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Listeria monocytogenes is a bacterial pathogen that can cause life-threatening central nervous system (CNS) infections. While mechanisms by which L. monocytogenes and other pathogens traffic to the brain have been studied, a quantitative understanding of the underlying dynamics of colonization and replication within the brain is still lacking. In this study, we used barcoded L. monocytogenes to quantify the bottlenecks and dissemination patterns that lead to cerebral infection. Following intravenous (IV) inoculation, multiple independent invasion events seeded all parts of the CNS from the blood, however, only one clone usually became dominant in the brain. Sequential IV inoculations and intracranial inoculations suggested that clones that had a temporal advantage (i.e., seeded the CNS first), rather than a spatial advantage (i.e., invaded a particular brain region), were the main drivers of clonal dominance. In a foodborne model of cerebral infection with immunocompromised mice, rare invasion events instead led to a highly infected yet monoclonal CNS. This restrictive bottleneck likely arose from pathogen transit into the blood, rather than directly from the blood to the brain. Collectively, our findings provide a detailed quantitative understanding of the L. monocytogenes population dynamics that lead to CNS infection and a framework for studying the dynamics of other cerebral infections.

Listeria monocytogenes (Lm) is a Gram-positive facultative intracellular pathogen that leads a biphasic lifecycle, transitioning its metabolism and selectively inducing virulence genes when it encounters mammalian hosts. Virulence gene expression is controlled by the master virulence regulator PrfA, which is allosterically activated by the host- and bacterially derived glutathione (GSH). The amino acid cysteine is the rate-limiting substrate for GSH synthesis in bacteria and is essential for bacterial growth. Unlike many bacteria, Lm is auxotrophic for cysteine and must import exogenous cysteine for growth and virulence. GSH is enriched in the host cytoplasm, and previous work suggests that Lm utilizes exogenous GSH for PrfA activation. Despite these observations, the import mechanism(s) for GSH remains elusive. Analysis of known GSH importers predicted a homologous importer in Lm comprised of the Ctp ABC transporter and the OppDF ATPases of the Opp oligopeptide importer. Here, we demonstrated that the Ctp complex is a high-affinity GSH/GSSG importer that is required for Lm growth at physiologically relevant concentrations. Furthermore, we demonstrated that OppDF is required for GSH/GSSG import in an Opp-independent manner. These data support a model where Ctp and OppDF form a unique complex for GSH/GSSG import that supports growth and pathogenesis. In addition, we show that Lm utilizes the inorganic sulfur sources thiosulfate and H2S for growth in a CysK-dependent manner in the absence of other cysteine sources. These findings suggest a pathoadaptive role for partial cysteine auxotrophy in Lm, where locally high GSH/GSSG or inorganic sulfur concentrations may signal arrival to distinct host niches.

Background: The foodborne bacterium Listeria monocytogenes (Lm) causes a range of diseases, from mild gastroenteritis to invasive infections that have high fatality rate in vulnerable individuals. Understanding the population genomic structure of invasive Lm is critical to informing public health interventions and infection control policies that will be most effective especially in local and regional communities. Methods: We sequenced the whole draft genomes of 936 Lm isolates from human clinical samples obtained in a two-decade active surveillance program across 58 counties in New York State, USA. Samples came mostly from blood and cerebrospinal fluid. We characterized the phylogenetic relationships, population structure, antimicrobial resistance genes, virulence genes, and mobile genetic elements. Results: The population is genetically heterogenous, consisting of lineages I–IV, 89 clonal complexes, 200 sequence types, and six known serogroups. In addition to intrinsic antimicrobial resistance genes (fosX, lin, norB, and sul), other resistance genes tetM, tetS, ermG, msrD, and mefA were sparsely distributed in the population. Within each lineage, we identified clusters of isolates with ≤ 20 single nucleotide polymorphisms in the core genome alignment. These clusters may represent isolates that share a most recent common ancestor, e.g., they are derived from the same contamination source or demonstrate evidence of transmission or outbreak. We identified 38 epidemiologically linked clusters of isolates, confirming eight previously reported disease outbreaks and the discovery of cryptic outbreaks and undetected chains of transmission, even in the rarely reported Lm lineage III (ST3171). The presence of animal-associated lineages III and IV may suggest a possible spillover of animal-restricted strains to humans. Many transmissible clones persisted over several years and traversed distant sites across the state. Conclusions: Our findings revealed the bacterial determinants of invasive listeriosis, driven mainly by the diversity of locally circulating lineages, intrinsic and mobile antimicrobial resistance and virulence genes, and persistence across geographical and temporal scales. Our findings will inform public health efforts to reduce the burden of invasive listeriosis, including the design of food safety measures, source traceback, and outbreak detection. [ABSTRACT FROM AUTHOR]

In the dairy industry, traditional heat treatments are known for their high water and energy consumption, and more economically and environmentally friendly solutions are being sought. Infrared (IR) technology offers advantages in energy efficiency and environmental sustainability; however, its effectiveness in milk processing, particularly in pathogen inactivation, remains relatively unexplored. In this study, homogenized raw milk was subjected to IR treatment, and its impact on Listeria monocytogenes, Salmonella spp., and Enterobacteriaceae was assessed. Results indicate that IR treatment effectively reduces the microbial load, achieving levels of inactivation comparable to conventional pasteurization methods (around 6 Log10 CFU/mL). Moreover, the treatment maintains milk pH levels, suggesting minimal alteration to its composition. Further research is needed to explore the full extent of IR treatment on milk sanitation efficacy, deeply exploring IR technology to fully assess its applicability and integration into dairy processing practices. Despite regulatory challenges, the Wir System Milk shows promise as a cost-effective and eco-friendly alternative for raw milk treatment. [ABSTRACT FROM AUTHOR]

The list of standard abbreviations for JDS is available at adsa.org/jds-abbreviations-24. Nonstandard abbreviations are available in the Notes. The use of essential oils (EO) has attracted interest in the food industry because of their wide range of beneficial properties. In this study, a new functional yogurt was developed using 2 EO, marjoram and geranium, at 3 different concentrations (0.2%, 0.4%, and 0.6% vol/vol). The physicochemical properties, including syneresis, viscosity, pH, and chemical composition; bioactivities, including antioxidant activity, anticancer and antibacterial effects, total phenolic content (TPC), and total flavonoid content (TFC); and sensory characteristics of the developed yogurt were evaluated. The findings indicated that the yogurts fortified with 0.6% marjoram or geranium exhibited higher viscosity and lower syneresis compared with other treatments. The yogurt supplemented with 0.6% marjoram displayed significant antibacterial activity against Listeria monocytogenes, Staphylococcus aureus, Salmonella typhimurium , and Escherichia coli. In addition, the yogurt enriched with geranium and marjoram oils at a concentration of 0.6% had notably significant (P < 0.05) higher TFC levels compared with the control sample and other concentrations. In the same context, in terms of TPC, yogurt supplemented with 0.6% marjoram displayed significantly (P < 0.05) elevated levels in comparison to the other samples tested. Yogurt enriched with marjoram oil exhibited noteworthy antioxidant activity, followed by geranium oil, compared with the control samples. The yogurt supplemented with 0.6% marjoram demonstrated strong radical scavenging activity, and the yogurt fortified with 0.6% geranium showed higher anticancer activity against HepG2 human liver carcinoma cells and oxidative stress enzyme activities. Among the various concentrations of EO tested, the yogurts fortified with 0.6% marjoram or geranium EO exhibited the most favorable outcomes, followed by 0.4% marjoram or geranium. To summarize, geranium and marjoram EO can be used as a potential nutritious ingredient and as a natural preservative for milk and related products. [Display omitted] [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]

We investigate the relationship between the level of food safety risk in retail food establishments and average incomes in surrounding communities. Building on the environmental justice literature, we hypothesize that there is a relationship between community income levels and levels of food safety risk. Using data on the prevalence of Listeria monocytogenes (Lm) obtained from grocery store delis, we find that stores located in census tracts whose residents are in lower income quartiles have greater Lm prevalence. An indicator for American Indian and Alaskan Native residents also has a positive statistically significant relationship with food safety risk. [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]

Listeriosis is highly prevalent in the animal farming industry, with Listeria monocytogenes as the causative pathogen. To identify potential therapeutic targets for LM infection, we investigated the mechanisms of LM infection in goat uteri. We inoculated a group of goats with LM via jugular vein injection, isolated and raised them, and subsequently collected sterile samples of their uterine tissue after they exhibited clinical symptoms of LM infection. We used Giemsa staining, immunohistochemical staining, real-time qPCR, and Western blotting as experimental methods.First, we investigated the mechanism of Listeria monocytogenes (LM) infection in the goat uterus by examining the expression levels of listeriolysin O, E-cadherin, and tyrosine kinase c-Met in the uterus. Furthermore, we investigated the impact of LM infection on uterine autophagy and cell apoptosis. The results indicate that the injection of LM into the goats' jugular veins leads to LM infection in the goats' uteri. During LM survival inside the goat uterine cells, there is a significant increase in the expression levels of LLO, E-cadherin, and c-Met in the host uterine tissue. This suggests that LM may potentially infect goat uteri through the InlA/E-cadherin and InlB/c-Met pathways. Furthermore, LM infection increases the levels of apoptosis and autophagy in goat uteri. Apoptosis genes Bcl-2 and Bax, as well as autophagyrelated genes LC3B, PINK1, and Parkin, exhibit varying degrees of changes in localization and expression in goat uteri, mediating the occurrence of apoptotic and autophagic responses. [ABSTRACT FROM AUTHOR]

Background: Listeria monocytogenes brain abscess is a rare phenomenon that is common in immunocompromised patients. Streptococcus equinus brain abscess has never been reported in the literature to our knowledge. In this case report, we describe a case of brain abscess secondary to Listeria monocytogenes and Streptococcus equinus in an immunocompetent patient with transient low CD4 count. Case presentation: A 27-year-old white, male patient, previously healthy, nonalcoholic, and occasional smoker, presented to the emergency department for confusion and headache. The patient was found to have a left parietal abscess, which was drained and the fluid was sent for culture. Culture grew Listeria monocytogenes and Streptococcus equinus. The patient was treated with intravenous ampicillin followed by oral amoxicillin for a total of 6 weeks. The CD4 count was low initially. However, after the resolution of the infection, the CD4 count came back within normal range. Another brain magnetic resonance imaging was done that showed a significantly decreased hyperintensity within the left parietal subcortical white matter at the site of surgery with significantly decreased enhancement and almost total resolution of the previous abscess. Conclusion: Transient low CD4 count is a rare phenomenon that exposes patients to unusual and atypical infections. Since low CD4 count is transient, patients treated promptly recover from their illness. Our patient developed a Listeria monocytogenes and Streptococcus equinus brain abscess, which is considered rare and has not been previously described in the literature to our knowledge. [ABSTRACT FROM AUTHOR]

AbstractLiposomal encapsulated phytogenics, such as liposomal hesperetin, are considered novel substitutes for antibiotics in the broilers industry owing to their improved nutritional and therapeutic properties. Therefore, our key goal was to investigate liposomal hesperetin impact on broilers' growth performance, health, antioxidant status, tight junction proteins (TJP), and resistance against Listeria monocytogenes. Four broilers' groups were fed 0, 150, 250, and 400 mg/kg of liposomal hesperetin-supplemented diets and experimentally infected with L. monocytogenes strain. Herein, liposomal hesperetin, especially at higher concentrations, augmented broilers FCR with upregulation of genes encoding TJP (occludin, JAM-2, MUC-2), and antioxidant attributes (GPX-1, SOD-1, CAT, HO-1, NQO1, COX2), which reflect enhancing health and welfare of broilers. Muscle antioxidant biomarkers were enhanced; meanwhile, muscle MDA, ROS, and H2O2 levels were reduced in response to 400 mg/kg of liposomal hesperetin. Liposomal hesperetin fortification reduced L. monocytogenes loads and its virulence-related genes expression levels (flaA, hlyA, and ami). Remarkably, histopathological alterations in intestinal and brain tissues of L. monocytogenes infected broilers were restored post-inclusion at higher levels liposomal hesperetin, which reflects increasing the bird’s resistance to L. monocytogenes infection. Transcription levels of genes encoding cytokines/chemokines (MyD88, AVBD6, CCL20, IL-1β, IL-18), and autophagy (Bcl-2, LC3, AMPK, AKT, CHOP, Bip, p62, XBP1) were ameliorated following dietary liposomal hesperetin fortification, which suggests enhancing the birds’ immunity and health. Collectively, our research recommends liposomal hesperetin application in broilers` diets owing to its promoting impact on growth performance, antioxidant status, immunity, health, and welfare besides its antibacterial, and antivirulence characteristics to fight against L. monocytogenes. [ABSTRACT FROM AUTHOR]

Specialty mushrooms have been implicated in foodborne illness outbreaks in the U.S. in recent years. These mushrooms are available to consumers in both their fresh and dried states. Dehydrating mushrooms is a convenient way to increase shelf life. The dehydration process results in a lowered water activity (aw) of the commodity, creating an environment where both spoilage and pathogenic bacteria cannot proliferate. Prior to food preparation and consumption, these mushrooms are typically rehydrated and possibly stored for later use which could lead to increased levels of pathogens. This study examined the survival and growth of Listeria monocytogenes and Salmonella enterica on dehydrated enoki and wood ear mushrooms during rehydration and subsequent storage. Mushrooms were heat dehydrated, inoculated at 3 log CFU/g, and rehydrated at either 5 or 25°C for 2 h. Rehydrated mushrooms were stored at 5, 10, or 25°C for up to 14 d. L. monocytogenes and S. enterica survived on enoki and wood ear mushroom types during rehydration at 5 and 25°C, with populations often <2.39 log CFU/g. During subsequent storage, no growth was observed on wood ear mushrooms, regardless of the rehydration or storage temperature, with populations remaining <2.39 log CFU/g for both pathogens. When stored at 5°C, no growth was observed for either pathogen on enoki mushrooms. During storage at 10 and 25°C, pathogen growth rates and populations after 14 d were generally significantly higher on the enoki mushrooms rehydrated at 25°C; the highest growth rate (3.56 ± 0.75 log CFU/g/d) and population (9.48 ± 0.62 log CFU/g) after 14 d for either pathogen was observed by S. enterica at 25°C storage temperature. Results indicate a marked difference in pathogen survival and proliferation on the two specialty mushrooms examined in this study and highlight the need for individual product assessments. Data can be used to assist in informing guidelines for time and temperature control for the safety of rehydrated mushrooms. [ABSTRACT FROM AUTHOR]

Lactic acid bacteria (LAB) are the most common probiotics, and they present excellent inhibitory effects on pathogenic bacteria. This study aimed to explore the anti-biofilm potential of the purified active substance of Lactiplantibacillus plantarum, named Z102-E. The effects of Z102-E on Listeria monocytogenes were investigated in detail, and a transcriptomic analysis was conducted to reveal the anti-biofilm mechanism. The results indicated that the sub-MIC of Z102-E (3.2, 1.6, and 0.8 mg/mL) decreased the bacterial growth and effectively reduced the self-aggregation, surface hydrophobicity, sugar utilization, motility, biofilm formation, AI-2 signal molecule, contents of extracellular polysaccharides, and extracellular protein of L. monocytogenes. Moreover, the inverted fluorescence microscopy observation confirmed the anti-biofilm effect of Z102-E. The transcriptomic analysis indicated that 117 genes were up-regulated and 214 were down-regulated. Z102-E regulated the expressions of genes related to L. monocytogenes quorum sensing, biofilm formation, etc. These findings suggested that Z102-E has great application potential as a natural bacteriostatic agent. [ABSTRACT FROM AUTHOR]

To investigate the effects of nitrogen source nutrients on the growth and metabolism of Lactobacillus rhamnosus GG (LGG), this study used soybean protein isolates (dSPI) and soybean peptides (dPEP) from simulated gastrointestinal digestion as raw materials. The number of viable cells and the production of lactic acid and acetic acid in LGG were measured through mono-culture. LGG was co-cultured with Listeria monocytogenes to determine its utilization of soybean protein isolates and soybean peptides in the presence of pathogens. The results of mono-culture showed that both dPEP and dSPI could increase the viable number of LGG (P<0.05), and the effect of dPEP was earlier four hours than that of dSPI, and they could significantly increase the production of SCFAs (P<0.05). In the co-culture system, dSPI weakened the competitiveness of Listeria monocytogenes (List m) and improved the competitiveness of LGG. After 4 h and 8 h of culture, the number of living cells of LGG was higher than that of mono-culture (P<0.05). The results of this study identify nitrogen sources as potentially beneficial nutrients, and provide a theoretical basis for the development of soybean protein and soybean peptide functional foods. [ABSTRACT FROM AUTHOR]

Introduction: Listeria monocytogenes is an ubiquitous foodborne pathogen that represents a serious threat to public health and the food industry. Methods: In this study Whole Genome Sequencing (WGS) was used to characterize 160 L. monocytogenes isolates obtained from 22,593 different food sources in Montenegro during the years 2014-2022. Results: Isolates belonged to 21 different clonal complexes (CCs), 22 sequence types (STs) and 73 core genome multilocus sequence types (cgMLST) revealing a high diversity. The most prevalent STs were ST8 (n = 29), ST9 (n = 31), ST121 (n = 19) and ST155 (n = 20). All isolates carried virulence genes (VGs), 111 isolates carried mobile genetic elements (MGEs) (ranging from 1 to 7 MGEs) and 101 isolates carried plasmids (ranging from 1 to 3 plasmids). All isolates carried the intrinsic resistance genes fosX and lin. None of the isolates carried acquired antimicrobial resistance genes (ARGs). Discussion/conclusion: Continuous monitoring and surveillance of L. monocytogenes is needed for improving and ameliorating the public health. [ABSTRACT FROM AUTHOR]

Copyright of Shipin Kexue/ Food Science is the property of Food Science Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Bacteriocin producing strain Brevibacillus laterosporus TK3, was isolated from 'Tatwakhar'- a flour prepared from seeds of Indian Horse Chestnut (Aesculus indica). Bacterial strain Brevibacillus laterosporus TK3 identified by morphological, biochemical techniques followed by 16S rRNA gene sequencing. The 16S rRNA sequence of bacteriocin producer was deposited in NCBI GenBank under accession no. KP861913.1. Bacteriocin of Brevibacillus laterosporus TK3 showed strong antagonistic activity against food spoiling/pathogenic bacteria viz. Listeria monocytogenes, Staphylococcus aureus and Clostridium perfringens. Bacteriocin production by Brevibacillus laterosporus TK3 was enhanced by optimizing production time, pH of the medium, inoculum size and incubation temperature. Maximum bacteriocin activity (6000 AU/ml) was recorded/obtained in basal salt medium of pH 5.5 with an inoculum size of 1.5 OD at 10% and incubation period of 24h at 35 °C. The bacteriocin was purified by single step gel exclusion chromatography. Molecular weight of active bacteriocin from Brevibacillus laterosporous TK3 was found to be 6 kDa according to SDS PAGE. The molecular mass of purified bacteriocin was confirmed as 5953.89 Da by MALDI TOF analysis. The purified bacteriocin was found desirable/suitable for food preservation as it showed wide spectrum of antimicrobial activity, resistance to high temperature, wide pH range and sensitivity to proteolytic enzymes thus, making it safe for human consumption. [ABSTRACT FROM AUTHOR]

Practical Application Time‐temperature data for queso fresco (QF) cheese varieties stored in a residential refrigerator operating at 5°C and a predictive microbiology secondary model for Listeria monocytogenes in QF were used to estimate a refrigerator performance indicator (RPI) of microbial preservation. RPI values were used to assess how compressor technology (single [SS] and variable speed [VS]), ambient temperature (21.1°C [LT] and 32.2°C [HT]), and refrigerator load (22.5 kg regular load and 39 kg higher load) affected preservation performance. All deterministic and probabilistic RPI estimations slightly exceeded the desirable 1.0 value, i.e., the variable temperatures for the QF kept in the refrigerator were worse than keeping it constantly at the temperature recommended by food safety agencies for QF. Furthermore, the mean comparison of estimates of the time‐temperature equivalent indicator previously developed by French researchers showed similar behavior to those observed for RPI. Finally, statistical analysis showed that Tambient was the factor with the highest impact on refrigerator performance because of its impact on the sample temperature increase during door openings and when exposed to ambient temperature during product use. This highlights the need to reduce the time for product temperature recovery by improving the compressor operation logic. Also important are consumer behavior changes such as a reduction in product exposure to ambient temperature and in the door opening duration and frequency.This study demonstrated how a quantitative tool (RPI) can assess refrigerator preservation performance. Although the findings presented can be applied to any cold chain segment, the data used was collected for its weakest link, the domestic refrigerator. Surveys show that 77% of them operate above the recommended 4°C. The RPI methodology is ready for use by refrigerator designers to assess performance improvements possible by modifications of the compressor operation logic. Moreover, it can be integrated into smart‐hubs monitoring the frequency and duration of refrigerator door openings to inform consumers when their habits are compromising the preservation performance of the refrigerator. [ABSTRACT FROM AUTHOR]

Kombucha, a beverage traditionally obtained through the fermentation of tea, is believed to have beneficial health properties. Therefore, characterizing the microorganisms responsible for this fermentation is essential to demonstrate its potential health benefits and to identify candidates for new probiotics. In this study, four probiotic yeast strains isolated from kombucha tea were identified, by the PCR-RFLP analysis of the ribosomal ITS region and the sequence of the D1/D2 domain of the 26S rDNA, as Brettanomyces bruxellensis (UVI55 and UVI56) and B. anomalus (UVI57 and UVI58). Properties relevant to probiotics were also studied in these strains. All of them showed excellent survival in simulated gastric (99%-100%) and duodenal (95%-100%) juices. The ability to self-aggregate (38%-100%), adhesion to xylene (15%-50%) and, above all, adhesion to Caco-2 cells (4%-21%), revealed its potential capacity to adhere to the intestinal epithelium. In addition, the tested strains showed excellent antioxidant capacity (82%-94%), antimicrobial activity against different pathogens (Escherichia coli, Staphylococcus aureus, Salmonella enterica, Listeria monocytogenes, and Bacillus cereus), as well as remarkable cytotoxic activity against colon, melanoma and ovarian tumor cell lines. Finally, using Caenorhabditis elegans as a model, strain UVI56 exhibited ability to both extend the lifespan of the nematode and protect it against infection by S. enterica. These results support the probiotic and functional properties of the analyzed strains. In conclusion, the study revealed that kombucha tea could be a source of potential probiotics that contribute to its health-promoting properties and that the characterized Brettanomyces strains could be exploited directly as probiotics or for the development of new functional foods. [ABSTRACT FROM AUTHOR]

Grapevines (Vitis spp.) produce several valuable polyphenol-type secondary metabolites including various stilbenoids. Although the potential application of stilbenes may offer alternative solutions to food safety or health challenges, only little information is available on their antibacterial activity against foodborne pathogens. In this work, high-performance liquid chromatography was used to analyze the stilbenoid profile of various wild Vitis species, including V. amurensis, V. davidii, V. pentagona, and V. romanetii, selected from the gene bank for grapes at the University of Pécs, Hungary. We found that the stilbene profile of cane extracts is strongly genotype-dependent, showing the predominant presence of ε-viniferin with a wide concentration range ≈ 320–3870 µg/g dry weight. A novel yet simple and efficient extraction procedure was developed and applied for the first time on grape canes, resulting in ε-viniferin-rich crude extracts that were tested against Listeria monocytogenes, an important foodborne pathogen. After 24 h exposure, V. pentagona and V. amurensis crude extracts completely eliminated the bacteria at a minimum bactericidal concentration of 42.3 µg/mL and 39.2 µg/mL of ε-viniferin, respectively. On the other hand, V. romanetii extract with 7.8 µg/mL of ε-viniferin resulted in 4 log reduction in the viable bacterial cells, while V. davidii extract with 1.4 µg/mL of ε-viniferin did not show significant antibacterial activity. These findings indicate that the ε-viniferin content was directly responsible for the antibacterial effect of cane extract. However, pure ε-viniferin (purity > 95%) required a higher concentration (188 µg/mL) to eradicate the bacteria under the same conditions, suggesting the presence of other antibacterial compounds in the cane extracts. Investigating the onset time of the bactericidal action was conducted through a kinetic experiment, and results showed that the reduction in living bacterial number started after 2 h; however, the bactericidal action demanded 24 h of exposure. Our results revealed that the canes of V. pentagona and V. amurensis species are a crucial bio-source of an important stilbene with antimicrobial activity and health benefits. [ABSTRACT FROM AUTHOR]

In this study, we investigated the antibacterial activity of the coumarin component isolated from lime peel and coumarin derivatives synthesized using various techniques against eight types of food-poisoning bacteria. The minimum inhibitory concentration (MIC) for the 3b [5,7-dihydroxy-4-trifluoromethylcoumarin] derivative was measured as 1.5 mM in Bacillus cereus, Micrococcus luteus, Listeria monocytogenes, and Staphylococcus aureus subsp. aureus; that for the 3c [7-hydroxy-4-trifluoromethylcoumarin] derivative was 1.7 mM in Enterococcus facium; and that for the 3n [dicoumarol] derivative was 1.2 mM in L. monocytogenes. These results confirmed that coumarin derivatives with CF3 and OH substituents had enhanced antibacterial activity. [ABSTRACT FROM AUTHOR]

A novel colorimetric aptasensor assay based on the excellent magnetic responsiveness and oxidase-like activity of Fe3O4@MIL-100(Fe) was developed. Fe3O4@MIL-100(Fe) absorbed with aptamer and blocked by BSA served as capture probe for selective isolation and enrichment of Listeria monocytogenes one of the most common and dangerous foodborne pathogenic bacteria. The aptamer absorbed on Fe3O4@MIL-100(Fe) was further used as signal probe that specifically binds with target bacteria conjugation of capture probe for colorimetric detection of Listeria monocytogenes, taking advantages of its oxidase-like activity. The linear range of the detection of Listeria monocytogenes was from 102 to 107 CFU mL−1, with the limit of detection as low as 14 CFU mL−1. The approach also showed good feasibility for detection of Listeria monocytogenes in milk and meat samples. The spiked recoveries were in the range 81–114% with relative standard deviations ranging from 1.28 to 5.19%. Thus, this work provides an efficient, convenient, and practical tool for selective isolation and colorimetric detection of Listeria monocytogenes in food. [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]

This manuscript presents a new report on the in vitro antimicrobial photo-inactivation of foodborne microorganisms (Salmonella spp. and Listeria monocytogenes) using tetra-cationic porphyrins. Isomeric tetra-cationic porphyrins (3MeTPyP, 4MeTPyP, 3PtTPyP, and 4PtTPyP) were tested, and antimicrobial activity assays were performed at specific photosensitizer concentrations under dark and white-light LED irradiation conditions. Among the tested bacterial strains, 4MeTPyP exhibited the highest efficiency, inhibiting bacterial growth within just 60 min at low concentrations (17.5 μM). The minimal inhibitory concentration of 4MeTPyP increased when reactive oxygen species scavengers were present, indicating the significant involvement of singlet oxygen species in the photooxidation mechanism. Furthermore, the checkerboard assay testing the association of 4MeTPyP showed an indifferent effect. Atomic force microscopy analyses and dynamic simulations were conducted to enhance our understanding of the interaction between this porphyrin and the strain's membrane. [ABSTRACT FROM AUTHOR]

Copyright of Food Research & Development is the property of Food Research & Development Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Background: Listeria monocytogenes is a bacterial pathogen known for causing listeriosis, a foodborne illness with a wide spectrum of clinical presentations ranging from mild gastroenteritis to severe invasive disease, particularly affecting immunocompromised individuals, pregnant women, newborns, and the elderly. Successful treatment of patients with recurring listeria episodes due to colonised foreign material is often challenging, typically requiring a combination of antimicrobial treatment and surgical removal. Case presentation: Here, we present a particularly complex case of chronic invasive listeriosis with a total of six relapses. After extensive investigations, the patient's ICD device was identified as the focus of infection. Conclusion: The confirmation of relapses through cgMLST analysis highlights the persistence of Listeria monocytogenes and the potential for recurrence even after apparent resolution of symptoms in patients with foreign material. It emphasises the necessity for a comprehensive assessment to identify and mitigate the risk of relapses, thereby ensuring optimal management and outcomes. [ABSTRACT FROM AUTHOR]

Increases in the virulence and survival of some pathogens in the presence of subinhibitory concentrations of antibiotics have been reported. However, research on the effects of subinhibitory concentrations of antimicrobial substances derived from traditional Chinese medicine on pathogens is still insufficient. Glabridin is a well-known active isoflavone found in licorice roots that possesses a wide range of biological activities. Therefore, in this study, Listeria monocytogenes (L. monocytogenes) exposed to subinhibitory concentrations of glabridin was used as the research object. The minimum inhibitory concentration (MIC) was determined for L. monocytogenes. We investigated the impacts of subinhibitory concentrations of glabridin on the morphology, motility, biofilm formation, adherence, and survival of L. monocytogenes. The results indicated that the MIC of glabridin for L. monocytogenes was 31.25 µg/mL. At 1/8, 1/4, or 1/2 of the MIC, glabridin did not affect the growth, morphology, flagellar production, or biofilm formation of L. monocytogenes. However, subinhibitory concentrations of glabridin inhibited bacterial swimming and swarming motility and decreased the hemolytic activity of L. monocytogenes. Glabridin reduced the hemolytic activity of L. monocytogenes culture supernatants. The results also showed that subinhibitory concentrations of glabridin had no toxic effect on RAW264.7 cells but decreased the intracellular growth of L. monocytogenes in RAW264.7 cells. Furthermore, subinhibitory concentrations of glabridin triggered ROS production but did not induce MET formation in macrophages. In addition, glabridin did not enhance the capacity of L. monocytogenes to trigger METs or the extracellular killing of macrophages by METs. Thus, we conclude that subinhibitory concentrations of glabridin reduce L. monocytogenes motility and hemolytic activity but do not exhibit antimicrobial activity. Glabridin could be an interesting food additive as a bacteriostatic agent with anti-Listeria activity. [ABSTRACT FROM AUTHOR]

In this study, a molecular beacon (MB) was designed for colorimetric loop-mediated isothermal amplification (cLAMP). The length of complementary bases on the MB, guanine and cytosine content (GC content), and hybridization sites of complementary bases were investigated as key factors affecting the design of the MB. We designed MBs consisting of 10, 15, and 20 complementary bases located at both ends of the HRPzyme. In the case of the long dumbbell DNA structure amplified from the hlyA gene of Listeria monocytogenes, possessing a flat region (F1c-B1) of 61 base pairs (bp), an MB was designed to intercalate into the flat region between the F1c and B1 regions of the LAMP amplicons. In the case of the short dumbbell DNA structure amplified from the bcfD gene of Salmonella species possessing a flat region (F1c-B1) length of 6 bp, another MB was designed to intercalate into the LoopF or LoopB regions of the LAMP amplicons. The results revealed that the hybridization site of the MB on the LAMP amplicons was not crucial in designing the MB, but the GC content was an important factor. The highest hybridization efficiencies for LAMP amplicons were obtained from hlyA gene-specific and bcfD gene-specific MBs containing 20- and 15-base complementary sequences, respectively, which exhibited the highest GC content. Therefore, designing MBs with a high GC content is an effective solution to overcome the low hybridization efficiency of cLAMP assays. The results obtained can be used as primary data for designing MBs to improve cLAMP accessibility. [ABSTRACT FROM AUTHOR]

The establishment of Listeria (L.) monocytogenes within food processing environments constitutes a significant public health concern. This versatile bacterium demonstrates an exceptional capacity to endure challenging environmental conditions in the food processing environment, where contamination of food products regularly occurs. The diverse repertoire of stress resistance genes, the potential to colonize biofilms, and the support of a co-existing microbiota have been proposed as root causes for the survival of L. monocytogenes in food processing environments. In this study, 71 sites were sampled after cleaning and disinfection in a European frozen vegetable processing facility, where L. monocytogenes in-house clones persisted for years. L. monocytogenes and L. innocua were detected by a culture-dependent method at 14 sampling sites, primarily on conveyor belts and associated parts. The presence of biofilms, as determined by the quantification of bacterial load and the analysis of extracellular matrix components (carbohydrates, proteins, extracellular DNA) was confirmed at nine sites (12.7%). In two cases, L. innocua was detected in a biofilm. Furthermore, we explored the resident microbial community in the processing environment and on biofilm-positive sites, as well as the co-occurrence of bacterial taxa with Listeria by 16S rRNA gene sequencing. Pseudomonas, Acinetobacter, and Exiguobacterium dominated the microbial community of the processing environment. Using differential abundance analysis, amplicon sequence variants (ASVs) assigned to Enterobacterales (Enterobacter, Serratia, unclassified Enterobacteriaceae) and Carnobacterium were found to be significantly higher abundant in Listeria-positive samples. Several Pseudomonas ASVs were less abundant in Listeria-positive compared to Listeria-negative samples. Acinetobacter, Pseudomonas, Janthinobacterium, Brevundimonas, and Exiguobacterium were key players in the microbial community in biofilms, and Exiguobacterium and Janthinobacterium were more relatively abundant in biofilms. Further, the microbial composition varied between the different areas and the surface materials. [ABSTRACT FROM AUTHOR]

Dissemination of food-borne L. monocytogenes in the host relies on internalinmediated invasion, but the underlying invasion strategies remain elusive. Here we use live-cell microscopy to follow single cell interactions between individual human cells and L. monocytogenes and elucidate mechanisms associated with internalin B (InlB)-mediated invasion. We demonstrate that whilst a replicative invasion of nonphagocytic cells is a rare event even at high multiplicities of invasion, L. monocytogenes overcomes this by utilising a strategy relaying on PrfA-mediated ActA-based aggregation. We show that L. monocytogenes forms aggregates in extracellular host cell environment, which promote approximately 5-fold more host cell adhesions than the non-aggregating actA-DC mutant (which lacks the C-terminus coding region), with the adhering bacteria inducing 3-fold more intracellular invasions. Aggregation is associated with robust MET tyrosine kinase receptor clustering in the host cells, a hallmark of InlB-mediated invasion, something not observed with the actA-DC mutant. Finally, we show via RNA-seq analyses that aggregation involves a global adaptive response to host cell environment (including iron depletion), resulting in metabolic changes in L. monocytogenes and upregulation of the PrfA virulence regulon. Overall, our analyses provide new mechanistic insights into internalin-mediated host-pathogen interactions of L. monocytogenes. [ABSTRACT FROM AUTHOR]

Controlling foodborne pathogens in buffalo milk is crucial for ensuring food safety. This study estimated the prevalence of nine target genes representing seven critical foodborne bacteria in milk and milk products, and identified factors associated with their presence in buffalo milk chain nodes in Bangladesh. One hundred and forty-three milk samples from bulk tank milk (n = 34), middlemen (n = 37), milk collection centers (n = 37), and milk product shops (n = 35) were collected and analyzed using RT-PCR. Escherichia (E.) coli, represented through yccT genes, was the most prevalent throughout the milk chain (81–97%). Chi-squared tests were performed to identify the potential risk factors associated with the presence of foodborne bacteria encoded for different genes. At the middleman level, the prevalence of E. coli was associated with the Mymensingh, Noakhali, and Bhola districts (P = 0.01). The prevalence of Listeria monocytogenes, represented through inlA genes, and Yersinia (Y.) enterocolitica, represented through yst genes, were the highest at the farm level (65–79%). The prevalence of both bacteria in bulk milk was associated with the Noakhali and Bhola districts (P < 0.05). The prevalence of Y. enterocolitica in bulk milk was also associated with late autumn and spring (P = 0.01) and was higher in buffalo-cow mixed milk than in pure buffalo milk at the milk collection center level (P < 0.01). The gene stx2 encoding for Shiga toxin-producing (STEC) E. coli was detected in 74% of the milk products. At the middleman level, the prevalence of STEC E. coli was associated with the use of cloths or tissues when drying milk containers (P = 0.01). Salmonella enterica, represented through the presence of invA gene, was most commonly detected (14%) at the milk collection center. The use of plastic milk containers was associated with a higher prevalence of Staphylococcus aureus, represented through htrA genes, at milk product shops (P < 0.05). These results suggest that raw milk consumers in Bangladesh are at risk if they purchase and consume unpasteurized milk. [ABSTRACT FROM AUTHOR]

Listeria monocytogenes, a potentially fatal foodborne pathogen commonly found in food processing facilities, creates a significant economic burden that totals more than $2 billion annually in the United States due to outbreaks. Quaternary ammonium compounds (QACs), including benzalkonium chloride (BAC), are among the most widely used sanitizers to inhibit the growth and spread of L. monocytogenes from food processing facilities. However, resistance to QACs has been increasing in L. monocytogenes and different genetic mechanisms conferring resistance have been discovered. Here, we used ethyl methanesulfonate (EMS) to chemically mutagenize the BAC-susceptible strain, L. monocytogenes FSL-N1-304. We isolated two mutants with increased tolerance to BAC compared to the parental strain. Next, we assessed the off-target effect of increased tolerance to BAC by measuring the minimum inhibitory concentrations (MICs) of a diverse set of antibiotics, revealing that mut-1 and mut-2 displayed significantly increased resistance to fluoroquinolone antibiotics compared to the parental strain. A hemolysis assay was then used to investigate a potential correlation between BAC tolerance and virulence. Interestingly, mut-1 and mut-2 both exhibited significantly higher hemolysis percentage than the parental strain. We then sequenced the genomes of the parental strain and both mutants to identify mutations that may be involved in the increased resistance to BAC. We identified 3 and 29 mutations in mut-1 and mut-2, respectively. mut-1 contained nonsynonymous mutations in dagK (a diacylglycerol kinase), lmo2768 (a permease-encoding gene), and lmo0186 (resuscitation promoting factor). mut-2 contained a nonsense mutation in the nucleotide excision repair enzyme UvrABC system protein B encoding gene, uvrB, which likely accounts for the higher number of mutations observed. Transcriptome analysis in the presence of BAC revealed that genes related to the phosphotransferase system and internalins were up-regulated in both mutants, suggesting their significance in the BAC stress response. These two mutants provide insights into alternative mechanisms for increased BAC tolerance and could further our understanding of how L. monocytogenes persists in the food processing environment. [ABSTRACT FROM AUTHOR]

Background: European hedgehogs (Erinaceus europaeus) are widely distributed across Europe. They may play an important role by spreading zoonotic bacteria in the environment and to humans and animals. The aim of our work was to study the prevalence and characteristics of the most important foodborne bacterial pathogens in wild hedgehogs. Results: Faecal samples from 148 hospitalised wild hedgehogs originating from the Helsinki region in southern Finland were studied. Foodborne pathogens were detected in 60% of the hedgehogs by PCR. Listeria (26%) and STEC (26%) were the most common foodborne pathogens. Salmonella, Yersinia, and Campylobacter were detected in 18%, 16%, and 7% of hedgehogs, respectively. Salmonella and Yersinia were highly susceptible to the tested antimicrobials. Salmonella Enteritidis and Listeria monocytogenes 2a were the most common types found in hedgehogs. All S. Enteritidis belonged to one sequence type (ST11), forming four clusters of closely related isolates. L. monocytogenes was genetically more diverse than Salmonella, belonging to 11 STs. C. jejuni ST45 and ST677, Y. pseudotuberculosis O:1 of ST9 and ST42, and Y. enterocolitica O:9 of ST139 were also found. Conclusions: Our study shows that wild European hedgehogs should be considered an important source of foodborne pathogens, and appropriate hygiene measures after any contact with hedgehogs and strict biosecurity around farms are therefore important. [ABSTRACT FROM AUTHOR]

Copyright of Revista Foco (Interdisciplinary Studies Journal) is the property of Revista Foco and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The study aimed to assess the nutritional properties of fruit juices using the microwave flow pasteurization (MFP) method. The innovative spray deaeration process was also employed at two different temperatures, 25 °C and 50 °C, with three rotational speeds for the spray nozzle: 150, 450, and 750 rpm. The research focused on two not-from-concentrate (NFC) juices: apple–peach and apple–chokeberry. The innovative MFP method demonstrated significant results over 12 months of storage: no presence of Listeria monocytogenes or Salmonella spp. bacteria was detected. Polyphenol oxidases (PPOs) were inactivated, while peroxidase (POD) activity in apple–peach juice was minimal. The total polyphenol content (TPC) in the juices gradually decreased over storage time, but MFP resulted in a slower degradation of TPC than traditional pasteurization (TP). Additionally, anthocyanin and carotenoid content gradually decreased during storage time. Still, with MFP, higher concentrations of these compounds were noted up to 4 and 6 months of storage in apple–peach and apple–chokeberry juices, respectively, than with TP. The research findings indicate that MFP may be a suitable and promising technique for preserving high-quality juices with superior retention of essential nutrients. However, the recommended storage time should be at most four months. [ABSTRACT FROM AUTHOR]

Ensuring the microbiological safety of food products is majorly important to regulatory agencies, producers, and consumers. This study aimed to examine the effects of three different antimicrobial agents, including chitosan (CH), mastic oil (M), and citric acid (CA), individually or as a combination, against Salmonella spp., Escherichia coli O157:H7, and Listeria monocytogenes (artificially inoculated) in Guacamole, a ready-to-eat (RTE) avocado-based salad. The Guacamole samples included untreated samples, designated as CNL, and samples treated as follows: CA 0.15% and CA 0.30% with citric acid added at 0.15% and 0.30% v/w; CH 0.5% and CH 1% with chitosan at 0.5 and 1% v/w; M 0.2% and M 0.4% with mastic essential oil (EO) at 0.2% and 0.4% v/w; CACH with CA 0.30% and CH 1% v/w; CAM with CA 0.30% and M 0.4% v/w; CHM with CH 1% and M 0.4% v/w; and CACHM with CA 0.30%, CH 1%, and M 0.4% v/w. Microbiological evaluation, monitoring of the pH values, and proximate analyses (moisture, fat, protein, ash, and water activity) were performed at different time intervals (days 0, 1, 3, 5, and 7) at two storage temperatures (4 and 10 °C). Antimicrobial treatments, particularly CH 1% and CACHM, effectively (p < 0.05) reduced Salmonella spp. and E. coli O157:H7 populations at 4 °C, while CACHM showed the most efficacy against L. monocytogenes. However, at 10 °C, antimicrobials had limited impact, and the bacterial counts exhibited an increasing trend during storage. The pH values in the avocado-based salad samples showed, in general, higher decreases at 10 compared to 4 °C, with the CHM combination showing the highest antimicrobial effect. [ABSTRACT FROM AUTHOR]

Foodborne illnesses caused by consuming contaminated fresh produce not only pose serious public health risks but also lead to huge economic losses. Rockmelons (cantaloupes) have emerged as a recurrent source of disease outbreaks caused by foodborne pathogens, including Listeria monocytogenes, Salmonella, and Escherichia coli. The most common factor of the outbreaks was the microbial contamination of rockmelons at the farm, and subsequently, the pathogenic bacteria were transferred to the flesh during cutting and processing. One of the deadliest outbreaks occurred in the USA due to L. monocytogenes contamination of rockmelons which caused 33 deaths in 2011. Since then, several guidelines and recommendations have been developed for food safety management to reduce the microbial contamination of melons on farms and post-harvest operations. This article explicitly provides an updated overview of microbiological contamination, disease outbreaks, pathogens prevalence, and mitigation strategies to reduce public health risks due to the consumption of rockmelons. [ABSTRACT FROM AUTHOR]

Background: Listeriosis is a global health threat to both animals and humans, especially in developing countries. This study was designed to isolate Listeria monocytogenes from faeces; environmental samples; and cow, sheep and goat milk, as well as human stool, to study its molecular characteristics and antibiotic sensitivity in the New Valley and Beheira Governorates, Egypt. The isolation and identification of L. monocytogenes were carried out using traditional culture and biochemical methods, followed by antibiography, genus confirmation of some isolates and detection and sequencing of InlB genes via PCR. Results: Out of 2097 examined samples, the prevalence of L. monocytogenes was 13.4% in animals; the prevalence was 9.2%, 2.4%, 25.4%, 4%, 42.4%, and 6.4% in cattle faeces, cattle milk, sheep faeces, sheep milk, goat faeces, and goat milk, respectively. However, the prevalence of L. monocytogenes was 8.3% in human samples. Both animal and human isolates showed 100% resistance to trimethoprim-sulfamethoxazole, and the isolates showed the highest sensitivity to flumequine (100%), amikacin (99.2%), gentamicin (97.6%), and levofloxacin (94.6%). Multidrug resistance (MDR) was detected in 86.9% of the tested isolates. The 16 S rRNA and inlB genes were detected in 100% of the randomly selected L. monocytogenes isolates. Phylogenetic analysis of three isolates based on the inlB gene showed 100% identity between faecal, milk and human stool isolates. Conclusions: Faeces and milk are major sources of listeriosis, and the high degree of genetic similarity between animal and human isolates suggests the possibility of zoonotic circulation. The high prevalence of MDR L. monocytogenes in both animal and human samples could negatively impact the success of prevention and treatments for animal and human diseases, thereby imposing serious risks to public health. [ABSTRACT FROM AUTHOR]

We present a rare case of Listeria monocytogenes (LM) rhombencephalitis with the formation of multifocal abscesses in a young immunocompetent patient. His initial symptoms of dizziness, headache, and feeling generally unwell were put down to a coincidental coinfection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The unfortunate rapid progression to trigeminal, hypoglossal, vagal, facial, and abducens nuclei palsies, and then an acquired central hypoventilation syndrome, known as Ondine's curse, required a prolonged intensive care unit (ICU) stay, and prolonged mechanical ventilation. As they continued to deteriorate despite targeted antibiotic treatment, surgical drainage of the abscesses was seen as the only meaningful available treatment option left to contain the disease. Postoperatively, the patient's strength rapidly improved as well as the severity of the cranial nerve palsies. After prolonged rehabilitation, at 3 months of follow-up, the patient was weaned off mechanical ventilation, independently mobile, and was left with only minor residual neurologic deficits. This case highlights a number of interesting findings only touched upon in current literature including the route of entry of LM into the central nervous system, the rare entity of acquired central hypoventilation syndrome, and finally the use of surgical intervention in cerebral LM infections. [ABSTRACT FROM AUTHOR]

Aims This study aimed to prospect and isolate lactic acid bacteria (LAB) from an artisanal cheese production environment, to assess their safety, and to explore their bacteriocinogenic potential against Listeria monocytogenes. Methods and results Samples were collected from surfaces of an artisanal-cheese production facility and after rep-PCR and 16S rRNA sequencing analysis, selected strains were identified as to be belonging to Lactococcus garvieae (1 strain) and Enterococcus faecium (14 isolates, grouped into three clusters) associated with different environments (worktables, cheese mold, ripening wooden shelves). All of them presented bacteriocinogenic potential against L. monocytogenes ATCC 7644 and were confirmed as safe (γ-hemolytic, not presenting antibiotic resistance, no mucus degradation properties, and no proteolytic or gelatinase enzyme activity). Additionally, cell growth, acidification and bacteriocins production kinetics, bacteriocin stability in relation to different temperatures, pH, and chemicals were evaluated. According to performed PCR analysis all studied strains generated positive evidence for the presence of ent A and ent P genes (for production of enterocins A and enterocins P, respectively). However, pediocin PA-1 associated gene was recorded only in DNA obtained from E. faecium ST02JL and Lc. garvieae ST04JL. Conclusions It is worth considering the application of these safe LAB or their bacteriocins in situ as an alternative means of controlling L. monocytogenes in cheese production environments, either alone or in combination with other antimicrobials. [ABSTRACT FROM AUTHOR]

Background: Listeriosis is caused by the facultative anaerobic bacterium Listeria monocytogenes. Infection from Listeria-contaminated food or water is the main etiology. If Listeria travels outside the intestines, it can cause invasive listeriosis, such as sepsis, meningitis, and meningoencephalitis. Invasive illness is especially dangerous for pregnant women and their newborns, elderly people, and people with compromised immune systems or medical conditions such as end-stage kidney disease (ESKD) patients receiving long-term dialysis. Purpose: Describe the manifestations and hospital outcomes of invasive listeriosis and identify the risk factors for in-hospital and one-year mortality in ESKD patients receiving long-term dialysis. Patients and Methods: This retrospective observational study examined hospitalized patient records at a Taiwanese tertiary medical center from August 1, 2000, to August 31, 2021. ESKD patients on chronic dialysis were identified with invasive listeriosis by blood culture and discharge diagnosis. Over 21 years, we accurately recorded 26 cases. Results: ESKD patients on chronic dialysis with invasive listeriosis have a poor prognosis. Only 53.8% of chronic dialysis patients with invasive listeriosis survived their first hospital episode. 42.3% of hospitalized ESKD patients with invasive listeriosis survived one year later. In univariate analysis, shock, tachypnea (RR ≥ 22), respiratory failure, qSOFA score ≥ 2, and lower initial platelet count were linked to greater in-hospital mortality rates. Conclusion: ESKD patients with invasive listeriosis have a grave prognosis. Our research reveals that an early blood sample for a bacterial culture may identify invasive listeriosis in chronic dialysis patients with fever, nausea or vomiting, confusion, and respiratory distress. This study is the first to identify a lower platelet count and qSOFA score ≥ 2 as markers of high-risk invasive listeriosis in ESKD patients. [ABSTRACT FROM AUTHOR]

The high Salmonella and Listeria monocytogenes risk in poultry products reinforces the urgent need for new technologies with high antimicrobial effects. In that sense, a combined technology consisting of encapsulated extra virgin olive oil (EVOO) during chicken nugget breading combined with infrared processing was hereby studied at three levels (experiments). The high in vitro EVOO antimicrobial activity (up to 74%), which was 1.2-fold higher against L. monocytogenes than Salmonella, was enhanced after encapsulation (α-cyclodextrin) by 1.5–2.0 and 1.2–1.6-fold, respectively (experiment 1). Oil-free processing (infrared and convection ovens) combined with encapsulated EVOO (2.5 and 1.6% EVOO doses) even enhanced the high in vitro antimicrobial activity of encapsulated EVOO (experiment 2). In the in vivo study (experiment 3), infrared (180 °C, 6.4 min) + convection air (120 °C, 10 min) processing combined with encapsulated EVOO (1.6 and 2.5%) within chicken nugget breading of the chicken nuggets achieved in vivo antimicrobial reductions of 60 and 80% against Salmonella and L. monocytogenes, respectively. In conclusion, this new technology including encapsulated EVOO (1.6–2.5%) within the breading of chicken nuggets and innovative oil-free processing may ensure the food safety of these poultry products very susceptible to the incidence of Salmonella and L. monocytogenes. [ABSTRACT FROM AUTHOR]

Fresh insects in the form of paste can be conveniently utilised for further food preparations and processing at both household and industrial levels. However, due to the high moisture content and particular physiochemical properties, insect paste is highly unstable and susceptible to significant quality changes during storage. The aim of this study was to evaluate the microbiological and physicochemical stability of high hydrostatic pressure (HHP) treated Tenebrio molitor paste stored at different modified atmosphere packaging (MAP) conditions. Three different MAP compositions and normal air were applied. pH, colour, lipid oxidation, fluorescence spectra and microbiological parameters were evaluated along 28 days of refrigerated storage (4 °C). HHP treatment (600 MPa, 5 min) resulted in a significant reduction in mesophilic aerobic bacteria, anaerobic bacteria and yeast and mould counts. Growth of mesophilic aerobic and anaerobic bacteria remained low for 7 days at 4 °C, regardless of the applied atmospheric conditions, while high microbial growth was observed after 14 days without any significant differences among the treatments. The number of mesophilic spores remained low throughout the entire storage period when MAP was applied, whereas high values were observed after 28 days in the samples stored in normal air. Listeria monocytogenes, Salmonella spp. and Escherichia coli were not detected in any of the samples, nor in the raw paste. Lipid oxidation was initiated by the HHP treatment and displayed an increasing trend during the storage period, although the oxidation levels were lower in the MAP without oxygen compared to the normal air packaging and in MAPs with high O2 or CO2 levels. Fluorescence spectroscopy showed high potential for rapid detection of chemical changes in insect products during processing and storage. Overall, this study showed that MAP can effectively be applied on HHP-treated insect paste to extend its storage period. Absence of oxygen has been identified as a crucial factor in achieving reduced microbial growth and ensuring high physiochemical quality of the final product. Therefore, the present research offers a valuable insight for creating new edible insect-based products within the food industry. [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]

The quality of squab meat subjected to "faisandage" treatment during the usual aging time was evaluated through the evolution of microbial and physicochemical properties. Twenty-seven whole squabs (young pigeon) were slaughtered, hung, and stored at 0–4°C in a cooling chamber. After 0, 7, and 14 aging days, the carcasses of squabs were obtained to carry out different analyses (total viable bacteria, Enterobacteriaceae and Escherichia coli (E. coli) counts, detection of Salmonella spp., Campylobacter spp., Listeria monocytogenes, and E. coli O157:H7, and pH, thaw and cooking losses, and shear force). In general, the squab meat subjected to "faisandage" treatment over 7 or 14 days at 0–4°C presented microbiological quality and physicochemical properties similar to that squab meat from day 0. The values of thaw losses, shear force, and pH obtained in this study allowed to distinguish among squab meat aging during 7 or 14 days and meat squab without aging. [ABSTRACT FROM AUTHOR]

In the current investigation, the antibacterial activity of zinc oxide nanoparticles (ZnO-NPs) formed by an aqueous extract of Psidium guajava leaves against foodborne pathogenic bacterial strains was investigated. To achieve this goal, 33 bacterial isolates were obtained from spoiled fruits. Among these isolates, 79% showed cellulase activity, 82% showed amylase activity, 81% exhibited xylanase potential, and 65% exhibited lipase activity. Moreover, 12 isolates showed complete hemolysis (β-hemolysis). The identification of these isolates was done using sequencing and amplification of 16s rRNA as Staphylococcus aureus (two strains), Pseudomonas syringae (one strain), E. coli (two strains), Salmonella typhimurium (two strains), Listeria monocytogenes (one isolate), Bacillus cereus (two isolates), and Bacillus subtilis (two isolates). The formed ZnO-NPs by aqueous Psidium guajava leaf extract were characterized using UV, FT-IR, TEM, EDX, XRD, DLS, and Zeta potential. The data revealed the successful formation of a spherical shape, crystallographic structure, and well-arranged ZnO-NPs. FT-IR showed the effect of different functional groups in the plant extract in the formation of ZnO-NPs through reducing, capping, and stabilizing of end products. Moreover, EDX analysis showed that the Zn ion occupied the main component of the produced NPs. Interestingly, the obtained bacterial strains showed varied sensitivity toward green-synthesized ZnO-NPs. The growth inhibition of foodborne pathogenic strains by ZnO-NPs was concentration dependent, forming a zone of inhibition in the range of 20–23 mm at a concentration of 200 µg mL−1, which decreased to 15–18 mm at 100 µg mL−1. Moreover, the values of MIC were 25 and 50 µg mL−1 based on the bacterial strain. Overall, the green-synthesized ZnO-NPs can be a useful approach for inhibiting the growth of spoilage bacterial strains that destroy fruits and hence reduce the harmful effects of traditional treatment methods on the environment and human health. [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]

[Objective] The paper aimed to isolate and identify the Exosomes (Exos) of macrophages infected with Listeria monocytogenes (LM) in monocyte proliferation mice, and analyze their miRNA expression profile, laying a solid research foundation for revealing the regulatory mechanism of macrophage Exos miRNA in LM infection. [Method] Macrophages infected with LM were used as the experimental group, while macrophages not infected with LM were used as the control group. Exos in the supernatant of macrophages were isolated and extracted using ultracentrifugation. The morphology, size and surface marker characteristics of Exos were identified by transmission electron microscopy, nanoparticle tracking technology and Western blot. Small RNA-seq sequencing of miRNA in macrophage Exos from the two groups was performed using the Illumina SE50 sequencing platform to screen for significantly differentially expressed miRNA. Targetscan, miRDB and miRWalk databases were used to predict the target genes of differentially expressed miRNA. GO and KEGG-Pathway functional enrichment analysis were conducted on the different miRNA target genes. The miRNA-mRNA regulatory network diagram of the top 20 Hub genes was drawn using Cytoscape software. [Result] The diameter of Exos ranged from 30 to 150 nm, with a typical double-layer membrane structure, and the surface marker molecules CD9, CD63 and TSG101 were positively expressed. High-throughput sequencing results showed that compared to the control group, 9 significantly differentially expressed miRNA were screened in the experimental group Exos, including 8 significantly down-regulated genes (mmu-miR-7a-5p, mmu-miR-365-2-5p, г u-miR-365-2-5p, mmu-miR-122-5p, mmu-miR-122b-3p, mmu-let-7i-5p, mmu-miR151-3p, mmu-miR-182-5p and mmu-miR-1198-5p) and 1 significantly up-regulated gene (mmu-miR-192-5p), with a total of 1064 predicted miRNA-regulated target genes. GO enrichment analysis results showed that the different miRNA target genes were mainly enriched in processes such as axon formation, cell junction assembly, actin binding and metal ion transmembrane transport; KEGG analysis showed that the target genes were significantly enriched in the cGMP-PKG signaling pathway and the FeyR-mediated phagocytosis pathway. [Conclusion] The miRNA expression profile of macrophage Exos in mice infected with LM underwent significant changes, and the potential target genes regulated by them were mainly involved in signaling pathways related to infection and immune response. [ABSTRACT FROM AUTHOR]