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Wang C, Nambu T, Takigawa H, Maruyama H, Mashimo C, Okinaga T. Effect of 5-aminolevulinic acid-mediated photodynamic therapy against Fusobacterium nucleatum in periodontitis prevention. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY. B, BIOLOGY 2024; 256:112926. [PMID: 38714001 DOI: 10.1016/j.jphotobiol.2024.112926] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2024] [Revised: 04/20/2024] [Accepted: 04/25/2024] [Indexed: 05/09/2024]
Abstract
Periodontitis, a chronic infectious disease leading to gingival atrophy and potential tooth loss through alveolar bone resorption, is closely linked to the oral microbiome. Fusobacterium nucleatum, known to facilitate late-stage bacterial colonization in the oral microbiome, plays a crucial role in the onset of periodontitis. Controlling F. nucleatum abundance is vital for preventing and treating periodontal disease. Photodynamic therapy combined with 5-aminolevulinic acid (ALA-PDT) has been reported to be bactericidal against Pseudomonas aeruginosa and Staphylococcus aureus. We aimed to investigate the bactericidal potential of ALA-PDT against F. nucleatum, which was evaluated by examining the impact of varying 5-ALA concentrations, culture time, and light intensity. After ALA-PDT treatment, DNA was extracted from interdental plaque samples collected from 10 volunteers and sequenced using the Illumina MiSeq platform. To further elucidate the bactericidal mechanism of ALA-PDT, porphyrins were extracted from F. nucleatum following cultivation with 5-ALA and subsequently analyzed using fluorescence spectra. ALA-PDT showed a significant bactericidal effect against F. nucleatum. Its bactericidal activity demonstrated a positive correlation with culture time and light intensity. Microbiota analysis revealed no significant alteration in α-diversity within the ALA-PDT group, although there was a noteworthy reduction in the proportion of the genus Fusobacterium. Furthermore, fluorescence spectral analysis indicated that F. nucleatum produced an excitable photosensitive substance following the addition of 5-ALA. Overall, if further studies confirm these results, this combined therapy could be an effective strategy for reducing the prevalence of periodontitis.
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Affiliation(s)
- Chao Wang
- Graduate School of Dentistry (Bacteriology), Osaka Dental University, Hirakata, Osaka 573-1121, Japan
| | - Takayuki Nambu
- Department of Microbiology, Osaka Dental University, Hirakata, Osaka 573-1121, Japan.
| | - Hiroki Takigawa
- Department of Microbiology, Osaka Dental University, Hirakata, Osaka 573-1121, Japan
| | - Hugo Maruyama
- Department of Microbiology, Osaka Dental University, Hirakata, Osaka 573-1121, Japan
| | - Chiho Mashimo
- Department of Microbiology, Osaka Dental University, Hirakata, Osaka 573-1121, Japan
| | - Toshinori Okinaga
- Department of Microbiology, Osaka Dental University, Hirakata, Osaka 573-1121, Japan.
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El-Gendy AO, Ezzat S, Samad FA, Dabbous OA, Dahm J, Hamblin MR, Mohamed T. Studying the viability and growth kinetics of vancomycin-resistant Enterococcus faecalis V583 following femtosecond laser irradiation (420-465 nm). Lasers Med Sci 2024; 39:144. [PMID: 38809462 PMCID: PMC11136855 DOI: 10.1007/s10103-024-04080-5] [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: 01/02/2024] [Accepted: 05/12/2024] [Indexed: 05/30/2024]
Abstract
Enterococcus faecalis is among the most resistant bacteria found in infected root canals. The demand for cutting-edge disinfection methods has rekindled research on photoinactivation with visible light. This study investigated the bactericidal activity of femtosecond laser irradiation against vancomycin-resistant Enterococcus faecalis V583 (VRE). The effect of parameters such as wavelength and energy density on the viability and growth kinetics of VRE was studied to design an optimized laser-based antimicrobial photoinactivation approach without any prior addition of exogenous photosensitizers. The most effective wavelengths were 430 nm and 435 nm at a fluence of 1000 J/cm2, causing a nearly 2-log reduction (98.6% and 98.3% inhibition, respectively) in viable bacterial counts. The colony-forming units and growth rate of the laser-treated cultures were progressively decreased as energy density or light dose increased at 445 nm but reached a limit at 1250 J/cm2. At a higher fluence of 2000 J/cm2, the efficacy was reduced due to a photobleaching phenomenon. Our results highlight the importance of optimizing laser exposure parameters, such as wavelength and fluence, in bacterial photoinactivation experiments. To our knowledge, this is the first study to report an optimized wavelength for the inactivation of VRE using visible femtosecond laser light.
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Affiliation(s)
- Ahmed O El-Gendy
- Laser Institute for Research and Applications LIRA, Beni-Suef University, Beni-Suef, 62511, Egypt
- Department of Microbiology and Immunology, Faculty of Pharmacy, Beni-Suef University, Beni-Suef, 62514, Egypt
| | - Sarah Ezzat
- Department of Microbiology and Immunology, Faculty of Pharmacy, Beni-Suef University, Beni-Suef, 62514, Egypt
| | - Fatma Abdel Samad
- Department of Microbiology and Immunology, Faculty of Pharmacy, Beni-Suef University, Beni-Suef, 62514, Egypt
| | - Ola Ali Dabbous
- Department of Medical Applications of Lasers, National Institute of Laser Enhanced Science (NILES), Cairo University, Giza, 12611, Egypt
| | | | - Michael R Hamblin
- Laser Research Centre, Faculty of Health Science, University of Johannesburg, Doornfontein, 2028, South Africa
| | - Tarek Mohamed
- Laser Institute for Research and Applications LIRA, Beni-Suef University, Beni-Suef, 62511, Egypt.
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Jusuf S, Dong PT. Chromophore-Targeting Precision Antimicrobial Phototherapy. Cells 2023; 12:2664. [PMID: 37998399 PMCID: PMC10670386 DOI: 10.3390/cells12222664] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2023] [Revised: 11/11/2023] [Accepted: 11/18/2023] [Indexed: 11/25/2023] Open
Abstract
Phototherapy, encompassing the utilization of both natural and artificial light, has emerged as a dependable and non-invasive strategy for addressing a diverse range of illnesses, diseases, and infections. This therapeutic approach, primarily known for its efficacy in treating skin infections, such as herpes and acne lesions, involves the synergistic use of specific light wavelengths and photosensitizers, like methylene blue. Photodynamic therapy, as it is termed, relies on the generation of antimicrobial reactive oxygen species (ROS) through the interaction between light and externally applied photosensitizers. Recent research, however, has highlighted the intrinsic antimicrobial properties of light itself, marking a paradigm shift in focus from exogenous agents to the inherent photosensitivity of molecules found naturally within pathogens. Chemical analyses have identified specific organic molecular structures and systems, including protoporphyrins and conjugated C=C bonds, as pivotal components in molecular photosensitivity. Given the prevalence of these systems in organic life forms, there is an urgent need to investigate the potential impact of phototherapy on individual molecules expressed within pathogens and discern their contributions to the antimicrobial effects of light. This review delves into the recently unveiled key molecular targets of phototherapy, offering insights into their potential downstream implications and therapeutic applications. By shedding light on these fundamental molecular mechanisms, we aim to advance our understanding of phototherapy's broader therapeutic potential and contribute to the development of innovative treatments for a wide array of microbial infections and diseases.
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Affiliation(s)
- Sebastian Jusuf
- Division of Infectious Diseases, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA;
| | - Pu-Ting Dong
- Department of Microbiology, The Forsyth Institute, Boston, MA 02142, USA
- Department of Oral Medicine, Infection and Immunity, Harvard School of Dental Medicine, Boston, MA 02115, USA
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Mathematical modelling for antimicrobial photodynamic therapy mediated by 5-aminolaevulinic acid: An in vitro study. Photodiagnosis Photodyn Ther 2022; 40:103116. [PMID: 36100198 DOI: 10.1016/j.pdpdt.2022.103116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2022] [Revised: 09/09/2022] [Accepted: 09/09/2022] [Indexed: 12/14/2022]
Abstract
BACKGROUND Antimicrobial photodynamic therapy (aPDT) using aminolaevulinic acid (ALA) is a promising alternative to antibiotic therapy. ALA administration induces protoporphyrin IX (PpIX) accumulation in bacteria, and light excitation of the accumulated PpIX generates singlet oxygen to bacterial toxicity. Several factors, including drug administration and light irradiation conditions, contribute to the antibiotic effect. Such multiple parameters should be determined moderately for effective aPDT in clinical practice. METHODS A mathematical model to predict bacterial dynamics in ALA-aPDT following clinical conditions was constructed. Applying a pharmacokineticspharmacodynamics (PK-PD) approach, which is widely used in antimicrobial drug evaluation, viable bacteria count by defining the bactericidal rate as the concentration of singlet oxygen produced when PpIX in bacteria is irradiated by light. RESULTS The in vitro experimental results of ALA-aPDT for Pseudomonas aeruginosa demonstrated the PK-PD model validity. The killing rate has an upper limit, and the lower power density for a long irradiation time can suppress the viable bacteria number when the light dosages are the same. CONCLUSIONS This study proposed a model of bacterial viability change in ALA-aPDT based on the PK-PD model and confirmed, by in vitro experiments using PA, that the variation of bacterial viability with light-sensitive substance concentration and light irradiation power densities could be expressed. Further validation of the PK-PD model with other gram negative and gram positive strains will be needed.
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Matafonova G, Batoev V. Dual-wavelength light radiation for synergistic water disinfection. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 806:151233. [PMID: 34715208 DOI: 10.1016/j.scitotenv.2021.151233] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Revised: 10/18/2021] [Accepted: 10/22/2021] [Indexed: 06/13/2023]
Abstract
Development of the narrow-band mercury-free light sources, such as light emitting diodes (LEDs) and excilamps, has stimulated research on inactivation of pathogenic microorganisms by dual-wavelength light radiation. To date, dual-wavelength light radiation has emerged as an advanced tool for enhancing microbial inactivation in water in view of potential synergistic effect. This is the first review that aims at elucidating its mechanisms under dual-wavelength light exposure and surveying a body of related literature in terms of yes-or-no synergy. We have proposed three key inactivation mechanisms, which function in the estimated spectrum ranges I (190-254 nm), II (250-320 nm) and III (300-405 nm) and provide a synergistic effect when combined. These mechanisms involve proteins damage and DNA repair suppression (I), direct and indirect DNA damage (II) and generation of reactive oxygen species (ROS) by endogenous photosensitizers (III), such as porphyrins and flavins. A synergy under dual-wavelength light irradiation simultaneously or sequentially occurs if coupling two wavelengths of different ranges (I + II, I + III, II + III) in order to trigger different inactivation mechanisms. Recent advances of dual-wavelength light strategy in photodynamic therapy could be applied for water disinfection. They bring opportunities for applying the sources of near-UV and visible radiation and making the disinfection processes more energy- and cost-effective. From this standpoint, the synergistically efficient dual-wavelength combinations II + III and the combinations within the extended to 700 nm range III (near-UV + VIS) appear to be promising for developing novel advanced oxidation processes for disinfection of real turbid waters.
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Affiliation(s)
- Galina Matafonova
- Laboratory of Engineering Ecology, Baikal Institute of Nature Management, Siberian Branch of Russian Academy of Sciences, Ulan-Ude, Russia.
| | - Valeriy Batoev
- Laboratory of Engineering Ecology, Baikal Institute of Nature Management, Siberian Branch of Russian Academy of Sciences, Ulan-Ude, Russia
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Simultaneous exposure to intracellular and extracellular photosensitizers for the treatment of Staphylococcus aureus infections. Antimicrob Agents Chemother 2021; 65:e0091921. [PMID: 34516248 DOI: 10.1128/aac.00919-21] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Staphylococcus aureus is a serious threat to public health due to the rise of antibiotic resistance in this organism, which can prolong or exacerbate skin and soft tissue infections (SSTIs). Methicillin-resistant S. aureus is a Gram-positive bacterium and a leading cause of SSTIs. As such, many efforts are underway to develop therapies that target essential biological processes in S. aureus. Antimicrobial photodynamic therapy is effective alternative to antibiotics, therefore we developed an approach to simultaneously expose S. aureus to intracellular and extracellular photoactivators. A near infrared photosensitizer was conjugated to human monoclonal antibodies (mAbs) that target the S. aureus Isd heme acquisition proteins. Additionally, the compound VU0038882 was developed to increase photoactivatable porphyrins within the cell. Combinatorial PDT treatment of drug-resistant S. aureus exposed to VU0038882 and conjugated anti-Isd mAbs proved to be an effective antibacterial strategy in vitro and in a murine model of SSTIs.
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Ahmed E, El-Gendy AO, Hamblin MR, Mohamed T. The effect of femtosecond laser irradiation on the growth kinetics of Staphylococcus aureus: An in vitro study. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2021; 221:112240. [PMID: 34130092 DOI: 10.1016/j.jphotobiol.2021.112240] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Revised: 05/29/2021] [Accepted: 06/02/2021] [Indexed: 01/10/2023]
Abstract
We investigated the effect of femtosecond laser irradiation on the growth kinetics of Staphylococcus aureus. In order to improve laser-based antimicrobial therapy and develop a clinically viable modality, various laser parameters such as laser light wavelength, laser power, exposure time, and energy density were studied. The INSPIRE HF100 laser system (Spectra Physics) provided the femtosecond laser light, which was pumped by a mode-locked femtosecond Ti: sapphire laser MAI TAI HP (Spectra Physics). The survival of the bacterial cells was monitored after irradiation by determination of growth rate using optical density, which is a rapid, simple, and reliable method. The growth rate of laser-exposed cultures was compared to control cultures. Fifteen minutes of exposure to femtosecond laser radiation with a wavelength of 390 nm and 400 nm at an average power of 50 mW was enough to significantly reduce bacterial viability, with a lag in the growth phase of 5 h longer than the control culture (P < 0.0001 by ANOVA and Tukey test).
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Affiliation(s)
- Esraa Ahmed
- Laser Institute for Research and Applications LIRA, Beni-Suef University, Beni-Suef 62511, Egypt
| | - Ahmed O El-Gendy
- Laser Institute for Research and Applications LIRA, Beni-Suef University, Beni-Suef 62511, Egypt; Faculty of Pharmacy, Department of Microbiology and Immunology, Beni-Suef University, Beni-Suef 62514, Egypt
| | - Michael R Hamblin
- Department of Dermatology, Harvard Medical School, Boston, MA 02115, USA; Laser Research Centre, Faculty of Health Science, University of Johannesburg, Doornfontein 2028, South Africa
| | - Tarek Mohamed
- Laser Institute for Research and Applications LIRA, Beni-Suef University, Beni-Suef 62511, Egypt.
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Polat E, Kang K. Natural Photosensitizers in Antimicrobial Photodynamic Therapy. Biomedicines 2021; 9:584. [PMID: 34063973 PMCID: PMC8224061 DOI: 10.3390/biomedicines9060584] [Citation(s) in RCA: 68] [Impact Index Per Article: 22.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Revised: 05/17/2021] [Accepted: 05/18/2021] [Indexed: 12/19/2022] Open
Abstract
Health problems and reduced treatment effectiveness due to antimicrobial resistance have become important global problems and are important factors that negatively affect life expectancy. Antimicrobial photodynamic therapy (APDT) is constantly evolving and can minimize this antimicrobial resistance problem. Reactive oxygen species produced when nontoxic photosensitizers are exposed to light are the main functional components of APDT responsible for microbial destruction; therefore, APDT has a broad spectrum of target pathogens, such as bacteria, fungi, and viruses. Various photosensitizers, including natural extracts, compounds, and their synthetic derivatives, are being investigated. The main limitations, such as weak antimicrobial activity against Gram-negative bacteria, solubility, specificity, and cost, encourage the exploration of new photosensitizer candidates. Many additional methods, such as cell surface engineering, cotreatment with membrane-damaging agents, nanotechnology, computational simulation, and sonodynamic therapy, are also being investigated to develop novel APDT methods with improved properties. In this review, we summarize APDT research, focusing on natural photosensitizers used in in vitro and in vivo experimental models. In addition, we describe the limitations observed for natural photosensitizers and the methods developed to counter those limitations with emerging technologies.
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Affiliation(s)
- Ece Polat
- Natural Product Informatics Research Center, Korea Institute of Science and Technology, Gangneung 25451, Gangwon-do, Korea;
| | - Kyungsu Kang
- Natural Product Informatics Research Center, Korea Institute of Science and Technology, Gangneung 25451, Gangwon-do, Korea;
- Division of Bio-Medical Science Technology, KIST School, University of Science and Technology (UST), Gangneung 25451, Gangwon-do, Korea
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Tsutsumi-Arai C, Arai Y, Terada-Ito C, Imamura T, Tatehara S, Ide S, Wakabayashi N, Satomura K. Microbicidal effect of 405-nm blue LED light on Candida albicans and Streptococcus mutans dual-species biofilms on denture base resin. Lasers Med Sci 2021; 37:857-866. [PMID: 33931832 DOI: 10.1007/s10103-021-03323-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Accepted: 04/20/2021] [Indexed: 12/01/2022]
Abstract
This study investigated: (1) the microbicidal effect of 405-nm blue LED light irradiation on biofilm formed by Candida albicans hyphae and Streptococcus mutans under dual-species condition on denture base resin, (2) the generation of intracellular reactive oxygen species (ROS) induced by irradiation, and (3) the existence of intracellular porphyrins, which act as a photosensitizer. Denture base resin specimens were prepared and C. albicans and S. mutans dual-species biofilms were allowed to form on the specimens. The biofilms were irradiated with 405-nm blue LED light and analyzed using the colony-forming unit assay, fluorescence microscopy, and scanning electron microscopy (SEM). Single-species biofilms of C. albicans and S. mutans formed on the specimens were irradiated with 405-nm blue LED light. After the irradiation, the intracellular ROS levels in C. albicans and S. mutans cells were measured. In addition, the level of intracellular porphyrins in C. albicans and S. mutans were measured. Irradiation for more than 30 min significantly inhibited the colony formation ability of C. albicans and S. mutans. Fluorescence microscopy revealed that almost all C. albicans and S. mutans cells were killed by irradiation. SEM images showed various cell damage patterns. Irradiation led to the generation of intracellular ROS and porphyrins were present in both C. albicans and S. mutans cells. In conclusion, irradiation with 405-nm blue light-emitting diode light for 40 min effectively disinfect C. albicans hyphae and S. mutans dual-species biofilms and possibly react with intracellular porphyrins resulting in generation of ROS in each microorganism.
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Affiliation(s)
- Chiaki Tsutsumi-Arai
- Department of Oral Medicine and Stomatology, Tsurumi University School of Dental Medicine, 2-1-3, Tsurumi, Tsurumi-ku, Yokohama, Kanagawa, 230-8501, Japan.
| | - Yuki Arai
- Department of Removable Partial Prosthodontics, Graduate School, Tokyo Medical and Dental University (TMDU), 1-5-45, Yushima, Bunkyo-ku, Tokyo, 113-8549, Japan
| | - Chika Terada-Ito
- Department of Oral Medicine and Stomatology, Tsurumi University School of Dental Medicine, 2-1-3, Tsurumi, Tsurumi-ku, Yokohama, Kanagawa, 230-8501, Japan
| | - Takahiro Imamura
- Department of Oral Medicine and Stomatology, Tsurumi University School of Dental Medicine, 2-1-3, Tsurumi, Tsurumi-ku, Yokohama, Kanagawa, 230-8501, Japan
| | - Seiko Tatehara
- Department of Oral Medicine and Stomatology, Tsurumi University School of Dental Medicine, 2-1-3, Tsurumi, Tsurumi-ku, Yokohama, Kanagawa, 230-8501, Japan
| | - Shinji Ide
- Department of Oral Medicine and Stomatology, Tsurumi University School of Dental Medicine, 2-1-3, Tsurumi, Tsurumi-ku, Yokohama, Kanagawa, 230-8501, Japan
| | - Noriyuki Wakabayashi
- Department of Removable Partial Prosthodontics, Graduate School, Tokyo Medical and Dental University (TMDU), 1-5-45, Yushima, Bunkyo-ku, Tokyo, 113-8549, Japan
| | - Kazuhito Satomura
- Department of Oral Medicine and Stomatology, Tsurumi University School of Dental Medicine, 2-1-3, Tsurumi, Tsurumi-ku, Yokohama, Kanagawa, 230-8501, Japan
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Pérez C, Zúñiga T, Palavecino CE. Photodynamic therapy for treatment of Staphylococcus aureus infections. Photodiagnosis Photodyn Ther 2021; 34:102285. [PMID: 33836278 DOI: 10.1016/j.pdpdt.2021.102285] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Revised: 03/10/2021] [Accepted: 04/02/2021] [Indexed: 12/09/2022]
Abstract
BACKGROUND Staphylococcus aureus is a Gram-positive spherical bacterium that commonly causes various infections which can range from superficial to life-threatening. Hospital strains of S. aureus are often resistant to antibiotics, which has made their treatment difficult in recent decades. Other therapeutic alternatives have been postulated to overcome the drawbacks of antibiotic multi-resistance. Of these, photodynamic therapy (PDT) is a promising approach to address the notable shortage of new active antibiotics against multidrug-resistant S. aureus. PDT combines the use of a photosensitizer agent, light, and oxygen to eradicate pathogenic microorganisms. Through a systematic analysis of published results, this work aims to verify the usefulness of applying PDT in treating multidrug-resistant S.aureus infections. METHODS This review was based on a bibliographic search in various databases and the analysis of relevant publications. RESULTS There is currently a large body of evidence demonstrating the efficacy of photodynamic therapy in eliminating S.aureus strains. Both biofilm-producing strains, as well as multidrug-resistant strains. CONCLUSION We conclude that there is sufficient scientific evidence that PDT is a useful adjunct to traditional antibiotic therapy for treating S. aureus infections. Clinical application through appropriate trials should be introduced to further define optimal treatment protocols, safety and efficay.
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Affiliation(s)
- Camila Pérez
- Escuela de Tecnología Médica, Facultad de Ciencias de la Salud, Universidad Central de Chile, Chile.
| | - Tania Zúñiga
- Escuela de Tecnología Médica, Facultad de Ciencias de la Salud, Universidad Central de Chile, Chile.
| | - Christian Erick Palavecino
- Laboratorio de Microbiología Celular, Instituto de Investigación e Innovación en Salud, Facultad de Ciencias de la Salud, Universidad Central de Chile, Lord Cochrane 418, 8330546, Santiago, Chile.
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Chatterjee S, Budidha K, Kyriacou PA. Investigating the origin of photoplethysmography using a multiwavelength Monte Carlo model. Physiol Meas 2020; 41:084001. [PMID: 32585642 DOI: 10.1088/1361-6579/aba008] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Photoplethysmography (PPG) is a photometric technique used for the measurement of volumetric changes in the blood. The recent interest in new applications of PPG has invigorated more fundamental research regarding the origin of the PPG waveform, which since its discovery in 1937, remains inconclusive. A handful of studies in the recent past have explored various hypotheses for the origin of PPG. These studies relate PPG to mechanical movement, red blood cell orientation or blood volume variations. OBJECTIVE Recognising the significance and need to corroborate a theory behind PPG formation, the present work rigorously investigates the origin of PPG based on a realistic model of light-tissue interactions. APPROACH A three-dimensional comprehensive Monte Carlo model of finger-PPG was developed and explored to quantify the optical entities pertinent to PPG (e.g. absorbance, reflectance, and penetration depth) as the functions of multiple wavelengths and source-detector separations. Complementary to the simulations, a pilot in vivo investigation was conducted on eight healthy volunteers. PPG signals were recorded using a custom-made multiwavelength sensor with an adjustable source-detector separation. MAIN RESULTS Simulated results illustrate the distribution of photon-tissue interactions in the reflectance PPG geometry. The depth-selective analysis quantifies the contributions of the dermal and subdermal tissue layers in the PPG wave formation. A strong negative correlation (r = -0.96) is found between the ratios of the simulated absorbances and measured PPG amplitudes. SIGNIFICANCE This work quantified for the first time the contributions of different tissue layers and sublayers in the formation of the PPG signal.
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Affiliation(s)
- Subhasri Chatterjee
- Research Centre for Biomedical Engineering, City, University of London, United Kingdom
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