Visible and near-infrared radiation is now widely employed in health science and technology. Pre-clinical trials are still essential to allow appropriate translation of optical methods into clinical ...practice. Our results stress the importance of considering the mouse strain and gender when planning pre-clinical experiments that depend on light–skin interactions. Here, we evaluated the optical properties of depilated albino and pigmented mouse skin using reproducible methods to determine parameters that have wide applicability in biomedical optics. Light penetration depth (δ), absorption (μa), reduced scattering (μ′s) and reduced attenuation (μ′t) coefficients were calculated using the Kubelka–Munk model of photon transport and spectrophotometric measurements. Within a broad wavelength coverage (400–1400nm), the main optical tissue interactions of visible and near infrared radiation could be inferred. Histological analysis was performed to correlate the findings with tissue composition and structure. Disperse melanin granules present in depilated pigmented mouse skin were shown to be irrelevant for light absorption. Gender mostly affected optical properties in the visible range due to variations in blood and abundance of dense connective tissue. On the other hand, mouse strains could produce more variations in the hydration level of skin, leading to changes in absorption in the infrared spectral region. A spectral region of minimal light attenuation, commonly referred as the “optical window”, was observed between 600 and 1350nm.
Light-based technologies have been widely employed in health sciences. Since skin is the most common optical barrier in non-invasive techniques, its optical properties must be very well known. Our study investigated the light interaction with skin of bother genders from albino and pigmented strains. Our findings show a band of minimal light attenuation, referred as the “optical window”, between 600 and 1350nm. Heme-containing proteins and water are main absorbing components in mouse skin, while melanin and fatty acids are minimally important. Gender mostly affects mouse skin optical properties in the visible range due to variations in blood and dense connective tissue abundance, while strains can introduce variations in the hydration level of skin, leading to absorption divergences in the infrared spectral region. Display omitted
•We present μa, μ′s, μ′t and δ of albino and pigmented mice skin from both genders, from 400 to 1400nm.•Dense connective tissues are more abundant in males and present strong scattering.•Males present stronger absorption by heme-proteins indicating higher blood content.•Albino mice present more intense infrared absorption due to higher water content.•Melanin in depilated pigmented mouse skin is irrelevant for light absorption.
The global dissemination of the novel coronavirus disease (COVID-19) has accelerated the need for the implementation of effective antimicrobial strategies to target the causative agent SARS-CoV-2. ...Light-based technologies have a demonstrable broad range of activity over standard chemotherapeutic antimicrobials and conventional disinfectants, negligible emergence of resistance, and the capability to modulate the host immune response. This perspective article identifies the benefits, challenges, and pitfalls of repurposing light-based strategies to combat the emergence of COVID-19 pandemic.
•Light-based technologies currently are cost-effective and widely available in market.•Photons can be used to inactivate SARS-CoV-2 in air, liquids and on surfaces.•Phototherapy can be used as an adjuvant to control virus infection and to modulate host immune system.•Light-based solutions can significantly contribute to mitigate the impacts of COVID-19 pandemic
The emergence and rapid spread of colistin-resistant
carrying the
gene have generated an urgent need to strengthen surveillance. We performed a meticulous investigation of strains of this sort, which ...resulted in the identification of international clones of
carrying IncX4-plasmid-mediated
and
genes in recreational waters of public urban beaches in cities with high tourist turnover, highlighting a new environmental reservoir.
Enterococcus faecium has emerged as one of the most important pathogens in healthcare-associated infections worldwide due to its intrinsic and acquired resistance to many antibiotics, including ...vancomycin. Antimicrobial photodynamic therapy (aPDT) is an alternative therapeutic platform that is currently under investigation for the control and treatment of infections. PDT is based on the use of photoactive dye molecules, widely known as photosensitizer (PS). PS, upon irradiation with visible light, produces reactive oxygen species that can destroy lipids and proteins causing cell death. We employed Galleria mellonella (the greater wax moth) caterpillar fatally infected with E. faecium to develop an invertebrate host model system that can be used to study the antimicrobial PDT (alone or combined with antibiotics). In the establishment of infection by E. faecium in G. mellonella, we found that the G. mellonella death rate was dependent on the number of bacterial cells injected into the insect hemocoel and all E. faecium strains tested were capable of infecting and killing G. mellonella. Antibiotic treatment with ampicillin, gentamicin or the combination of ampicillin and gentamicin prolonged caterpillar survival infected by E. faecium (P = 0.0003, P = 0.0001 and P = 0.0001, respectively). In the study of antimicrobial PDT, we verified that methylene blue (MB) injected into the insect followed by whole body illumination prolonged the caterpillar survival (P = 0.0192). Interestingly, combination therapy of larvae infected with vancomycin-resistant E. faecium, with antimicrobial PDT followed by vancomycin, significantly prolonged the survival of the caterpillars when compared to either antimicrobial PDT (P = 0.0095) or vancomycin treatment alone (P = 0.0025), suggesting that the aPDT made the vancomycin resistant E. faecium strain more susceptible to vancomycin action. In summary, G. mellonella provides an invertebrate model host to study the antimicrobial PDT and to explore combinatorial aPDT-based treatments.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The emergence and rapid dissemination of colistin-resistant
carrying the plasmid-mediated
gene have created an urgent need to develop specific screening methods. In this study, we evaluated four ...assays based on the inhibition of MCR-1 activity by EDTA: (i) a combined-disk test (CDT) comparing the inhibition zones of colistin and colistin (10 μg) plus EDTA (100 mM); (ii) reduction of colistin MIC (CMR) in the presence of EDTA (80 μg/ml); (iii) a modified rapid polymyxin Nordmann/Poirel test (MPNP); and (iv) alteration of zeta potential (R
= ZP
/ZP
). We obtained encouraging results for the detection of MCR-1 in
isolates recovered from human, food, and animal samples, using the following assay parameters: ≥3 mm difference in the inhibition zones between colistin disks without and with EDTA; ≥4-fold colistin MIC decrease in the presence of EDTA; R
of ≥2.5; and the absence of metabolic activity and proliferation, indicated by unchanged color of phenol red in the presence of colistin-EDTA, in the MPNP test. In this regard, the CDT, CMR, R
, and MPNP assays exhibited sensitivities of 96.7, 96.7, 95.1, and 96.7% and specificities of 89.6, 83.3, 100, and 100%, respectively, for detecting MCR-1-positive
Our results demonstrate that inhibition by EDTA and zeta potential assays may provide simple and inexpensive methods for the presumptive detection of MCR-1-producing
isolates in human and veterinary diagnostic laboratories.
UV-C (254 nm) lethal doses for SARS-CoV-2 Sabino, Caetano P.; Sellera, Fábio P.; Sales-Medina, Douglas F. ...
Photodiagnosis and photodynamic therapy,
12/2020, Letnik:
32
Journal Article
Recenzirano
Odprti dostop
•We developed a controlled assay to investigate the UV-C inactivation kinetics for SARS-CoV-2.•We established the UV-C lethal doses for the virus in vitro.•LD90 for SARS-CoV-2 was reached at 0.016 ...mJ/cm2.•LD99.999 was achieved at 108.714 mJ/cm2 with exposure time less than 50 s.
•Hypervirulent Klebsiella pneumoniae infections are associated with high mortality rates.•Five hypervirulent strains were challenged by methylene blue-antimicrobial photodynamic therapy (MB-aPDT) and ...blue light photoinactivation.•All strains were effectively inactivated by both light-based antimicrobial platforms.•Hypermucoviscosity phenotype did not confer tolerance to MB-aPDT or blue light.•Photoinactivation could be used to treat localised infections and hospital environments.
Introduction: Infections caused by hypervirulent and/or hypermucoviscous Klebsiella pneumoniae (K. pneumoniae) strains are frequently reported worldwide. Since convergence of hypervirulence and drug-resistance emerged as a serious clinical problem, novel therapeutic strategies are worthy of investigation. In this regard, antimicrobial photodynamic therapy and blue light have proven to be effective against a broad-spectrum of clinically relevant pathogens but have never been tested for hypervirulent/hypermucoviscous strains. Thus, this study investigated the influence of hypermucoviscosity and hypervirulence over the photoinactivation efficacy of blue light alone or antimicrobial photodynamic therapy mediated by methylene blue and red light.
Methods: Five clinical isolates of K. pneumoniae were screened for hypermucoviscosity by string test and for hypervirulence by a Galleria mellonella model of systemic infection. Strains were then challenged by both photoinactivation methods performed in vitro. All tests also included a non-hypervirulent/hypermucoviscous control strain for comparison.
Results: All K. pneumoniae strains were effectively inactivated by both light-based antimicrobial strategies. Hypervirulent/hypermucoviscous strains exposed to photodynamic therapy presented rapid and consistent inactivation kinetics, while blue light led to slower and more variable inactivation kinetics.
Conclusion: Hypermucoviscosity and hypervirulence does not confer tolerance in K. pneumoniae against photoinactivation. Antimicrobial photodynamic therapy represents an interesting alternative to treat localised infections because it is a fast procedure with high effectiveness. On the other hand, antimicrobial blue light could be used to decontaminate hospital environments since no photosensitiser administration is required and harmful effects of ultraviolet light are avoided. Therefore, visible light-based strategies present great potential for the development of safe and effective antimicrobial technologies against such aggressive pathogens.
Cutaneous leishmaniasis (CL) is a neglected disease that promotes destructive lesions. Difficulties in treatment are related to accessibility of drugs, resistance and toxicity. Antimicrobial ...photodynamic therapy (APDT) has been emerging as a promising treatment for CL. In this work, we evaluated methylene blue (MB)‐mediated APDT (MB‐APDT) on Leishmania amazonensis in vitro and in vivo by bioluminescence technique. In vitro, MB‐APDT was performed using a red LED (λ = 660 ± 11 nm, 100 mW cm−2) and MB (100 µm) at different light doses. In vivo, mice were infected and 4 weeks later, randomly divided into three groups: control, APDT 1 (single session) and APDT 2 (two sessions of MB‐APDT). MB was used at 100 µm and energy dose was established at 150 J cm−2. Parasite burden, lesion size and pain were evaluated weekly for 4 weeks. In vitro, lethal dose for 90% parasite inactivation was achieved at 48.8 J cm−2. In vivo, although APDT 1 and APDT 2 groups have showed similar parasite burden after 4 weeks, two sessions were clinically better, especially considering the inflammatory process associated to CL. Our findings reinforce MB‐APDT as a cost‐effective treatment to combat CL.
Cutaneous leishmaniasis (CL) is a neglected disease that causes ulcerated lesions. Current treatments are limited due to high cost, resistance and toxicity. Photodynamic therapy has been put forward as an alternative treatment for CL. Here, we investigated methylene blue‐mediated photodynamic therapy (MB‐APDT) on Leishmania (L.) amazonensis in vitro using a red LED at different fluences. In vivo, we compared one and two MB‐APDT sessions at L. amazonensis‐induced CL in mice. Disease progress was evaluated by bioluminescence, lesion size and pain score. Our results indicate that MB‐APDT could be a cost‐effective strategy to apply in public health.
We report the occurrence and genomic analysis of extended-spectrum β-lactamase (CTX-M)-producing Escherichia coli in anthropogenically polluted coastal waters of Southeast Brazil. E. coli strains ...belonging to sequence types (STs) ST10, ST38, ST155 and ST1284 exhibited a wide resistome, with genes conferring resistance to medically relevant antimicrobials and heavy metals, and a halophilic behavior (tolerance to 9–10% NaCl). These findings suggest a heavy contamination in this area by critical priority bacteria adapted to marine environments, which might have negative impacts on human and ocean health.
•Occurrence of MDR bacteria in urban-impacted coastal waters has been investigated.•Presence of halotolerant CTX-M-producing E. coli is highlighted.•Genomic analysis revealed several genes conferring resistance to antimicrobials and heavy metals.•Dissemination of CTX-M-producing bacteria in marine ecosystems has been discussed.
•The COVID-19 pandemic led to a global crisis.•UVC-light systems have been proposed to inactivate the SARS-CoV-2 virus.•Low-pressure Hg vapor, KrCl excimer lamps, and LEDs are feasible UVC ...emitters.•Effective SARS-CoV-2 inactivation depends on UVC light parameters and contaminated material.•Pronounced viral titer reduction is reached in low exposure times.
A significant amount of epidemiological evidence has underlined that human-to-human transmission due to close contacts is considered the main pathway of transmission, however since the SARS-CoV-2 can also survive in aerosols, water, and surfaces, the development and implementation of effective decontamination strategies are urgently required. In this regard, ultraviolet germicidal irradiation (UVGI) using ultraviolet C (UVC) has been proposed to disinfect different environments and surfaces contaminated by SARS-CoV-2. Herein, we performed a systematic scoping review strictly focused on peer-reviewed studies published in English that reported experimental results of UVC-based technologies against the SARS-CoV-2 virus. Studies were retrieved from PubMed and the Web of Science database. After our criterious screening, we identified 13 eligible articles that used UVC-based systems to inactivate SARS-CoV-2. We noticed the use of different UVC wavelengths, technologies, and light doses. The initial viral titer was also heterogeneous among studies. Most studies reported virus inactivation in well plates, even though virus persistence on N95 respirators and different surfaces were also evaluated. SARS-CoV-2 inactivation reached from 90% to 100% depending on experimental conditions. We concluded that there is sufficient evidence to support the use of UVC-based technologies against SARS-CoV-2. However, appropriate implementation is required to guarantee the efficacy and safety of UVC strategies to control the COVID-19 pandemic.
Display omitted
PDF
