J, Dungel P. Resistance of Bacteria toward 475 nm Blue Light Exposure and the Possible Role of the SOS Response. Life (Basel) 2022; 12:1499. [PMID: 36294934 PMCID: PMC9605056 DOI: 10.3390/life12101499] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Revised: 09/19/2022] [Accepted: 09/20/2022] [Indexed: 11/07/2023] Open
Abstract
The increase in antibiotic resistance represents a major global challenge for our health systems and calls for alternative treatment options, such as antimicrobial light-based therapies. Blue light has shown promising results regarding the inactivation of a variety of microorganisms; however, most often, antimicrobial blue light (aBL) therapy is performed using wavelengths close to the UV range. Here we investigated whether inactivation was possible using blue light with a wavelength of 475 nm. Both Gram-positive and -negative bacterial strains were treated with blue light with fluences of 7.5-45 J/cm2. Interestingly, only some bacterial strains were susceptible to 475 nm blue light, which was associated with the lack of RecA, i.e., a fully functional DNA repair mechanism. We demonstrated that the insertion of the gene recA reduced the susceptibility of otherwise responsive bacterial strains, indicating a protective mechanism conveyed by the bacterial SOS response. However, mitigating this pathway via three known RecA inhibiting molecules (ZnAc, curcumin, and Fe(III)-PcTs) did not result in an increase in bactericidal action. Nonetheless, creating synergistic effects by combining a multitarget therapy, such as aBL, with an RecA targeting treatment could be a promising strategy to overcome the dilemma of antibiotic resistance in the future.
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Affiliation(s)
- Magdalena Metzger
- Ludwig Boltzmann Institute for Traumatology, The Research Center in Cooperation with AUVA, 1200 Vienna, Austria
- Austrian Cluster for Tissue Regeneration, 1200 Vienna, Austria
- Institute of Molecular Biotechnology, University of Natural Resources and Life Sciences, 1190 Vienna, Austria
| | - Ara Hacobian
- Ludwig Boltzmann Institute for Traumatology, The Research Center in Cooperation with AUVA, 1200 Vienna, Austria
- Austrian Cluster for Tissue Regeneration, 1200 Vienna, Austria
| | - Lisa Karner
- Austrian Cluster for Tissue Regeneration, 1200 Vienna, Austria
| | - Leonie Krausgruber
- Ludwig Boltzmann Institute for Traumatology, The Research Center in Cooperation with AUVA, 1200 Vienna, Austria
- Austrian Cluster for Tissue Regeneration, 1200 Vienna, Austria
| | - Johannes Grillari
- Ludwig Boltzmann Institute for Traumatology, The Research Center in Cooperation with AUVA, 1200 Vienna, Austria
- Austrian Cluster for Tissue Regeneration, 1200 Vienna, Austria
- Institute of Molecular Biotechnology, University of Natural Resources and Life Sciences, 1190 Vienna, Austria
| | - Peter Dungel
- Ludwig Boltzmann Institute for Traumatology, The Research Center in Cooperation with AUVA, 1200 Vienna, Austria
- Austrian Cluster for Tissue Regeneration, 1200 Vienna, Austria
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Akasov R, Khaydukov EV, Yamada M, Zvyagin AV, Leelahavanichkul A, Leanse LG, Dai T, Prow T. Nanoparticle enhanced blue light therapy. Adv Drug Deliv Rev 2022; 184:114198. [PMID: 35301045 DOI: 10.1016/j.addr.2022.114198] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Revised: 12/13/2021] [Accepted: 03/08/2022] [Indexed: 11/26/2022]
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7
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Bauer R, Hoenes K, Meurle T, Hessling M, Spellerberg B. The effects of violet and blue light irradiation on ESKAPE pathogens and human cells in presence of cell culture media. Sci Rep 2021; 11:24473. [PMID: 34963696 PMCID: PMC8714816 DOI: 10.1038/s41598-021-04202-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Accepted: 12/16/2021] [Indexed: 12/18/2022] Open
Abstract
Bacteria belonging to the group of ESKAPE pathogens are responsible for the majority of nosocomial infections. Due to the increase of antibiotic resistance, alternative treatment strategies are of high clinical relevance. In this context visible light as disinfection technique represents an interesting option as microbial pathogens can be inactivated without adjuvants. However cytotoxic effects of visible light on host cells have also been reported. We compared the cytotoxicity of violet and blue light irradiation on monocytic THP-1 and alveolar epithelium A549 cells with the inactivation effect on ESKAPE pathogens. THP-1 cells displayed a higher susceptibility to irradiation than A549 cells with first cytotoxic effects occurring at 300 J cm−2 (405 nm) and 400 J cm−2 (450 nm) in comparison to 300 J cm−2 and 1000 J cm−2, respectively. We could define conditions in which a significant reduction of colony forming units for all ESKAPE pathogens, except Enterococcus faecium, was achieved at 405 nm while avoiding cytotoxicity. Irradiation at 450 nm demonstrated a more variable effect which was species and medium dependent. In summary a significant reduction of viable bacteria could be achieved at subtoxic irradiation doses, supporting a potential use of visible light as an antimicrobial agent in clinical settings.
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Affiliation(s)
- Richard Bauer
- Institute of Medical Microbiology and Hygiene, University Hospital Ulm, 89081, Ulm, Germany
| | - Katharina Hoenes
- Institute of Medical Engineering and Mechatronics, Ulm University of Applied Sciences, 89081, Ulm, Germany
| | - Tobias Meurle
- Institute of Medical Engineering and Mechatronics, Ulm University of Applied Sciences, 89081, Ulm, Germany
| | - Martin Hessling
- Institute of Medical Engineering and Mechatronics, Ulm University of Applied Sciences, 89081, Ulm, Germany
| | - Barbara Spellerberg
- Institute of Medical Microbiology and Hygiene, University Hospital Ulm, 89081, Ulm, Germany.
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8
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The effect of a geometric-shaped tool with blue led light on the activation of human dermal fibroblasts and cancer cells. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY 2021. [DOI: 10.1016/j.jpap.2021.100087] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
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9
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Lusche I, Dirk C, Frentzen M, Meister J. Cavity Disinfection With a 445 nm Diode Laser Within the Scope of Restorative Therapy - A Pilot Study. J Lasers Med Sci 2021; 11:417-426. [PMID: 33425292 DOI: 10.34172/jlms.2020.66] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Introduction: Cavity disinfection is necessary to prevent a progressive infection of the crown dentin and pulp. Increasing intolerance and resistance to antiseptics and antibiotics as well as the controversy over the effects of those on the dental hard tissue and composite have prompted the investigation of alternative treatment options. The objective of this pilot study is to evaluate the antibacterial potential of a diode laser with a wavelength of 445 nm in the cavity preparation using the bacterium Streptococcus salivarius associated with caries in conjunction with the characteristics and influences of dentin on light transmission. Methods: The bactericidal effect of the laser irradiation was determined in culture experiments by using caries-free human dentin samples on bacteria-inoculated agar. For this, dentin discs (horizontally cut coronal dentin) of 500 µm and 1000 µm thicknesses were produced and irradiated with the laser with irradiation parameters of 0.7-1 W in a cw-mode and exposure times of between 5-30 s. Based on the different sample thicknesses, the penetration depth effect of the irradiation was ascertained after the subsequent incubation of the bacteria-inoculated agar. Additional influential parameters on the irradiation transmission were investigated, including surface moisture, tooth color as well as the presence of a smear layer on the dentin surface. Results: The optical transmission values of the laser radiation for dentin were significantly dependent on the sample thickness (P = 0.006) as well as its moisture content (P = 0.013) and were independent of the presence of a smear layer. There was a 40% reduction in bacteria after the radiography of the 500-µm-thick dentin samples, which was shown as the lowest laser dose (443 J/cm2). Conclusion: These findings indicate that the diode laser with light emission at a wavelength of 445 nm is interesting for the supportive cavity disinfection within the scope of caries therapy and show potential for clinical applications.
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Affiliation(s)
- Inés Lusche
- Department of Operative and Preventive Dentistry, Bonn University, Welschnonnenstrasse 17, D-53111 Bonn, Germany
| | - Cornelius Dirk
- Oral Technology, Bonn University, Wilhelmsplatz 5, 53111 Bonn, Germany
| | - Matthias Frentzen
- Department of Operative and Preventive Dentistry, Bonn University, Welschnonnenstrasse 17, D-53111 Bonn, Germany.,Center of Dento-Maxillo-Facial Medicine, Bonn University, Welschnonnenstrasse 17, D-53111 Bonn, Germany
| | - Jörg Meister
- Center of Dento-Maxillo-Facial Medicine, Bonn University, Welschnonnenstrasse 17, D-53111 Bonn, Germany.,Center of Applied Medical Laser Research and Biomedical Optics (AMLaReBO), Bonn University, Welschnonnenstrasse 17, D-53111 Bonn, Germany.,Laser Application in Medical Sciences Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
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10
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In Vitro Evidences of Different Fibroblast Morpho-Functional Responses to Red, Near-Infrared and Violet-Blue Photobiomodulation: Clues for Addressing Wound Healing. APPLIED SCIENCES-BASEL 2020. [DOI: 10.3390/app10217878] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Although photobiomodulation (PBM) has proven promising to treat wounds, the lack of univocal guidelines and of a thorough understanding of light–tissue interactions hampers its mainstream adoption for wound healing promotion. This study compared murine and human fibroblast responses to PBM by red (635 ± 5 nm), near-infrared (NIR, 808 ± 1 nm), and violet-blue (405 ± 5 nm) light (0.4 J/cm2 energy density, 13 mW/cm2 power density). Cell viability was not altered by PBM treatments. Light and confocal laser scanning microscopy and biochemical analyses showed, in red PBM irradiated cells: F-actin assembly reduction, up-regulated expression of Ki67 proliferation marker and of vinculin in focal adhesions, type-1 collagen down-regulation, matrix metalloproteinase-2 and metalloproteinase-9 expression/functionality increase concomitant to their inhibitors (TIMP-1 and TIMP-2) decrease. Violet-blue and even more NIR PBM stimulated collagen expression/deposition and, likely, cell differentiation towards (proto)myofibroblast phenotype. Indeed, these cells exhibited a higher polygonal surface area, stress fiber-like structures, increased vinculin- and phospho-focal adhesion kinase-rich clusters and α-smooth muscle actin. This study may provide the experimental groundwork to support red, NIR, and violet-blue PBM as potential options to promote proliferative and matrix remodeling/maturation phases of wound healing, targeting fibroblasts, and to suggest the use of combined PBM treatments in the wound management setting.
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11
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Silverman RG, Comey A, Sammons T. Effects of a single treatment with two nonthermal laser wavelengths on chronic neck and shoulder pain. MEDICAL DEVICES-EVIDENCE AND RESEARCH 2019; 12:319-325. [PMID: 31564998 PMCID: PMC6724421 DOI: 10.2147/mder.s218649] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2019] [Accepted: 08/02/2019] [Indexed: 11/23/2022] Open
Abstract
Introduction Nonthermal lasers provide pain relief for a variety of musculoskeletal disorders and improve physical functioning. A nonthermal laser that employs a 635 nm red diode is cleared for the temporary reduction of neck and shoulder pain of musculoskeletal origin. As a 405 nm violet laser has shown synergy with the 635 nm red laser when used together for treating other conditions, the objective of this study was to compare the efficacy of 635 nm red and 405 nm violet lasers vs the 635 nm red laser for treating neck and shoulder pain of musculoskeletal origin. Materials and methods Otherwise healthy adult subjects with chronic neck or shoulder pain for ≥30 days were enrolled and randomized to receive a single 13-min treatment with combined red and violet lasers (n=44) or the red laser alone (n=43). The primary efficacy measure was change in baseline VAS pain scores 3 mins after treatment. Subject success was predefined as a ≥30% decrease in VAS scores and study success was predefined as 65±5% individual subject successes. Results Among subjects treated with the red and violet lasers, mean VAS neck and shoulder pain scores decreased from 65.0 to 35.2 (p<0.0001). Most subjects in the study (75%) achieved ≥30% decrease in VAS scores. The decreased mean (SD) VAS scores remained 29.6 (16.7) and 29.3 (19.2) after 24 and 48 hrs, respectively. The secondary efficacy measures of change in range of motion ROM) and patient satisfaction also improved. There were no adverse events. Conclusion Overall, treatment with the red and violet lasers outperformed the FDA-approved red laser with respect to change in pain scores and improvement in shoulder ROM.
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Affiliation(s)
| | - Albert Comey
- Clinical Study Site, Comey Chiropractic Clinic, Largo, FL, USA
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12
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Wang Y, Ferrer-Espada R, Baglo Y, Goh XS, Held KD, Grad YH, Gu Y, Gelfand JA, Dai T. Photoinactivation of Neisseria gonorrhoeae: A Paradigm-Changing Approach for Combating Antibiotic-Resistant Gonococcal Infection. J Infect Dis 2019; 220:873-881. [PMID: 30629196 PMCID: PMC6667797 DOI: 10.1093/infdis/jiz018] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2018] [Accepted: 01/08/2019] [Indexed: 01/22/2023] Open
Abstract
Antimicrobial resistance in Neisseria gonorrhoeae is a major issue of public health, and there is a critical need for the development of new antigonococcal strategies. In this study, we investigated the effectiveness of antimicrobial blue light (aBL; wavelength, 405 nm), an innovative nonpharmacological approach, for the inactivation of N. gonorrhoeae. Our findings indicated that aBL preferentially inactivated N. gonorrhoeae, including antibiotic-resistant strains, over human vaginal epithelial cells in vitro. Furthermore, no aBL-induced genotoxicity to the vaginal epithelial cells was observed at the radiant exposure used to inactivate N. gonorrhoeae. aBL also effectively inactivated N. gonorrhoeae that had attached to and invaded into the vaginal epithelial cells in their cocultures. No gonococcal resistance to aBL developed after 15 successive cycles of inactivation induced by subtherapeutic exposure to aBL. Endogenous aBL-activatable photosensitizing porphyrins in N. gonorrhoeae were identified and quantified using ultraperformance liquid chromatography, with coproporphyrin being the most abundant species in all N. gonorrhoeae strains studied. Singlet oxygen was involved in aBL inactivation of N. gonorrhoeae. Together, these findings show that aBL represents a potential potent treatment for antibiotic-resistant gonococcal infection.
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Affiliation(s)
- Ying Wang
- Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
- Department of Laser Medicine, Chinese PLA General Hospital, Beijing
| | - Raquel Ferrer-Espada
- Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
- Vaccine and Immunotherapy Center, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
| | - Yan Baglo
- Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
| | - Xueping S Goh
- Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
- Vaccine and Immunotherapy Center, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
| | - Kathryn D Held
- Department of Radiation Oncology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
| | - Yonatan H Grad
- Department of Immunology and Infectious Diseases, Harvard T. H. Chan School of Public Health, Boston, Massachusetts
| | - Ying Gu
- Department of Laser Medicine, Chinese PLA General Hospital, Beijing
| | - Jeffrey A Gelfand
- Vaccine and Immunotherapy Center, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
| | - Tianhong Dai
- Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
- Vaccine and Immunotherapy Center, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
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13
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Halstead FD, Ahmed Z, Bishop JRB, Oppenheim BA. The potential of visible blue light (405 nm) as a novel decontamination strategy for carbapenemase-producing enterobacteriaceae (CPE). Antimicrob Resist Infect Control 2019; 8:14. [PMID: 30675341 PMCID: PMC6335786 DOI: 10.1186/s13756-019-0470-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Accepted: 01/10/2019] [Indexed: 12/21/2022] Open
Abstract
Background Carbapenemase-producing Enterobacteriaceae (CPE) pose a considerable threat to modern medicine. New treatment options and methods to limit spread need to be investigated. Blue light (BL) is intrinsically antimicrobial, and we have previously demonstrated significant antimicrobial effects on biofilms of a panel of isolates, including two CPEs. This study was performed to assess the antibacterial activity of 405 nm BL against a panel of CPE isolates (four encoding blaNDM, three blaKPC, two blaOXA-48, and three encoding both NDM and OXA-48 carbapenemases). Methods In vitro experiments were conducted on 72 h old biofilms of CPEs which were exposed to 60 mW/cm2 of BL. Changes to biofilm seeding were assessed by measuring the optical density of treated and untreated biofilms. Results Twelve bacterial clinical isolates (comprising eight Klebsiella pnemoniae, one K. oxytoca, and three Escherichia coli) were tested. BL was delivered for 5, 15 and 30 min, achieving doses of 162, 54, and 108 J/cm2, respectively. All of the CPEs were susceptible to BL treatment, with increasing reductions in seeding with increasing durations of exposure. At 30 min, reductions in biofilm seeding of ≥80% were observed for 11 of the 12 isolates, compared to five of 12 after 15 min. CPE_8180 was less susceptible than the rest, with a maximum reduction in seeding of 66% at 30 min. Conclusions BL is effective at reducing the seeding of mature CPE biofilms in vitro, and offers great promise as a topical decontamination/treatment agent for both clinical and environmental applications. Electronic supplementary material The online version of this article (10.1186/s13756-019-0470-1) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Fenella D Halstead
- 1NIHR Surgical Reconstruction and Microbiology Research Centre, Queen Elizabeth Hospital, B15 2GW, Birmingham, UK.,2Queen Elizabeth Hospital, University Hospitals Birmingham NHS Foundation Trust, B15 2GW, Birmingham, UK
| | - Zahra Ahmed
- 1NIHR Surgical Reconstruction and Microbiology Research Centre, Queen Elizabeth Hospital, B15 2GW, Birmingham, UK.,2Queen Elizabeth Hospital, University Hospitals Birmingham NHS Foundation Trust, B15 2GW, Birmingham, UK
| | - Jonathan R B Bishop
- 1NIHR Surgical Reconstruction and Microbiology Research Centre, Queen Elizabeth Hospital, B15 2GW, Birmingham, UK
| | - Beryl A Oppenheim
- 1NIHR Surgical Reconstruction and Microbiology Research Centre, Queen Elizabeth Hospital, B15 2GW, Birmingham, UK
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14
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Fila G, Krychowiak M, Rychlowski M, Bielawski KP, Grinholc M. Antimicrobial blue light photoinactivation of Pseudomonas aeruginosa: Quorum sensing signaling molecules, biofilm formation and pathogenicity. JOURNAL OF BIOPHOTONICS 2018; 11:e201800079. [PMID: 29952074 DOI: 10.1002/jbio.201800079] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2018] [Accepted: 06/26/2018] [Indexed: 06/08/2023]
Abstract
Pseudomonas aeruginosa is a common causative bacterium of acute and chronic infections that have been responsible for high mortality over the past decade. P. aeruginosa produces many virulence factors such as toxins, enzymes and dyes that are strongly dependent on quorum sensing (QS) signaling systems. P. aeruginosa has three major QS systems (las, rhl and Pseudomonas quinolone signal) that regulate the expression of genes encoding virulence factors as well as biofilm production and maturation. Antimicrobial blue light (aBL) is considered a therapeutic option for bacterial infections and has other benefits, such as reducing bacterial virulence. Therefore, this study investigated the efficacy of aBL to reduce P. aeruginosa pathogenicity. aBL treatment resulted in the reduced activity of certain QS signaling molecules in P. aeruginosa and inhibited biofilm formation. in vivo tests using a Caenorhabditis elegans infection model indicated that sublethal aBL decreased the pathogenicity of P. aeruginosa. aBL may be a new virulence-targeting therapeutic approach.
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Affiliation(s)
- Grzegorz Fila
- Laboratory of Molecular Diagnostics, Department of Biotechnology, Intercollegiate Faculty of Biotechnology, University of Gdansk and Medical University of Gdansk, Gdansk, Poland
| | - Marta Krychowiak
- Laboratory of Biologically Active Compounds, Department of Biotechnology, Intercollegiate Faculty of Biotechnology, University of Gdansk and Medical University of Gdansk, Gdansk, Poland
| | - Michal Rychlowski
- Laboratory of Virus Molecular Biology, Intercollegiate Faculty of Biotechnology, University of Gdansk and Medical University of Gdansk, Gdansk, Poland
| | - Krzysztof Piotr Bielawski
- Laboratory of Molecular Diagnostics, Department of Biotechnology, Intercollegiate Faculty of Biotechnology, University of Gdansk and Medical University of Gdansk, Gdansk, Poland
| | - Mariusz Grinholc
- Laboratory of Molecular Diagnostics, Department of Biotechnology, Intercollegiate Faculty of Biotechnology, University of Gdansk and Medical University of Gdansk, Gdansk, Poland
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15
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Tomb RM, White TA, Coia JE, Anderson JG, MacGregor SJ, Maclean M. Review of the Comparative Susceptibility of Microbial Species to Photoinactivation Using 380-480 nm Violet-Blue Light. Photochem Photobiol 2018; 94:445-458. [DOI: 10.1111/php.12883] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Accepted: 12/08/2017] [Indexed: 12/24/2022]
Affiliation(s)
- Rachael M. Tomb
- The Robertson Trust Laboratory for Electronic Sterilisation Technologies (ROLEST); Department of Electronic & Electrical Engineering; University of Strathclyde; Glasgow UK
| | - Tracy A. White
- The Robertson Trust Laboratory for Electronic Sterilisation Technologies (ROLEST); Department of Electronic & Electrical Engineering; University of Strathclyde; Glasgow UK
| | - John E. Coia
- Department of Clinical Microbiology; Glasgow Royal Infirmary; Glasgow UK
| | - John G. Anderson
- The Robertson Trust Laboratory for Electronic Sterilisation Technologies (ROLEST); Department of Electronic & Electrical Engineering; University of Strathclyde; Glasgow UK
| | - Scott J. MacGregor
- The Robertson Trust Laboratory for Electronic Sterilisation Technologies (ROLEST); Department of Electronic & Electrical Engineering; University of Strathclyde; Glasgow UK
| | - Michelle Maclean
- The Robertson Trust Laboratory for Electronic Sterilisation Technologies (ROLEST); Department of Electronic & Electrical Engineering; University of Strathclyde; Glasgow UK
- Department of Biomedical Engineering; University of Strathclyde; Glasgow UK
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16
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Tomb RM, Maclean M, Coia JE, MacGregor SJ, Anderson JG. Assessment of the potential for resistance to antimicrobial violet-blue light in Staphylococcus aureus. Antimicrob Resist Infect Control 2017; 6:100. [PMID: 29046782 PMCID: PMC5639585 DOI: 10.1186/s13756-017-0261-5] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Accepted: 09/18/2017] [Indexed: 01/28/2023] Open
Abstract
BACKGROUND Antimicrobial violet-blue light in the region of 405 nm is emerging as an alternative technology for hospital decontamination and clinical treatment. The mechanism of action is the excitation of endogenous porphyrins within exposed microorganisms, resulting in ROS generation, oxidative damage and cell death. Although resistance to 405 nm light is not thought likely, little evidence has been published to support this. This study was designed to establish if there is potential for tolerance development, using the nosocomial pathogen Staphylococcus aureus as the model organism. METHODS The first stage of this study investigated the potential for S. aureus to develop tolerance to high-intensity 405 nm light if pre-cultured in low-level stress violet-blue light (≤1 mW/cm2) conditions. Secondly, the potential for tolerance development in bacteria subjected to repeated sub-lethal exposure was compared by carrying out 15 cycles of exposure to high-intensity 405 nm light, using a sub-lethal dose of 108 J/cm2. Inactivation kinetics and antibiotic susceptibility were also compared. RESULTS When cultured in low-level violet-blue light conditions, S. aureus required a greater dose of high-intensity 405 nm light for complete inactivation, however this did not increase with multiple (3) low-stress cultivations. Repeated sub-lethal exposures indicated no evidence of bacterial tolerance to 405 nm light. After 15 sub-lethal exposures 1.2 and 1.4 log10 reductions were achieved for MSSA and MRSA respectively, which were not significantly different to the initial 1.3 log10 reductions achieved (P = 0.242 & 0.116, respectively). Antibiotic susceptibility was unaffected, with the maximum change in zone of inhibition being ± 2 mm. CONCLUSIONS Repeated sub-lethal exposure of non-proliferating S. aureus populations did not affect the susceptibility of the organism to 405 nm light, nor to antibiotics. Culture in low-level violet-blue light prior to 405 nm light exposure may increase oxidative stress responses in S. aureus, however, inactivation still occurs and results demonstrate that this is unlikely to be a selective process. These results demonstrate that tolerance from repeated exposure is unlikely to occur, and further supports the potential development of 405 nm light for clinical decontamination and treatment applications.
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Affiliation(s)
- Rachael M Tomb
- The Robertson Trust Laboratory for Electronic Sterilisation Technologies (ROLEST), Department of Electronic & Electrical Engineering, University of Strathclyde, Glasgow, UK
| | - Michelle Maclean
- The Robertson Trust Laboratory for Electronic Sterilisation Technologies (ROLEST), Department of Electronic & Electrical Engineering, University of Strathclyde, Glasgow, UK.,Department of Biomedical Engineering, University of Strathclyde, Glasgow, UK
| | - John E Coia
- Department of Clinical Microbiology, Glasgow Royal Infirmary, Glasgow, UK
| | - Scott J MacGregor
- The Robertson Trust Laboratory for Electronic Sterilisation Technologies (ROLEST), Department of Electronic & Electrical Engineering, University of Strathclyde, Glasgow, UK
| | - John G Anderson
- The Robertson Trust Laboratory for Electronic Sterilisation Technologies (ROLEST), Department of Electronic & Electrical Engineering, University of Strathclyde, Glasgow, UK
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17
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Affiliation(s)
- Tianhong Dai
- a Wellman Center for Photomedicine , Massachusetts General Hospital, Harvard Medical School , Boston , MA , USA
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18
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Gillespie JB, Maclean M, Given MJ, Wilson MP, Judd MD, Timoshkin IV, MacGregor SJ. Efficacy of Pulsed 405-nm Light-Emitting Diodes for Antimicrobial Photodynamic Inactivation: Effects of Intensity, Frequency, and Duty Cycle. Photomed Laser Surg 2016; 35:150-156. [PMID: 27759498 PMCID: PMC5346950 DOI: 10.1089/pho.2016.4179] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
Objective: This study investigates possible advantages in pulsed over continuous 405-nm light-emitting diode (LED) light for bacterial inactivation and energy efficiency. Background: Alternative nonantibiotic methods of disinfection and infection control have become of significant interest. Recent studies have demonstrated the application of systems using 405-nm LEDs for continuous disinfection of the clinical environment, and also for potential treatment of contaminated wounds. Methods: Liquid suspensions of 103 colony-forming units/mL populations of Staphylococcus aureus were subject to pulsed 405-nm light of different frequencies, duty cycles, and intensities and for different lengths of time. Results: Pulsed exposures with the same average irradiance of 16 mW/cm2 and varying duty cycle (25%, 50%, 75%) showed very similar performance compared with continuous exposures, with 95–98% reduction of S. aureus achieved for all duty cycles. The pulsing frequency was varied in intervals from 100 Hz to 10 kHz and appeared to have little effect on antimicrobial efficacy. However, when comparing pulsed with continuous exposure, an improvement in inactivation per unit optical energy was achieved, with results showing an increase of approximately 83% in optical efficiency. Conclusions: These results suggest that under pulsed conditions, a lower energy consumption and lower perceived brightness could be achieved, thus potentially providing improved operating conditions for medical/infection control applications without compromising antimicrobial efficacy.
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Affiliation(s)
- Jonathan B Gillespie
- 1 Department of Electronic & Electrical Engineering, The Robertson Trust Laboratory for Electronic Sterilisation Technologies, University of Strathclyde , Glasgow, Scotland, United Kingdom
| | - Michelle Maclean
- 1 Department of Electronic & Electrical Engineering, The Robertson Trust Laboratory for Electronic Sterilisation Technologies, University of Strathclyde , Glasgow, Scotland, United Kingdom .,2 Department of Biomedical Engineering, The Robertson Trust Laboratory for Electronic Sterilisation Technologies, University of Strathclyde , Glasgow, Scotland, United Kingdom
| | - Martin J Given
- 3 Department of Electronic & Electrical Engineering, High Voltage Technologies, University of Strathclyde , Glasgow, Scotland, United Kingdom
| | - Mark P Wilson
- 3 Department of Electronic & Electrical Engineering, High Voltage Technologies, University of Strathclyde , Glasgow, Scotland, United Kingdom
| | - Martin D Judd
- 3 Department of Electronic & Electrical Engineering, High Voltage Technologies, University of Strathclyde , Glasgow, Scotland, United Kingdom
| | - Igor V Timoshkin
- 1 Department of Electronic & Electrical Engineering, The Robertson Trust Laboratory for Electronic Sterilisation Technologies, University of Strathclyde , Glasgow, Scotland, United Kingdom .,3 Department of Electronic & Electrical Engineering, High Voltage Technologies, University of Strathclyde , Glasgow, Scotland, United Kingdom
| | - Scott J MacGregor
- 1 Department of Electronic & Electrical Engineering, The Robertson Trust Laboratory for Electronic Sterilisation Technologies, University of Strathclyde , Glasgow, Scotland, United Kingdom .,3 Department of Electronic & Electrical Engineering, High Voltage Technologies, University of Strathclyde , Glasgow, Scotland, United Kingdom
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19
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A New Proof of Concept in Bacterial Reduction: Antimicrobial Action of Violet-Blue Light (405 nm) in Ex Vivo Stored Plasma. JOURNAL OF BLOOD TRANSFUSION 2016; 2016:2920514. [PMID: 27774337 PMCID: PMC5059568 DOI: 10.1155/2016/2920514] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/11/2016] [Accepted: 08/28/2016] [Indexed: 11/17/2022]
Abstract
Bacterial contamination of injectable stored biological fluids such as blood plasma and platelet concentrates preserved in plasma at room temperature is a major health risk. Current pathogen reduction technologies (PRT) rely on the use of chemicals and/or ultraviolet light, which affects product quality and can be associated with adverse events in recipients. 405 nm violet-blue light is antibacterial without the use of photosensitizers and can be applied at levels safe for human exposure, making it of potential interest for decontamination of biological fluids such as plasma. As a pilot study to test whether 405 nm light is capable of inactivating bacteria in biological fluids, rabbit plasma and human plasma were seeded with bacteria and treated with a 405 nm light emitting diode (LED) exposure system (patent pending). Inactivation was achieved in all tested samples, ranging from low volumes to prebagged plasma. 99.9% reduction of low density bacterial populations (≤103 CFU mL−1), selected to represent typical “natural” contamination levels, was achieved using doses of 144 Jcm−2. The penetrability of 405 nm light, permitting decontamination of prebagged plasma, and the nonrequirement for photosensitizing agents provide a new proof of concept in bacterial reduction in biological fluids, especially injectable fluids relevant to transfusion medicine.
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20
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McKenzie K, Maclean M, Grant MH, Ramakrishnan P, MacGregor SJ, Anderson JG. The effects of 405 nm light on bacterial membrane integrity determined by salt and bile tolerance assays, leakage of UV-absorbing material and SYTOX green labelling. MICROBIOLOGY-SGM 2016; 162:1680-1688. [PMID: 27499074 PMCID: PMC5068139 DOI: 10.1099/mic.0.000350] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Bacterial inactivation by 405 nm light is accredited to the photoexcitation of intracellular porphyrin molecules resulting in energy transfer and the generation of reactive oxygen species that impart cellular oxidative damage. The specific mechanism of cellular damage, however, is not fully understood. Previous work has suggested that destruction of nucleic acids may be responsible for inactivation; however, microscopic imaging has suggested membrane damage as a major constituent of cellular inactivation. This study investigates the membrane integrity of Escherichia coli and Staphylococcus aureus exposed to 405 nm light. Results indicated membrane damage to both species, with loss of salt and bile tolerance by S. aureus and E. coli, respectively, consistent with reduced membrane integrity. Increased nucleic acid release was also demonstrated in 405 nm light-exposed cells, with up to 50 % increase in DNA concentration into the extracellular media in the case of both organisms. SYTOX green fluorometric analysis, however, demonstrated contradictory results between the two test species. With E. coli, increasing permeation of SYTOX green was observed following increased exposure, with >500 % increase in fluorescence, whereas no increase was observed with S. aureus. Overall, this study has provided good evidence that 405 nm light exposure causes loss of bacterial membrane integrity in E. coli, but the results with S. aureus are more difficult to explain. Further work is required to gain greater understanding of the inactivation mechanism in different bacterial species, as there are likely to be other targets within the cell that are also impaired by the oxidative damage from photo-generated reactive oxygen species.
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Affiliation(s)
- Karen McKenzie
- Robertson Trust Laboratory for Electronic Sterilisation Technologies (ROLEST), University of Strathclyde, 204 George Street, Glasgow, Scotland G1 1XW, UK
| | - Michelle Maclean
- Robertson Trust Laboratory for Electronic Sterilisation Technologies (ROLEST), University of Strathclyde, 204 George Street, Glasgow, Scotland G1 1XW, UK.,Department of Biomedical Engineering, University of Strathclyde, Wolfson Centre, 106 Rottenrow, Glasgow, Scotland G4 0NW, UK
| | - M Helen Grant
- Department of Biomedical Engineering, University of Strathclyde, Wolfson Centre, 106 Rottenrow, Glasgow, Scotland G4 0NW, UK
| | - Praveen Ramakrishnan
- Robertson Trust Laboratory for Electronic Sterilisation Technologies (ROLEST), University of Strathclyde, 204 George Street, Glasgow, Scotland G1 1XW, UK.,Department of Biomedical Engineering, University of Strathclyde, Wolfson Centre, 106 Rottenrow, Glasgow, Scotland G4 0NW, UK
| | - Scott J MacGregor
- Robertson Trust Laboratory for Electronic Sterilisation Technologies (ROLEST), University of Strathclyde, 204 George Street, Glasgow, Scotland G1 1XW, UK
| | - John G Anderson
- Robertson Trust Laboratory for Electronic Sterilisation Technologies (ROLEST), University of Strathclyde, 204 George Street, Glasgow, Scotland G1 1XW, UK
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21
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Blue light does not impair wound healing in vitro. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2016; 160:53-60. [DOI: 10.1016/j.jphotobiol.2016.04.007] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Revised: 04/04/2016] [Accepted: 04/06/2016] [Indexed: 11/19/2022]
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Antibacterial Activity of Blue Light against Nosocomial Wound Pathogens Growing Planktonically and as Mature Biofilms. Appl Environ Microbiol 2016; 82:4006-4016. [PMID: 27129967 PMCID: PMC4907187 DOI: 10.1128/aem.00756-16] [Citation(s) in RCA: 87] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2016] [Accepted: 04/17/2016] [Indexed: 12/25/2022] Open
Abstract
The blue wavelengths within the visible light spectrum are intrinisically antimicrobial and can photodynamically inactivate the cells of a wide spectrum of bacteria (Gram positive and negative) and fungi. Furthermore, blue light is equally effective against both drug-sensitive and -resistant members of target species and is less detrimental to mammalian cells than is UV radiation. Blue light is currently used for treating acnes vulgaris and Helicobacter pylori infections; the utility for decontamination and treatment of wound infections is in its infancy. Furthermore, limited studies have been performed on bacterial biofilms, the key growth mode of bacteria involved in clinical infections. Here we report the findings of a multicenter in vitro study performed to assess the antimicrobial activity of 400-nm blue light against bacteria in both planktonic and biofilm growth modes. Blue light was tested against a panel of 34 bacterial isolates (clinical and type strains) comprising Acinetobacter baumannii, Enterobacter cloacae, Stenotrophomonas maltophilia, Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus, Enterococcus faecium, Klebsiella pneumoniae, and Elizabethkingia meningoseptica. All planktonic-phase bacteria were susceptible to blue light treatment, with the majority (71%) demonstrating a ≥5-log10 decrease in viability after 15 to 30 min of exposure (54 J/cm2 to 108 J/cm2). Bacterial biofilms were also highly susceptible to blue light, with significant reduction in seeding observed for all isolates at all levels of exposure. These results warrant further investigation of blue light as a novel decontamination strategy for the nosocomial environment, as well as additional wider decontamination applications. IMPORTANCE Blue light shows great promise as a novel decontamination strategy for the nosocomial environment, as well as additional wider decontamination applications (e.g., wound closure during surgery). This warrants further investigation.
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Ramakrishnan P, Maclean M, MacGregor SJ, Anderson JG, Grant MH. Cytotoxic responses to 405nm light exposure in mammalian and bacterial cells: Involvement of reactive oxygen species. Toxicol In Vitro 2016; 33:54-62. [PMID: 26916085 DOI: 10.1016/j.tiv.2016.02.011] [Citation(s) in RCA: 80] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2015] [Revised: 02/12/2016] [Accepted: 02/17/2016] [Indexed: 02/07/2023]
Abstract
Light at wavelength 405 nm is an effective bactericide. Previous studies showed that exposing mammalian cells to 405 nm light at 36 J/cm(2) (a bactericidal dose) had no significant effect on normal cell function, although at higher doses (54 J/cm(2)), mammalian cell death became evident. This research demonstrates that mammalian and bacterial cell toxicity induced by 405 nm light exposure is accompanied by reactive oxygen species production, as detected by generation of fluorescence from 6-carboxy-2',7'-dichlorodihydrofluorescein diacetate. As indicators of the resulting oxidative stress in mammalian cells, a decrease in intracellular reduced glutathione content and a corresponding increase in the efflux of oxidised glutathione were observed from 405 nm light treated cells. The mammalian cells were significantly protected from dying at 54 J/cm(2) in the presence of catalase, which detoxifies H2O2. Bacterial cells were significantly protected by sodium pyruvate (H2O2 scavenger) and by a combination of free radical scavengers (sodium pyruvate, dimethyl thiourea (OH scavenger) and catalase) at 162 and 324 J/cm(2). Results therefore suggested that the cytotoxic mechanism of 405 nm light in mammalian cells and bacteria could be oxidative stress involving predominantly H2O2 generation, with other ROS contributing to the damage.
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Affiliation(s)
- Praveen Ramakrishnan
- University of Strathclyde, Department of Biomedical Engineering, Wolfson Centre, 106 Rottenrow, Glasgow, Scotland G4 0NW, United Kingdom
| | - Michelle Maclean
- University of Strathclyde, Department of Biomedical Engineering, Wolfson Centre, 106 Rottenrow, Glasgow, Scotland G4 0NW, United Kingdom; University of Strathclyde, The Robertson Trust Laboratory for Electronic Sterilisation Technologies, 204 George street, Glasgow, Scotland G1 1XW, United Kingdom
| | - Scott J MacGregor
- University of Strathclyde, The Robertson Trust Laboratory for Electronic Sterilisation Technologies, 204 George street, Glasgow, Scotland G1 1XW, United Kingdom
| | - John G Anderson
- University of Strathclyde, The Robertson Trust Laboratory for Electronic Sterilisation Technologies, 204 George street, Glasgow, Scotland G1 1XW, United Kingdom
| | - M Helen Grant
- University of Strathclyde, Department of Biomedical Engineering, Wolfson Centre, 106 Rottenrow, Glasgow, Scotland G4 0NW, United Kingdom.
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24
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Wang Y, Wu X, Chen J, Amin R, Lu M, Bhayana B, Zhao J, Murray CK, Hamblin MR, Hooper DC, Dai T. Antimicrobial Blue Light Inactivation of Gram-Negative Pathogens in Biofilms: In Vitro and In Vivo Studies. J Infect Dis 2016; 213:1380-7. [PMID: 26908743 DOI: 10.1093/infdis/jiw070] [Citation(s) in RCA: 91] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Accepted: 02/01/2016] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Biofilms affect >80% bacterial infections in human and are usually difficult to eradicate because of their inherent drug resistance. METHODS We investigated the effectiveness of antimicrobial blue light (aBL) (wavelength, 415 nm) for inactivating Acinetobacter baumannii or Pseudomonas aeruginosa biofilms in 96-well microplates or infected mouse burn wounds. RESULTS In vitro, in 96-well microplates, exposure of 24-hour-old and 72-hour-old A. baumannii biofilms to 432 J/cm(2) aBL resulted in inactivation of 3.59 log10 and 3.18 log10 colony-forming units (CFU), respectively. For P. aeruginosa biofilms, similar levels of inactivation-3.02 log10 and 3.12 log10 CFU, respectively-were achieved. In mouse burn wounds infected with 5 × 10(6) CFU ofA. baumannii, approximately 360 J/cm(2) and 540 J/cm(2) aBL was required to inactivate 3 log10 CFU in biofilms when delivered 24 and 48 hours, respectively, after bacterial inoculation. High-performance liquid chromatography analysis revealed the presence of endogenous porphyrins in both A. baumannii and P. aeruginosa TUNEL assay detected no apoptotic cells in aBL-irradiated mouse skin at up to 24 hours after aBL exposure (540 J/cm(2)). CONCLUSIONS aBL has antimicrobial activity in biofilms ofA. baumannii and P. aeruginosa and is a potential therapeutic approach for biofilm-related infections.
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Affiliation(s)
- Yucheng Wang
- Department of Laser Medicine, Chinese PLA General Hospital, Beijing College of Medicine, Nankai University, Tianjin Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston
| | - Ximing Wu
- Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston
| | - Jia Chen
- Shanghai Dermatology Hospital, China Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston
| | - Rehab Amin
- Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston
| | - Min Lu
- Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston
| | - Brijesh Bhayana
- Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston
| | - Jie Zhao
- Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston
| | - Clinton K Murray
- Infectious Disease Service, Brooke Army Medical Center, Fort Sam Houston, Texas
| | - Michael R Hamblin
- Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston Harvard-MIT Division of Health Sciences and Technology, Cambridge, Massachusetts
| | - David C Hooper
- Division of Infectious Diseases, Massachusetts General Hospital, Harvard Medical School, Boston
| | - Tianhong Dai
- Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston
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25
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Merchant N, Smith K, Jeschke MG. An Ounce of Prevention Saves Tons of Lives: Infection in Burns. Surg Infect (Larchmt) 2015. [PMID: 26207399 DOI: 10.1089/sur.2013.135] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
BACKGROUND Modern day burn care continues to wage an uphill battle against an enemy that evolves faster than we can develop weapons. Bacteria (bioburden) are everywhere and can infiltrate anywhere within our susceptible population of burn patients. This is why prevention of infection is key to improving their survival and outcome. PURPOSE To reduce the incidence of infection in the burn patient population. MATERIALS Review of pertinent recent literature regarding infection prevention and control in the intensive care unit setting. RESULTS We propose that bioburden is one of the central elements in the infectious cycle that is ever-present in burn units. The mechanism of bacterial entry into the unit and subsequent transmission and infection are delineated. Recommendations for mitigating this risk are provided to guide future clinicians in their care of burn patients. CONCLUSIONS The treatment of infection and sepsis against highly adaptable bacteria is often insurmountable by ill patients. In this process, bioburden needs to be corralled to have any success. Thus, preventing organisms from entering the unit and transferring onto other patients, and eliminating the bacteria dwelling in the unit are all necessary actions in this battle. Ultimately, maintaining a culture that is constantly wary of this risk only can achieve this goal.
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Affiliation(s)
- Nishant Merchant
- 1 Ross Tilley Burn Centre, Sunnybrook Health Sciences Centre , Toronto, Ontario, Canada .,2 Department of Surgery, Division of Plastic Surgery, Department of Immunology, University of Toronto , Ontario, Canada .,3 TECC Program Sunnybrook Health Sciences Centre, University of Toronto , Toronto, Ontario, Canada
| | - Karen Smith
- 1 Ross Tilley Burn Centre, Sunnybrook Health Sciences Centre , Toronto, Ontario, Canada .,2 Department of Surgery, Division of Plastic Surgery, Department of Immunology, University of Toronto , Ontario, Canada .,3 TECC Program Sunnybrook Health Sciences Centre, University of Toronto , Toronto, Ontario, Canada
| | - Marc G Jeschke
- 1 Ross Tilley Burn Centre, Sunnybrook Health Sciences Centre , Toronto, Ontario, Canada .,2 Department of Surgery, Division of Plastic Surgery, Department of Immunology, University of Toronto , Ontario, Canada .,3 TECC Program Sunnybrook Health Sciences Centre, University of Toronto , Toronto, Ontario, Canada
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Gupta S, Maclean M, Anderson JG, MacGregor SJ, Meek RMD, Grant MH. Inactivation of micro-organisms isolated from infected lower limb arthroplasties using high-intensity narrow-spectrum (HINS) light. Bone Joint J 2015; 97-B:283-8. [PMID: 25628296 DOI: 10.1302/0301-620x.97b2.35154] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
High-intensity narrow-spectrum (HINS) light is a novel violet-blue light inactivation technology which kills bacteria through a photodynamic process, and has been shown to have bactericidal activity against a wide range of species. Specimens from patients with infected hip and knee arthroplasties were collected over a one-year period (1 May 2009 to 30 April 2010). A range of these microbial isolates were tested for sensitivity to HINS-light. During testing, suspensions of the pathogens were exposed to increasing doses of HINS-light (of 123mW/cm(2) irradiance). Non-light exposed control samples were also used. The samples were then plated onto agar plates and incubated at 37°C for 24 hours before enumeration. Complete inactivation (greater than 4-log10 reduction) was achieved for all of the isolates. The typical inactivation curve showed a slow initial reaction followed by a rapid period of inactivation. The doses of HINS-light required ranged between 118 and 2214 J/cm(2). Gram-positive bacteria were generally found to be more susceptible than Gram-negative. As HINS-light uses visible wavelengths, it can be safely used in the presence of patients and staff. This unique feature could lead to its possible use in the prevention of infection during surgery and post-operative dressing changes. Cite this article: Bone Joint J 2015;97-B:283-8.
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Affiliation(s)
- S Gupta
- Southern General Hospital, 1345 Govan Road, Glasgow, G51 4TF and ROLEST, University of Strathclyde, Royal College Building, 204 George Street, Glasgow, G1 1XW, UK
| | - M Maclean
- ROLEST, University of Strathclyde, Royal College Building, 204 George Street, Glasgow, G1 1XWUK
| | - J G Anderson
- ROLEST, University of Strathclyde, Royal College Building, 204 George Street, Glasgow, G1 1XWUK
| | - S J MacGregor
- ROLEST, University of Strathclyde, Royal College Building, 204 George Street, Glasgow, G1 1XWUK
| | - R M D Meek
- Southern General Hospital, 1345 Govan Road, Glasgow, G51 4TF, UK
| | - M H Grant
- Department of Biomedical Engineering, University of Strathclyde, Wolfson Building, Glasgow G4 0NW, UK
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Maclean M, McKenzie K, Anderson J, Gettinby G, MacGregor S. 405 nm light technology for the inactivation of pathogens and its potential role for environmental disinfection and infection control. J Hosp Infect 2014; 88:1-11. [DOI: 10.1016/j.jhin.2014.06.004] [Citation(s) in RCA: 94] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2013] [Accepted: 06/17/2014] [Indexed: 01/22/2023]
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Tomb RM, Maclean M, Herron PR, Hoskisson PA, MacGregor SJ, Anderson JG. Inactivation of Streptomyces phage ɸC31 by 405 nm light: Requirement for exogenous photosensitizers? BACTERIOPHAGE 2014; 4:e32129. [PMID: 25101216 PMCID: PMC4116386 DOI: 10.4161/bact.32129] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/29/2014] [Revised: 07/04/2014] [Accepted: 07/24/2014] [Indexed: 01/08/2023]
Abstract
Exposure to narrowband violet-blue light around 405 nm wavelength can induce lethal oxidative damage to bacteria and fungi, however effects on viruses are unknown. As photosensitive porphyrin molecules are involved in the microbicidal inactivation mechanism, and since porphyrins are absent in viruses, then any damaging effects of 405 nm light on viruses might appear unlikely. This study used the bacteriophage ɸC31, as a surrogate for non-enveloped double-stranded DNA viruses, to establish whether 405 nm light can induce virucidal effects. Exposure of ɸC31 suspended in minimal media, nutrient-rich media, and porphyrin solution, demonstrated differing sensitivity of the phage. Significant reductions in phage titer occurred when exposed in nutrient-rich media, with ~3-, 5- and 7-log10 reductions achieved after exposure to doses of 0.3, 0.5 and 1.4 kJ/cm2, respectively. When suspended in minimal media a 0.3-log10 reduction (P = 0.012) occurred after exposure to 306 J/cm2: much lower than the 2.7- and > 2.5-log10 reductions achieved with the same dose in nutrient-rich, and porphyrin-supplemented media, suggesting inactivation is accelerated by the photo-activation of light-sensitive components in the media. This study provides the first evidence of the interaction of narrowband 405 nm light with viruses, and demonstrates that viral susceptibility to 405 nm light can be significantly enhanced by involvement of exogenous photosensitive components. The reduced susceptibility of viruses in minimal media, compared with that of other microorganisms, provides further evidence that the antimicrobial action of 405 nm light is predominantly due to the photo-excitation of endogenous photosensitive molecules such as porphyrins within susceptible microorganisms.
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Affiliation(s)
- Rachael M Tomb
- The Robertson Trust Laboratory for Electronic Sterilisation Technologies; University of Strathclyde; Glasgow, Scotland UK ; Strathclyde Institute of Pharmacy and Biomedical Sciences; University of Strathclyde; Glasgow, Scotland UK
| | - Michelle Maclean
- The Robertson Trust Laboratory for Electronic Sterilisation Technologies; University of Strathclyde; Glasgow, Scotland UK
| | - Paul R Herron
- Strathclyde Institute of Pharmacy and Biomedical Sciences; University of Strathclyde; Glasgow, Scotland UK
| | - Paul A Hoskisson
- Strathclyde Institute of Pharmacy and Biomedical Sciences; University of Strathclyde; Glasgow, Scotland UK
| | - Scott J MacGregor
- The Robertson Trust Laboratory for Electronic Sterilisation Technologies; University of Strathclyde; Glasgow, Scotland UK
| | - John G Anderson
- The Robertson Trust Laboratory for Electronic Sterilisation Technologies; University of Strathclyde; Glasgow, Scotland UK
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Zhang Y, Zhu Y, Gupta A, Huang Y, Murray CK, Vrahas MS, Sherwood ME, Baer DG, Hamblin MR, Dai T. Antimicrobial blue light therapy for multidrug-resistant Acinetobacter baumannii infection in a mouse burn model: implications for prophylaxis and treatment of combat-related wound infections. J Infect Dis 2013; 209:1963-71. [PMID: 24381206 DOI: 10.1093/infdis/jit842] [Citation(s) in RCA: 101] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
In this study, we investigated the utility of antimicrobial blue light therapy for multidrug-resistant Acinetobacter baumannii infection in a mouse burn model. A bioluminescent clinical isolate of multidrug-resistant A. baumannii was obtained. The susceptibility of A. baumannii to blue light (415 nm)-inactivation was compared in vitro to that of human keratinocytes. Repeated cycles of sublethal inactivation of bacterial by blue light were performed to investigate the potential resistance development of A. baumannii to blue light. A mouse model of third degree burn infected with A. baumannii was developed. A single exposure of blue light was initiated 30 minutes after bacterial inoculation to inactivate A. baumannii in mouse burns. It was found that the multidrug-resistant A. baumannii strain was significantly more susceptible than keratinocytes to blue light inactivation. Transmission electron microscopy revealed blue light-induced ultrastructural damage in A. baumannii cells. Fluorescence spectroscopy suggested that endogenous porphyrins exist in A. baumannii cells. Blue light at an exposure of 55.8 J/cm(2) significantly reduced the bacterial burden in mouse burns. No resistance development to blue light inactivation was observed in A. baumannii after 10 cycles of sublethal inactivation of bacteria. No significant DNA damage was detected in mouse skin by means of a skin TUNEL assay after a blue light exposure of 195 J/cm(2).
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Affiliation(s)
- Yunsong Zhang
- Wellman Center for Photomedicine Department of Dermatology, Harvard Medical School, Boston Department of Burn and Plastic Surgery, Guangzhou Red Cross Hospital, Jinan University, Guangzhou
| | - Yingbo Zhu
- Wellman Center for Photomedicine School of Medicine, Tongji University, Shanghai, China
| | - Asheesh Gupta
- Wellman Center for Photomedicine Department of Dermatology, Harvard Medical School, Boston Defense Institute of Physiology and Allied Sciences, Delhi, India
| | - Yingying Huang
- Wellman Center for Photomedicine Department of Dermatology, Harvard Medical School, Boston
| | | | - Mark S Vrahas
- Department of Orthopaedic Surgery, Massachusetts General Hospital
| | | | - David G Baer
- US Army Institute of Surgical Research, Fort Sam Houston, Texas
| | - Michael R Hamblin
- Wellman Center for Photomedicine Department of Dermatology, Harvard Medical School, Boston Harvard-MIT Division of Health Sciences and Technology, Cambridge, Massachusetts
| | - Tianhong Dai
- Wellman Center for Photomedicine Department of Dermatology, Harvard Medical School, Boston
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Dai T, Gupta A, Huang YY, Sherwood ME, Murray CK, Vrahas MS, Kielian T, Hamblin MR. Blue light eliminates community-acquired methicillin-resistant Staphylococcus aureus in infected mouse skin abrasions. Photomed Laser Surg 2013; 31:531-8. [PMID: 23406384 DOI: 10.1089/pho.2012.3365] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
BACKGROUND AND OBJECTIVE Bacterial skin and soft tissue infections (SSTI) affect millions of individuals annually in the United States. Treatment of SSTI has been significantly complicated by the increasing emergence of community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) strains. The objective of this study was to demonstrate the efficacy of blue light (415 ± 10 nm) therapy for eliminating CA-MRSA infections in skin abrasions of mice. METHODS The susceptibilities of a CA-MRSA strain (USA300LAC) and human keratinocytes (HaCaT) to blue light inactivation were compared by in vitro culture studies. A mouse model of skin abrasion infection was developed using bioluminescent USA300LAC::lux. Blue light was delivered to the infected mouse skin abrasions at 30 min (acute) and 24 h (established) after the bacterial inoculation. Bioluminescence imaging was used to monitor in real time the extent of infection in mice. RESULTS USA300LAC was much more susceptible to blue light inactivation than HaCaT cells (p=0.038). Approximately 4.75-log10 bacterial inactivation was achieved after 170 J/cm(2) blue light had been delivered, but only 0.29 log10 loss of viability in HaCaT cells was observed. Transmission electron microscopy imaging of USA300LAC cells exposed to blue light exhibited disruption of the cytoplasmic content, disruption of cell walls, and cell debris. In vivo studies showed that blue light rapidly reduced the bacterial burden in both acute and established CA-MRSA infections. More than 2-log10 reduction of bacterial luminescence in the mouse skin abrasions was achieved when 41.4 (day 0) and 108 J/cm(2) (day 1) blue light had been delivered. Bacterial regrowth was observed in the mouse wounds at 24 h after the blue light therapy. CONCLUSIONS There exists a therapeutic window of blue light for bacterial infections where bacteria are selectively inactivated by blue light while host tissue cells are preserved. Blue light therapy has the potential to rapidly reduce the bacterial load in SSTI.
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Affiliation(s)
- Tianhong Dai
- 1 Wellman Center for Photomedicine, Massachusetts General Hospital , Boston, Massachusetts
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Blue light rescues mice from potentially fatal Pseudomonas aeruginosa burn infection: efficacy, safety, and mechanism of action. Antimicrob Agents Chemother 2012; 57:1238-45. [PMID: 23262998 DOI: 10.1128/aac.01652-12] [Citation(s) in RCA: 143] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Blue light has attracted increasing attention due to its intrinsic antimicrobial effect without the addition of exogenous photosensitizers. However, the use of blue light for wound infections has not been established yet. In this study, we demonstrated the efficacy of blue light at 415 nm for the treatment of acute, potentially lethal Pseudomonas aeruginosa burn infections in mice. Our in vitro studies demonstrated that the inactivation rate of P. aeruginosa cells by blue light was approximately 35-fold higher than that of keratinocytes (P = 0.0014). Transmission electron microscopy revealed blue light-mediated intracellular damage to P. aeruginosa cells. Fluorescence spectroscopy suggested that coproporphyrin III and/or uroporphyrin III are possibly the intracellular photosensitive chromophores associated with the blue light inactivation of P. aeruginosa. In vivo studies using an in vivo bioluminescence imaging technique and an area-under-the-bioluminescence-time-curve (AUBC) analysis showed that a single exposure of blue light at 55.8 J/cm(2), applied 30 min after bacterial inoculation to the infected mouse burns, reduced the AUBC by approximately 100-fold in comparison with untreated and infected mouse burns (P < 0.0001). Histological analyses and terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling (TUNEL) assays indicated no significant damage in the mouse skin exposed to blue light at the effective antimicrobial dose. Survival analyses revealed that blue light increased the survival rate of the infected mice from 18.2% to 100% (P < 0.0001). In conclusion, blue light therapy might offer an effective and safe alternative to conventional antimicrobial therapy for P. aeruginosa burn infections.
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Maclean M, Murdoch LE, MacGregor SJ, Anderson JG. Sporicidal effects of high-intensity 405 nm visible light on endospore-forming bacteria. Photochem Photobiol 2012; 89:120-6. [PMID: 22803813 DOI: 10.1111/j.1751-1097.2012.01202.x] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Resistance of bacterial endospores to treatments, including biocides, heat and radiation is a persistent problem. This study investigates the susceptibility of Bacillus and Clostridium endospores to 405 nm visible light, wavelengths which have been shown to induce inactivation of vegetative bacterial cells. Suspensions of B. cereus endospores were exposed to high-intensity 405 nm light generated from a light-emitting diode array and results demonstrate the induction of a sporicidal effect. Up to a 4-log(10) CFU mL(-1) reduction in spore population was achieved after exposure to a dose of 1.73 kJ cm(-2). Similar inactivation kinetics were demonstrated with B. subtilis, B. megaterium and C. difficile endospores. The doses required for inactivation of endospores were significantly higher than those required for inactivation of B. cereus and C. difficile vegetative cells, where ca 4-log(10) CFU mL(-1) reductions were achieved after exposure to doses of 108 and 48 J cm(-2), respectively. The significant increase in dose required for inactivation of endospores compared with vegetative cells is unsurprising due to the notorious resilience of these microbial structures. However, the demonstration that visible light of 405 nm can induce a bactericidal effect against endospores is significant, and could have potential for incorporation into decontamination methods for the removal of bacterial contamination including endospores.
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Affiliation(s)
- Michelle Maclean
- The Robertson Trust Laboratory for Electronic Sterilisation Technologies, University of Strathclyde, Glasgow, Scotland.
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Blue light for infectious diseases: Propionibacterium acnes, Helicobacter pylori, and beyond? Drug Resist Updat 2012; 15:223-36. [PMID: 22846406 DOI: 10.1016/j.drup.2012.07.001] [Citation(s) in RCA: 190] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2012] [Accepted: 07/03/2012] [Indexed: 02/07/2023]
Abstract
Blue light, particularly in the wavelength range of 405-470 nm, has attracted increasing attention due to its intrinsic antimicrobial effect without the addition of exogenous photosensitizers. In addition, it is commonly accepted that blue light is much less detrimental to mammalian cells than ultraviolet irradiation, which is another light-based antimicrobial approach being investigated. In this review, we discussed the blue light sensing systems in microbial cells, antimicrobial efficacy of blue light, the mechanism of antimicrobial effect of blue light, the effects of blue light on mammalian cells, and the effects of blue light on wound healing. It has been reported that blue light can regulate multi-cellular behavior involving cell-to-cell communication via blue light receptors in bacteria, and inhibit biofilm formation and subsequently potentiate light inactivation. At higher radiant exposures, blue light exhibits a broad-spectrum antimicrobial effect against both Gram-positive and Gram-negative bacteria. Blue light therapy is a clinically accepted approach for Propionibacterium acnes infections. Clinical trials have also been conducted to investigate the use of blue light for Helicobacter pylori stomach infections and have shown promising results. Studies on blue light inactivation of important wound pathogenic bacteria, including Staphylococcus aureus and Pseudomonas aeruginosa have also been reported. The mechanism of blue light inactivation of P. acnes, H. pylori, and some oral bacteria is proved to be the photo-excitation of intracellular porphyrins and the subsequent production of cytotoxic reactive oxygen species. Although it may be the case that the mechanism of blue light inactivation of wound pathogens (e.g., S. aureus, P. aeruginosa) is the same as that of P. acnes, this hypothesis has not been rigorously tested. Limited and discordant results have been reported regarding the effects of blue light on mammalian cells and wound healing. Under certain wavelengths and radiant exposures, blue light may cause cell dysfunction by the photo-excitation of blue light sensitizing chromophores, including flavins and cytochromes, within mitochondria or/and peroxisomes. Further studies should be performed to optimize the optical parameters (e.g., wavelength, radiant exposure) to ensure effective and safe blue light therapies for infectious disease. In addition, studies are also needed to verify the lack of development of microbial resistance to blue light.
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