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Summary Pork cutlets are susceptible to cross‐contamination with foodborne pathogens during processing. Food irradiation effectively improves food hygiene by eliminating microbes. We investigated the application of X‐ray irradiation (0.5–10 kGy) on pathogen inactivation (D10 value), quality changes [total aerobic bacteria (TAB), yeast and mould (Y&M), total coliform (TC), colour, thiobarbituric acid reactive substance (TBARS), and pH], and the hydrocarbon profile of pork cutlets. D10 values of Escherichia coli O157:H7, Salmonella typhimurium, Listeria monocytogenes, and Staphylococcus aureus were 0.37, 0.62, 0.52, and 0.36 kGy, respectively. At least 3.10 kGy (5‐D10 values) is required to ensure the microbiological safety of pork cutlets. X‐ray irradiation dose‐dependently reduced all microbial counts, and up to 7 kGy had no adverse effects on colour, TBARS, and pH. Furthermore, 1,7‐hexadecadiene and 8‐heptadecene were potential markers for irradiated pork cutlets. X‐ray irradiation of up to 7 kGy is effective in improving hygiene levels while maintaining pork cutlet quality. [ABSTRACT FROM AUTHOR]

ABSTRACT Bacteria adapt the biosynthesis of their envelopes to specific growth conditions and prevailing stress factors. Peptidoglycan (PG) is the major component of the cell wall in Gram‐positive bacteria, where PASTA kinases play a central role in PG biosynthesis regulation. Despite their importance for growth, cell division and antibiotic resistance, the mechanisms of PASTA kinase activation are not fully understood. ReoM, a recently discovered cytosolic phosphoprotein, is one of the main substrates of the PASTA kinase PrkA in the Gram‐positive human pathogen Listeria monocytogenes. Depending on its phosphorylation, ReoM controls proteolytic stability of MurA, the first enzyme in the PG biosynthesis pathway. The late cell division protein GpsB has been implicated in PASTA kinase signalling. Consistently, we show that L. monocytogenes prkA and gpsB mutants phenocopied each other. Analysis of in vivo ReoM phosphorylation confirmed GpsB as an activator of PrkA leading to the description of structural features in GpsB that are important for kinase activation. We further show that ReoM phosphorylation is growth phase‐dependent and that this kinetic is reliant on the protein phosphatase PrpC. ReoM phosphorylation was inhibited in mutants with defects in MurA degradation, leading to the discovery that MurA overexpression prevented ReoM phosphorylation. Overexpressed MurA must be able to bind its substrates and interact with ReoM to exert this effect, but the extracellular PASTA domains of PrkA or MurJ flippases were not required. Our results indicate that intracellular signals control ReoM phosphorylation and extend current models describing the mechanisms of PASTA kinase activation. [ABSTRACT FROM AUTHOR]

Summary: This study explores the antibacterial potential of hydrolysates derived from rice bran protein (RBP) and sesame protein (SP) against Escherichia coli O157:H7 and Listeria monocytogenes. RBP and SP were hydrolysed by protease from Bacillus licheniformis (labelled as RBPH‐B and SPH‐B) and α‐chymotrypsin (denoted as RBPH‐C and SPH‐C), and subsequently fractionated into four molecular weight (MW) categories: F1 (>100 kDa), F2 (10–100 kDa), F3 (1–10 kDa), and F4 (<1 kDa). The antibacterial activities of these hydrolysates and their fractions were systematically evaluated. The results indicated that RBPH‐B and RBPH‐C, along with their fractions, exhibited notable efficacy against L. monocytogenes. Conversely, both SPH‐B, SPH‐C, and their fractions showed pronounced antibacterial activities against both pathogens. Notably, lower MW fractions (SPH‐B, SPH‐B‐F2, and SPH‐B‐F3) demonstrated superior antibacterial properties, effectively reducing bacterial populations to below detection limits (≥6 log CFU mL−1) at a concentration of 100 mg mL−1. Further analysis revealed that SPH‐B‐F3 markedly reduced the reaction time required to inhibit or eliminate E. coli O157:H7 and L. monocytogenes, with comparable times of 6 and 4 h, respectively. These findings highlight the potential application of specific SPH‐B fractions as antibacterial agents in the food industry. [ABSTRACT FROM AUTHOR]

Summary Persistent bacteria are subset of cells capable of surviving bactericidal treatments longer. They originate in response to environmental stressors and show a longer lag phase compared to the rest of the population they are part of. Impact of persistent cells on food safety and role of common food preservation techniques in their formation are still unclear. This study aims to investigate whether osmotic stress induces formation of persistent cells in Listeria monocytogenes capable of resisting longer during cooking cycle of pork sausages. Lag‐phase duration at single‐cell level of a strain grown in 6%‐NaCl broth using image processing software was first investigated. Then, trend of the strain inactivation curve was evaluated in experimentally contaminated pork sausages cooked at 65 °C for 11 min. Results showed that salt triggers the formation of persistent cells characterised by a longer lag phase and increased heat resistance, posing a concern especially for ready‐to‐eat foods. [ABSTRACT FROM AUTHOR]

In recent years, development of biopolymeric nanofibers as an active biodegradable packaging system has attracted specific attention. The objective of this research was to develop zein‐based electrospun nanofibers (NFs) incorporated with geraniol‐loaded nanoliposomes (G‐loaded NLPs). Geraniol was encapsulated into NLPs with an efficiency of 79.23%. The particle size and zeta potential of G‐loaded NLPs were 121.50 nm and −38.30 mV, respectively. The successful loading of geraniol in the NLPs was approved by Fourier transform infrared (FT‐IR) spectroscopy. The liposomal vesicles showed spherical shapes. G‐loaded NLPs were added in the zein‐based electrospun NFs at three different concentrations (0.25, 0.5, and 1%w/v). All NFs samples exhibited fibrillar structure. The increase of NLPs concentration enhanced the thermal stability of the NFs. However, the crystalline structure of zein NFs did not change by the addition of G‐loaded NLPs. The highest surface hydrophobicity was related to the NFs containing 1% G‐loaded NLPs. The mechanical parameters of NFs depend on the concentration of NLPs. The NFs incorporated with G‐loaded NLPs showed inhibition activity against four foodborne pathogenic bacteria (Staphylococcus aureus, Listeria monocytogenes, Escherichia coli, and Salmonella typhimurium) with an inhibition zone of 4.5–22 mm. Moreover, the α‐diphenyl‐β‐picrylhydrazyl (DPPH) scavenging activity of NFs samples was located at the range of 20%–48%. These findings represent the Efficiency of the G‐loaded NLPs for use as bioactive compound in the zein‐based NFs as an active packaging material. [ABSTRACT FROM AUTHOR]

Background and Objectives: Platelet concentrates (PC) are stored at 20–24°C to maintain platelet functionality, which may promote growth of contaminant bacteria. Alternatively, cold storage of PC limits bacterial growth; however, data related to proliferation of psychotrophic species in cold‐stored PC (CSP) are scarce, which is addressed in this study. Materials and Methods: Eight laboratories participated in this study with a pool/split approach. Two split PC units were spiked with ~25 colony forming units (CFU)/PC of Staphylococcus aureus, Klebsiella pneumoniae, Serratia liquefaciens, Pseudomonas fluorescens and Listeria monocytogenes. One unit was stored under agitation at 20–24°C/7 days while the second was stored at 1–6°C/no agitation for 21 days. PC were sampled periodically to determine bacterial loads. Five laboratories repeated the study with PC inoculated with lyophilized inocula (~30 CFU/mL) of S. aureus and K. pneumoniae. Results: All species proliferated in PC stored at 20–24°C, reaching concentrations of ≤109 CFU/mL by day 7. Psychrotrophic P. fluorescens and S. liquefaciens proliferated in CSP to ~106 CFU/mL and ~105 CFU/mL on days 10 and 17 of storage, respectively, followed by L. monocytogenes, which reached ~102 CFU/mL on day 21. S. aureus and K. pneumoniae did not grow in CSP. Conclusion: Psychrotrophic bacteria, which are relatively rare contaminants in PC, proliferated in CSP, with P. fluorescens reaching clinically significant levels (≥105 CFU/mL) before day 14 of storage. Cold storage reduces bacterial risk of PC to levels comparable with RBC units. Safety of CSP could be further improved by implementing bacterial detection systems or pathogen reduction technologies if storage is beyond 10 days. [ABSTRACT FROM AUTHOR]

Atlantic mackerel (Scomber scombrus) caught during the summer months in Icelandic waters after intensive feeding is rich in lipids and, thus, sensitive to lipid degradation. Recent studies have led to improved cooling and handling on board, ensuring high‐quality raw material. However, studies on the development of high‐quality products for human consumption are lacking. The study aimed to investigate the effects of hot‐smoking on the physicochemical, microbial, and sensory quality of deep‐skinned Atlantic mackerel fillets during chilled storage (1 ± 0.6°C). In addition, the quality of smoked mackerel from frozen–thawed fillets (9 months at −25 ± 1.8°C) was compared to that of fresh‐smoked fillets to evaluate the possibility of the industry being able to provide smoked fillets throughout the year, despite the short fishing season. Brining and hot‐smoking reduced total viable counts and inactivated Listeria monocytogenes. Hot‐smoking positively affected the sensory attributes of the fillets and sensory quality was largely maintained for at least 21 days of chilled storage. Although slightly lower sensory and texture scores were obtained for frozen–thawed smoked fillets, they remained within acceptable limits throughout the period of cold storage. The shelf‐life of smoked Atlantic mackerel deep‐skinned fillets stored at 1°C is, therefore, assessed to be at least 21 days. Well‐fed Atlantic mackerel is suitable for developing high‐quality and stable smoked fillet products from both fresh and frozen–thawed raw materials. [ABSTRACT FROM AUTHOR]

Listeria monocytogenes is a ubiquitous opportunistic bacterium responsible for deadly listeriosis outbreaks. This pathogen has been recognized as a significant food‐borne pathogen in seafood products. The present study aimed to investigate the transcript levels of virulence, adhesion, and stress response genes of L. monocytogenes upon exposure to sublethal levels of lime juice and NaCl in shrimp matrix. For this purpose, minced and broth shrimp samples (control, 2% NaCl, 5% NaCl, 25 μL/mL lime, and 50 μL/mL lime, as well as 2% NaCl+25 μL/mL lime) were inoculated with approximately 107 CFU/g or ml of L. monocytogenes, and subsequently, the samples were stored at 12°C or 37°C. For the minced samples, the transcription of one stress‐related (sigB), two adhesion (imo1634 and imo1847), and four virulence (hly, prf, intA, and plc) genes was assessed by RT‐qPCR after different storage times (0 and 48 h). Results showed that the transcript levels of sigB, imo1847, and imo1634 genes increased with increasing storage temperatures of shrimp broth (12°C to 37°C). At the beginning, the transcription of the studied genes decreased in all treatments of minced shrimp; however, after 48 h of storage at 12°C, the transcript levels of hly, prf, imo1847, imo1634, and intA genes were significantly upregulated up to 0.5–9 log2 fold‐change in all treatments compared to the control group (p <.05). These results highlight that the survived L. monocytogenes after exposure to moderate salt content or lime juice could represent enhanced virulence and adhesion capabilities, posing a significant public health risk. [ABSTRACT FROM AUTHOR]

This article explores the role of Akkermansia muciniphila, a type of gut bacteria, in preventing Listeria monocytogenes infection in mice. The study found that mice treated with A. muciniphila had reduced bacterial loads and improved intestinal barrier function compared to control mice. A. muciniphila was also found to increase levels of linoleic acid in the intestines, which strengthened the epithelial barrier and protected against L. monocytogenes infection. These findings suggest that A. muciniphila or linoleic acid-based strategies could be potential approaches for preventing listeriosis. [Extracted from the article]

The essential oils from Thymus vulgaris, Salvia officinalis, and Ocimum basilicum were extracted by hydrodistillation, characterized by gas chromatography/mass spectrometry, and quantified by gas chromatography/flame ionization detector. The principal constituents were thymol, ρ‐cymene and carvacrol (T. vulgaris); camphor, β‐pinene, and 1,8‐cineole (S. officinalis); and (E)‐anethole, linalool, and 1,8‐cineole (O. basilicum). The essential oil from T. vulgaris was the most effective, forming inhibition halos of 46.16 ± 0.16 and 26.38 ± 0.33 mm, respectively, for Salmonella choleraesuis and Listeria monocytogenes. This essential oil was also more effective against S. choleraesuis, with a minimum inhibitory concentration of 8.85 mg mL−1, and a minimum inhibitory concentration of 17.71 mg mL−1 for L. monocytogenes. No bactericidal activity against S. choleraesuis and L. monocytogenes was observed for the essential oils from S. officinalis, and O. basilicum. Scanning electron micrographs showed that the addition of essential oils left the bacterial cells damaged and deformed. Significant 2,2‐diphenyl‐1‐picrylhydrazyl free radical scavenging capacity and lipid substrate protection were observed in the β‐carotene bleaching assay for the essential oil from T. vulgaris, with IC50 of 231.13 ± 0.53 and 15.25 ± 0.38 μg mL−1, respectively. A dose‐dependent relationship between antioxidant activity and concentrations was observed in the tests. Toxicities of LC50 = 1.24, 3.51 and 1.19 mg mL−1 against Drosophila suzukii flies, respectively, were observed for the essential oils from T. vulgaris, S. officinalis, and O. basilicum. Results suggest that essential oils can be promising antioxidant agents, insecticides, and inhibitors of pathogenic bacteria. [ABSTRACT FROM AUTHOR]

Fresh apples are vulnerable to Listeria monocytogenes (L. monocytogenes) contamination during handling and storage causing subsequent foodborne outbreaks. Gaseous chlorine dioxide (ClO2) is an effective antimicrobial agent against L. monocytogenes and could augment food safety. This study investigates the stress and virulence response of L. monocytogenes on apples exposed to a sublethal concentration of ClO2. L. monocytogenes was inoculated on the surface of apples and exposed to gaseous ClO2 for 1 h. Gene expression analysis via Real‐Time quantitative polymerase chain reaction (RT‐qPCR) revealed minimal changes in gene expression compared to control samples. However, a surface‐dependent response was observed, with slight upregulation of relevant virulence (hly) and stress (clpC) genes on more hydrophilic surfaces. These findings indicate that gaseous ClO2 treatment can provide a biostatic effect against L. monocytogenes on fresh produce, shedding light on its antimicrobial mechanism and potential for enhancing apple safety. [ABSTRACT FROM AUTHOR]

Between 2012 and 2024, a prolonged outbreak of 73 cases of L. monocytogenes ST173 infections ('My2' ‐cluster) has been ongoing in Belgium (5), Czechia (1), Germany (39), Finland (2), Italy (1), the Netherlands (20), and the United Kingdom (UK) (5). Fourteen deaths have been recorded as associated with this outbreak. Males aged over 60 years represent the most affected population group. Most patients with available information from case interviews report consuming various fish products before illness. Among 73 cases, an ongoing 'My2' sub‐cluster 1 was identified with 38 cases reported in six EU countries and the UK. The 'My2' sub‐cluster 1 includes 83 non‐human isolates, of which 48 are food isolates and six are environmental isolates with traceability data corresponding to 37 fish products (different typologies) and 12 fish manufacturers (located in six EU countries and one third country). The epidemiological and traceability information did not allow identification of a single common point or food business operator in the traceability of all products. Five countries reported the implementation of control measures. The whole genome analysis (WGS) analysis, the tracing evidence, and the detection in fish products between 2017 and 2024 suggest that the strain has been geographically spread in Europe for several years, most likely originated from a past single source high up in the production chain, and has been established in different fish processing plants. Overall, the evidence supports the hypothesis of fish products as the vehicle of infections. Given the detection of the outbreak strain in multiple types of fish products and its wide circulation in the EU/EEA fish production chain, new cases are likely to be reported. Corrective measures should be implemented in the plants where the contamination is detected, and further investigations should be carried out to identify the point of entry and prevent possible re‐contamination. [ABSTRACT FROM AUTHOR]

The identification of the coproporphyrin‐dependent heme biosynthetic pathway, which is used almost exclusively by monoderm bacteria in 2015 by Dailey et al. triggered studies aimed at investigating the enzymes involved in this pathway that were originally assigned to the protoporphyrin‐dependent heme biosynthetic pathway. Here, we revisit the active site of coproporphyrin ferrochelatase by a biophysical and biochemical investigation using the physiological substrate coproporphyrin III, which in contrast to the previously used substrate protoporphyrin IX has four propionate substituents and no vinyl groups. In particular, we have compared the reactivity of wild‐type coproporphyrin ferrochelatase from the firmicute Listeria monocytogenes with those of variants, namely, His182Ala (H182A) and Glu263Gln (E263Q), involving two key active site residues. Interestingly, both variants are active only toward the physiological substrate coproporphyrin III but inactive toward protoporphyrin IX. In addition, E263 exchange impairs the final oxidation step from ferrous coproheme to ferric coproheme. The characteristics of the active site in the context of the residues involved and the substrate binding properties are discussed here using structural and functional means, providing a further contribution to the deciphering of this enigmatic reaction mechanism. [ABSTRACT FROM AUTHOR]

The study aims to identify antibacterial properties in unfertilized eggs of Scyliorhinus canicula and Scyliorhinus stellaris. Despite challenging marine conditions, these eggs retain their integrity for extended periods and remain unaffected by pathogens. The antibacterial activity was measured using minimum inhibitory and minimum bactericidal concentration analysis. The eggs of S. stellaris exhibited a slight inhibitory effect against Staphylococcus aureus and Listeria monocytogenes, whereas both species' eggs showed no activity against gram‐negative microorganisms. [ABSTRACT FROM AUTHOR]

The contamination of Listeria monocytogenes (L. monocytogenes) in dairy products poses a significant risk to human health. It is urgent to develop on‐site rapid strategy to reduce associated threats. We employed carbon dots (CDs) and silicon nanoparticles (SiNPs) as energy donors and acceptors respectively. The CDs and SiNPs were functionalised with vancomycin and aptamers correspondingly, leading to the establishment of ratiometric fluorescent sensor. With a portable smartphone‐integrated device, the ratios of blue/green values from the colour images depended on L. monocytogenes concentrations for quantification. The sensors were demonstrated for monitoring L. monocytogenes in dairy products within 30 min. [ABSTRACT FROM AUTHOR]

CdaA is the most widespread diadenylate cyclase in many bacterial species, including several multidrug‐resistant human pathogens. The enzymatic product of CdaA, cyclic di‐AMP, is a secondary messenger that is essential for the viability of many bacteria. Its absence in humans makes CdaA a very promising and attractive target for the development of new antibiotics. Here, the structural results are presented of a crystallographic fragment screen against CdaA from Listeria monocytogenes, a saprophytic Gram‐positive bacterium and an opportunistic food‐borne pathogen that can cause listeriosis in humans and animals. Two of the eight fragment molecules reported here were localized in the highly conserved ATP‐binding site. These fragments could serve as potential starting points for the development of antibiotics against several CdaA‐dependent bacterial species. [ABSTRACT FROM AUTHOR]

A prolonged genomic cluster of 20 human Listeria monocytogenes ST1607 infections has been reported to the European Centre for Disease Prevention and Control, with cases identified in Denmark (17), Germany (1), and Italy (2) since 2019. The number of cases has sharply increased after 2021. The most recent case was reported in March 2024 in Denmark, indicating an ongoing risk of further infections. Of 20 listeriosis cases, five have died (one due to another cause than L. monocytogenes infection), indicating high severity of infection particularly among elderly people with underlying chronic conditions. The national investigations the traceability and genomic data analyses revealed the detection of five matching L. monocytogenes ST1607 isolates from four sliced smoked salmon products (four batches) produced by the Danish Processing Plant A between 2021 and 2024. These contaminated products were distributed to the three countries (Denmark, Germany, and Italy) reporting human cases to ECDC. The identification of the outbreak strain from the environment of the Danish Processing Plant A in 2023 and in the products since 2021 indicates the persistence of the L. monocytogenes ST1607 within the plant and suggests that the point(s) of the contamination in the plant have not been identified and controlled. Although control measures had been implemented at the plant and withdrawals and recalls of contaminated batches were performed, new batches of contaminated products could still be placed on the market until the site(s) at the plant and the root(s) of the contamination in the fish production chain are identified and properly controlled. Based on the available information from case interviews, microbiological and traceability analysis, the conclusion is that sliced smoked salmon products are the likely sources of infection. New cases could occur in EU/EEA countries, particularly among vulnerable people, until the root(s) of contaminations are identified and corrective measures are implemented. [ABSTRACT FROM AUTHOR]

Resident memory T (TRM) cells have been recently established as an important subset of memory T cells that provide early and essential protection against reinfection in the absence of circulating memory T cells. Recent findings showing that TRM expand in vivo after repeated antigenic stimulation indicate that these memory T cells are not terminally differentiated. This suggests an opportunity for in vitro TRM expansion to apply in an immunotherapy setting. However, it has also been shown that TRM may not maintain their identity and form circulating memory T cells after in vivo restimulation. Therefore, we set out to determine how TRM respond to antigenic activation in culture. Using Listeria monocytogenes and LCMV infection models, we found that TRM from the intraepithelial compartment of the small intestine expand in vitro after antigenic stimulation and subsequent resting in homeostatic cytokines. A large fraction of the expanded TRM retained their phenotype, including the expression of key TRM markers CD69 and CD103 (ITGAE). The optimal culture of TRM required low O2 pressure to maintain the expression of these and other TRM‐associated molecules. Expanded TRM retained their effector capacity to produce cytokines after restimulation, but did not acquire a highly glycolytic profile indicative of effector T cells. The proteomic analysis confirmed TRM profile retention, including expression of TRM‐related transcription factors, tissue retention factors, adhesion molecules, and enzymes involved in fatty acid metabolism. Collectively, our data indicate that limiting oxygen conditions supports in vitro expansion of TRM cells that maintain their TRM phenotype, at least in part, suggesting an opportunity for therapeutic strategies that require in vitro expansion of TRM. [ABSTRACT FROM AUTHOR]

Listeria monocytogenes biofilms formed on food-contact surfaces within foodprocessing facilities pose a significant challenge, serving as persistent sources of cross-contamination. In this review, we examined documented cases of foodborne outbreaks and recalls linked to L. monocytogenes contamination on equipment surfaces and in the food production environment, provided an overview of the prevalence and persistence of L. monocytogenes in different foodprocessing facilities, and discussed environmental factors influencing its biofilm formation. We further delved into antimicrobial interventions, such as chemical sanitizers, thermal treatments, biological control, physical treatment, and other approaches for controlling L. monocytogenes biofilms on food-contact surfaces. This review provides valuable insights into the persistent challenge of L. monocytogenes biofilms in food processing, offering a foundation for future research and practical strategies to enhance food safety. [ABSTRACT FROM AUTHOR]

Summary: The aim of this work was to evaluate the prevalence of Listeria monocytogenes and other Listeria spp. in chicken, duck, quail, turkey and pork meat, including the antibiotic resistance of isolated strains. A total of 184 meat samples were collected from different retailers in La Rioja (Spain). The presence of Listeria spp. and L. monocytogenes were detected in 24.46% and 10.32% of the meat samples respectively. L. monocytogenes was the predominant Listeria spp. found in chicken, quail and pork meat, while L. innocua and L. welshimeri were the predominant species in duck and turkey meat respectively. A total of thirty‐three strains (55.93%) of Listeria spp. were found to be multi‐resistant (resistant to ≥3 families of antibiotics). The highest multi‐resistant rates were observed in L. monocytogenes (73.68%) and L. innocua (70.59%), followed by L. ivanovii (50%). Resistance to ampicillin and trimethoprim–sulfamethoxazole were found in L. monocytogenes strains isolated from chicken, being of special concern, since these antibiotics are used in the treatment of listeriosis. Special measures should be taken to reduce meat contamination such as adequate handling, correct preparation (cooking) and cleaning and disinfection in order to avoid cross‐contamination. [ABSTRACT FROM AUTHOR]

This study evaluated the impact of different food residues on the recovery of Listeria monocytogenes and Salmonella Typhimurium from stainless steel surfaces. Food residues tested include lettuce rinsate, blended lettuce, low-fat milk, and whole milk for Listeria monocytogenes, and powdered infant formula, all-purpose flour, and whole milk dairy powder for Salmonella Typhimurium. Bacterial suspensions were inoculated on stainless steel surfaces with or without food residues and held for different time periods. Significant differences (P < 0.0001) in Salmonella Typhimurium recovery were observed between the no food residue control and all food residues over 24 hours. For Listeria monocytogenes, minimal variability in recovery was observed among food residue types, with significant differences from the no food residue control (P < 0.05) observed after 24 hours. The study also found that surface sampling can spread Listeria monocytogenes and Salmonella Typhimurium on stainless steel surfaces, suggesting that food residue type may affect microbial recovery during environmental monitoring. [ABSTRACT FROM AUTHOR]

This is a comparative study to evaluate the effectiveness of six pomegranate peel extracts (PPEs) as antibacterial and antiproliferative agents. The Six PPEs were prepared using four solvent systems and each filtrate was concentrated to a gummy material to be used in the evaluation. The well‐diffusion method was used to evaluate their antimicrobial activity against bacteria typically associated with food spoilage: Escherichia coli, Pseudomonas aeruginosa, Salmonella typhimurium, Listeria monocytogenes, Staphylococcus epidermidis, Staphylococcus aureus, and three Bacillus species. The 3‐(4,5‐dimethylthiazol‐2‐yl)‐5‐(3‐carboxymethoxyphenyl)‐2‐(4‐sulfophenyl)‐2H‐tetrazolium (MTT) was used to evaluate the cytotoxicity against colorectal carcinoma cells (HCT116), prostate adenocarcinoma (PC3), ovarian cancer cells (SKOV‐3), and fibroblasts (MRC‐5). The antioxidant evaluation was done using the 2,2‐diphenyl‐1‐picrylhydrazyl‐hydrate (DPPH) assay. The pH of the water‐containing extracts was acidic and almost the same over 6 weeks. The six PPEs inhibited the bacterial growth in a comparable level to standard antibiotics. The effectiveness of each extract was dependent on the bacterial strain, and the Listeria showed a remarkable inhibition when exposed to the aqueous extract prepared at room temperature (RT). The aqueous (RT) and methanol PPEs had a significant antioxidant scavenging capability and a remarkable cytotoxic activity against the PC3 with half maximal inhibitory concentration (IC50) of 0.1 μg/mL. The boiled aqueous extract exhibited antiproliferative activity against HCT116 with an IC50 of 21.45 μg/mL. The effect on SKOV‐3 and fibroblasts was insignificant. With the exception of butanol, the antioxidant screening shows an inverse correlation between the polarity of the extraction solvent and the IC50 exhibited by the PPEs. The variation in the effectiveness of PPEs is suggested to be due to variable soluble bioactive compounds that may interact differently with different cells, though water‐containing extracts are promising antibacterial agents. The findings clearly show that pomegranate peel possessed the potential to be an eco‐friendly novel source for natural compounds that can be implemented in the food industry as a natural antimicrobial and natural food additive to prevent foodborne illnesses. [ABSTRACT FROM AUTHOR]

Objective: Listeriosis is caused by the bacterium, Listeria monocytogenes, and is a significant health concern because of high hospitalization and mortality rates. This study reports seven cases of pregnancy‐associated listeriosis diagnosed with matrix‐assisted laser desorption ionization‐time of flight (MALDI‐TOF) mass spectrometry performed on infection‐positive blood culture. Methods: Blood culture‐positive samples of seven patients whose pregnancy was complicated by Listeria infection and treated at Xuanwu Hospital of Capital Medical University between January 2016 and December 2021 were analyzed retrospectively. Strains identified by MALDI‐TOF mass spectrometry were compared with colony identification results. Identification accuracy and consistency were assessed. Results: A total of seven strains of Listeria were collected from seven pregnant women presented with fever (37.6–39.9°C). Clinical abnormalities included abnormal liver function, emaciation, hypoalbuminemia, hypocalcemia, hypokalemia, hyponatremia, ketosis, mild to moderate anemia, leukopenia, and thrombocytopenia. Compared with the traditional culture method, MALDI‐TOF mass spectrometry led to much earlier identification (4–6 h vs. 3–4 days) with 100% identification accuracy. Of the seven pregnancies complicated by Listeria, only two led to live births. Of the five fetal deaths, three occurred in the second trimester. Conclusion: In this series of pregnancy‐associated listeriosis cases, the fetal mortality rate was 71%. MALDI‐TOF mass spectrometry is a valuable method that can identify Listeria from blood culture rapidly and accurately. [ABSTRACT FROM AUTHOR]

Summary: This is the first known case report of encephalitic listeriosis in a donkey (Equus asinus). A 5‐day‐old female donkey foal presented for fever, progressive weakness and loss of suckle reflex. Upon arrival, its vital parameters were normal, but the foal was collapsed. It had horizontal nystagmus, front limb paddling, minimal response to stimuli, prolapse of the left third eyelid and curling the neck to the left when in sternal recumbency. Samples collected for diagnostic evaluation included blood and cerebral spinal fluid. The cerebrospinal fluid (CSF) showed a pleocytosis consisting mainly of nondegenerative neutrophils and a normal protein concentration. Bacteria were not seen on Gram stain. After 24 h of treatment with intravenous fluids, anti‐inflammatories, antibiotics, nasogastric feedings of the dam's milk and supplemental nasal oxygen, little improvement was observed and the owners elected to euthanise the foal. Post‐mortem examination revealed multifocal, irregularly distributed hepatic necrosis and multifocal lymphohistiocytic encephalitis. Listeria monocytogenes was isolated from a section of brainstem. [ABSTRACT FROM AUTHOR]

The aim of this work was to evaluate the resistance of two pathogenic bacteria (Listeria monocytogenes and Salmonella enterica subsp. enterica serotype Senftenberg), and three airborne food‐spoiling filamentous fungi (Hyphopichia burtonii, Penicillium nordicum, and Aspergillus brasiliensis ATCC 16404) to gaseous ozone on stainless steel. Tests were carried out by exposing inoculated tiles to gaseous ozone in a laboratorial chamber at concentrations up to 50 mg/L and at times up to 180 min (bacteria) or 300 min (filamentous fungi). For bacteria, the resistance to gaseous ozone of L. monocytogenes proved markedly higher than that of S. enterica. Their D‐values increased by seven times (from 27.3 to 200.7 min for the strain of L. monocytogenes studied; from 7.3 to 48.0 min for the Salmonella species studied) when the ozone concentration were reduced from 12 to 4 mg/L. For filamentous fungi, a substantial effect was observed only at 50 mg/L on single‐layered inocula: at these conditions, A. brasiliensis ATCC 16404 proved the most resistant strain to gaseous ozone, its D‐value (134.4 min) being higher than those registered for the tested strains of H. burtonii (9.9 min) and P. nordicum (17.1 min). The results demonstrated that the use of gaseous ozone as a sanitizing agent for environments and working surfaces seems to be a potential alternative to chemical sanitizers against the two pathogens studied, whereas it seemed effective against the three filamentous fungi studied only in limited circumstances. [ABSTRACT FROM AUTHOR]

Recurring Listeria outbreaks in the United States is a growing public healthcare concern. Although no associated reported death, 17 were hospitalized out of the 18 reported illnesses in the recent outbreak in 15 US states. The United States has experienced about 30 Listeria outbreaks in the last decade with 524 Listeriosis cases and 80 deaths. The identified origin were ice cream, leafy greens, mushroom, meat slice, dairy products like cheese, packaged salads, cooked chicken, hard‐boiled egg, pork product, frozen vegetable, raw milk, packaged caramel apple, bean sprout and soya products. Although rare, Listeria may lead to serious illness (invasive listeriosis) or death. Listeriosis is critically harmful and medically complicated, especially in the pregnant, the old above 65 years and in the immunocompromised. It could cause premature birth, miscarriage or even neonatal death. Hospitalization is often necessary in the geriatric, being fatal at times. Among Listeria sp., Listeria monocytogenes is often human infection‐associated. It is a gram‐positive, non‐sporulating, motile bacillus opportunistic pathogen. Food‐borne listeriosis is often associated with frozen foods due to its ability to thrive at low temperatures. Hypervirulent strains of L. monocytogenes with an ability to infect the respiratory system (the lungs) was recently reported in the coronavirus disease‐19 patients during the pandemic. L. monocytogenes seemed to have developed antimicrobial resistance to ciprofloxacin and meropenem, possibly acquired through the food chain. An early onset of listeriosis in the newborn is evident in the first 7 days postparturition. As the bacteria colonize the genitourinary tract, majority of such cases result from teratogenic transfer during vaginal delivery. Premature newborns, neonates born outside healthcare facilities and low‐birth‐weight babies were increasingly predisposed to an early onset of listeriosis. Listeria outbreaks were earlier reported in South Africa, Australia and Europe, with an unclear origin of the outbreaks. Social media updates about such outbreaks, the most likely food source, and measures to self‐protect are suggested as preventive measures. The article deals on various such aspects related to listeriosis primarily originating from food, to ensure better public healthcare and human wellness. [ABSTRACT FROM AUTHOR]

In this study a series of N‐(4‐methoxy‐2‐nitrophenyl)‐β‐alanine derivatives were prepared, characterized by the NMR and IR spectroscopic and microanalysis techniques and evaluated for their antibacterial potency against Gram‐positive Staphylococcus aureus and Listeria monocytogenes bacteria strains as well Gram‐negative Escherichia coli and Salmonella enteritidis. The assessment was carried out using the in vitro methodologies. According to the results, the best antibacterial properties were shown by hydrazones with the incorporated thien‐2‐yl and dimethylaminophenyl fragments. According to the data, almost all compounds except N‐alkylated dimethylaminophenyl‐having hydrazone are regarded as bactericidal agents for the used bacteria. The obtained data demonstrate that the above‐mentioned hydrazones could be further selectively explored for the development of antibacterial candidates targeting Gram‐positive and Gram‐negative bacteria. [ABSTRACT FROM AUTHOR]

Background: Listeriosis is a severe foodborne infection caused by Listeria monocytogenes, an important foodborne pathogen of animals and humans. Listeriosis is a rare disease in cats. Objective: To describe the clinical, diagnostic imaging, histological, and microbiological features of L. monocytogenes‐associated mesenteric lymphadenitis in a cat. Animals: Listeria monocytogenes‐associated mesenteric lymphadenitis was confirmed in a cat by histology and microbiology. Results: Two distinct isolates of L. monocytogenes were cultured from the affected mesenteric lymph node and whole genome sequencing was performed. Conclusion and Clinical Importance: This report should alert veterinary clinicians and microbiologists to the syndrome, which may have implications for health and food safety in animals and humans. [ABSTRACT FROM AUTHOR]

Pulsed light (PL) technology has received significant attention as a sustainable alternative for food processing. PL involves a photochemical and photothermal mechanism for microbial inactivation. However, the simultaneous description of both effects to evaluate the technology's efficiency remains unexplored. Furthermore, the process efficiency strongly depends on the optical properties of treated food products. This work evaluated the performance of a non‐isothermal model, previously reported in the literature for different emergent technologies, compared to the conventional Weibull model to describe the inactivation of Escherichia coli ATTC 25922 and Listeria monocytogenes Scott A by pulsed light (from 0 to 300 J/cm2) inoculated in the tested systems. Five food products and two model solutions with different optical characteristics were treated, and their optical properties were correlated to both microbial inactivation and temperature increase, resulting from the photothermal effect. The non‐isothermal mathematical model effectively captures both aspects within the PL mechanism. The inclusion of ascorbic acid in the analyzed samples significantly (p < 0.05) reduced the efficiency of microbial inactivation. Practical applications: Using pulsed light technology in food processing is a remarkable innovation that harnesses the potential to amplify and optimize natural resources while reducing energy consumption and time processing. This approach harnesses the controlled application of short, intense light bursts to perform various tasks such as preservation, disinfection, and decontamination. By effectively targeting and inactivating harmful microorganisms, pulsed light avoids the need for excessive chemical treatments or prolonged exposure to high temperatures, thus preserving the innate nutritional value, flavor, and texture of food products. This method avoids the generation of hazardous by‐products or excess waste, aligning perfectly with sustainable practices. [ABSTRACT FROM AUTHOR]

The foodborne pathogen Listeria monocytogenes can grow in a wide range of environmental conditions. For the study of the physiology of this organism, several chemically defined media have been developed over the past decades. Here, we examined the ability of L. monocytogenes wildtype strains EGD‐e and 10403S to grow under salt and pH stress in Listeria synthetic medium (LSM). Furthermore, we determined that a wide range of carbon sources could support the growth of both wildtype strains in LSM. However, for hexose phosphate sugars such as glucose‐1‐phosphate, both L. monocytogenes strains need to be pre‐grown under conditions, where the major virulence regulator PrfA is active. In addition, growth of both L. monocytogenes strains was observed when LSM was supplemented with the amino acid sugar N‐acetylmannosamine (ManNAc). We were able to show that some of the proteins encoded in the operon lmo2795‐nanE, such as the ManNAc‐6‐phosphate epimerase NanE, are required for growth in the presence of ManNAc. The first gene of the operon, lmo2795, encodes a transcriptional regulator of the RpiR family. Using electrophoretic mobility shift assays and quantitative real‐time PCR analysis, we were able to show that Lmo2795 binds to the promoter region of the operon lmo2795‐nanE and activates its expression. [ABSTRACT FROM AUTHOR]

BACKGROUND: Electrolyzed water (EW) is recognized as an effective way to control and reduce pathogens in vegetables. However, the disinfection efficacy of EW alone is limited. In this work, the bactericidal activity and biofilm removal capability of EW, generated by adding NaCl to a portable EW generator, were investigated with special reference to Listeria monocytogenes. Furthermore, the impact of EW in combination with dimethyl dicarbonate (DMDC) in reducing the microbial load and improving the overall quality of lettuce during refrigerated storage was evaluated. RESULTS: EW with 0.3% NaCl (SEW) had the highest bactericidal activity against L. monocytogenes. The pathogen treated with SEW exhibited lower superoxide dismutase activity and more leakage of proteins and nucleic acids than in the case of EW. Furthermore, the use of SEW resulted in changes in the cell permeability and morphology of L. monocytogenes. A decrease in adhesion and collapse of the biofilm architecture were also observed, indicating that SEW was more effective for inactivating L. monocytogenes cells compared to EW. For untreated lettuce, the populations of the total plate count and inoculated L. monocytogenes decreased by 2.47 and 2.35 log CFU g−1, respectively, after the combined SEW/DMDC treatment for 3 min. The use of SEW alone or combined with DMDC did not negatively impact the lettuce color values, titratable acid, ascorbic acid and soluble solids compared to the control group. CONCLUSION: SEW in combination with DMDC can be used as a novel and potentially effective disinfection strategy for ensuring the safety of vegetable consumption. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Foodborne pathogens are a persistent threat to food and consumer safety. To mitigate outbreaks and contamination incited by these pathogens, the development of novel preventative safety controls and biorational inactivation measures are paramount. The objectives of this research were to evaluate the efficacy of pyrrolidine‐based amide derivatives of decanoic (DEPY), lauric (LAPY), myristic (MYPY) and palmitic (PAPY) fatty acids for in‐vitro inhibition and inactivation of various Gram‐positive bacterial strains including Listeria monocytogenes (typically associated with foodborne illness), Bacillus subtilis, and Streptococcus mutans and Streptococcus sobrinus (both normally present in the oral cavity and involved with dental caries). Compared to no treatment (control), significant differences (P < 0.05) in the growth of Listeria strains were seen in‐vitro with increased inhibition at higher amide concentrations (10,000–20,000 ppm). Furthermore, in‐vitro growth inhibition of B. subtilis, S. sobrinus, and S. mutans was also observed with an effectiveness of LAPY>MYPY>PAPY>DEPY. In co‐inoculation assays, LAPY treatment significantly reduced Listeria growth from 1.55 to >5.0 Log CFU/mL when a concentration range of 5 to 250 ppm was applied. Moreover, Listeria populations on pathogen‐inoculated produce were significantly (P < 0.05) reduced from 0.51 to >3.00 Log CFU/g with greater inactivation on carrots compared to alfalfa, soybean, and pistachio. These results demonstrated the potential value of these FA amides against Gram‐positive pathogenic bacteria. Biorational applications of antibacterial FA amides on fresh produce as a postharvest intervention process offers a great potential for enhancement of food safety. [ABSTRACT FROM AUTHOR]

A genomic cluster of Listeria monocytogenes sequence type (ST) 155, serogroup IIa, infections has been identified in the European Union/European Economic Area (EU/EEA) and the United Kingdom (UK). Based on genomic similarity, the cluster can be divided into three sub‐clusters, of which only cases due to sub‐cluster 1 continue to be reported. Sub‐cluster 1 is therefore the focus of this assessment, with 64 cases reported in five EU/EEA countries between 2016 and 2023, of which 17 were in 2022 and 2023 (one in Austria, one in Belgium, eight in Italy, six in Germany, and one in the Netherlands). It includes 10 fatal cases between 2019 and 2023. Sub‐clusters 2 and 3 are historical, with 30 cases reported between 2011 and 2021. Based on case interviews, ready‐to‐eat (RTE) fish products have been implicated as vehicles of infection. National food investigations, traceability, and genomic data identified 34 L. monocytogenes isolates from 12 fish products and one isolate from a fish processing environment within sub‐cluster 1. Sequencing analysis identified a link with two processing plants in Lithuania. In 2022–2023, contaminated fish products from these plants had reached retail markets in Germany and Italy, but there was no information on the product distribution in the other three countries reporting cases. The recurrent detection of the sub‐cluster 1 strain from marketed sealed RTE fish products revealed the persistence of the strain in one processing plant over eight years. Further targeted investigation in the RTE fish production chain is needed to identify the point(s) of contamination. The interruption of the production of RTE fish products in one of the processing plants is likely to reduce infections, but until all sources and sites of contaminations are properly controlled new cases are expected to occur, particularly among vulnerable people (the immunosuppressed and those aged over 75 years). [ABSTRACT FROM AUTHOR]

In present study, sodium alginate biodegradable films containing different concentrations of resveratrol (RES: 0.002% and 0.004%) or thymol (THY: 0.5% and 1%) and their combinations were prepared, and evaluated for their effects on spoilage‐related microbial profile, lipid oxidation, sensory properties, and protective effects against Listeria monocytogenes in beef mortadella sausage during 40 days storage at 4°C. The release rate of phenolic compounds was determined by the Folin–Ciocalteu test. To assess the shelf life of the product, changes in total viable count (TVC), lactic acid bacteria count (LAB), psychrotrophic bacteria count (PTC), pH levels, thiobarbituric acid reactive substances (TBARS) levels, and sensory characteristics (taste, color, odor, and overall acceptability) were evaluated. For the sensory evaluation, a panel of 70 semi‐trained judges was selected according to their initial performance. Samples wrapped with sodium alginate films containing 1% THY (alone or combined with different concentrations of RES) exhibited lower bacterial counts compared to other experimental groups at the end of the storage period (6.01–6.35 vs. 6.71–8.17 log10 CFU/g for TVC, 5.37–5.83 vs. 6.07–7.11 log10 CFU/g for LAB, 5.08–5.18 vs. 5.40–7.23 log10 CFU/g for PTC, and 6.53–6.92 vs. 7.23–9.01 log10 CFU/g for inoculated L. monocytogenes). Sodium alginate films containing the combination of 0.004% RES and different concentrations of THY showed higher antioxidant effects than other experimental groups (TBARS values of 1.68–1.99 vs. 2.23–3.80 mg MDA/kg sample). The sodium alginate film containing 0.004% RES + 1% THY exhibited the highest antimicrobial and antioxidant activities and highest sensory scores among all treatments. These findings highlight the potential application of the sodium alginate film containing a combination of RES and THY as an active packaging material with natural preservatives in the meat products industry. This application can effectively extend the shelf life and enhance the microbial safety of clean‐label cooked sausages during refrigerated storage. [ABSTRACT FROM AUTHOR]

Listeria monocytogenes is a foodborne bacterium that naturally occurs in the soil. Originating from there, it contaminates crops and infects farm animals and their consumption by humans may lead to listeriosis, a systemic life‐threatening infectious disease. The adaptation of L. monocytogenes to such contrastive habitats is reflected by the presence of virulence genes for host infection and other genes for survival under environmental conditions. Among the latter are ABC transporters for excretion of antibiotics produced by environmental competitors; however, most of these transporters have not been characterized. Here, we generated a collection of promoter‐lacZ fusions for genes encoding ABC‐type drug transporters of L. monocytogenes and screened this reporter strain collection for induction using a library of natural compounds produced by various environmental microorganisms. We found that the timABR locus (lmo1964‐lmo1962) was induced by the macrodiolide antibiotic tartrolon B, which is synthesized by the soil myxobacterium Sorangium cellulosum. Tartrolon B resistance of L. monocytogenes was dependent on timAB, encoding the ATPase and the permease component of a novel ABC transporter. Moreover, transplantation of timAB was sufficient to confer tartrolon B resistance to Bacillus subtilis. Expression of the timABR locus was found to be auto‐repressed by the TimR repressor, whose repressing activity was lost in the presence of tartrolon B. We also demonstrate that tartrolon sensitivity was suppressed by high external potassium concentrations, suggesting that tartrolon acts as potassium ionophore. Our results help to map the ecological interactions of an important human pathogen with its co‐residing species within their joint natural reservoir. [ABSTRACT FROM AUTHOR]

Key Clinical Message: Listeria monocytogenes is an important pathogen in older patients and immunosuppressed patients, often causing bacteremia. Complications resulting from infections other than COVID‐19 must also be considered during COVID‐19 treatment. [ABSTRACT FROM AUTHOR]

Listeriosis, an invasive illness with a fatality rate between 20% and 30%, is caused by the ubiquitous bacterium Listeria monocytogenes. Human listeriosis has long been associated with foods. This is because the ubiquitous nature of the bacteria renders it a common food contaminant, posing a significant risk to the food processing sector. Although several sophisticated stress coping mechanisms have been identified as significant contributing factors toward the pathogen's persistence, a complete understanding of the mechanisms underlying persistence across various strains remains limited. Moreover, aside from genetic aspects that promote the ability to cope with stress, various environmental factors that exist in food manufacturing plants could also contribute to the persistence of the pathogen. The objective of this review is to provide insight into the challenges faced by the dairy industry because of the pathogens' environmental persistence. Additionally, it also aims to emphasize the diverse adaptation and response mechanisms utilized by L. monocytogenes in food manufacturing plants to evade environmental stressors. The persistence of L. monocytogenes in the food processing environment poses a serious threat to food safety and public health. The emergence of areas with high levels of L. monocytogenes contamination could facilitate Listeria transmission through aerosols, potentially leading to the recontamination of food, particularly from floors and drains, when sanitation is implemented alongside product manufacturing. Hence, to produce safe dairy products and reduce the frequency of outbreaks of listeriosis, it is crucial to understand the factors that contribute to the persistence of this pathogen and to implement efficient control strategies. [ABSTRACT FROM AUTHOR]

Collation of the current scope of literature related to population dynamics (i.e., growth, die‐off, survival) of foodborne pathogens on fresh produce can aid in informing future research directions and help stakeholders identify relevant research literature. A scoping review was conducted to gather and synthesize literature that investigates population dynamics of pathogenic and non‐pathogenic Listeria spp., Salmonella spp., and Escherichia coli on whole unprocessed fresh produce (defined as produce not having undergone chopping, cutting, homogenization, irradiation, or pasteurization). Literature sources were identified using an exhaustive search of research and industry reports published prior to September 23, 2021, followed by screening for relevance based on strict, a priori eligibility criteria. A total of 277 studies that met all eligibility criteria were subjected to an in‐depth qualitative review of various factors (e.g., produce commodities, study settings, inoculation methodologies) that affect population dynamics. Included studies represent investigations of population dynamics on produce before (i.e., pre‐harvest; n = 143) and after (i.e., post‐harvest; n = 144) harvest. Several knowledge gaps were identified, including the limited representation of (i) pre‐harvest studies that investigated population dynamics of Listeria spp. on produce (n = 13, 9% of pre‐harvest studies), (ii) pre‐harvest studies that were carried out on non‐sprouts produce types grown using hydroponic cultivation practices (n = 7, 5% of pre‐harvest studies), and (iii) post‐harvest studies that reported the relative humidity conditions under which experiments were carried out (n = 56, 39% of post‐harvest studies). These and other knowledge gaps summarized in this scoping review represent areas of research that can be investigated in future studies. [ABSTRACT FROM AUTHOR]

Summary: This study aimed to investigate the effect of cinnamaldehyde (CIN)‐loaded nanoliposomes (CIN‐NLs) on pre‐established biofilms of L. monocytogenes and S. enteritidis. The MIC and MBC values of CIN were 1.25 and 5 μg mL−1 against L. monocytogenes, respectively; while for S. enteritidis, MIC of 0.625 and MBC of 2.5 μg mL−1 were obtained. The CIN‐NLs displayed particle size in the range of 130.5–414.2 nm, polydispersity index (PDI) values in the range of 0.28–0.59, and ζ‐potential values above −30 mV. The encapsulation efficiency of CIN in NLs ranged from 7.47% to 27.42%. Transmission electron microscopy (TEM) displayed smooth spherical particles, and Fourier transform infrared spectroscopy (FT‐IR) results showed the successful loading of the CIN into NLs. The anti‐biofilm assays confirmed that the CIN‐NLs more efficiently prevented the formation of biofilm and extends the action time than that of free CIN. Therefore, NLs could improve the stability and long‐lasting antibacterial effect of CIN. [ABSTRACT FROM AUTHOR]

Ultrafine bubbles (UFB) are a novel concept that has the potential to enhance the potency of antimicrobials to eliminate biofilms. This study investigated the impact of incorporating gas (air, CO2, and N2) UFB on the potency of chlorine (Cl2; 50, 100, and 200 ppm) and peracetic acid (PAA; 20, 40, and 80 ppm) antimicrobial (AM) solutions against fresh (3 days) and aged (30 days) Listeria monocytogenes biofilms on polypropylene, silicone, and stainless steel surfaces. Listeria monocytogenes biofilms were statically grown on polypropylene, silicone, and stainless steel coupons (7.62 × 2.54 cm) at 25°C for 3 or 30 days, by immersing in a three‐strain cocktail of L. monocytogenes in brain heart infusion (BHI) broth. The coupons were treated by submerging in AM solutions with or without UFB for 1 min, then swabbed into Dey‐Engley neutralizing broth and enumerated on BHI agar. Incorporation of air, CO2, and N2 UFB in AM solutions resulted in significantly increased log reductions (0.4–1.5 logs) of fresh and aged L. monocytogenes biofilms on polypropylene and stainless steel surfaces, whereas incorporation of CO2 UFB in AM solutions resulted in ~1 log greater reductions of fresh and aged L. monocytogenes biofilms on silicone surfaces compared with AM solutions without UFB. This study also demonstrated that 200 ppm Cl2 was most effective against fresh and aged L. monocytogenes biofilms on polypropylene, silicone, and stainless steel surfaces compared with 50 ppm Cl2, 20 ppm PAA, and 40 ppm PAA. [ABSTRACT FROM AUTHOR]

This study determined the prevalence, risk factors, and molecular characteristics of Listeria species detected in beef and beef products sampled in Mpumalanga province, South Africa. Four hundred beef and beef products were collected from 30 retail outlets in three districts (Bronkhorstspruit, Emalahleni, and Middelburg) within the province. Standard bacteriological and polymerase chain reaction (PCR) assays were used in the study. The overall prevalence of L. monocytogenes and other Listeria spp. in the samples was 8.3% (33/400) and 30% (120/400) (p <.05), respectively. For the five variables investigated, statistically significant effects were evident only for the region (p <.001) and type of product (p <.0001) for L. monocytogenes, the type of outlet (p =.011) and the type of product (p <.0001) for Listeria spp. Of the 20 types of beef and beef products tested, 15 (75%) and 17 (85%) were contaminated by L. monocytogenes and Listeria spp., respectively (p =.429). Among the four categories of products tested, the prevalence of L. monocytogenes was 7.3% (8/109), 10.6% (11/104), 7.5% (8/106), and 7.4% (6/81) for raw beef, ready‐to‐eat (RTE) products, milled beef, and offal & organs, respectively (p >.799). Among the 33 L. monocytogenes isolates, PCR genoserogroup IIa (42.4%, 1/2a‐3a) was most frequently detected. All (100%) of the isolates carried one or more of the eight virulence‐associated genes assessed, with genes inlC and inlJ detected in all the isolates. The overall prevalence of L. monocytogenes (8.3%) and the high frequency of virulent serogroups of L. monocytogenes commonly associated with human listeriosis pose a food safety risk to consumers of beef and beef‐based products contaminated by L. monocytogenes. [ABSTRACT FROM AUTHOR]

Key Clinical Message: Listeria can cause neurological symptoms in immunocompromised and older patients. Additionally, it is impossible to rule out meningitis by the absence of typical meningeal irritation signs. Therefore, patients with fever and neurological impairments should be rapidly examined for blood and cerebrospinal fluid cultures to rule out Listeria meningitis. A woman in her 90s developed fever, dysarthria, and transient disturbance of consciousness. Physical examination revealed no meningeal irritation signs. Listeria monocytogenes were detected in her blood culture the following day. Because of an increased number of cells in cerebrospinal fluid, she was diagnosed with Listeria meningitis. [ABSTRACT FROM AUTHOR]

The high mortality rate associated with Listeria monocytogenes can be attributed to its ability to invade the body systemically and to activate inflammasomes. Both of these processes are facilitated by expressing a major virulence factor known as listeriolysin O, a 56 kDa pore‐forming protein encoded by the hly gene. Listeriolysin O plays a crucial role in the pathogenesis of the bacterium by facilitating the escape of the pathogen from the phagosome into the cytosol. This process is essential for the successful establishment of infection. In addition, listeriolysin O is known as an immunomodulator that activates host signal transduction. In addition to listeriolysin O, Listeria expresses a variety of bacterial ligands, such as lipoteichoic acid, nucleotide, and flagellin, that are recognized by host intracellular pattern‐recognition receptors including Nod‐like receptors, AIM2‐like receptors, and RIG‐I‐like receptors. This review introduces intracellular recognition of Listeria monocytogenes since recent studies have revealed that the activation of inflammasome exacerbates Gram‐positive bacteria infection. [ABSTRACT FROM AUTHOR]

Homozygous mutations in the autoimmune regulator (AIRE) gene that cripple thymic negative selection of autoreactive T cells result in autoimmune polyendocrinopathy‐candidiasis‐ectodermal dystrophy (APECED). However, how AIRE regulates the T‐cell response against foreign pathogens is not well understood. Here, we observed comparable primary CD8+ T cells but a markedly reduced memory T‐cell population and protective function in Aire−/− mice compared with wild‐type after infection with a strain of recombinant Listeria monocytogenes. In adoptive transfer models, exogenous congenic CD8+ T cells transferred into Aire−/− mice also showed a reduction in the memory T‐cell population, indicating an important role for extrathymic Aire‐expressing cells in shaping or sustaining memory T cells. Moreover, using a bone marrow chimeric model, we found that Aire expressed in radioresistant cells plays an important role in maintaining the memory phenotype. These results provide important insights into the role of extrathymic Aire in the T‐cell response to infection. [ABSTRACT FROM AUTHOR]

Seal populations in Canadian waters provide sustenance to coastal communities. There is potential for pathogenic and/or antimicrobial‐resistant bacteria to transfer to humans through inadvertent faecal contamination of seal products. The objective of this study was to investigate the occurrence and potential antimicrobial resistance of Salmonella spp., Escherichia coli and Listeria monocytogenes in faecal samples collected from grey seals (Halichoerus grypus) in the Gulf of St. Lawrence and from ringed seals (Pusa hispida) in Frobisher Bay and Eclipse Sound, Nunavut, Canada. Grey seals were harvested during commercial hunts or during scientific sampling; ringed seals were collected by Inuit hunters during subsistence harvests. Virulence genes defining pathogenic E. coli were identified by PCR, and antimicrobial susceptibility testing was performed on recovered isolates. In grey seals, E. coli was detected in 34/44 (77%) samples, and pathogenic E. coli (extraintestinal E. coli [ExPEC], enteropathogenic E. coli [EPEC] or ExPEC/EPEC) was detected in 13/44 (29%) samples. Non‐susceptibility to beta‐lactams and quinolones was observed in isolates from 18 grey seals. In ringed seals from Frobisher Bay, E. coli was detected in 4/45 (9%) samples; neither virulence genes nor antimicrobial resistance was detected in these isolates. In ringed seals from Eclipse Sound, E. coli was detected in 8/50 (16%) samples and pathogenic E. coli (ExPEC and ExPEC/EPEC) in 5/50 (10%) samples. One seal from Eclipse Sound had an E. coli isolate resistant to beta‐lactams. A monophasic Salmonella Typhimurium was recovered from 8/50 (16%) seals from Eclipse Sound. All Salmonella isolates were resistant to ampicillin, streptomycin, sulfisoxazole and tetracycline. L. monocytogenes was not detected in any sample. These findings suggest that seals may act as important sentinel species and as reservoirs or vectors for antimicrobial‐resistant and virulent E. coli and Salmonella species. Further characterization of these isolates would provide additional insights into the source and spread of antimicrobial resistance and virulence genes in these populations of free‐living seals. [ABSTRACT FROM AUTHOR]

In 2023, Listeria monocytogenes persistence remains a problem in the food business. A profound understanding of how this pathogen persists may lead to better aimed intervention/prevention strategies. The lack of a uniform definition of persistence makes the comparison between studies complex. Harborage sites offer protection against adverse environmental conditions and form the ideal habitat for the formation of biofilms, one of the major persistence strategies. A retarded growth rate, disinfectant resistance/tolerance, desiccation resistance/tolerance, and protozoan protection complete the list of persistence strategies for Listeria monocytogenes and can occur on themselves or in combination with biofilms. Based on the discussed persistence strategies, intervention strategies are proposed. By enhancing the focus on four precaution principles (cleaning and disinfection, infrastructure/hygienic design, technical maintenance, and work methodology) as mentioned in Regulation (EC) No. 852/2004, the risk of persistence can be decreased. All of the intervention strategies result in obtaining and maintaining a good general hygiene status throughout the establishment at all levels ranging from separate equipment to the entire building. [ABSTRACT FROM AUTHOR]

Summary: In African public health systems, Listeria monocytogenes is a pathogen of relatively low priority. Yet, the biggest listeriosis outbreak recorded to date occurred in Africa in 2018. This review highlights the factors that potentially impact L. monocytogenes transmission risks through African food value chains (FVCs). With the high rate of urbanisation, African FVCs have become spatially longer yet still informal. At the same time, dietary diversifications have resulted in increased consumption of processed ready‐to‐eat (RTE) meat, poultry, fishery and dairy products typically associated with a higher risk of L. monocytogenes consumer exposure. With frequent cold chain challenges, the potential of L. monocytogenes growth in contaminated RTE foods can further amplify consumer exposure risks. Moreover, the high prevalence of untreated HIV infections, endemic anaemia, high fertility rate and a gradually increasing proportion of elderly persons expands the fraction of listeriosis‐susceptible groups among African populations. With already warmer tropical conditions, the projected climate change‐induced increases in ambient temperatures are likely to exacerbate listeriosis risks in Africa. As precautionary approaches, African countries should implement systems for the detection and reporting of listeriosis cases and food safety regulations that provide L. monocytogenes standards and limits in high‐risk RTE foods. [ABSTRACT FROM AUTHOR]

In addition to triggering humoral responses, conventional B cells have been described in vitro to cross‐present exogenous antigens activating naïve CD8+ T cells. Nevertheless, the way B cells capture these exogenous antigens and the physiological roles of B cell‐mediated cross‐presentation remain poorly explored. Here, we show that B cells capture bacteria by trans‐phagocytosis from previously infected dendritic cells (DC) when they are in close contact. Bacterial encounter "instructs" the B cells to acquire antigen cross‐presentation abilities, in a process that involves autophagy. Bacteria‐instructed B cells, henceforth referred to as BacB cells, rapidly degrade phagocytosed bacteria, process bacterial antigens and cross‐prime naïve CD8+ T cells which differentiate into specific cytotoxic cells that efficiently control bacterial infections. Moreover, a proof‐of‐concept experiment shows that BacB cells that have captured bacteria expressing tumor antigens could be useful as novel cellular immunotherapies against cancer. Synopsis: B cells capturing Listeria monocytogenes acquire antigen cross‐presentation abilities in a process that involves autophagy. These bacteria‐instructed B cells (BacB) effectively cross‐prime naïve CD8+ T cells which differentiate into specific cytotoxic cells that efficiently control bacterial infections. Conventional B cells capture bacteria by transphagocytosis.The capture of L. monocytogenes instructs B cells (BacB) to became antigen cross‐presenting cells.BacB capturing bacteria expressing tumor antigens could be useful as novel cellular immunotherapy against cancer. [ABSTRACT FROM AUTHOR]

Intracellular bacterial pathogens remodel the plasma membrane of eukaryotic cells in order to establish infection. A common and well‐studied mechanism of plasma membrane remodelling involves bacterial stimulation of polymerization of the host actin cytoskeleton. Here, we discuss recent results showing that several bacterial pathogens also exploit the host vesicular trafficking pathway of 'polarized exocytosis' to expand and reshape specific regions in the plasma membrane during infection. Polarized exocytosis is mediated by an evolutionarily conserved octameric protein complex termed the exocyst. We describe examples in which the bacteria Listeria monocytogenes, Salmonella enterica serovar Typhimurium, and Shigella flexneri co‐opt the exocyst to promote internalization into human cells or intercellular spread within host tissues. We also discuss results showing that Legionella pneumophila or S. flexneri manipulate exocyst components to modify membrane vacuoles to favour intracellular replication or motility of bacteria. Finally, we propose potential ways that pathogens manipulate exocyst function, discuss how polarized exocytosis might promote infection and highlight the importance of future studies to determine how actin polymerization and polarized exocytosis are coordinated to achieve optimal bacterial infection. [ABSTRACT FROM AUTHOR]

Endogenous endophthalmitis caused by listeria monocytogenes is rare and serious, which is easily misdiagnosed initially. We present one case of endogenous endophthalmitis due to listeria monocytogenes in a cirrhotic patient, whose diagnosis was delayed 17 days after admission. [ABSTRACT FROM AUTHOR]