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Listeria monocytogenes Contamination Leads to Survival and Growth During Enoki Mushroom Cultivation.Journal of Food Protection Jun 2024Two recent outbreaks of listeriosis have been linked to the consumption of enoki mushrooms. After the first outbreak, import sampling by the U.S. FDA identified that 43%...
Two recent outbreaks of listeriosis have been linked to the consumption of enoki mushrooms. After the first outbreak, import sampling by the U.S. FDA identified that 43% of the samples evaluated were positive for Listeria monocytogenes (Lm). These observations raised questions about the potential sources of Lm contamination of enoki mushrooms. One potential source of contamination is during enoki mushroom cultivation, as growing conditions are comparatively cool and moist to induce mushroom germination, to which Lm is well adapted. Two varieties of enoki mushrooms were evaluated to determine the potential for Lm to contaminate enoki cultures when introduced at various points during cultivation (inoculation, scraping, pinning, and collaring). The results of two trials showed that Lm established contamination and grew to similar levels in the substrate regardless of when Lm was introduced and, with one exception, did not alter the rate of mushroom generation to below the control. Enumeration of Lm in enoki mushroom cultures at harvest found an average contamination of 10 cfu/g, though the results were variable. Refrigerated storage for six weeks was found to result in an increase in Lm. Additionally, no statistically significant difference in the levels of Lm was observed based on proximity to the substrate, though levels of Lm in the different enoki samples correlated with levels of Lm in the substrate at harvest, but not at scraping. The ability of Lm to grow independently in the media used to culture enoki was assessed, and Lm was found to be unable to grow but could sporadically survive in Masters Mix. No growth of Lm was observed in potato dextrose broth, though growth could occur on the agar. Overall, the data indicate a high potential for the establishment of Lm contamination at any point during enoki cultivation to result in Lm-contaminated mushrooms. These data indicate a need for active control mechanisms to prevent the introduction of Lm to enoki cultures.
Topics: Listeria monocytogenes; Colony Count, Microbial; Food Contamination; Humans; Agaricales; Food Microbiology
PubMed: 38701973
DOI: 10.1016/j.jfp.2024.100290 -
Swiss Medical Weekly May 2024Listeriosis is a notifiable disease in Switzerland. In summer 2022, the Swiss Federal Office of Public Health noticed an increase in reports of listeriosis cases,...
AIMS OF THE STUDY
Listeriosis is a notifiable disease in Switzerland. In summer 2022, the Swiss Federal Office of Public Health noticed an increase in reports of listeriosis cases, indicating a possible ongoing outbreak. Here we present the approaches applied for rapidly confirming the outbreak, detecting the underlying source of infection and the measures put in place to eliminate it and contain the outbreak.
METHODS
For close surveillance and early detection of outbreak situations with their possible sources, listeriosis patients in Switzerland are systematically interviewed about risk behaviours and foods consumed prior to the infection. Listeria monocytogenes isolates derived from patients in medical laboratories are sent to the National Reference Laboratory for Enteropathogenic Bacteria and Listeria, where they routinely undergo whole-genome sequencing. Interview and whole-genome sequencing data are continuously linked for comparison and analysis.
RESULTS
In summer 2022, 20 patient-derived L. monocytogenes serotype 4b sequence type 388 strains were found to belong to an outbreak cluster (≤10 different alleles between neighbouring isolates) based on core genome multilocus sequence typing analysis. Geographically, 18 of 20 outbreak cases occurred in northeastern Switzerland. The median age of patients was 77.4 years (range: 58.1-89.7), with both sexes equally affected. Rolling analysis of the interview data revealed smoked trout from a local producer as a suspected infection source, triggering an on-site investigation of the production facility and sampling of the suspected products by the responsible cantonal food inspection team on 15 July 2022. Seven of ten samples tested positive for L. monocytogenes and the respective cantonal authority ordered a ban on production and distribution as well as a product recall. The Federal Food Safety and Veterinary Office released a nationwide public alert covering the smoked fish products concerned. Whole-genome sequencing analysis confirmed the interrelatedness of the L. monocytogenes smoked trout product isolates and the patient-derived isolates. Following the ban on production and distribution and the product recall, reporting of new outbreak-related cases rapidly dropped to zero.
CONCLUSIONS
This listeriosis outbreak could be contained within a relatively short time thanks to identification of the source of contamination through the established combined approach of timely interviewing of every listeriosis patient or a representative and continuous molecular analysis of the patient- and food-derived L. monocytogenes isolates. These findings highlight the effectiveness of this well-established, joint approach involving the federal and cantonal authorities and the research institutions mandated to contain listeriosis outbreaks in Switzerland.
Topics: Humans; Switzerland; Disease Outbreaks; Listeria monocytogenes; Listeriosis; Whole Genome Sequencing; Male; Aged; Female; Aged, 80 and over; Multilocus Sequence Typing; Middle Aged; Food Microbiology; Foodborne Diseases; Interviews as Topic
PubMed: 38701492
DOI: 10.57187/s.3745 -
Journal of Controlled Release :... May 2024Although various types of mRNA-based vaccines have been explored, the optimal conditions for induction of both humoral and cellular immunity remain rather unknown. In...
Although various types of mRNA-based vaccines have been explored, the optimal conditions for induction of both humoral and cellular immunity remain rather unknown. In this study, mRNA vaccines of nucleoside-modified mRNA in lipoplexes (LPXs) or lipid nanoparticles (LNPs) were evaluated after administration in mice through different routes, assessing mRNA delivery, tolerability and immunogenicity. In addition, we investigated whether mRNA vaccines could benefit from the inclusion of the adjuvant alpha-galactosylceramide (αGC), an invariant Natural Killer T (iNKT) cell ligand. Intramuscular (IM) vaccination with ovalbumin (OVA)-encoding mRNA encapsulated in LNPs adjuvanted with αGC showed the highest antibody- and CD8 T cell responses. Furthermore, we observed that addition of signal peptides and endocytic sorting signals of either LAMP1 or HLA-B7 in the OVA-encoding mRNA sequence further enhanced CD8 T cell activation although reducing the induction of IgG antibody responses. Moreover, mRNA LNPs with the ionizable lipidoid C12-200 exhibited higher pro-inflammatory- and reactogenic activity compared to mRNA LNPs with SM-102, correlating with increased T cell activation and antitumor potential. We also observed that αGC could further enhance the cellular immunity of clinically relevant mRNA LNP vaccines, thereby promoting therapeutic antitumor potential. Finally, a Listeria monocytogenes mRNA LNP vaccine supplemented with αGC showed synergistic protective effects against listeriosis, highlighting a key advantage of co-activating iNKT cells in antibacterial mRNA vaccines. Taken together, our study offers multiple insights for optimizing the design of mRNA vaccines for disease applications, such as cancer and intracellular bacterial infections.
PubMed: 38697317
DOI: 10.1016/j.jconrel.2024.04.052 -
Acta Crystallographica. Section D,... May 2024CdaA is the most widespread diadenylate cyclase in many bacterial species, including several multidrug-resistant human pathogens. The enzymatic product of CdaA, cyclic...
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.
Topics: Listeria monocytogenes; Crystallography, X-Ray; Binding Sites; Bacterial Proteins; Models, Molecular; Dinucleoside Phosphates; Anti-Bacterial Agents; Humans; Phosphorus-Oxygen Lyases; Protein Conformation
PubMed: 38682668
DOI: 10.1107/S205979832400336X -
Microorganisms Apr 2024is a ubiquitous pathogen found both in the environment and food. It can cause listeriosis in a wide range of animals as well as in humans. Investigations on presence,...
is a ubiquitous pathogen found both in the environment and food. It can cause listeriosis in a wide range of animals as well as in humans. Investigations on presence, spread and virulence are still limited to terrestrial and human environments. Embracing the One Health Approach, investigating the presence and spread of in marine ecosystems and among wildlife, would provide us with useful information for human health. This study investigated the presence of and spp. in two species of sea turtles common in the Mediterranean Sea ( and ). A total of one hundred and sixty-four carcasses of sea turtles ( = 161 and = 3) stranded along the Abruzzo, Molise, Campania, and Calabria coasts, were collected. Brain and fecal samples were taken, enriched, and cultured for the detection of spp. From the specimens collected, strains of (brain = 1, brain and feces = 1, multiorgan = 1 and feces = 1), (feces = 1 and brain = 1), and (brain = 1) were isolated. Typical colonies were isolated for Whole Genome Sequencing (WGS). Virulence genes, disinfectants/metal resistance, and antimicrobial resistance were also investigated. , and were detected in , whilst only and in . Notable among the results is the lack of significant differences in gene distribution between human and sea turtle strains. Furthermore, potentially pathogenic strains of were found in sea turtles.
PubMed: 38674761
DOI: 10.3390/microorganisms12040817 -
Microorganisms Apr 2024poses a threat to both human and animal health. This work describes an outbreak in a Portuguese rabbit farm, detailing the isolates' clinical manifestations, necropsy...
poses a threat to both human and animal health. This work describes an outbreak in a Portuguese rabbit farm, detailing the isolates' clinical manifestations, necropsy findings, and phenotypic and genomic profiles. Clinical signs, exclusively observed in does, included lethargy and reproductive signs. examination of does revealed splenomegaly, hepatomegaly with a reticular pattern, pulmonary congestion, and haemorrhagic lesions in the uterus, with thickening of the uterine wall and purulent greyish exudates. Positive samples were identified in fattening and maternity units across different samples, encompassing does and environmental samples. Core-genome Multi Locus Sequence Typing (cgMLST) analysis confirmed the outbreak, with the 16 sequenced isolates (lineage II, CC31, and ST325) clustering within a ≤2 allelic difference (AD) threshold. Antimicrobial susceptibility testing for five antibiotics revealed that 15 out of 19 outbreak isolates were resistant to sulfamethoxazole-trimethoprim (SXT). Concordantly, all SXT-resistant sequenced isolates were found to exclusively harbour a plasmid containing a trimethoprim-resistance gene (), along with loci linked to resistance to lincosamides (lnuG), macrolides (mphB), and polyether ionophores (NarAB operon). All sequenced outbreak isolates carried the antibiotic resistance-related genes , , , , , , and . The outbreak cluster comprises isolates from does and the environment, which underscores the ubiquitous presence of and emphasizes the importance of biosecurity measures. Despite limited data on listeriosis in rabbit farming, this outbreak reveals its significant impact on animal welfare and production.
PubMed: 38674729
DOI: 10.3390/microorganisms12040785 -
Antibiotics (Basel, Switzerland) Apr 2024Among the foodborne illnesses, listeriosis has the third highest case mortality rate (20-30% or higher). Emerging drug-resistant strains of , a causative bacterium of... (Review)
Review
Among the foodborne illnesses, listeriosis has the third highest case mortality rate (20-30% or higher). Emerging drug-resistant strains of , a causative bacterium of listeriosis, exacerbate the seriousness of this public health concern. Novel anti-Listerial compounds are therefore needed to combat this challenge. In recent years, marine actinobacteria have come to be regarded as a promising source of novel antimicrobials. Hence, our aim was to provide a narrative of the available literature and discuss trends regarding bioprospecting marine actinobacteria for new anti-Listerial compounds. Four databases were searched for the review: Academic Search Ultimate, Google Scholar, ScienceDirect, and South African Thesis and Dissertations. The search was restricted to peer-reviewed full-text manuscripts that discussed marine actinobacteria as a source of antimicrobials and were written in English from 1990 to December 2023. In total, for the past three decades (1990-December 2023), only 23 compounds from marine actinobacteria have been tested for their anti-Listerial potential. Out of the 23 reported compounds, only 2-allyoxyphenol, adipostatins E-G, 4-bromophenol, and ansamycins (seco-geldanamycin B, 4.5-dihydro-17-O-demethylgeldanamycin, and seco-geldanamycin) have been found to possess anti-Listerial activity. Thus, our literature survey reveals the scarcity of published assays testing the anti-Listerial capacity of bioactive compounds sourced from marine actinobacteria during this period.
PubMed: 38667038
DOI: 10.3390/antibiotics13040362 -
Frontiers in Immunology 2024Previous studies have demonstrated an association between lymphatic vessels and diseases caused by bacterial infections. (LM) bacterial infection can affect multiple...
Previous studies have demonstrated an association between lymphatic vessels and diseases caused by bacterial infections. (LM) bacterial infection can affect multiple organs, including the intestine, brain, liver and spleen, which can be fatal. However, the impacts of LM infection on morphological and functional changes of lymphatic vessels remain unexplored. In this study, we found that LM infection not only induces meningeal and mesenteric lymphangiogenesis in mice, but also impairs meningeal lymphatic vessels (MLVs)-mediated macromolecules drainage. Interestingly, we found that the genes associated with lymphatic vessel development and function, such as and , were downregulated, suggesting that LM infection may affect cellular polarization and valve development. On the other hand, photodynamic ablation of MLVs exacerbated inflammation and bacterial load in the brain of mice with LM infection. Overall, our findings indicate that LM infection induces lymphangiogenesis and may affect cell polarization, cavity formation, and valve development during lymphangiogenesis, ultimately impairing MLVs drainage.
Topics: Animals; Mice; Listeria monocytogenes; Listeriosis; Lymphatic Vessels; Lymphangiogenesis; Meninges
PubMed: 38638427
DOI: 10.3389/fimmu.2024.1382971 -
Proceedings of the National Academy of... Apr 2024is a bacterial pathogen that can cause life-threatening central nervous system (CNS) infections. While mechanisms by which and other pathogens traffic to the brain...
is a bacterial pathogen that can cause life-threatening central nervous system (CNS) infections. While mechanisms by which 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 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 population dynamics that lead to CNS infection and a framework for studying the dynamics of other cerebral infections.
Topics: Mice; Animals; Listeria monocytogenes; Listeriosis; Brain; Central Nervous System Infections
PubMed: 38635627
DOI: 10.1073/pnas.2320311121 -
Foods (Basel, Switzerland) Apr 2024A review of quantitative risk assessment (QRA) models of in produce was carried out, with the objective of appraising and contrasting the effectiveness of the control... (Review)
Review
A review of quantitative risk assessment (QRA) models of in produce was carried out, with the objective of appraising and contrasting the effectiveness of the control strategies placed along the food chains. Despite nine of the thirteen QRA models recovered being focused on fresh or RTE leafy greens, none of them represented important factors or sources of contamination in the primary production, such as the type of cultivation, water, fertilisers or irrigation method/practices. Cross-contamination at processing and during consumer's handling was modelled using transfer rates, which were shown to moderately drive the final risk of listeriosis, therefore highlighting the importance of accurately representing the transfer coefficient parameters. Many QRA models coincided in the fact that temperature fluctuations at retail or temperature abuse at home were key factors contributing to increasing the risk of listeriosis. In addition to a primary module that could help assess current on-farm practices and potential control measures, future QRA models for minimally processed produce should also contain a refined sanitisation module able to estimate the effectiveness of various sanitisers as a function of type, concentration and exposure time. Finally, growth in the products down the supply chain should be estimated by using realistic time-temperature trajectories, and validated microbial kinetic parameters, both of them currently available in the literature.
PubMed: 38611415
DOI: 10.3390/foods13071111