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NicAogáin K, Magill D, O'Donoghue B, Conneely A, Bennett C, O'Byrne CP. Solar irradiance limits the long-term survival of Listeria monocytogenes in seawater. Lett Appl Microbiol 2018; 66:169-174. [PMID: 29281856 DOI: 10.1111/lam.12831] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Revised: 11/15/2017] [Accepted: 11/27/2017] [Indexed: 11/30/2022]
Abstract
Seafood has often been implicated in outbreaks of food-borne illness caused by Listeria monocytogenes but the source of contamination is usually not known. In this study we investigated the possibility that this pathogen could survive in seawater for an extended time period. Freshly collected seawater samples were inoculated with 1 × 108 CFU per ml of L. monocytogenes EGD-e and survival was monitored by plate counting for up to 25 days. When incubated in the dark, either at ambient temperatures (4-14°C) or at 16°C, >104 CFU per ml survivors were present after 25 days. However, when the seawater cell suspensions were exposed to ambient light (solar irradiation) and temperatures, L. monocytogenes lost viability rapidly and no survivors could be detected after the 80 h time point. Both UV-A and visible light in the blue region of the spectrum (470 nm) were found to contribute to this effect. The stress inducible sigma factor σB was found to play a role in survival of L. monocytogenes in seawater. Together these data demonstrate that solar irradiation is a critical determinant of L. monocytogenes survival in marine environments. The data further suggest the possibility of controlling this food-borne pathogen in food-processing environments using visible light. SIGNIFICANCE AND IMPACT OF THE STUDY Listeria monocytogenes is a food-borne bacterial pathogen capable of causing the life-threatening infection, listeriosis. In seafood the route of contamination from the environment is often not well understood as this pathogen is not generally thought to survive well in seawater. Here we provide evidence that L. monocytogenes is capable of surviving for long periods of time in seawater when light is excluded. Sunlight is demonstrated to have a significant effect on the survival of this pathogen in seawater, and both visible (470 nm) and UV-A light are shown to contribute to this effect.
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Affiliation(s)
- K NicAogáin
- Bacterial Stress Response Group, Microbiology, School of Natural Sciences, National University of Ireland, Galway, Ireland
| | - D Magill
- Bacterial Stress Response Group, Microbiology, School of Natural Sciences, National University of Ireland, Galway, Ireland
| | - B O'Donoghue
- Bacterial Stress Response Group, Microbiology, School of Natural Sciences, National University of Ireland, Galway, Ireland
| | - A Conneely
- National Centre for Laser Applications, School of Physics, NUI Galway, Galway, Ireland
| | - C Bennett
- National Centre for Laser Applications, School of Physics, NUI Galway, Galway, Ireland
| | - C P O'Byrne
- Bacterial Stress Response Group, Microbiology, School of Natural Sciences, National University of Ireland, Galway, Ireland
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Wang Y, Wang Y, Wang Y, Murray CK, Hamblin MR, Hooper DC, Dai T. Antimicrobial blue light inactivation of pathogenic microbes: State of the art. Drug Resist Updat 2017; 33-35:1-22. [PMID: 29145971 DOI: 10.1016/j.drup.2017.10.002] [Citation(s) in RCA: 167] [Impact Index Per Article: 23.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Revised: 06/28/2017] [Accepted: 10/02/2017] [Indexed: 12/20/2022]
Abstract
As an innovative non-antibiotic approach, antimicrobial blue light in the spectrum of 400-470nm has demonstrated its intrinsic antimicrobial properties resulting from the presence of endogenous photosensitizing chromophores in pathogenic microbes and, subsequently, its promise as a counteracter of antibiotic resistance. Since we published our last review of antimicrobial blue light in 2012, there have been a substantial number of new studies reported in this area. Here we provide an updated overview of the findings from the new studies over the past 5 years, including the efficacy of antimicrobial blue light inactivation of different microbes, its mechanism of action, synergism of antimicrobial blue light with other angents, its effect on host cells and tissues, the potential development of resistance to antimicrobial blue light by microbes, and a novel interstitial delivery approach of antimicrobial blue light. The potential new applications of antimicrobial blue light are also discussed.
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Affiliation(s)
- Yucheng Wang
- Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA; Cancer Center, Aviation General Hospital, Beijing, China; Department of Medical Oncology, Beijing Institute of Translational Medicine, Chinese Academy of Sciences, Beijing, China
| | - Ying Wang
- Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA; Department of Laser Medicine, Chinese PLA General Hospital, Beijing, China
| | - Yuguang Wang
- Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA; Center of Digital Dentistry, School and Hospital of Stomatology, Peking University, Beijing, China
| | - Clinton K Murray
- Infectious Disease Service, San Antonio Military Medical Center, JBSA-Fort Sam Houston, TX, USA
| | - Michael R Hamblin
- Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - David C Hooper
- Division of Infectious Diseases, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Tianhong Dai
- Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.
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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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Tomb RM, Maclean M, Coia JE, Graham E, McDonald M, Atreya CD, MacGregor SJ, Anderson JG. New Proof-of-Concept in Viral Inactivation: Virucidal Efficacy of 405 nm Light Against Feline Calicivirus as a Model for Norovirus Decontamination. FOOD AND ENVIRONMENTAL VIROLOGY 2017; 9:159-167. [PMID: 28040848 PMCID: PMC5429381 DOI: 10.1007/s12560-016-9275-z] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2016] [Accepted: 12/10/2016] [Indexed: 06/01/2023]
Abstract
The requirement for novel decontamination technologies for use in hospitals is ever present. One such system uses 405 nm visible light to inactivate microorganisms via ROS-generated oxidative damage. Although effective for bacterial and fungal inactivation, little is known about the virucidal effects of 405 nm light. Norovirus (NoV) gastroenteritis outbreaks often occur in the clinical setting, and this study was designed to investigate potential inactivation effects of 405 nm light on the NoV surrogate, feline calicivirus (FCV). FCV was exposed to 405 nm light whilst suspended in minimal and organically-rich media to establish the virucidal efficacy and the effect biologically-relevant material may play in viral susceptibility. Antiviral activity was successfully demonstrated with a 4 Log10 (99.99%) reduction in infectivity when suspended in minimal media evident after a dose of 2.8 kJ cm-2. FCV exposed in artificial faeces, artificial saliva, blood plasma and other organically rich media exhibited an equivalent level of inactivation using between 50-85% less dose of the light, indicating enhanced inactivation when the virus is present in organically-rich biologically-relevant media. Further research in this area could aid in the development of 405 nm light technology for effective NoV decontamination within the hospital environment.
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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, Royal College Building, 204 George Street, Glasgow, G1 1XW, Scotland, UK.
| | - Michelle Maclean
- The Robertson Trust Laboratory for Electronic Sterilisation Technologies (ROLEST), Department of Electronic & Electrical Engineering, University of Strathclyde, Royal College Building, 204 George Street, Glasgow, G1 1XW, Scotland, UK
- Department of Biomedical Engineering, University of Strathclyde, Wolfson Centre, 106 Rottenrow, Glasgow, Scotland, UK
| | - John E Coia
- Department of Clinical Microbiology, Glasgow Royal Infirmary, Glasgow, Scotland, UK
| | - Elizabeth Graham
- School of Veterinary Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, Scotland, UK
| | - Michael McDonald
- School of Veterinary Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, Scotland, UK
| | - Chintamani D Atreya
- Office of Blood Research and Review, Center for Biologics Evaluation and Research, Food and Drug Administration, Bethesda, MD, USA
| | - Scott J MacGregor
- The Robertson Trust Laboratory for Electronic Sterilisation Technologies (ROLEST), Department of Electronic & Electrical Engineering, University of Strathclyde, Royal College Building, 204 George Street, Glasgow, G1 1XW, Scotland, UK
| | - John G Anderson
- The Robertson Trust Laboratory for Electronic Sterilisation Technologies (ROLEST), Department of Electronic & Electrical Engineering, University of Strathclyde, Royal College Building, 204 George Street, Glasgow, G1 1XW, Scotland, UK
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Vollmerhausen T, Conneely A, Bennett C, Wagner V, Victor J, O'Byrne C. Visible and UVA light as a potential means of preventing Escherichia coli biofilm formation in urine and on materials used in urethral catheters. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2017; 170:295-303. [DOI: 10.1016/j.jphotobiol.2017.04.018] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Revised: 04/13/2017] [Accepted: 04/17/2017] [Indexed: 12/25/2022]
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Antibacterial Mechanism of 405-Nanometer Light-Emitting Diode against Salmonella at Refrigeration Temperature. Appl Environ Microbiol 2017; 83:AEM.02582-16. [PMID: 28003197 DOI: 10.1128/aem.02582-16] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2016] [Accepted: 12/10/2016] [Indexed: 11/20/2022] Open
Abstract
The aim of this study was to elucidate the antibacterial mechanism of 405 ± 5-nm light-emitting diode (LED) illumination against Salmonella at 4°C in phosphate-buffered saline (PBS) by determining endogenous coproporphyrin content, DNA oxidation, damage to membrane function, and morphological change. Gene expression levels, including of oxyR, recA, rpoS, sodA, and soxR, were also examined to understand the response of Salmonella to LED illumination. The results showed that Salmonella strains responded differently to LED illumination, revealing that S. enterica serovar Enteritidis (ATCC 13076) and S. enterica subsp. enterica serovar Saintpaul (ATCC 9712) were more susceptible and resistant, respectively, than the 16 other strains tested. There was no difference in the amounts of endogenous coproporphyrin in the two strains. Compared with that in nonilluminated cells, the DNA oxidation levels in illuminated cells increased. In illuminated cells, we observed a loss of efflux pump activity, damage to the glucose uptake system, and changes in membrane potential and integrity. Transmission electron microscopy revealed a disorganization of chromosomes and ribosomes due to LED illumination. The levels of the five genes measured in the nonilluminated and illuminated S Saintpaul cells were upregulated in PBS at a set temperature of 4°C, indicating that increased gene expression levels might be due to a temperature shift and nutrient deficiency rather than to LED illumination. In contrast, only oxyR in S Enteritidis cells was upregulated. Thus, different sensitivities of the two strains to LED illumination were attributed to differences in gene regulation.IMPORTANCE Bacterial inactivation using visible light has recently received attention as a safe and environmentally friendly technology, in contrast with UV light, which has detrimental effects on human health and the environment. This study was designed to understand how 405 ± 5-nm light-emitting diode (LED) illumination kills Salmonella strains at refrigeration temperature. The data clearly demonstrated that the effectiveness of LED illumination on Salmonella strains depended highly on the serotype and strain. Our findings also revealed that its antibacterial mechanism was mainly attributed to DNA oxidation and a loss of membrane functions rather than membrane lipid peroxidation, which has been proposed by other researchers who studied the antibacterial effect of LED illumination by adding exogenous photosensitizers, such as chlorophyllin and hypericin. Therefore, this study suggests that the detailed antibacterial mechanisms of 405-nm LED illumination without additional photosensitizers may differ from that by exogenous photosensitizers. Furthermore, a change in stress-related gene regulation may alter the susceptibility of Salmonella cells to LED illumination at refrigeration temperature. Thus, our study provides new insights into the antibacterial mechanism of 405 ± 5-nm LED illumination on Salmonella cells.
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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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58
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Hessling M, Spellerberg B, Hoenes K. Photoinactivation of bacteria by endogenous photosensitizers and exposure to visible light of different wavelengths - a review on existing data. FEMS Microbiol Lett 2016; 364:fnw270. [PMID: 27915252 DOI: 10.1093/femsle/fnw270] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Revised: 10/29/2016] [Accepted: 11/25/2016] [Indexed: 12/31/2022] Open
Abstract
Visible light has strong disinfectant properties, a fact that is not well known in comparison to the antibacterial properties of UV light. This review compiles the published data on bacterial inactivation caused by visible light and endogenous photosensitizers. It evaluates more than 50 published studies containing information on about 40 different bacterial species irradiated within the spectral range from 380 to 780 nm. In the available data a high variability of photoinactivation sensitivity is observed, which may be caused by undefined illumination conditions. Under aerobic conditions almost all bacteria except spores should be reduced by at least three log-levels with a dose of about 500 J cm-2 of 405 nm irradiation, including both Gram-positive as well as Gram-negative microorganisms. Irradiation of 470 nm is also appropriate for photoinactivating all bacteria species investigated so far but compared to 405 nm illumination it is less effective by a factor between 2 and 5. The spectral dependence of the observed photoinactivation sensitivities gives reason to the assumption that a so far unknown photosensitizer may be involved at 470 nm photoinactivation.
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Affiliation(s)
- M Hessling
- Institute of Medical Engineering and Mechatronics, Ulm University of Applied Sciences, Ulm, Germany
| | - B Spellerberg
- Institute of Medical Microbiology and Hygiene, University of Ulm, Ulm, Germany
| | - K Hoenes
- Institute of Medical Engineering and Mechatronics, Ulm University of Applied Sciences, Ulm, Germany
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Barneck MD, Rhodes NL, de la Presa M, Allen JP, Poursaid AE, Nourian MM, Firpo MA, Langell JT. Violet 405-nm light: a novel therapeutic agent against common pathogenic bacteria. J Surg Res 2016; 206:316-324. [DOI: 10.1016/j.jss.2016.08.006] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2015] [Revised: 06/27/2016] [Accepted: 08/02/2016] [Indexed: 01/12/2023]
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NicAogáin K, O’Byrne CP. The Role of Stress and Stress Adaptations in Determining the Fate of the Bacterial Pathogen Listeria monocytogenes in the Food Chain. Front Microbiol 2016; 7:1865. [PMID: 27933042 PMCID: PMC5120093 DOI: 10.3389/fmicb.2016.01865] [Citation(s) in RCA: 124] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Accepted: 11/04/2016] [Indexed: 12/15/2022] Open
Abstract
The foodborne pathogen Listeria monocytogenes is a highly adaptable organism that can persist in a wide range of environmental and food-related niches. The consumption of contaminated ready-to-eat foods can cause infections, termed listeriosis, in vulnerable humans, particularly those with weakened immune systems. Although these infections are comparatively rare they are associated with high mortality rates and therefore this pathogen has a significant impact on food safety. L. monocytogenes can adapt to and survive a wide range of stress conditions including low pH, low water activity, and low temperature, which makes it problematic for food producers who rely on these stresses for preservation. Stress tolerance in L. monocytogenes can be explained partially by the presence of the general stress response (GSR), a transcriptional response under the control of the alternative sigma factor sigma B (σB) that reconfigures gene transcription to provide homeostatic and protective functions to cope with the stress. Within the host σB also plays a key role in surviving the harsh conditions found in the gastrointestinal tract. As the infection progresses beyond the GI tract L. monocytogenes uses an intracellular infectious cycle to propagate, spread and remain protected from the host's humoral immunity. Many of the virulence genes that facilitate this infectious cycle are under the control of a master transcriptional regulator called PrfA. In this review we consider the environmental reservoirs that enable L. monocytogenes to gain access to the food chain and discuss the stresses that the pathogen must overcome to survive and grow in these environments. The overlap that exists between stress tolerance and virulence is described. We review the principal measures that are used to control the pathogen and point to exciting new approaches that might provide improved means of control in the future.
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Affiliation(s)
| | - Conor P. O’Byrne
- Bacterial Stress Response Group, Microbiology, School of Natural Sciences, College of Science, National University of IrelandGalway, Ireland
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Lacombe A, Niemira BA, Sites J, Boyd G, Gurtler JB, Tyrell B, Fleck M. Reduction of Bacterial Pathogens and Potential Surrogates on the Surface of Almonds Using High-Intensity 405-Nanometer Light. J Food Prot 2016; 79:1840-1845. [PMID: 28221904 DOI: 10.4315/0362-028x.jfp-15-418] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The disinfecting properties of high-intensity monochromatic blue light (MBL) were investigated against Escherichia coli O157:H7, Salmonella , and nonpathogenic bacteria inoculated onto the surface of almonds. MBL was generated from an array of narrow-band 405-nm light-emitting diodes. Almonds were inoculated with higher or lower levels (8 or 5 CFU/g) of pathogenic E. coli O157:H7 and Salmonella , as well as nonpathogenic E. coli K-12 and an avirulent strain of Salmonella Typhimurium, for evaluation as potential surrogates for their respective pathogens. Inoculated almonds were treated with MBL for 0, 1, 2, 4, 6, 8, and 10 min at a working distance of 7 cm. Simultaneous to treatment, cooling air was directed onto the almonds at a rate of 4 ft3/min (1.89 ×10-3 m3/s), sourced through a container of dry ice. An infrared camera was used to monitor the temperature readings after each run. For E. coli K-12, reductions of up to 1.85 or 1.63 log CFU/g were seen for higher and lower inoculum levels, respectively; reductions up to 2.44 and 1.44 log CFU/g were seen for E. coli O157:H7 (higher and lower inoculation levels, respectively). Attenuated Salmonella was reduced by up to 0.54 and 0.97 log CFU/g, whereas pathogenic Salmonella was reduced by up to 0.70 and 0.55 log CFU/g (higher and lower inoculation levels, respectively). Inoculation level did not significantly impact minimum effective treatment times, which ranged from 1 to 4 min. Temperatures remained below ambient throughout treatment, indicating that MBL is a nonthermal antimicrobial process. The nonpathogenic strains of E. coli and Salmonella each responded to MBL in a comparable manner to their pathogenic counterparts. These results suggest that these nonpathogenic strains may be useful in experiments with MBL in which a surrogate is required, and that MBL warrants further investigation as a potential antimicrobial treatment for low-moisture foods.
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Affiliation(s)
- Alison Lacombe
- National College of Natural Medicine, 014 Southeast Porter Street, Portland, Oregon 97201
| | - Brendan A Niemira
- Food Safety and Intervention Technologies Research Unit, U.S. Department of Agriculture, Agricultural Research Service, Eastern Regional Research Center, 600 Mermaid Lane, Wyndmoor, Pennsylvania 19038, USA
| | - Joseph Sites
- Food Safety and Intervention Technologies Research Unit, U.S. Department of Agriculture, Agricultural Research Service, Eastern Regional Research Center, 600 Mermaid Lane, Wyndmoor, Pennsylvania 19038, USA
| | - Glenn Boyd
- Food Safety and Intervention Technologies Research Unit, U.S. Department of Agriculture, Agricultural Research Service, Eastern Regional Research Center, 600 Mermaid Lane, Wyndmoor, Pennsylvania 19038, USA
| | - Joshua B Gurtler
- Food Safety and Intervention Technologies Research Unit, U.S. Department of Agriculture, Agricultural Research Service, Eastern Regional Research Center, 600 Mermaid Lane, Wyndmoor, Pennsylvania 19038, USA
| | - Breanna Tyrell
- Food Safety and Intervention Technologies Research Unit, U.S. Department of Agriculture, Agricultural Research Service, Eastern Regional Research Center, 600 Mermaid Lane, Wyndmoor, Pennsylvania 19038, USA
| | - Melissa Fleck
- Food Safety and Intervention Technologies Research Unit, U.S. Department of Agriculture, Agricultural Research Service, Eastern Regional Research Center, 600 Mermaid Lane, Wyndmoor, Pennsylvania 19038, USA
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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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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 (READING, ENGLAND) 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] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Accepted: 08/05/2016] [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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O'Donoghue B, NicAogáin K, Bennett C, Conneely A, Tiensuu T, Johansson J, O'Byrne C. Blue-Light Inhibition of Listeria monocytogenes Growth Is Mediated by Reactive Oxygen Species and Is Influenced by σB and the Blue-Light Sensor Lmo0799. Appl Environ Microbiol 2016; 82:4017-4027. [PMID: 27129969 PMCID: PMC4907204 DOI: 10.1128/aem.00685-16] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2016] [Accepted: 04/19/2016] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Listeria monocytogenes senses blue light via the flavin mononucleotide-containing sensory protein Lmo0799, leading to activation of the general stress response sigma factor SigB (σ(B)). In this study, we investigated the physiological response of this foodborne pathogen to blue light. We show that blue light (460 to 470 nm) doses of 1.5 to 2 mW cm(-2) cause inhibition of growth on agar-based and liquid culture media. The inhibitory effects are dependent on cell density, with reduced effects evident when high cell numbers are present. The addition of 20 mM dimethylthiourea, a scavenger of reactive oxygen species, or catalase to the medium reverses the inhibitory effects of blue light, suggesting that growth inhibition is mediated by the formation of reactive oxygen species. A mutant strain lacking σ(B) (ΔsigB) was found to be less inhibited by blue light than the wild type, likely indicating the energetic cost of deploying the general stress response. When a lethal dose of light (8 mW cm(-2)) was applied to cells, the ΔsigB mutant displayed a marked increase in sensitivity to light compared to the wild type. To investigate the role of the blue-light sensor Lmo0799, mutants were constructed that either had a deletion of the gene (Δlmo0799) or alteration in a conserved cysteine residue at position 56, which is predicted to play a pivotal role in the photocycle of the protein (lmo0799 C56A). Both mutants displayed phenotypes similar to the ΔsigB mutant in the presence of blue light, providing genetic evidence that residue 56 is critical for light sensing in L. monocytogenes Taken together, these results demonstrate that L. monocytogenes is inhibited by blue light in a manner that depends on reactive oxygen species, and they demonstrate clear light-dependent phenotypes associated with σ(B) and the blue-light sensor Lmo0799. IMPORTANCE Listeria monocytogenes is a bacterial foodborne pathogen that can cause life-threatening infections in humans. It is known to be able to sense and respond to visible light. In this study, we examine the effects of blue light on the growth and survival of this pathogen. We show that growth can be inhibited at comparatively low doses of blue light, and that at higher doses, L. monocytogenes cells are killed. We present evidence suggesting that blue light inhibits this organism by causing the production of reactive oxygen species, such as hydrogen peroxide. We help clarify the mechanism of light sensing by constructing a "blind" version of the blue-light sensor protein. Finally, we show that activation of the general stress response by light has a negative effect on growth, probably because cellular resources are diverted into protective mechanisms rather than growth.
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Affiliation(s)
- Beth O'Donoghue
- Bacterial Stress Response Group, Microbiology, School of Natural Sciences, National University of Ireland, Galway, Galway, Ireland
| | - Kerrie NicAogáin
- Bacterial Stress Response Group, Microbiology, School of Natural Sciences, National University of Ireland, Galway, Galway, Ireland
| | - Claire Bennett
- National Centre for Laser Applications, School of Physics, National University of Ireland, Galway, Galway, Ireland
| | - Alan Conneely
- National Centre for Laser Applications, School of Physics, National University of Ireland, Galway, Galway, Ireland
| | - Teresa Tiensuu
- Department of Molecular Biology, Molecular Infection Medicine, Sweden, and Umeå Centre for Microbial Research, Umeå University, Umeå, Sweden
| | - Jörgen Johansson
- Department of Molecular Biology, Molecular Infection Medicine, Sweden, and Umeå Centre for Microbial Research, Umeå University, Umeå, Sweden
| | - Conor O'Byrne
- Bacterial Stress Response Group, Microbiology, School of Natural Sciences, National University of Ireland, Galway, Galway, Ireland
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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: 106] [Impact Index Per Article: 13.3] [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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66
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Lui GY, Roser D, Corkish R, Ashbolt NJ, Stuetz R. Point-of-use water disinfection using ultraviolet and visible light-emitting diodes. THE SCIENCE OF THE TOTAL ENVIRONMENT 2016; 553:626-635. [PMID: 26967007 DOI: 10.1016/j.scitotenv.2016.02.039] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Revised: 02/05/2016] [Accepted: 02/05/2016] [Indexed: 06/05/2023]
Abstract
Improvements in point-of-use (POU) drinking water disinfection technologies for remote and regional communities are urgently needed. Conceptually, UV-C light-emitting diodes (LEDs) overcome many drawbacks of low-pressure mercury tube based UV devices, and UV-A or visible light LEDs also show potential. To realistically evaluate the promise of LED disinfection, our study assessed the performance of a model 1.3 L reactor, similar in size to solar disinfection bottles. In all, 12 different commercial or semi-commercial LED arrays (270-740 nm) were compared for their ability to inactivate Escherichia coli K12 ATCC W3110 and Enterococcus faecalis ATCC 19433 over 6h. Five log10 and greater reductions were consistently achieved using the 270, 365, 385 and 405 nm arrays. The output of the 310 nm array was insufficient for useful disinfection while 430 and 455 nm performance was marginal (≈ 4.2 and 2.3-log10s E. coli and E. faecalis over the 6h). No significant disinfection was observed with the 525, 590, 623, 660 and 740 nm arrays. Delays in log-phase inactivation of E. coli were observed, particularly with UV-A wavelengths. The radiation doses required for >3-log10 reduction of E. coli and E. faecalis differed by 10 fold at 270 nm but only 1.5-2.5 fold at 365-455 nm. Action spectra, consistent with the literature, were observed with both indicators. The design process revealed cost and technical constraints pertaining to LED electrical efficiency, availability and lifetime. We concluded that POU LED disinfection using existing LED technology is already technically possible. UV-C LEDs offer speed and energy demand advantages, while UV-A/violet units are safer. Both approaches still require further costing and engineering development. Our study provides data needed for such work.
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Affiliation(s)
- Gough Yumu Lui
- UNSW Water Research Centre, School of Civil and Environmental Engineering, University of New South Wales, Sydney, NSW 2052, Australia; School of Photovoltaics and Renewable Energy Engineering, University of New South Wales, Sydney, NSW 2052, Australia.
| | - David Roser
- UNSW Water Research Centre, School of Civil and Environmental Engineering, University of New South Wales, Sydney, NSW 2052, Australia.
| | - Richard Corkish
- School of Photovoltaics and Renewable Energy Engineering, University of New South Wales, Sydney, NSW 2052, Australia.
| | - Nicholas J Ashbolt
- UNSW Water Research Centre, School of Civil and Environmental Engineering, University of New South Wales, Sydney, NSW 2052, Australia; School of Public Health, South Academic Building, University of Alberta, Edmonton, Alberta T6G 2G7, Canada.
| | - Richard Stuetz
- UNSW Water Research Centre, School of Civil and Environmental Engineering, University of New South Wales, Sydney, NSW 2052, Australia.
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Kim MJ, Mikš-Krajnik M, Kumar A, Yuk HG. Inactivation by 405 ± 5 nm light emitting diode on Escherichia coli O157:H7, Salmonella Typhimurium, and Shigella sonnei under refrigerated condition might be due to the loss of membrane integrity. Food Control 2016. [DOI: 10.1016/j.foodcont.2015.05.012] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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68
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Buchovec I, Lukseviciute V, Marsalka A, Reklaitis I, Luksiene Z. Effective photosensitization-based inactivation of Gram (−) food pathogens and molds using the chlorophyllin–chitosan complex: towards photoactive edible coatings to preserve strawberries. Photochem Photobiol Sci 2016; 15:506-16. [DOI: 10.1039/c5pp00376h] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
This study is focused on the novel approaches to enhance the inactivation of the Gram (−) food pathogen Salmonella enterica and harmful molds in vitro and on the surface of strawberries using the chlorophyllin–chitosan complex.
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Affiliation(s)
- Irina Buchovec
- Vilnius University
- Institute of Applied Research
- Vilnius
- Lithuania
| | | | - Arunas Marsalka
- Vilnius University
- Department of General Physics and Spectroscopy
- Vilnius
- Lithuania
| | - Ignas Reklaitis
- Vilnius University
- Institute of Applied Research
- Vilnius
- Lithuania
| | - Zivile Luksiene
- Vilnius University
- Institute of Applied Research
- Vilnius
- Lithuania
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69
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Rhodes NLR, de la Presa M, Barneck MD, Poursaid A, Firpo MA, Langell JT. Violet 405 nm light: A novel therapeutic agent against β-lactam-resistant Escherichia coli. Lasers Surg Med 2015; 48:311-7. [PMID: 26711625 DOI: 10.1002/lsm.22457] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/25/2015] [Indexed: 12/30/2022]
Abstract
BACKGROUND AND OBJECTIVE Approximately 1.7 million patients are affected by hospital-acquired infections every year in the United States. The increasing prevalence of multidrug-resistant bacteria associated with these infections prompts the investigation of alternative sterilization and antibacterial therapies. One method currently under investigation is the antibacterial properties of visible light. This study examines the effect of a visible light therapy (VLT) on β-lactam-resistant Escherichia coli, a common non-skin flora pathogen responsible for a large percentage of indwelling medical device-associated clinical infection. MATERIALS AND METHODS 405 nm light-emitting diodes were used to treat varying concentrations of a common laboratory E. coli K-12 strain transformed with the pCIG mammalian expression vector. This conferred ampicillin resistance via expression of the β-lactamase gene. Bacteria were grown on sterile polystyrene Petri dishes plated with Luria-Bertani broth. Images of bacterial growth colonies on plates were processed and analyzed using ImageJ. Irradiance levels between 2.89 ± 0.19 and 9.45 ± 0.63 mW cm(-2) and radiant exposure levels between 5.60 ± 0.39 and 136.91 ± 4.06 J cm(-2) were tested. RESULTS VLT with variable irradiance and constant treatment time (120 minutes) demonstrated significant reduction (P < 0.001) in E. coli between an irradiance of 2.89 mW cm(-2) (81.70%) and 9.37 mW cm(-2) (100.00%). Similar results were found with variable treatment time with constant irradiance. Log10 reduction analysis produced between 1.98 ± 0.53 (60 minute treatment) and 6.27 ± 0.54 (250 minute treatment) log10 reduction in bacterial concentration (P < 0.001). CONCLUSIONS We have successfully demonstrated a significant bacterial reduction using high intensity 405 nm light. Illustrating the efficacy of this technology against a β-lactam-resistant E. coli is especially relevant to the need for novel methods of sterilization in healthcare settings. These results suggest that VLT using 405 nm light could be a suitable clinical option for eradication of β-lactam-resistant E. coli. Visible light kills statistically significant concentrations of E. coli. Antibiotic-resistant Gram-negative bacteria exhibits sensitivity to 405 nm light. Greater than 6 log10 reduction in β-lactam-resistant E. coli when treated with visible light therapy.
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Affiliation(s)
| | - Martin de la Presa
- Department of General Surgery, University of Utah, Salt Lake City, Utah, 84132
| | - Mitchell D Barneck
- School of Medicine, Oregon Health and Sciences University, Portland, Oregon, 97239
| | - Ahrash Poursaid
- Department of Bioengineering, University of Utah, Salt Lake City, Utah, 84112
| | - Matthew A Firpo
- Department of General Surgery, University of Utah, Salt Lake City, Utah, 84132
| | - John T Langell
- Department of Bioengineering, University of Utah, Salt Lake City, Utah, 84112.,Department of General Surgery, University of Utah, Salt Lake City, Utah, 84132
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70
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Kumar A, Ghate V, Kim M, Zhou W, Khoo G, Yuk H. Antibacterial efficacy of 405, 460 and 520 nm light emitting diodes on Lactobacillus plantarum
, Staphylococcus aureus
and Vibrio parahaemolyticus. J Appl Microbiol 2015; 120:49-56. [DOI: 10.1111/jam.12975] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2015] [Revised: 09/24/2015] [Accepted: 10/12/2015] [Indexed: 11/29/2022]
Affiliation(s)
- A. Kumar
- Food Science and Technology Programme; Department of Chemistry; National University of Singapore; Singapore Singapore
| | - V. Ghate
- Food Science and Technology Programme; Department of Chemistry; National University of Singapore; Singapore Singapore
| | - M.J. Kim
- Food Science and Technology Programme; Department of Chemistry; National University of Singapore; Singapore Singapore
| | - W. Zhou
- Food Science and Technology Programme; Department of Chemistry; National University of Singapore; Singapore Singapore
- National University of Singapore (Suzhou) Research Institute; Suzhou Jiangsu China
| | - G.H. Khoo
- Post-Harvest Technology Department; Technology & Industry Development Group; Agri-Food & Veterinary Authority of Singapore; Singapore Singapore
| | - H.G. Yuk
- Food Science and Technology Programme; Department of Chemistry; National University of Singapore; Singapore Singapore
- National University of Singapore (Suzhou) Research Institute; Suzhou Jiangsu China
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71
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Synergistic efficacy of 405 nm light and chlorinated disinfectants for the enhanced decontamination of Clostridium difficile spores. Anaerobe 2015; 37:72-7. [PMID: 26708703 DOI: 10.1016/j.anaerobe.2015.12.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Accepted: 12/13/2015] [Indexed: 01/05/2023]
Abstract
The ability of Clostridium difficile to form highly resilient spores which can survive in the environment for prolonged periods causes major contamination problems. Antimicrobial 405 nm light is being developed for environmental decontamination within hospitals, however further information relating to its sporicidal efficacy is required. This study aims to establish the efficacy of 405 nm light for inactivation of C. difficile vegetative cells and spores, and to establish whether spore susceptibility can be enhanced by the combined use of 405 nm light with low concentration chlorinated disinfectants. Vegetative cells and spore suspensions were exposed to increasing doses of 405 nm light (at 70-225 mW/cm(2)) to establish sensitivity. A 99.9% reduction in vegetative cell population was demonstrated with a dose of 252 J/cm(2), however spores demonstrated higher resilience, with a 10-fold increase in required dose. Exposures were repeated with spores suspended in the hospital disinfectants sodium hypochlorite, Actichlor and Tristel at non-lethal concentrations (0.1%, 0.001% and 0.0001%, respectively). Enhanced sporicidal activity was achieved when spores were exposed to 405 nm light in the presence of the disinfectants, with a 99.9% reduction achieved following exposure to 33% less light dose than required when exposed to 405 nm light alone. In conclusion, C. difficile vegetative cells and spores can be successfully inactivated using 405 nm light, the sporicidal efficacy can be significantly enhanced when exposed in the presence of low concentration chlorinated disinfectants. Further research may lead to the potential use of 405 nm light decontamination in combination with selected hospital disinfectants to enhance C. difficile cleaning and infection control procedures.
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72
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Effect of organic acids on the photodynamic inactivation of selected foodborne pathogens using 461 nm LEDs. Food Control 2015. [DOI: 10.1016/j.foodcont.2015.04.029] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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73
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Kumar A, Ghate V, Kim MJ, Zhou W, Khoo GH, Yuk HG. Kinetics of bacterial inactivation by 405nm and 520nm light emitting diodes and the role of endogenous coproporphyrin on bacterial susceptibility. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2015; 149:37-44. [DOI: 10.1016/j.jphotobiol.2015.05.005] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2015] [Revised: 05/04/2015] [Accepted: 05/06/2015] [Indexed: 10/23/2022]
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74
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Bumah VV, Masson-Meyers DS, Enwemeka CS. Blue 470 nm light suppresses the growth of Salmonella enterica
and methicillin-resistant Staphylococcus aureus
(MRSA) in vitro. Lasers Surg Med 2015; 47:595-601. [DOI: 10.1002/lsm.22385] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/04/2015] [Indexed: 12/23/2022]
Affiliation(s)
- Violet V. Bumah
- College of Health Sciences; University of Wisconsin-Milwaukee; Milwaukee Wisconsin 53211
| | | | - Chukuka S. Enwemeka
- College of Health Sciences; University of Wisconsin-Milwaukee; Milwaukee Wisconsin 53211
- San Diego State University; San Diego; California 92182
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75
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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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76
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Rapid inactivation of Mycobacterium and nocardia species before identification using matrix-assisted laser desorption ionization-time of flight mass spectrometry. J Clin Microbiol 2014; 52:3654-9. [PMID: 25078917 DOI: 10.1128/jcm.01728-14] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The identification of mycobacteria outside biocontainment facilities requires that the organisms first be rendered inactive. Exposure to 70% ethanol (EtOH) either before or after mechanical disruption was evaluated in order to establish a safe, effective, and rapid inactivation protocol that is compatible with identification of Mycobacterium and Nocardia species using matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). A combination of 5 min of bead beating in 70% EtOH followed by a 10-min room temperature incubation period was found to be rapidly bactericidal and provided high-quality spectra compared to spectra obtained directly from growth on solid media. The age of the culture, the stability of the refrigerated or frozen lysates, and freeze-thaw cycles did not adversely impact the quality of the spectra or the identification obtained.
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77
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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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78
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Birmpa A, Vantarakis A, Paparrodopoulos S, Whyte P, Lyng J. Efficacy of three light technologies for reducing microbial populations in liquid suspensions. BIOMED RESEARCH INTERNATIONAL 2014; 2014:673939. [PMID: 24724092 PMCID: PMC3960526 DOI: 10.1155/2014/673939] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/29/2013] [Accepted: 01/24/2014] [Indexed: 12/02/2022]
Abstract
The aim of the current study was to evaluate the effectiveness of three nonthermal light technologies (NUV-Vis, continuous UV, and HILP) on their ability to inactivate Escherichia coli K12 and Listeria innocua. E. coli K12 was selected as a representative microorganism for the enterohaemorrhagic foodborne pathogen E. coli O157:H7 and L. innocua as a surrogate microorganism for the common foodborne pathogen Listeria monocytogenes, respectively. The liquid matrix used for the disinfection experiments was a liquid matrix (MRD solution). The results of the present study show that the HILP treatment inactivated both E. coli and L. innocua more rapidly and effectively than either continuous UV-C or NUV-vis treatment. With HILP at 2.5 cm from the lamp, E. coli and L. innocua populations were reduced by 3.07 and 3.77 log10 CFU/mL, respectively, after a 5 sec treatment time, and were shown to be below the limit of detection (<0.22 log10 CFU/mL) following 30 sec exposure to HILP (106.2 J/cm(2)). These studies demonstrate the bactericidal efficacy of alternative nonthermal light technologies and their potential as decontamination strategies in the food industry.
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Affiliation(s)
- Angeliki Birmpa
- Environmental Microbiology Unit, Department of Public Health, Medical School, University of Patras, Rio, 26500 Patras, Greece
| | - Apostolos Vantarakis
- Environmental Microbiology Unit, Department of Public Health, Medical School, University of Patras, Rio, 26500 Patras, Greece
| | - Spyros Paparrodopoulos
- Environmental Microbiology Unit, Department of Public Health, Medical School, University of Patras, Rio, 26500 Patras, Greece
| | - Paul Whyte
- School of Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland
| | - James Lyng
- School of Agriculture and Food Science, University College Dublin, Belfield, Dublin 4, Ireland
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79
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Enhanced inactivation of Escherichia coli and Listeria monocytogenes by exposure to 405nm light under sub-lethal temperature, salt and acid stress conditions. Int J Food Microbiol 2014; 170:91-8. [DOI: 10.1016/j.ijfoodmicro.2013.10.016] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2013] [Accepted: 10/24/2013] [Indexed: 01/31/2023]
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80
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Sheinman V, Rudnitsky A, Toichuev R, Eshiev A, Abdullaeva S, Egemkulov T, Zalevsky Z. Implantable photonic devices for improved medical treatments. JOURNAL OF BIOMEDICAL OPTICS 2014; 19:108001. [PMID: 25279540 DOI: 10.1117/1.jbo.19.10.108001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2014] [Accepted: 09/05/2014] [Indexed: 06/03/2023]
Abstract
An evolving area of biomedical research is related to the creation of implantable units that provide various possibilities for imaging, measurement, and the monitoring of a wide range of diseases and intrabody phototherapy. The units can be autonomic or built-in in some kind of clinically applicable implants. Because of specific working conditions in the live body, such implants must have a number of features requiring further development. This topic can cause wide interest among developers of optical, mechanical, and electronic solutions in biomedicine. We introduce preliminary clinical trials obtained with an implantable pill and devices that we have developed. The pill and devices are capable of applying in-body phototherapy, low-level laser therapy, blue light (450 nm) for sterilization, and controlled injection of chemicals. The pill is also capable of communicating with an external control box, including the transmission of images from inside the patient’s body. In this work, our pill was utilized for illumination of the sinus-carotid zone in dog and red light influence on arterial pressure and heart rate was demonstrated. Intrabody liver tissue laser ablation and nanoparticle-assisted laser ablation was investigated. Sterilization effect of intrabody blue light illumination was applied during a maxillofacial phlegmon treatment.
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Affiliation(s)
- Victor Sheinman
- Bar-Ilan University, Faculty of Engineering, Ramat-Gan 5290002, Israel
| | - Arkady Rudnitsky
- Bar-Ilan University, Faculty of Engineering, Ramat-Gan 5290002, Israel
| | - Rakhmanbek Toichuev
- Institute of Medical Problems, Southern Branch of National Academy of Sciences of the Kyrgyz Republic, 723506 Osh, Kyrgyz Republic
| | | | | | | | - Zeev Zalevsky
- Bar-Ilan University, Faculty of Engineering, Ramat-Gan 5290002, Israel
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Yin R, Dai T, Avci P, Jorge AES, de Melo WCMA, Vecchio D, Huang YY, Gupta A, Hamblin MR. Light based anti-infectives: ultraviolet C irradiation, photodynamic therapy, blue light, and beyond. Curr Opin Pharmacol 2013; 13:731-62. [PMID: 24060701 DOI: 10.1016/j.coph.2013.08.009] [Citation(s) in RCA: 164] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2013] [Revised: 08/15/2013] [Accepted: 08/20/2013] [Indexed: 12/26/2022]
Abstract
Owing to the worldwide increase in antibiotic resistance, researchers are investigating alternative anti-infective strategies to which it is supposed microorganisms will be unable to develop resistance. Prominent among these strategies, is a group of approaches which rely on light to deliver the killing blow. As is well known, ultraviolet light, particularly UVC (200-280 nm), is germicidal, but it has not been much developed as an anti-infective approach until recently, when it was realized that the possible adverse effects to host tissue were relatively minor compared to its high activity in killing pathogens. Photodynamic therapy is the combination of non-toxic photosensitizing dyes with harmless visible light that together produce abundant destructive reactive oxygen species (ROS). Certain cationic dyes or photosensitizers have good specificity for binding to microbial cells while sparing host mammalian cells and can be used for treating many localized infections, both superficial and even deep-seated by using fiber optic delivered light. Many microbial cells are highly sensitive to killing by blue light (400-470 nm) due to accumulation of naturally occurring photosensitizers such as porphyrins and flavins. Near infrared light has also been shown to have antimicrobial effects against certain species. Clinical applications of these technologies include skin, dental, wound, stomach, nasal, toenail and other infections which are amenable to effective light delivery.
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Affiliation(s)
- Rui Yin
- Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, MA, USA; Department of Dermatology, Harvard Medical School, Boston, MA, USA; Department of Dermatology, Southwest Hospital, Third Military Medical University, Chongqing, China
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82
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McKenzie K, Maclean M, Timoshkin IV, Endarko E, MacGregor SJ, Anderson JG. Photoinactivation of bacteria attached to glass and acrylic surfaces by 405 nm light: potential application for biofilm decontamination. Photochem Photobiol 2013; 89:927-35. [PMID: 23550978 DOI: 10.1111/php.12077] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2013] [Accepted: 03/25/2013] [Indexed: 11/30/2022]
Abstract
Attachment of bacteria to surfaces and subsequent biofilm formation remains a major cause of cross-contamination capable of inducing both food-related illness and nosocomial infections. Resistance to many current disinfection technologies means facilitating their removal is often difficult. The aim of this study was to investigate the efficacy of 405 nm light for inactivation of bacterial attached as biofilms to glass and acrylic. Escherichia coli biofilms (10(3)-10(8) CFU mL(-1)) were generated on glass and acrylic surfaces and exposed for increasing times to 405 nm light (5-60 min) at ca 140 mW cm(-2). Successful inactivation of biofilms has been demonstrated, with results highlighting complete/near-complete inactivation (up to 5 log10 reduction on acrylic and 7 log10 on glass). Results also highlight that inactivation of bacterial biofilms could be achieved whether the biofilm was on the upper "directly exposed" surface or "indirectly exposed" underside surface. Statistically significant inactivation was also shown with a range of other microorganisms associated with biofilm formation (Staphylococcus aureus, Pseudomonas aeruginosa and Listeria monocytogenes). Results from this study have demonstrated significant inactivation of bacteria ranging from monolayers to densely populated biofilms using 405 nm light, highlighting that with further development this technology may have potential applications for biofilm decontamination in food and clinical settings.
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Affiliation(s)
- Karen McKenzie
- Department of Electronic and Electrical Engineering, ROLEST, University of Strathclyde, Glasgow, Scotland.
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83
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Guffey JS, Payne W, Jones T, Martin K. Evidence of resistance development by Staphylococcus aureus to an in vitro, multiple stage application of 405 nm light from a supraluminous diode array. Photomed Laser Surg 2013; 31:179-82. [PMID: 23484587 DOI: 10.1089/pho.2012.3450] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
OBJECTIVE The aim of this study was to determine whether Staphylococcus aureus could develop a resistance to 405 nm light. BACKGROUND DATA Research indicates that certain wavelengths and treatment parameters of light promote growth of bacteria; however, our earlier work indicated that blue light effectively inactivates growth of S. aureus in vitro. METHODS S. aureus was tested because of its frequent isolation from skin infections and wounds. The organism was treated with 405 nm light from supraluminous diodes at a dose of 9 J/cm(2). RESULTS As anticipated, blue light produced a significant (p≤0.05) inactivation of S. aureus growth. Subsequent applications of blue light to subcultured generations of S. aureus were increasingly effective through four stages (generations). Beginning with stage five, a decrease in effectiveness (resistance) was observed. CONCLUSIONS Appropriate doses of 405-nm blue light inhibit the growth of S. aureus in vitro. This research does suggest that S. aureus may be capable of developing resistance to blue light irradiation.
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Affiliation(s)
- J Stephen Guffey
- Department of Physical Therapy, Arkansas State University, State University, ArkaAR 72467, USA.
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84
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Wang Z, Hao Y, Wang Z, Liu X, Zhang Q, Zhu D. Double-grating displacement structure for improving the light extraction efficiency of LEDs. ScientificWorldJournal 2012; 2012:515468. [PMID: 23118613 PMCID: PMC3478720 DOI: 10.1100/2012/515468] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2012] [Accepted: 09/18/2012] [Indexed: 11/17/2022] Open
Abstract
To improve the light extraction efficiency of light-emitting diodes (LEDs), grating patterns were etched on GaN and silver film surfaces. The grating-patterned surface etching enabled the establishment of an LED model with a double-grating displacement structure that is based on the surface plasmon resonance principle. A numerical simulation was conducted using the finite difference time domain method. The influence of different grating periods for GaN surface and silver film thickness on light extraction efficiency was analyzed. The light extraction efficiency of LEDs was highest when the grating period satisfied grating coupling conditions. The wavelength of the highest value was also close to the light wavelength of the medium. The plasmon resonance frequencies on both sides of the silver film were affected by silver film thickness. With increasing film thickness, plasmon resonance frequency tended toward the same value and light extraction efficiency reached its maximum. When the grating period for the GaN surface was 365 nm and the silver film thickness was 390 nm, light extraction efficiency reached a maximum of 55%.
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Affiliation(s)
- Zhibin Wang
- College of Electrical Engineering, Yanshan University, Qinhuangdao 066004, China. wzb
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85
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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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