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Changes of Intracellular Porphyrin, Reactive Oxygen Species, and Fatty Acids Profiles During Inactivation of Methicillin-Resistant Staphylococcus aureus by Antimicrobial Blue Light
摘要： Antimicrobial blue light (aBL) has attracted increasing interest for its antimicrobial properties. However, the underlying bactericidal mechanism has not yet been verified. One hypothesis is that aBL causes the excitation of intracellular chromophores; leading to the generation of reactive oxygen species (ROS) and the resultant oxidization of various biomolecules. Thus, monitoring the levels of redox-sensitive intracellular biomolecules such as coproporphyrins, as well as singlet oxygen and various ROS may help to uncover the physiological changes induced by aBL and aid in establishing the underlying mechanism of action. Furthermore, the identification of novel targets of ROS, such as fatty acids, is of potential significance from a therapeutic perspective. In this study, we sought to investigate the molecular impact of aBL treatment on methicillin-resistant Staphylococcus aureus (MRSA). The results showed that aBL (5–80 J/cm2) exhibited a bactericidal effect on MRSA, and almost no bacteria survived when 80 J/cm2 had been delivered. Further studies revealed that the concentrations of certain intracellular molecules varied in response to aBL irradiation. Coproporphyrin levels were found to decrease gradually, while ROS levels increased rapidly. Moreover, imaging revealed the emergence and increase of singlet oxygen molecules. Concomitantly, the lipid peroxidation product malondialdehyde (MDA) increased in abundance and intracellular K+ leakage was observed, indicating permeability of the cell membrane. Atomic force microscopy showed that the cell surface exhibited a coarse appearance. Finally, fatty acid profiles at different illumination levels were monitored by GC-MS. The relative amounts of three unsaturated fatty acids (C16:1, C20:1, and C20:4) were decreased in response to aBL irradiation, which likely played a key role in the aforementioned membrane injuries. Collectively, these data suggest that the cell membrane is a major target of ROS during aBL irradiation, causing alterations to membrane lipid profiles, and in particular to the unsaturated fatty acid component.
关键词： membrane injuries,coproporphyrin,lipids,methicillin-resistant Staphylococcus aureus,antimicrobial blue light,unsaturated fatty acids
更新于2025-09-23 15:22:29
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[IEEE 2018 IEEE 8th International Conference Nanomaterials: Application & Properties (NAP) - Zatoka, Ukraine (2018.9.9-2018.9.14)] 2018 IEEE 8th International Conference Nanomaterials: Application & Properties (NAP) - The Study of the Activation of Antibacterial Activity of Silver Nanoparticles by Laser Radiation
摘要： Silver nanoparticles are known to have inhibitory and bactericidal effects and they play a significant role in the development of new antimicrobial substances against pathogenic microorganisms. In this article the minimum bactericidal concentration of the silver nanoparticles on two different bacteria cultures (Escherichia coli and Staphylococcus aureus) as well as the possibility to enhance their antimicrobial activity using laser irradiation was investigated. It was found, that solutions of silver nanoparticles at concentrations ≥ 3120 μg/ml cause death of both types of studied microorganisms. Dispersion of nanoparticles after laser irradiation caused the inhibition of Staphylococcus aureus at lower concentrations.
关键词： surface plasmon resonance,Escherichia coli,Staphylococcus aureus,bactericidal properties,silver nanoparticles
更新于2025-09-23 15:21:01
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Blood–Retinal Barrier Compromise and Endogenous <i>Staphylococcus aureus</i> Endophthalmitis
摘要： PURPOSE. To test the hypothesis that blood–retinal barrier compromise is associated with the development of endogenous Staphylococcus aureus endophthalmitis. METHODS. To compromise the blood–retinal barrier in vivo, streptozotocin-induced diabetes was induced in C57BL/6J mice for 1, 3, or 5 months. Diabetic and age-matched nondiabetic mice were intravenously injected with 108 colony-forming units (cfu) of S. aureus, a common cause of endogenous endophthalmitis in diabetics. After 4 days post infection, electroretinography, histology, and bacterial counts were performed. Staphylococcus aureus–induced alterations in in vitro retinal pigment epithelial (RPE) cell barrier structure and function were assessed by anti–ZO-1 immunohistochemistry, FITC-dextran conjugate diffusion, and bacterial transmigration assays. RESULTS. We observed one bilateral infection in a control, nondiabetic animal (mean ? 1.54 3 103 6 1.78 3 102 cfu/eye, 7% incidence). Among the 1-month diabetic mice, we observed culture-con?rmed unilateral infections in two animals (mean ? 5.54 3 102 6 7.09 3 102 cfu/ eye, 12% incidence). Among the 3-month diabetic mice, infections were observed in 11 animals, three with bilateral infections (mean ? 2.67 3 102 6 2.49 3 102 cfu/eye, 58% incidence). Among the 5-month diabetic mice, we observed infections in ?ve animals (mean ? 7.88 3 102 6 1.08 3 103 cfu/eye, 33% incidence). In vitro, S. aureus infection reduced ZO-1 immunostaining and disrupted the barrier function of cultured RPE cells, resulting in diffusion of ?uorophore-conjugated dextrans and transmigration of live bacteria across a permeabilized RPE barrier. CONCLUSIONS. Taken together, these results indicated that S. aureus is capable of inducing blood–retinal barrier permeability and causing endogenous bacterial endophthalmitis in normal and diabetic animals.
关键词： Staphylococcus aureus,endogenous endophthalmitis,blood–retinal barrier,bacteria,diabetes,retinal pigment epithelium
更新于2025-09-23 15:21:01
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[IEEE 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Huangshan, China (2019.8.5-2019.8.8)] 2019 18th International Conference on Optical Communications and Networks (ICOCN) - High sensitivity biosensor for Staphylococcus Aureus detection based on tapered a singlemode-no core-singlemode fiber structure
摘要： A fiber biosensor based on tapered singlemode-no core-singlemode (SNS) fiber structure was investigated for the detection of staphylococcus aureus. The fibre sensor was functionalised by depositing the pig IgG antibodies onto tapered biosensor surface, which has specific binding with staphylococcus aureus. The experimental results showed that transmission spectrum of functionalized sensor undergone wavelength blue shift when it was immersed into Staphylococcus aureus solution, and 1.1 nm wavelength shift was observed with a concentration of 101colony-forming units (CFU)/mL.
关键词： optical fiber sensor,biosensor,staphylococcus aureus,foodborne pathogens,the pig IgG
更新于2025-09-16 10:30:52
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2125. Staphylococcus Species Identification by Fourier Transform Infrared (FTIR) Spectroscopic Techniques: A Cross-Lab Study
摘要： Staphylococcus aureus is well known to be associated with atopic dermatitis. Recent studies also report S. aureus presence in lesional skin of squamous cell carcinoma (SCC) and its precursor lesion, actinic keratosis (AK). Therefore, it is of potential clinical interest to monitor skin S. aureus colonization on AK lesions. Fourier transform infrared (FTIR) spectroscopy is a cost-effective, nondestructive, and reagent-free technique for rapid microbial identification. It is based on the use of spectral databases developed with well-characterized strains in conjunction with the application of multivariate statistical analysis to elaborate classification models. In the present cross-lab study, spectral databases containing FTIR spectra of over 1000 staphylococcal isolates obtained from reference and clinical microbiology laboratories across Canada were employed in the FTIR spectroscopic identification of Staphylococcus spp. isolated from AK, SCC and perilesional skin of patients at the Princess Alexandra Hospital Dermatology Clinic in Brisbane, Australia.
关键词： atopic dermatitis,actinic keratosis,squamous cell carcinoma,microbial identification,Staphylococcus aureus,Fourier transform infrared spectroscopy
更新于2025-09-16 10:30:52
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Flexible organic light-emitting diodes for antimicrobial photodynamic therapy
摘要： Bacterial infection and the growth of antibiotic resistance is a serious problem that leads to patient suffering, death and increased costs of healthcare. To address this problem, we propose using flexible organic light-emitting diodes (OLEDs) as light sources for photodynamic therapy (PDT) to kill bacteria. PDT involves the use of light and a photosensitizer to generate reactive oxygen species that kill neighbouring cells. We have developed flexible top-emitting OLEDs with the ability to tune the emission peak from 669 to 737 nm to match the photosensitizer, together with high irradiance, low driving voltage, long operational lifetime and adequate shelf-life. These features enable OLEDs to be the ideal candidate for ambulatory PDT light sources. A detailed study of OLED–PDT for killing Staphylococcus aureus was performed. The results show that our OLEDs in combination with the photosensitizer methylene blue, can kill more than 99% of bacteria. This indicates a huge potential for using OLEDs to treat bacterial infections.
关键词： Photodynamic therapy,Flexible organic light-emitting diodes,Staphylococcus aureus,Antimicrobial,Methylene blue
更新于2025-09-12 10:27:22
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Efficacy of a novel ultraviolet light-emitting diode device for decontamination of shared pens in a health care setting
摘要： Shared pens and styluses are a potential source for transmission of health care?associated pathogens and respiratory viruses in health care facilities. A novel ultraviolet light-emitting diode device was effective in reducing bacteria and viruses inoculated on pens and in reducing methicillin-resistant Staphylococcus aureus transferred to pens by colonized patients. The device could be useful in reducing the risk of transmission of pathogens by shared writing utensils.
关键词： Methicillin-resistant Staphylococcus aureus,Candida auris,Vancomycin-resistant enterococci,Bacteriophage MS2,Environment
更新于2025-09-12 10:27:22
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Response surface methodology can be used to predict photoinactivation of foodborne pathogens using Rose Bengal excited by 530?nm LED
摘要： In this work, the photodynamic bactericidal effect of Rose Bengal (RB), combined with green LED light, against Staphylococcus aureus and Salmonella Typhimurium, was investigated. The interaction of RB concentration and illumination time was evaluated using a response surface methodology, and a second-order polynomial empirical model was adjusted to the experimental data. The derived model predicted the combined influences of these factors on S. aureus and S. Typhimurium counts, in accordance with predictions and experimental observations (R2 = 0.8483 and p = .0013 for S. aureus; R2 = 0.9191 and p = .0001 for S. Typhimurium). Total inhibition of S. aureus and S. Typhimurium was observed when applying a light dose of 0.125 J cm?2 and 152.0 J cm?2, respectively. The treatments also showed loss of membrane integrity, morphological changes, and internal cell structural alterations. In sum, the polynomial model developed could provide accurate information on the combined influences of RB and green LED light in aPDT treatment and, that this combination was able to inactivate S. aureus and S. Typhimurium.
关键词： Rose Bengal,green LED light,Salmonella Typhimurium,response surface methodology,Staphylococcus aureus,photodynamic bactericidal effect
更新于2025-09-11 14:15:04
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Photoinduced Antibacterial Activity of the Essential Oils from Eugenia brasiliensis Lam and Piper mosenii C. DC. by Blue Led Light
摘要： The objective of this work was to evaluate the phytochemical composition and the antibacterial and antibiotic-modulating activities of the essential oils of Eugenia brasiliensis Lam (OEEb) and Piper mosenii C. DC (OEPm) singly or in association with blue LED (Light-emitting diode) light. The antibacterial and antibiotic-modulatory activities of the essential oils on the activity of aminoglycosides were evaluated to determine the minimum inhibitory concentration (MIC, μg/mL) in the presence or absence of exposure to blue LED light. The chemical analysis showed α-pinene and bicyclogermacrene as major constituents of OEPm, whereas α-muurolol was the main compound of OEEb. Both OEEb and OEPm showed MIC ≥ 512 μg/mL against the strains under study. However, the association of these oils with the blue LED light enhanced the action of the aminoglycosides amikacin and gentamicin. In conclusion, the association of aminoglycosides with the blue LED light and essential oils was effective against resistant bacteria.
关键词： blue light,Piper mosenii,bacterial resistance,Eugenia brasiliensis,Staphylococcus aureus,Escherichia coli
更新于2025-09-11 14:15:04
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18F-FLT PET/CT imaging in a Wister rabbit inflammation model
摘要： The aim of the present study was to determine the tumour specificity of the newly developed nucleoside metabolic positron emission tomography (PET) tracer, 3'-deoxy-3'-18F-fluorothymidine (18F-FLT). Using 18F-FLT PET imaging, DNA synthesis and cell proliferation were detected in Staphylococcus aureus (S. aureus) abscess and calcium sulphate models in Wister rabbits. A total of eight rabbits were implanted with S. aureus in the left tibia to induce an inflammatory process. Calcium sulphate + gentamicin was implanted in the right tibia to induce a physical stimulus without bacterial multiplication. After four weeks, the animals underwent 18F-FLT PET imaging, bacterial culturing and tissue pathology. The uptake of 18F-FLT was significantly higher in the abscess site compared with that in the granuloma, with maximum standardised uptake values of 5.76±0.25 and 1.15±0.32, respectively (P<0.01). This indicates that 18F-FLT is not a specific tumour tracer since active inflammation also results in the uptake of this compound. However, the tumour specificity of this tracer is higher compared with that of 18F?fluorodeoxyglucose. Therefore, 18F-FLT may be useful in the differential diagnosis of benign and malignant tumours.
关键词： gentamicin + calcium sulphate model,3'-deoxy-3'-18F-fluorothymidine,Staphylococcus aureus model
更新于2025-09-10 09:29:36