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Food Research International (Ottawa,... Jul 2024Biopreservation strategies such as the use of Mediterranean plant extracts to ensure food safety are promising to deal with the emergence of antimicrobial resistances... (Meta-Analysis)
Meta-Analysis
Biopreservation strategies such as the use of Mediterranean plant extracts to ensure food safety are promising to deal with the emergence of antimicrobial resistances and the overreliance on food chemical additives. In the last few decades, antimicrobial susceptibility testing (AST) for evaluating the in vitro antibacterial potential of plant extracts against the most relevant foodborne pathogens has been widely reported in the literature. The current meta-analysis aimed to summarise and analyse the extensive evidence available in the literature regarding the in vitro antimicrobial capability of Allium, Ocimum and Thymus spp. extracts against foodborne pathogens. A systematic review was carried out to gather data on AST results of these extracts against Listeria monocytogenes, Staphylococcus aureus, Salmonella spp., Escherichia coli and Bacillus cereus, including inhibition diameters (ID) and minimum inhibitory concentrations (MIC). A total of 742 records were gathered from a raw collection of 2,065 articles. Weighted mixed-effect linear models were adjusted to data to obtain pooled ID, pooled MIC and the relationship between both model estimations and observations. The pooled results revealed B. cereus as the most susceptible bacteria to Allium sativum (pooled ID = 20.64 ± 0.61 mm) by diffusion methods and S. aureus (pooled MIC = 0.146 mg/mL) by dilution methods. Diffusion methods did not yield conclusive results for Ocimum spp. extracts; however, the lowest pooled MIC was obtained for S. aureus (0.263 mg/mL). Among the foodborne pathogens evaluated, B. cereus showed the highest sensitivity to Thymus spp. extracts by both diffusion and dilution methods (pooled ID = 28.90 ± 2.34 mm and MIC = 0.075 mg/mL). The methodology used for plant extraction was found to not significantly affect MIC values (p > 0.05). Overall, the antimicrobial effectiveness of the studied extracts against Gram-positive and Gram-negative bacteria was demonstrated. Finally, the robustness of the meta-regression model was confirmed, also revealing an inversely proportional correlation between the ID and MIC measurements (p < 0.0001). These results provide a robust scientific basis on the factors affecting the in vitro antimicrobial efficacy of extracts from Mediterranean plants. They also provide valuable information for stakeholders involved in their industrial application in food, including producers, regulatory agencies and consumers which demand green-labelled foods.
Topics: Thymus Plant; Plant Extracts; Ocimum; Microbial Sensitivity Tests; Allium; Anti-Bacterial Agents; Food Microbiology; Food Safety; Bacillus cereus; Listeria monocytogenes
PubMed: 38823853
DOI: 10.1016/j.foodres.2024.114408 -
Mikrochimica Acta Jun 2024A one-shot CO laser-based strategy to generate conductive reduced graphene oxide (rGO) decorated with nanoceria (nCe) is proposed. The 2D/0D rGO-nCe films, integrated as...
A one-shot CO laser-based strategy to generate conductive reduced graphene oxide (rGO) decorated with nanoceria (nCe) is proposed. The 2D/0D rGO-nCe films, integrated as catalytic sensing layers in paper-based sensors, were employed for on-site monitoring of indoor fogging treatments against Listeria monocytogenes (Lm), a ubiquitous pathogenic bacterium. The rGO-nCe laser-assisted synthesis was optimized to preserve the rGO film morphological and electron-transfer features and simultaneously integrate catalytic nCe. The films were characterized by microscopical (SEM), spectroscopical (EDX, Raman, and FTIR), and electrochemical techniques. The most performing film was integrated into a nitrocellulose substrate, and the complete sensor was assembled via a combination of xurography and stencil printing. The rGO-nCe sensor's catalytic activity was proved toward the detection of HO, obtaining sensitive determination (LOD = 0.3 µM) and an extended linear range (0.5-1500 µM). Eventually, the rGO-nCe sensor was challenged for the real-time continuous monitoring of hydrogen peroxide aerosol during no-touch fogging treatment conducted following the EU's recommendation for biocidal product use. Treatment effectiveness was proved toward three Lm strains characterized by different origins, i.e., type strain ATCC 7644, clinical strain 338, and food strain 641/6II. The sensor allows for discrimination and quantification treatments at different environmental biocidal amounts and fogging times, and correlates with the microbiological inhibition, promoting the proposed sensor as a useful tool to modulate and monitor no-touch treatments.
Topics: Graphite; Hydrogen Peroxide; Lasers; Paper; Listeria monocytogenes; Disinfection; Cerium; Limit of Detection; Electrochemical Techniques; Catalysis
PubMed: 38822891
DOI: 10.1007/s00604-024-06427-9 -
British Journal of Hospital Medicine... May 2024We present an unusual case of rhomboencephalitis in a young, healthy patient. Although meningitis is usually associated with immunodeficiency, rhomboencephalitis is...
We present an unusual case of rhomboencephalitis in a young, healthy patient. Although meningitis is usually associated with immunodeficiency, rhomboencephalitis is more commonly seen in immunocompetent patients. The wide differential for rhomboencephalitis can create a diagnostic challenge. Without prompt pathogen identification and appropriate antibiotic regimen, central nervous system infections can be fatal. Cerebro-Spinal Fluid (CSF) Polymerase Chain Reaction (PCR) aided a prompt diagnosis and adjustment of therapy to achieve a good patient outcome.
Topics: Humans; Listeria monocytogenes; Immunocompetence; Listeriosis; Anti-Bacterial Agents; Male; Rhombencephalon; Magnetic Resonance Imaging; Meningitis, Listeria; Adult; Encephalitis; Polymerase Chain Reaction
PubMed: 38815971
DOI: 10.12968/hmed.2023.0453 -
Frontiers in Bioscience (Landmark... May 2024, a Gram-positive bacterium, is a prominent foodborne pathogen that causes listeriosis and poses substantial health hazards worldwide. The continuing risk of listeriosis...
BACKGROUND
, a Gram-positive bacterium, is a prominent foodborne pathogen that causes listeriosis and poses substantial health hazards worldwide. The continuing risk of listeriosis outbreaks underlies the importance of designing an effective prevention strategy and developing a robust immune response by reverse vaccinology approaches. This study aimed to provide a critical approach for developing a potent multiepitope vaccine against this foodborne disease.
METHODS
A chimeric peptide construct containing 5 B-cell epitopes, 16 major histocompatibility complex I (MHC-I) epitopes, and 18 MHC-II epitopes were used to create a subunit vaccination against . The vaccine safety was evaluated by several online methods, and molecular docking was performed using ClusPro to determine the binding affinity. Immune simulation was performed using the C-ImmSimm server to demonstrate the immune response.
RESULTS
The results validated the antigenicity, non-allergenicity, and nontoxicity of the chimeric peptide construct, confirming its suitability as a subunit vaccine. Molecular docking showed a good score of 1276.5 and molecular dynamics simulations confirmed the construct's efficacy, demonstrating its promise as a good candidate for listeriosis prophylaxis. The population coverage was as high as 91.04% with a good immune response, indicating good antigen presentation with dendritic cells and production of memory cells.
CONCLUSIONS
The findings of this study highlight the potential of the designed chimeric peptide construct as an effective subunit vaccine against , paving the way for future advances in preventive methods and vaccine design.
Topics: Listeria monocytogenes; Molecular Docking Simulation; Bacterial Vaccines; Vaccines, Subunit; Listeriosis; Computational Biology; Epitopes, B-Lymphocyte; Humans; Epitopes; Molecular Dynamics Simulation; Animals; Foodborne Diseases; Immunoinformatics
PubMed: 38812301
DOI: 10.31083/j.fbl2905176 -
Scientific Reports May 2024Current knowledge about effects of disturbance on the fate of invaders in complex microbial ecosystems is still in its infancy. In order to investigate this issue, we...
Current knowledge about effects of disturbance on the fate of invaders in complex microbial ecosystems is still in its infancy. In order to investigate this issue, we compared the fate of Klebsiella pneumoniae (Kp) and Listeria monocytogenes (Lm) in soil microcosms. We then used environmental disturbances (freeze-thaw or heat cycles) to compare the fate of both invaders and manipulate soil microbial diversity. Population dynamics of the two pathogens was assessed over 50 days of invasion while microbial diversity was measured at times 0, 20 and 40 days. The outcome of invasion was strain-dependent and the response of the two invaders to disturbance differed. Resistance to Kp invasion was higher under the conditions where resident microbial diversity was the highest while a significant drop of diversity was linked to a higher persistence. In contrast, Lm faced stronger resistance to invasion in heat-treated microcosms where diversity was the lowest. Our results show that diversity is not a universal proxy of resistance to microbial invasion, indicating the need to properly assess other intrinsic properties of the invader, such as its metabolic repertoire, or the array of interactions between the invader and resident communities.
Topics: Soil Microbiology; Listeria monocytogenes; Humans; Microbiota; Klebsiella pneumoniae; Temperature; Biodiversity
PubMed: 38811807
DOI: 10.1038/s41598-024-63284-5 -
Science Advances May 2024Infusion of C-labeled metabolites provides a gold standard for understanding the metabolic processes used by T cells during immune responses in vivo. Through infusion of...
Infusion of C-labeled metabolites provides a gold standard for understanding the metabolic processes used by T cells during immune responses in vivo. Through infusion of C-labeled metabolites (glucose, glutamine, and acetate) in -infected mice, we demonstrate that CD8 T effector (Teff) cells use metabolites for specific pathways during specific phases of activation. Highly proliferative early Teff cells in vivo shunt glucose primarily toward nucleotide synthesis and leverage glutamine anaplerosis in the tricarboxylic acid (TCA) cycle to support adenosine triphosphate and de novo pyrimidine synthesis. In addition, early Teff cells rely on glutamic-oxaloacetic transaminase 1 (Got1)-which regulates de novo aspartate synthesis-for effector cell expansion in vivo. CD8 Teff cells change fuel preference over the course of infection, switching from glutamine- to acetate-dependent TCA cycle metabolism late in infection. This study provides insights into the dynamics of Teff metabolism, illuminating distinct pathways of fuel consumption associated with CD8 Teff cell function in vivo.
Topics: Glutamine; Animals; CD8-Positive T-Lymphocytes; Acetates; Mice; Carbon Isotopes; Listeriosis; Listeria monocytogenes; Citric Acid Cycle; Glucose; Mice, Inbred C57BL
PubMed: 38809979
DOI: 10.1126/sciadv.adj1431 -
MBio May 2024Pathogenic bacteria rely on secreted virulence factors to cause disease in susceptible hosts. However, in Gram-positive bacteria, the mechanisms underlying secreted...
UNLABELLED
Pathogenic bacteria rely on secreted virulence factors to cause disease in susceptible hosts. However, in Gram-positive bacteria, the mechanisms underlying secreted protein activation and regulation post-membrane translocation remain largely unknown. Using proteomics, we identified several proteins that are dependent on the secreted chaperone PrsA2. We followed with phenotypic, biochemical, and biophysical assays and computational analyses to examine the regulation of a detected key secreted virulence factor, listeriolysin O (LLO), and its interaction with PrsA2 from the bacterial pathogen (). Critical to virulence is internalization by host cells and the subsequent action of the cholesterol-dependent pore-forming toxin, LLO, which enables bacterial escape from the host cell phagosome. Since is a Gram-positive organism, the space between the cell membrane and wall is solvent exposed. Therefore, we hypothesized that the drop from neutral to acidic pH as the pathogen is internalized into a phagosome is critical to regulating the interaction of PrsA2 with LLO. Here, we demonstrate that PrsA2 directly interacts with LLO in a pH-dependent manner. We show that PrsA2 protects and sequesters LLO under neutral pH conditions where LLO can be observed to aggregate. In addition, we identify molecular features of PrsA2 that are required for interaction and ultimately the folding and activity of LLO. Moreover, protein-complex modeling suggests that PrsA2 interacts with LLO via its cholesterol-binding domain. These findings highlight a mechanism by which a Gram-positive secretion chaperone regulates the secretion, stability, and folding of a pore-forming toxin under conditions relevant to host cell infection.
IMPORTANCE
is a ubiquitous food-borne pathogen that can cause severe disease to vulnerable populations. During infection, relies on a wide repertoire of secreted virulence factors including the LLO that enables the bacterium to invade the host and spread from cell to cell. After membrane translocation, secreted factors must become active in the challenging bacterial cell membrane-wall interface. However, the mechanisms required for secreted protein folding and function are largely unknown. encodes a chaperone, PrsA2, that is critical for the activity of secreted factors. Here, we show that PrsA2 directly associates and protects the major virulence factor, LLO, under conditions corresponding to the host cytosol, where LLO undergoes irreversible denaturation. Additionally, we identify molecular features of PrsA2 that enable its interaction with LLO. Together, our results suggest that and perhaps other Gram-positive bacteria utilize secreted chaperones to regulate the activity of pore-forming toxins during infection.
PubMed: 38809022
DOI: 10.1128/mbio.00743-24 -
Microbiology Spectrum May 2024Bacterial genotyping through whole-genome sequencing plays a crucial role in disease surveillance and outbreak investigations in public health laboratories. This study...
UNLABELLED
Bacterial genotyping through whole-genome sequencing plays a crucial role in disease surveillance and outbreak investigations in public health laboratories. This study assessed the effectiveness of Oxford Nanopore Technologies (ONT) sequencing in the genotyping of and serovar Enteritidis. Our results indicated that ONT sequences, generated with the R10.4.1 flow cell and basecalled using the Dorado 0.5.0 Super Accurate 4.3 model, exhibited comparable accuracy to Illumina sequences, effectively discriminating among bacterial strains from outbreaks. These findings suggest that ONT sequencing has the potential to be a promising tool for rapid whole-genome sequencing of bacterial pathogens in public health laboratories for epidemiological investigations.
IMPORTANCE
This study unveils that Oxford Nanopore Technologies sequencing, by itself, holds the potential to serve as a whole-genome sequencing-based genotyping tool in public health laboratories, enabling routine subtyping of bacterial isolates for disease surveillance and outbreak investigations.
PubMed: 38809017
DOI: 10.1128/spectrum.00509-24 -
TheScientificWorldJournal 2024The dried stigmas of L. produce saffron, a precious spice used for its culinary and medicinal properties since ancient times, while its petals are considered the main... (Comparative Study)
Comparative Study
The dried stigmas of L. produce saffron, a precious spice used for its culinary and medicinal properties since ancient times, while its petals are considered the main by-product of saffron production. The present study aimed to comparatively evaluate the phenolic content, antioxidant capacity, and antibacterial activity of methanolic extracts of stigmas and petals of L. from Taliouine. The polyphenol content was measured using the Folin-Ciocalteu method, the antioxidant activity was determined using the DPPH free radical scavenging method, and the well-diffusion method was used to assess antibacterial activity against seven pathogenic bacterial strains (, , and ). Furthermore, the minimum inhibitory concentration (MIC) of the extracts was determined using the microdilution broth test. Our findings revealed that stigmas and petals contained phenolic compounds at the rate of 56.11 ± 4.70 and 64.73 ± 3.42 mg GAE/g, as well as DPPH radical scavenging capacity with IC of 1700 g/ml and 430 g/ml, respectively. Petal extract showed more effective antibacterial activity, with inhibition diameters ranging from 10.66 ± 0.57 to 22.00 ± 1.00 mm and MIC values ranging from 2.81 to 5.62 mg/ml, compared to the stigma extract, which displayed inhibition diameters from 10.00 ± 0.00 to 18.67 ± 0.76 mm and MIC from 2.81 to 11.25 mg/ml, against five of the seven bacterial strains tested, including S. aureus, E. coli, P. vulgaris, P. aeruginosa, and . Statistical analyses were performed to determine the significance of these results. Thus, stigmas and petals of L. might serve as a suitable source of natural antioxidant and antimicrobial agents for application in the food and pharmaceutical industries.
Topics: Crocus; Anti-Bacterial Agents; Antioxidants; Plant Extracts; Phenols; Microbial Sensitivity Tests; Flowers; Morocco; Bacteria
PubMed: 38808159
DOI: 10.1155/2024/6676404 -
Fitoterapia Jul 2024Thymus daenensis Celak (Lamiaceae family), known as denaian thyme, is an Iranian endemic plant, commonly used for its carminative, expectorant, antibacterial and...
Validation of the traditional antimicrobial use of the Iranian medicinal plant Thymus daenensis Celak through phytochemical characterization of its bioactive constituents.
Thymus daenensis Celak (Lamiaceae family), known as denaian thyme, is an Iranian endemic plant, commonly used for its carminative, expectorant, antibacterial and antifungal properties. Previous studies report the chemical profile of the essential oil of T. daenensis aerial parts, but little is known about its non volatile constituents. Herein, phytochemical and biological investigation of the polar extract of T. daenensis aerial parts to provide further insight into traditional use of this plant has been accomplished. High-performance liquid chromatography coupled to linear ion-trap and orbitrap high-resolution mass spectrometry (LC-ESI/LTQOrbitrap/MS/MS) analysis of MeOH extract was performed to guide the isolation of specialized metabolites and successive characterization by NMR analysis. MeOH extract displayed antioxidant activity evaluated by DPPH (EC = 48.99 ± 1.47 μg/mL) and TEAC assay (1.37 mg/mL). Successively, the biofilm inhibitory activity of extract and isolated compounds against mature biofilms of Escherichia coli, Pseudomonas aeruginosa, Acinetobacter baumannii, Listeria monocytogenes, and Staphylococcus aureus, and their influence on the metabolism of sessile bacterial cells were evaluated. Two previously unreported thymol derivatives have been identified. The biofilm inhibitory activity of isolated compounds highlighted a promising antimicrobial action for the tested compounds. In particular, vanillic acid, (3S,5R,6R,7E,9S)-megastigm-7-ene-3,5,6,9-tetrol 3-O-β-D-glucopyranoside, thymoquinol-2-O-β-D-glucopyranoside and the never reported compound daenol resulted capable of exerting inhibitory activity vs all pathogenic strains. All compounds tested at a concentration of 10 μg/mL inhibited the metabolism of the sessile cells of E. coli at a percentage ranging between 37.7% and 77.39%, and of L.monocytogenes at a percentage ranging between 21.79% and 71.17%.
Topics: Thymus Plant; Phytochemicals; Iran; Plant Extracts; Antioxidants; Plant Components, Aerial; Biofilms; Plants, Medicinal; Anti-Bacterial Agents; Molecular Structure; Microbial Sensitivity Tests
PubMed: 38801898
DOI: 10.1016/j.fitote.2024.106042