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Pericytes are located around blood vessels, in close contact with endothelial cells. We discovered that pericytes dampen pro-inflammatory endothelial cell responses. Endothelial cells co-cultured with pericytes had markedly reduced expression of adhesion molecules (PECAM-1 and ICAM-1) and proinflammatory cytokines (CCL-2 and IL-6) in response to bacterial stimuli (Brucella ovis, Listeria monocytogenes, or Escherichia coli lipopolysaccharide). Pericyte-depleted mice intraperitoneally inoculated with either B. ovis, a stealthy pathogen that does not trigger detectable inflammation, or Listeria monocytogenes, developed peritonitis. Further, during Citrobacter rodentium infection, pericyte-depleted mice developed severe intestinal inflammation, which was not evident in control mice. The anti-inflammatory effect of pericytes required connexin 43, as either chemical inhibition or silencing of connexin 43 abrogated pericyte-mediated suppression of endothelial inflammatory responses. Our results define a mechanism by which pericytes modulate inflammation during infection, which shifts our understanding of pericyte biology: from a structural cell to a pro-active player in modulating inflammation.ImportanceA previously unknown mechanism by which pericytes modulate inflammation was discovered. The absence of pericytes or blocking interaction between pericytes and endothelium through connexin 43 results in stronger inflammation, which shifts our understanding of pericyte biology, from a structural cell to a player in controlling inflammation.

Soil is an important reservoir of antibiotic resistance genes (ARGs) and understanding how corresponding environmental changes influence their emergence, evolution, and spread is crucial. The soil-dwelling bacterial genus Listeria, including L. monocytogenes, the causative agent of listeriosis, serves as a key model for establishing this understanding. Here, we characterize ARGs in 594 genomes representing 19 Listeria species that we previously isolated from soils in natural environments across the United States. Among the five putatively functional ARGs identified, lin, which confers resistance to lincomycin, is the most prevalent, followed by mprF, sul, fosX, and norB. ARGs are predominantly found in Listeria sensu stricto species, with those more closely related to L. monocytogenes tending to harbor more ARGs. Notably, phylogenetic and recombination analyses provide evidence of recent horizontal gene transfer (HGT) in all five ARGs within and/or across species, likely mediated by transformation rather than conjugation and transduction. In addition, the richness and genetic divergence of ARGs are associated with environmental conditions, particularly soil properties (e.g., aluminum and magnesium) and surrounding land use patterns (e.g., forest coverage). Collectively, our data suggest that recent HGT and environmental selection play a vital role in the acquisition and diversification of bacterial ARGs in natural environments. It remains elusive how environmental antibiotic resistance evolves and spreads. Goh et al. analyzed a nationwide genomic dataset of soil-dwelling Listeria and find evidence of horizontal gene transfer mediated by transformation and environmental selection acting on antibiotic resistance evolution in soil environments. [ABSTRACT FROM AUTHOR]

Background There is a high demand in the food industry and in public health for rapid automated methods capable of high-volume sample processing. Objective In an unpaired study, Roka Atlas® System performance was compared with Health Canada reference method MFHPB-30 for Listeria spp. (LSP Roka assay) and Listeria monocytogenes (LmG2 Roka Assay) detection on plastic (PL), sealed concrete (SC), and stainless-steel (SS) surfaces (45 samples each per candidate or reference method). Methods Seeking shorter enrichment time for the candidate method, R2 medium pre-enrichment for 14, 16, and 24 h at 35°C was combined with the Roka assay. Listeria welshimeri , L. innocua , and L. monocytogenes were employed to individually inoculate each of the three surfaces, with two competing microorganisms within the 10–100-fold higher concentration range. Results False negative, false positive, sensitivity, and specificity were 0, 0, 100, and 100%, respectively, for the plastic, sealed concrete, and stainless-steel surfaces, regardless of inoculation level (high, low, and uninoculated) and enrichment time. Candidate method detected 10, 7, and 9 true positives, versus 10, 6, and 10 by the reference method in individually inoculated SS, PL, and SC, respectively. Conclusions Probability of detection for all the three surfaces for the Roka Atlas System was comparable to the reference method in this unpaired study. Highlights The Roka Atlas System detected targets after as little as 14 h enrichment. Surface type did not negatively affect assay sensitivity or specificity. The Roka Atlas System was comparable to the reference method. [ABSTRACT FROM AUTHOR]

Listeria monocytogenes contamination of ready‐to‐eat (RTE) food products and food‐associated built environments (e.g., processing facilities) represents a food safety issue with major public health and business risk implications. A number of factors make L. monocytogenes control a particular challenge, including (i) its frequent presence in different environments, (ii) its propensity for establishing persistence in food‐associated environments, (iii) its ability to grow under a variety of stressful conditions, and (iv) its ability to cause severe illness, particularly in immunocompromised individuals and pregnant people. Key sources of L. monocytogenes contamination of RTE foods are food‐associated built environments. However, raw materials can also be an important source, particularly for products without a "kill step" (e.g., fresh produce, raw dairy products, cold‐smoked seafood). While certain RTE foods (e.g., deli meats, soft cheeses, produce) have commonly been linked to listeriosis outbreaks, cases, and recalls, a number of factors will influence the specific public health risk a given RTE food represents, including the likelihood of contamination, ability to support L. monocytogenes growth, and consumer‐related factors (including consumption by pregnant or immunocompromised individuals). Consequently, a risk‐based approach presents the most appropriate strategy to minimize the public health and business impact of L. monocytogenes. Key challenges to control L. monocytogenes include (i) development and implementation of food safety systems that prevent L. monocytogenes persistence in food‐associated built environments, (ii) minimizing L. monocytogenes contamination of raw material sources, (iii) implementation of effective root cause analysis procedures, (iv) minimizing L. monocytogenes growth in finished product, and (v) consumer education. [ABSTRACT FROM AUTHOR]

Aims Plant-based alternatives to meat and dairy products have become increasingly popular in the UK. Despite a public perception that they have a relatively low microbiological risk, outbreaks of illness have been linked with these foods. This study aimed to assess the microbiological safety and quality of vegan alternatives to dairy and meat products available in England. Methods and results Samples were collected between September 2022 and March 2023 from retail, production, and catering premises, and tested for a range of bacterial pathogens and hygiene indicators using standard procedures. A total of 937 samples were tested, of which 92% were of a satisfactory microbiological quality, 3% were borderline, and 5% were unsatisfactory. Those interpreted as unsatisfactory were due to elevated counts of Enterobacteriaceae and Escherichia coli (indicators of poor hygiene) rather than pathogenic microorganisms. Listeria monocytogenes was present in five samples of tofu, all from the same producer (all at counts of <100 CFU g–1), while other Listeria species were detected at counts of <20 CFU g–1 in two burgers and two 'vegan chicken' products. The majority of samples did not have pH and water activity values that would significantly contribute to preventing microbial growth: 62.4% had pH > 5.0 and 82.4% had A w > 0.94. Conclusions The majority of vegan products examined were of a satisfactory quality, but results demonstrate that microbiological control must be maintained using appropriate processing and storage temperatures, and application of a safe length of shelf life. [ABSTRACT FROM AUTHOR]

Listeria monocytogenes has been considered a significant food-borne pathogen in recent years, representing a major concern for public health and food safety. Consequently, the objective of the current investigation was to assess the prevalence of L. monocytogenes and other Listeria species in raw milk and certain cheese varieties. The presence of L. monocytogenes was screened in a total of 769 dairy samples, which were randomly collected from farms and dairy shops located in Cairo and Giza governorates. The samples included 212 raw milk samples from farms, 307 raw milk samples from dairy stores, and 250 cheese samples, including Kareish, Talaga, Feta, Processed, Ras, Gouda, and Cheddar (25 each). In total, twenty-two of the analyzed samples were contaminated with Listeria species, representing 2.86%. Additionally, there were only five positive samples for L. monocytogenes, accounting for 0.65%. The prevalence of Listeria spp. in the examined milk samples from dairy shops, farms, and cheese was 6.17%, 0.47%, and 0.8%, respectively. Depending on the outcomes of the biochemical identification assays, L. monocytogenes was detected in 1.30% and 0.47% of the examined milk samples from dairy shops and farms, respectively, while it couldn't be isolated from all cheese samples. L. monocytogenes isolates were confirmed positive using Polymerase Chain Reaction (PCR) targeting the hemolysin (hly A) gene. Furthermore, L.ivanovii and L.grayi were isolated from two samples of Kareish cheese representing 8%. In conclusion, the obtained results indicated a potential risk of milk and cheese contamination with Listeria. Thus, strict hygienic measures and frequent investigations must be applied to control such microorganisms. [ABSTRACT FROM AUTHOR]

Infective endocarditis (IE) is a disease associated with significant morbidity and mortality. It is more commonly caused by Gram-positive cocci, but Gram-positive bacilli may seldom cause the disease. Listeria monocytogenes is an aerobic Gram-positive coccobacillus and a foodborne and opportunistic pathogen most commonly causing gastrointestinal infections, even though bacteremia, sepsis, meningitis, and fetal infections may also occur. Listeria IE has rarely been described, with most reports being case reports or case series. Thus, the characteristics of this disease remain largely unknown. This systematic review aimed to present all published Listeria IE studies and describe their characteristics. A search of PubMed, Scopus, and the Cochrane Library for studies providing information on epidemiology, clinical findings, treatment, and outcome of Listeria IE cases was performed. A total of 54 studies containing data from 62 patients were included. Among all patients, 64.5% were male; the median age was 69 years. Among all patients, 54.8% had a history of a prosthetic valve. The aortic valve was the most commonly affected, followed by the mitral. Fever, heart failure, and embolic phenomena were the most commonly encountered clinical findings. The only isolated species was L. monocytogenes. Antimicrobial resistance was relatively low for aminopenicillins and aminoglycosides, the most commonly used antimicrobials for treating L. monocytogenes IE. Surgery was performed in 27.4% of patients. Mortality was 37.1%. Patients who survived were more likely to have had a prosthetic valve, to have necessitated transesophageal echocardiography for the diagnosis, to have mitral valve IE, and to have had surgical management; however, no factor was identified in a multivariate logistic regression model as an independent factor for overall mortality. [ABSTRACT FROM AUTHOR]

Theaflavin 3,3′‐digallate (TF3), a major polyphenolic component of black tea, exhibits antibacterial effects against many foodborne pathogens. However, the antibacterial mechanisms of TF3 against Listeria monocytogenes remain unclear. In this study, we investigated the effects of TF3 on viability, biofilm, and membrane function of L. monocytogenes by the conventional plating method, crystal violet staining, and microscopy using fluorescent dyes JC‐1 and Laurdan, respectively. It was found that TF3 showed excellent antibacterial activity against L. monocytogenes with the minimum inhibitory concentration of 62.5 mg/L. The viable count determined on TSA decreased by 3 log after the treatment for 2 h with TF3 at 62.5 mg/L. The viable count determined on TSA containing 4% NaCl decreased by more than 4 log after the treatment for 30 min with TF3 at the same concentration, suggesting that TF3 gave damage on the cells, enhancing the antibacterial action of 4% NaCl, but the damage was recoverable in the absence of 4% NaCl. To explore the antibacterial mechanisms of TF3, the effects of TF3 on membrane potential and membrane fluidity were investigated. TF3 reduced both membrane potential and fluidity of L. monocytogenes at 62.5 mg/L, suggesting that TF3 damaged the structural integrity of the cell membrane. TF3 reduced biofilm mass of mature biofilm of L. monocytogenes. Moreover, THEAFLAVIN TF40, a commercially available Camellia sinensis leaf extract containing TF3, reduced viable count of L. monocytogenes by 2 log on apple skin. These results suggest the potential of theaflavins as a natural anti‐Listeria disinfectant. [ABSTRACT FROM AUTHOR]

Stressed bacteria can enter a dormant viable but non-culturable (VBNC) state. VBNC pathogens pose an increased health risk as they are undetectable by growth-based techniques and can wake up back into a virulent state. Although widespread in bacteria, the mechanisms governing this phenotypic switch remain elusive. Here, we investigate the VBNC state transition in the human pathogen Listeria monocytogenes. We show that bacteria starved in mineral water become VBNC by converting into osmotically stable cell wall-deficient coccoid forms, a phenomenon that occurs in other Listeria species. We reveal the bacterial stress response regulator SigB and the autolysin NamA as major actors of VBNC state transition. We lastly show that VBNC Listeria revert to a walled and virulent state after passage in chicken embryos. Our study provides more detail on the VBNC state transition mechanisms, revealing wall-free bacteria naturally arising in aquatic environments as a potential survival strategy in hypoosmotic and oligotrophic conditions. Here, Carvalho et al show that Listeria starved in water shed their cell wall to form osmotically stable viable but non-culturable cells, that can revert back to walled, culturable and virulent forms. [ABSTRACT FROM AUTHOR]

Waterborne and foodborne illnesses caused by bacterial pathogens are major public health concerns, especially in developing countries like Nigeria—waterborne pathogens such as Escherichia coli, Salmonella spp. and Klebsiella spp. Contribute to the spread of health challenges, primarily due to poor sanitation, contaminated drinking water, and inadequate hygiene. Similarly, foodborne pathogens, including Escherichia coli, Listeria monocytogenes and Salmonella spp., are major causes of human illness, with animal-based foods often acting as transmission vectors. This review examines the current state of diagnosis, highlighting that most household water sources in Nigeria are vulnerable to contamination, with significant microbial loads exceeding WHO standards. It raises the need for effective interventions such as improved hygiene practices, water supply, sanitation and food safety management systems. Furthermore, this review discusses the impact of these pathogens on public health, noting that waterborne and foodborne diseases result in substantial mortality and economic burdens. Also, implementing good hygienic practices, Hazard Analysis Critical Control Point (HACCP) systems, and public health education are essential strategies for reducing the incidence of these diseases. This review concludes by calling for a collaborative effort among governments, policymakers, stakeholders, and researchers to develop and implement multifaceted interventions to combat these pervasive health threats. [ABSTRACT FROM AUTHOR]

The consumption of raw or smoked fish entails significant microbiological risks, including contamination by pathogens such as Listeria monocytogenes, which can cause severe foodborne illnesses. This study explores the preservative use of piscicolin CM22, a novel bacteriocin derived from the psychrotolerant strain Carnobacterium maltaromaticum CM22, in two types of edible coatings (EC): chitosan-based and fish gelatin-based. An initial in vitro characterization of the technological and antimicrobial properties of these ECs with and without bacteriocin was conducted. The efficacy of the edible coatings was subsequently evaluated through shelf life and challenge tests against L. monocytogenes in raw and smoked fish products. The results demonstrated significant antimicrobial activity, with the chitosan-based coating containing piscicolin CM22 being the most effective in reducing microbial counts and maintaining pH and color stability. Furthermore, in the challenge test studies, both ECs effectively controlled L. monocytogenes, showing significant reductions in bacterial counts compared to the controls in fresh tuna, salmon, and smoked salmon. The ECs containing piscicolin CM22 reduced Listeria counts by up to 4 log CFU/g in raw and smoked fish samples, with effective control in smoked salmon for up to 15 days at refrigeration temperature. While further research is required to fully assess their preservation potential, these findings strongly indicate that piscicolin CM22-functionalized edible coatings hold significant potential for improving the quality and safety of fish products. [ABSTRACT FROM AUTHOR]

Salmonella typhimurium and Listeria monocytogenes are relevant foodborne bacterial pathogens which may cause serious intoxications and infectious diseases in humans. In this study, a sensitive immunochromatographic analysis (ICA) for the simultaneous detection of these two pathogens was developed. For this, test strips containing two test zones with specific monoclonal antibodies (MAb) against lipopolysaccharides of S. typhimurium and L. monocytogenes and one control zone with secondary antibodies were designed, and the double-assay conditions were optimized to ensure high analytical parameters. Prussian blue nanoparticles (PBNPs) were used as nanozyme labels and were conjugated with specific MAbs to perform a sandwich format of the ICA. Peroxidase-mimic properties of PBNPs allowed for the catalytic amplification of the colorimetric signal on test strips, enhancing the assay sensitivity. The limits of detection (LODs) of Salmonella and Listeria cells were 2 × 102 and 7 × 103 cells/mL, respectively. LODs were 100-fold less than those achieved due to the ICA based on the traditional gold label. The developed double ICA was approbated for the detection of bacteria in cow milk samples, which were processed by simple dilution by buffer before the assay. For S. typhimurium and L. monocytogenes, the recoveries from milk were 86.3 ± 9.8 and 118.2 ± 10.5% and correlated well with those estimated by the enzyme-linked immunosorbent assay as a reference method. The proposed approach was characterized by high specificity: no cross-reactivity with other bacteria strains was observed. The assay satisfies the requirements for rapid tests: a full cycle from sample acquisition to result assessment in less than half an hour. The developed ICA has a high application potential for the multiplex detection of other foodborne pathogens. [ABSTRACT FROM AUTHOR]

Bacterial resistance and persistence in food environments are major concerns for the industry, which constantly seeks new strategies to reduce microbial contamination. Rhamnolipids (RL) biosurfactants are considered sustainable and green alternatives to synthetics; furthermore, they have demonstrated potential for controlling various foodborne pathogens. Food environments are typically exposed to diverse pH, solutes, temperatures, and water activity (aw) levels that may favor the survival of pathogens. Therefore, it is crucial to consider these factors in evaluating the performance of novel antimicrobials. Our study examined the influence of pH and sucrose on the antimicrobial activity of RL against both planktonic and biofilm of Listeria monocytogenes. We found that the presence of sucrose can enhance the antimicrobial effectiveness of RL against both planktonic and sessile bacteria. The addition of sugar particularly improved RL action at pH 6 and 7. Moreover, we observed that the type and size of RL self-assembly structures depend on the pH and sucrose concentration. These findings suggest potential for developing RL-based innovative methods to control L. monocytogenes in sugar-rich or -low aw foods and environments. [ABSTRACT FROM AUTHOR]

Listeriosis is a dangerous zoonosis caused by bacteria of the genus Listeria, with Listeria monocytogenes (LM) being the most pathogenic species. Listeria monocytogenes has been detected in various animal species and in humans, and its ability to evolve from an environmental saprophyte to a powerful intracellular pathogen is driven by the invasion mechanisms and virulence factors that enable cell invasion, replication and cell-to-cell spread. Key regulatory systems, including positive regulatory factor A (PrfA) and the stress-responsive sigma factor σB, control the expression of virulence genes and facilitate invasion of host cells. Listeriosis poses a significant threat to cattle, sheep and goat herds, leading to abortions, septicemia and meningoencephalitis, and ruminants are important reservoirs for Listeria, facilitating transmission to humans. Other Listeria species such as Listeria ivanovii and Listeria innocua can also cause disease in ruminants. Resilience of LM in food processing environments makes it an important foodborne pathogen that is frequently transmitted through contaminated meat and dairy products, with contamination often occurring along the food production chain. In humans, listeriosis primarily affects immunocompromised individuals, pregnant women and the elderly and leads to severe conditions, such as meningitis, septicemia and spontaneous abortion. Possible treatment requires antibiotics that penetrate the blood–brain barrier. Despite the relatively low antimicrobial resistance, multidrug-resistant LM strains have been detected in animals, food and the environment. Controlling and monitoring the disease at the herd level, along with adopting a One Health approach, are crucial to protect human and animal health and to minimize the potential negative impacts on the environment. [ABSTRACT FROM AUTHOR]

Abstract Consumption of fresh produce, such as leafy greens, is often encouraged as part of a healthy diet. Hence, indoor facilities for hydroponic production of leafy greens are increasingly being established. However, fresh produce entails a higher risk of microbial foodborne illnesses than processed foods. Listeria monocytogenes is a major source of fresh produce contamination and is among the leading causes of severe foodborne illnesses in the United States, with a 16% mortality rate. Tools for rapid monitoring are needed for pathogens such as L. monocytogenes to prevent outbreaks. In this manuscript, we have demonstrated the feasibility of a multi-aptamer approach for development of label-free aptasensors targeting L. monocytogenes in irrigation water for lettuce hydroponic production. We use screening studies with surface plasmon resonance to rationally develop mixtures of relevant aptamers for targeting L. monocytogenes. Based on this screening, multiple aptamers targeting extracellular structures on intact L. monocytogenes were tethered to platinum-modified laser inscribed graphene electrodes. This is the first report of a L. monocytogenes biosensor based on laser inscribed graphene. We show that mixing multiple aptamers with varying affinity improves the diagnostic performance over one aptamer alone in complex sample matrices (lettuce hydroponic water). Multi-aptamer biosensors showed high accuracy for L. monocytogenes and were at least three times more selective than Escherichia coli (Crooks, K12, O157:H7) with an accuracy of 85%. The limit of detection (10 CFU/10 mL) is based on data which were significantly different after calibration toward L. monocytogenes or E. coli (Crooks) and validated against gold standard molecular analysis (polymerase chain reaction). Rapid screening of pathogens is a global need to meet food safety and water quality regulations. This study shows the importance of sensors targeting more than one bacterial surface structure in complex samples relevant to the food-water nexus.

ABSTRACTThis study addresses the crucial protein Internalin A in the development of a possible vaccination against Listeria monocytogenes. A meticulous in silico strategy was used which included physiochemical analysis, epitope prediction, and molecular interaction studies. Computational techniques shed light on potential development of a vaccine candidate against Listeria, with a focus on the Internalin A protein along with its immune simulations. Insights into molecular interactions and physiochemical features aid in understanding of prospective Listeria vaccine candidates. Ultimately, the computational analysis in this study sets the groundwork for the creation of a possible vaccination against Listeria. The discovered epitopes and insights into molecular interactions are useful for experimental validation. In vitro and in vivo investigations should be conducted in the future to confirm the effectiveness of these anticipated epitopes. These findings advanced our understanding of vaccine design by providing insights into battling Listeria infections and perhaps guiding tactics for other diseases.

Form and function are often interdependent throughout biology. Inside cells, mitochondria have particularly attracted attention since both their morphology and functionality are altered under pathophysiological conditions. However, directly assessing their causal relationship has been beyond reach due to the limitations of manipulating mitochondrial morphology in a physiologically relevant manner. By engineering a bacterial actin regulator, ActA, we developed tools termed ActuAtor that inducibly trigger actin polymerization at arbitrary subcellular locations. The ActuAtor-mediated actin polymerization drives striking deformation and/or movement of target organelles, including mitochondria, Golgi apparatus, and nucleus. Notably, ActuAtor operation also disperses non-membrane-bound entities such as stress granules. We then implemented ActuAtor in functional assays, uncovering the physically fragmented mitochondria being slightly more susceptible to degradation, while none of the organelle functions tested are morphology dependent. The modular and genetically encoded features of ActuAtor should enable its application in studies of the form-function interplay in various intracellular contexts.

Listeria monocytogenes occurrence in food products has changed over the past twenty years. This dangerous foodborne pathogen has been historically associated with the consumption of soft cheeses (queso fresco, etc.) and ready-to-eat processed meats, but over the past two decades, there has been a notable increase in L. monocytogenes outbreaks in other food products. With the increasing frequency of recalls due to L. monocytogenes, and its frequent association with foods that are not normally considered a high risk for this pathogen, there is a need for understanding the factors that contribute to its survival and persistence in the food processing environments. Quaternary ammonium compounds (QACs) are the most common sanitizing agents used in the food processing environment and are essential in controlling the spread of L. monocytogenes. Of the seven generations of QACs have been developed over nearly 100 years, the first generation QAC, benzalkonium chloride (BAC) has been most widely used in various QAC formulations to kill bacteria, fungi, and viruses. Though QACs are used at very high concentrations of 150-200 ppm which is 50-100 times greater than the minimum inhibitory concentration (MIC), residual concentrations of 14 [micro]g/ml were found in the food processing environments. Therefore, the objective of this study is to investigate the survival of two strains of L. monocytogenes, Bug600 (serotype 1/2a) and ScottA (serotype 4b) in bactericidal concentrations of BAC in water, and their subsequent persistence in high or low nutrient conditions. Using a concentration range of BAC in 96 well plates, we first observed the real-time growth rate of L. monocytogenes strains possibly mimicking the sublethal BAC conditions that it may encounter in some environments. The MIC of BAC of L. monocytogenes varied for two strains which was 2 [micro]g/ml for Bug600 and 4 [micro]g/ml for ScottA. In a concentration-to-kill test, when 7 log CFU/ml of L. monocytogenes cells were exposed to the bactericidal concentrations of BAC at 10-14 [micro]g/ml, it resulted in the survivors of 1-3 log CFU/ml of Bug600 and 2-4 log CFU/ml of ScottA after 1 h, and none were detectable for both strains after 24 h. However, when such bactericidal concentrations were diluted to 1/2 or 1/4 with high or nutrient conditions which may possibly occur in the natural environments that resulted in exposure to sublethal BAC of 3.5-7 [micro]g/ml for 24 h, these aliquots yielded 1-2 log CFU/ml of L. monocytogenes. Under such sublethal BAC conditions, two distinct colony variants of L. monocytogenes (small and large colonies) were also observed on agar plates which were not published before. These colony variants were reconfirmed as L. monocytogenes and awaiting further characterization for BAC tolerance. These findings are useful in understanding the potential link between extensive QAC usage and occurrence of colony variants of L. monocytogenes cells which may create potential food safety risk. Keywords: Listeria monocytogenes, quaternary ammonium compounds, QAC, disinfectant tolerance, INTRODUCTION Listeria monocytogenes is a Gram-positive, rod-shaped bacterium that is the causative agent of the disease listeriosis, which is almost always acquired through the consumption of food contaminated with the [...]

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Foodborne diseases are a significant global public health concern due to their high prevalence, mortality, and economic losses. The aim of this study was to conduct a systematic review of identified foodborne pathogens and outbreaks in Iran over the past 23 years to provide an overview of the risk assessment and prevention approaches in the country. Using appropriate keywords and searching major databases, such as ScienceDirect, Scopus, PubMed, Google Scholar, and the Iranian Scientific Knowledge Database, we initially identified 4,740 articles. Finally, 328 articles were selected for evaluation. Among these articles, publications on Salmonella, Staphylococcus aureus, and Listeria were the most numerous. Poultry meat was found to be the main source of major foodborne pathogens in Iran, including Campylobacter (46.21%), Listeria monocytogenes (38.45), Salmonella (24.83%), and Yersinia enterocolitica (16.81%). Given the high prevalence of foodborne bacteria in Iranian foods, it is crucial to implement effective control measures to reduce the risk and burden of foodborne diseases. In particular, poultry meat, which poses a high risk for the occurrence of foodborne diseases in Iran, should be subjected to further risk assessment and control measures throughout the food chain.

The present study investigated the microbiological safety of the increasingly popular plant‐based milk alternatives. No (10/27) or only very low microbial counts (17/27) were detected in the tested products. These were mainly identified as spore formers via MALDI‐ToF‐MS. Three products contained Bacillus cereus group isolates, which were able to form considerable amounts of enterotoxins and exhibited cytotoxicity towards CaCo‐2 cells. Preliminary tests showed good growth of B. cereus, Listeria monocytogenes, and Salmonella enterica in all tested products (maximum bacterial counts: 5 × 1012 cfu/mL). These experiments also revealed strain‐, time‐, and temperature‐, but especially product‐specific enterotoxin production of B. cereus. In propagation and persistence tests according to DIN EN ISO 20976‐1:2019‐09, rapid bacterial proliferation was also detected in all products. B. cereus generally showed lower bacterial counts (106–107 cfu/mL) compared to L. monocytogenes and S. enterica (108–109 cfu/mL), but was detectable in a larger number of products over the test period of 6 weeks. pH values decreased (20/27) over time and visual and/or olfactory alterations (24/27) were observed. The present study provides information on the occurrence, growth and persistence of pathogenic bacteria in plant‐based drinking milk alternatives. It also points out that the accompanying changes in pH, odor, and appearance are not necessarily recognizable to the consumer. Practical Application: The present study contributes to the understanding of the microbial risk related to plant‐based drinking milk alternatives. It is crucial that the manufacturer ensures that particularly spore formers have been effectively eliminated from the products. Among them, especially toxin‐producing bacteria can pose a risk to the consumer, as these products promote proliferation and persistence of the bacteria. [ABSTRACT FROM AUTHOR]

Postconsumer household food residues can act as useful substrates for other industries, but transporting high‐moisture material corresponds to high fuel use and associated greenhouse gas production. Drying food residues at the household level reduces transportation weight, increases stability, and preserves the nutritional quality of recovered material. Mitigating foodborne microbiological safety risks is crucial to encourage the development of novel methods to rapidly dry and stabilize food residues. The objective of this study was to improve the prediction of bacterial pathogen inactivation under various thermal and drying processes in a synthetic mixture of residual food material (RFM). The log reduction rate was measured for Escherichia coli, Enterococcus faecium, and Listeria innocua (surrogates of common foodborne pathogens) in RFM under different moisture contents (12% and 25% by fresh weight) and temperatures (50, 55, and 60°C). Inactivation data were used to determine D‐ and z‐values and to fit a multiple regression model to predict log(D‐values) in response to temperature and moisture content. Across conditions, D‐values were measured to be 5.1–120, 4.6–123, and 32–545 min for E. coli, L. innocua, and E. faecium, respectively. Temperature sensitivities were significantly higher in lower moisture RFM for E. coli and L. innocua. Applying E. coli inactivation models during RFM at 55°C yielded inactivation rates that aligned with experimental values after 5 min (0.1 vs. 0–0.1 logs), 30 min (2.1 vs. 1.3–2.3 logs), and 90 min (7.2 vs. 7.1–8.9 logs). These results can inform the design of RFM drying and stabilization processes to promote pathogen inactivation and safety in downstream applications of dried material. [ABSTRACT FROM AUTHOR]

This study describes the discovery and characterization of raffinocyclicin, a novel plasmid-encoded circular bacteriocin, produced by the raw milk isolate Lactococcus raffinolactis APC 3967. This bacteriocin has a molecular mass of 6,092 Da and contains 61 amino acids with a three-amino acid leader peptide. It shows the highest identity to the circular bacteriocins bacicyclicin XIN-1 (42.62%), aureocyclicin 4185 (42.62%), and garvicin ML (41.53%). A broad inhibitory spectrum includes strains from Staphylococcus, Enterococcus, Streptococcus, Micrococcus, Lactobacillus, Leuconostoc, and Listeria, in addition to a pronounced inhibitory effect against Lactococcus and Clostridium. It displays low sensitivity to trypsin, most likely as a result of its circular nature. The raffinocyclicin gene cluster is composed of 10 genes: 6 core genes, genes encoding an accessory three-component ABC transporter (rafCDE), and a putative transcriptional regulator related to the MutR family. A lack of inhibitory activity in the cell-free supernatant combined with the pronounced activity of cell extracts suggests that the majority of raffinocyclicin is associated with the cell rather than being released to the extracellular environment. This is the first report of a bacteriocin produced by the L. raffinolactis species. [ABSTRACT FROM AUTHOR]

Objectives: Worldwide, but especially in emerging nations, concerns about food safety pose a serious obstacle to societal and economic progress. This research aimed to examine the prevalence of Listeria spp. in raw milk and dairy products in Burdur, as well as the presence of genes associated with biofilm formation and antibiotic resistance in the isolates. Methods: A total of 185 samples, including raw milk, curd, cream, butter, yogurt and cheese, were randomly collected in Burdur. The enrichment and isolation methods specified by the United States Department of Agriculture was used to identify Listeria species in milk and dairy product samples. Culture‐positive strains were identified as Listeria genus and as species by PCR. Antibiotic susceptibility of the isolates was evaluated against 14 antibiotics using the disc diffusion technique (EUCAST). Results: Of them, 2.2% (4/185) were positive for Listeria spp. Listeria species were isolated from cheese and yogurt samples. Two of them were Listeria innocua 1.1% (2/185), one was Listeria ivanovii 0.5% (1/185) and the other was Listeria welshimeri 0.5% (1/185). As a result of multiplex PCR of the biofilm genotypic marker luxS and flaA genes, the flaA gene was detected in three of four isolates, the luxS gene was detected in one isolate, and these two genes were not found in one isolate. Although all isolates were resistant to gentamicin and rifampicin, they also showed multidrug resistance. Conclusion: This study revealed that the diversity of prevalence of Listeria spp. in Burdur requires microbial risk assessment in the milk and dairy products value chain and the need to focus on the problem of multiple antibiotic resistance. [ABSTRACT FROM AUTHOR]

The aim of this work was to assess the microbiological safety and quality of horsemeat. A total of 19 fresh horsemeat samples were analysed. Mesophile counts were 4.89 ± 1.08 log CFU/g, and Enterobacteriaceae, Staphylococcus spp., and enterococci were only isolated from 36.84%, 21.05%, and 15.79% of the samples, respectively. Neither Staphylococcus aureus nor Escherichia coli were found in any sample. Listeria spp. and Listeria monocytogenes were detected in 31.58% and 21.05% of the samples, respectively. Campylobacter jejuni was not detected in any sample. The dominant bacteria were lactic acid bacteria. Seven different Staphylococcus spp. were identified, the most common being S. delphini, S. saprophyticus, and S. warneri. S. delphini showed resistance against mupirocin and cefoxitin. All the L. monocytogenes strains showed resistance against ampicillin, cefotaxime, and oxacillin. Multi-resistant Yersinia enterocolitica, Stenotrophomonas maltophilia, and Vagococcus. fluvialis strains were found, with resistance to 11, 7, and 8 antibiotics, respectively, causing significant concern. Therefore, specific actions should be taken to decrease the contamination of horsemeat. [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]

This study aimed to investigate the probiogenomic features of artisanal bacteriocin-producing Enterococcus faecium BGPAS1-3 and the use of the improved pMALc5HisEk expression vector for overexpressing class II bacteriocins and the application of purified bacteriocin 31 in a milk model as a preservative against L. monocytogenes. The BGPAS1-3 strain was isolated from traditional fresh soft cheese manufactured in households on a small scale in rural locations surrounding Pale Mountain City in Bosnia and Herzegovina. The whole-genome sequencing approach and bioinformatics analyses revealed that the strain BGPAS1-3 was non-pathogenic to humans. The presence of bacteriocin operons suggested the ability of the isolate to suppress the growth of pathogens. Coding regions for three maturated bacteriocins (bacteriocin 31, bacteriocin 32, and enterocin P) produced by BGPAS1-3 were amplified and expressed in Escherichia coli ER2523 using the pMALc5HisEk system. All three bacteriocins were successfully overexpressed and purified after enterokinase cleavage but showed different antimicrobial activity. Bacteriocin 31 showed significantly stronger antimicrobial activity compared with bacteriocin 32. It was the only one that proved to be suitable for use as a food preservative against L. monocytogenes in a milk model. [ABSTRACT FROM AUTHOR]

The persistence of Listeria monocytogenes biofilms on equipment surfaces poses a significant risk of cross-contamination, necessitating effective surface decontamination strategies. This study assessed the effectiveness of hurdle treatments combining peroxyacetic acid (PAA) and saturated steam against 7-day-old L. innocua (a non-pathogenic surrogate for L. monocytogenes) biofilms on stainless steel (SS), polyester (PET), and rubber surfaces. Results demonstrated >6 log10 CFU/coupon L. innocua reductions on SS and PET surfaces after PAA (40 ppm, 1 min) followed by steam treatment (100 °C, 6 s). On rubber surfaces, PAA (80 ppm, 1 min) followed by steam treatment (100 °C, 6 s) resulted in ~5 log10 CFU/coupon L. innocua reduction. The presence of apple juice soil reduced the efficacy of hurdle treatments, with PAA (40 ppm, 1 min) and steam exposure (6 s) resulting in 5.6, 5.8, and 4.2 log10 CFU/coupon reductions of L. innocua on SS, PET, and rubber, respectively. The efficacy of this antimicrobial combination was further reduced by surface defects, especially in the presence of organic matter. Nevertheless, the treatment still achieved >5 log10 CFU/coupon reductions of L. innocua on worn SS and PET soiled with apple juice and ~4.5 log10 CFU/coupon reduction on worn, soiled rubber surfaces. These findings highlight that PAA treatments followed by a brief steam exposure are effective strategies for controlling Listeria on food-contact surfaces. [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]

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.)

Background: The various species of the Listeria genus are frequently isolated from food and drink products. They are classified into two categories according to their pathogenicity. Pathogenic species are frequently incriminated in infections of the elderly, immunocompromised and pregnant women. The Listeria grayi species is rarely isolated as a pathogen in human pathologies. We report a case of L. grayi meningitis in a polypathological patient. Antimicrobial susceptibility testing revealed resistance to ampicillin and susceptibility to Meropenem. Therapeutic failure was recorded despite in vitro sensitivity. Methods: Conventional biochemical test and Api Listeria gallery was used for identification of the isolate. Results: We report a case of L. grayi meningitis in a polypathological patient. Antimicrobial susceptibility testing revealed resistance to ampicillin and susceptibility to Meropenem. Therapeutic failure was recorded despite in vitro sensitivity. Conclusion: Given its infrequent reporting, Listeria grayi meningitis warrants consideration, especially in elderly patients with multiple pathologies. [ABSTRACT FROM AUTHOR]

Listeriosis is a foodborne infection caused by Listeria monocytogenes. Three main forms of listeriosis are well characterised, but little is known about L monocytogenes -associated spontaneous bacterial peritonitis. We used data from the French national surveillance of listeriosis to perform a nationwide retrospective study. All patients with L monocytogenes isolated by culture from a peritoneal fluid sample in France between April 1, 1993, and Dec 31, 2022, were included. Individuals for whom bacterial peritonitis was not confirmed and those who also had another type of invasive listeriosis were excluded. A standardised checklist was used to collect demographic, clinical, and biological data as well as antibiotic treatment and follow-up data. The primary outcome was to determine the characteristics of L monocytogenes -associated spontaneous bacterial peritonitis. We did descriptive analyses and assessed risk factors for 1-month mortality using an exploratory multivariable Cox model analysis. Among the 8768 L monocytogenes cases reported, 208 (2%) were patients with L monocytogenes -associated spontaneous bacterial peritonitis. Mean age was 65 years (SD 13), 50 (24%) of 208 patients were female, and 158 (76%) were male (no data on race or ethnicity were available). 200 (98%) of 205 patients with L monocytogenes -associated spontaneous bacterial peritonitis with available data had immunosuppressive comorbidities, including cirrhosis (148 [74%] of 201 with available data), ongoing alcoholism (58 [62%] of 94), and ongoing neoplasia (60 [31%] of 195). Causes of ascites included cirrhosis (146 [70%] of 208), ongoing neoplasia (26 [13%]), end-stage heart failure (13 [6%]), and peritoneal dialysis (11 [5%]). Among those with available data, presentation was pauci-symptomatic and non-specific; only 67 (50%) of 135 patients presented with fever, 49 (37%) of 132 with abdominal pain, and 27 (21%) of 129 with diarrhoea. 61 (29%) of 208 patients were dead at 1 month, 92 (44%) were dead at 3 months, and 109 (52%) were dead at 6 months after diagnosis. Ongoing neoplasia (hazard ratio 2·42 [95% CI 1·05–5·56]; p=0·039), septic shock (8·03 [2·66–24·02]; p=0·0021), and high blood leukocyte count (1·05 [1·00–1·09]; p=0·045) were independently associated with 1-month mortality. Despite the non-specific and mild presentation of L monocytogenes -associated spontaneous bacterial peritonitis, the outcome is poor and similar to that of neurolisteriosis, and so identification of L monocytogenes in ascitic fluid samples requires urgent parenteral amoxicillin-based treatment to avoid a fatal outcome. Institut Pasteur, Inserm, and French Public Health Agency. For the French translation of the abstract see Supplementary Materials section. [ABSTRACT FROM AUTHOR]

The current study was conducted to determine the occurrence of Listeria species in live chicken and some chicken products (fillets, burger and luncheon). In addition, determine the antibiogram profile of Listeria strains and detection of some virulence genes of Listeria monocytogenes which recovered from the examined samples. The study included 100 samples including cloacal swabs from broiler chicken (n =25) from 5 different broiler chicken farms beside as well as chicken products (25 samples each of chicken fillets, burger and luncheon) that were randomly purchased from supermarkets. Isolation and identification of Listeria was performed according to the standard protocol provided by ISO (2017). It was recorded that the recovery rate of Listeria species from the examined samples was 24, 20, 8 and 16%, in cloacal swabs, chicken fillets, burger and luncheon, respectively with an overall incidence of 17%. In addition, biochemical identification of the recovered Listeria isolates revealed the presence of L. monocytogenes, L. innocua, L. ivanovii, L. seeligeri and L. grayi with various rates where L. monocytogenes scored the highest rate 29.4% (5 isolates). Antimicrobial susceptibility of Listeria strains (n=17) clarified that the highest antibiotic resistance was recorded when using streptomycin (82.4%) followed by Neomycin (76.5%) then Doxycycline and Cefotaxime (52.9%) while the lowest resistance was noticed when using Amikacin (11.8%) then Ciprofloxacin (35.3%). Finally, molecular detection of virulence genes in the identified L. monocytogenesstrains (n= 5) clarified the detection of iap and actA genes in the five isolates while hylA gene was detected in three isolates only. At the end, results obtained by this study emphasize a significant occurrence of resistant Listeria in chicken and chicken products including processed animal-originated foods commonly purchased by the public in including; chicken fillets, burger and luncheon. Seriously, the presence of such resistant bacteria endangers human health by making routine antibiotic courses useless in the treatment of such infections. Finally, data proved that retail foods of animal origin pose a risk to human health so it is advisable to examine chicken and chicken products routinely for presence of antibiotic resistant bacteria as well as antibiotic residues. [ABSTRACT FROM AUTHOR]

Copyright of Medicina (Buenos Aires) is the property of Medicina (Buenos Aires) 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.)

Foodborne diseases are a significant global public health concern due to their high prevalence, mortality, and economic losses. The aim of this study was to conduct a systematic review of identified foodborne pathogens and outbreaks in Iran over the past 23 years to provide an overview of the risk assessment and prevention approaches in the country. Using appropriate keywords and searching major databases, such as ScienceDirect, Scopus, PubMed, Google Scholar, and the Iranian Scientific Knowledge Database, we initially identified 4,740 articles. Finally, 328 articles were selected for evaluation. Among these articles, publications on Salmonella, Staphylococcus aureus, and Listeria were the most numerous. Poultry meat was found to be the main source of major foodborne pathogens in Iran, including Campylobacter (46.21%), Listeria monocytogenes (38.45), Salmonella (24.83%), and Yersinia enterocolitica (16.81%). Given the high prevalence of foodborne bacteria in Iranian foods, it is crucial to implement effective control measures to reduce the risk and burden of foodborne diseases. In particular, poultry meat, which poses a high risk for the occurrence of foodborne diseases in Iran, should be subjected to further risk assessment and control measures throughout the food chain. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study was to create and validate a food safety survey for older adults. Design/methodology/approach: The survey was designed to measure food handling and consumption behaviors related to high-risk foods. Survey questions were also designed to capture behavioral constructs from the health belief model (HBM). The first administration of the survey was completed by 349 participants, 55 years of age and older. Exploratory factor analysis was used to assess construct validity, and Cronbach's alpha was used to assess the internal consistency of the subscales generated through factor analysis. Two weeks after the first administration, the survey was completed a second time by 149 participants from the original sample. The intraclass correlation coefficient was used to evaluate test-retest reliability. Findings: Exploratory factor analysis yielded four factors related to the HBM (perceived susceptibility, perceived severity, perceived barriers and cues to action) and three factors related to food handling practices (handling of processed meats, food thermometer use with poultry and washing or rinsing poultry). Inclusion in a factor meant that the related questions measured the same underlying construct. Cronbach's alpha for these factors ranged from 0.63 to 0.77. Modification of the survey following validation resulted in the development of a 44-question instrument that can be used with older adults. Practical implications: This survey will next be administered to a representative sample of older adults to assess relationships between HBM constructs and food handling behaviors and is available for use by other researchers. Originality/value: There are few validated tools that can be used with older adults to evaluate food safety risks. [ABSTRACT FROM AUTHOR]

The effect of plasma-activated water (PAW) generated with a dielectric barrier discharge diffusor (DBDD) system on microbial load and organoleptic quality of cucamelons was investigated and compared to the established sanitizer, sodium hypochlorite (NaOCl). Pathogenic serotypes of Escherichia coli, Salmonella enterica, and Listeria monocytogenes were inoculated onto the surface of cucamelons (6.5 log CFU g-1) and into the wash water (6 log CFU mL-1). PAW treatment involved 2 min in situ with water activated at 1,500 Hz and 120 V and air as the feed gas; NaOCl treatment was a wash with 100 ppm total chlorine; control treatment was a wash with tap water. PAW treatment produced a 3-log CFU g-1 reduction of pathogens on the cucamelon surface without negatively impacting quality or shelf life. NaOCl treatment reduced the pathogenic bacteria on the cucamelon surface by 3 to 4 log CFU g-1; however, this treatment also reduced fruit shelf life and quality. Both systems reduced 6-log CFU mL-1 pathogens in the wash water to below detectable limits. The critical role of superoxide anion radical (·O2-) in the antimicrobial power of DBDD-PAW was demonstrated through a Tiron scavenger assay, and chemistry modeling confirmed that ·O2- generation readily occurs in DBDD-PAW generated with the employed settings. Modeling of the physical forces produced during plasma treatment showed that bacteria likely experience strong local electric fields and polarization. We hypothesize that these physical effects synergize with reactive chemical species to produce the acute antimicrobial activity seen with the in situ PAW system. IMPORTANCE Plasma-activated water (PAW) is an emerging sanitizer in the fresh food industry, where food safety must be achieved without a thermal kill step. Here, we demonstrate PAW generated in situ to be a competitive sanitizer technology, providing a significant reduction of pathogenic and spoilage microorganisms while maintaining the quality and shelf life of the produce item. Our experimental results are supported by modeling of the plasma chemistry and applied physical forces, which show that the system can generate highly reactive ·O2- and strong electric fields that combine to produce potent antimicrobial power. In situ PAW has promise in industrial applications as it requires only low power (12 W), tap water, and air. Moreover, it does not produce toxic by-products or hazardous effluent waste, making it a sustainable solution for fresh food safety.

Recent listeriosis and salmonellosis outbreaks in the U.S. have been associated with consumption of specialty mushrooms, including enoki and wood ear. These mushrooms are commonly consumed in Asian dishes such as ramen noodle soup and are often used as raw garnishes. No current guidelines exist for the serving temperature of ramen broth in restaurants for safety. The objective of this study was to evaluate the inactivation of both Listeria monocytogenes and Salmonella enterica on enoki and wood ear mushrooms based on the ramen broth temperature. Fresh mushrooms were chopped into pieces, inoculated with four-strain cocktails of L. monocytogenes or S. enterica, dried at ambient conditions for 30 min, then placed into bowls. Ramen broth (i.e., pork bone broth, Tonkotsu) at initial temperatures of 60, 70, 80, 90, or 100°C was poured over the mushrooms, submerging them. The bowls were held at ambient conditions while the broth temperatures were monitored, and mushrooms were sampled at intervals up to 60 min. From the broth temperature profiles and the pathogen log reductions of each mushroom type, the non-isothermal log-linear model was used to obtain maximum inactivation rates. The maximum pathogen inactivation on both mushroom types occurred within the first 5 min, regardless of the initial broth temperature. Broth temperatures of 60 and 70°C resulted in reductions of only 1–3 log CFU/g (inactivation rates of 0.33–4.72 log CFU/g/min), while reductions of 4–5 log CFU/g (inactivation rates of 8.74–17.21 log CFU/g/min) were observed with 80°C broth. The use of 90 and 100°C broth resulted in higher reductions of >5 log CFU/g (inactivation rates of 8.56–28.08 log CFU/g/min). In all cases, surviving populations, often >2.4 log CFU/g, were observed after 60 min. The results from this study can assist in the development of guidelines on the safe serving temperature of ramen soup at restaurants.

This article evaluates and summarizes Food and Beverages (F&B) recalls managed or mandated by the U.S. Food and Drug Administration (FDA) over the past 20 years: the database includes over 35,000 recalls. For recall classification purposes, the causes were separated into 2 overall categories consisting of product contaminants or processing issues. The product contaminants category was further separated into 5 groups: allergens, biological contaminants, chemical contaminants, foreign objects, and undeclared food colors. The processing issues category was separated into 6 groups: cGMP issues, HACCP issues, manufacturing issues, mislabeling or misbranding, refrigeration issues, and under-processing. Product contaminants accounted for 91% of the F&B recalls, while processing issues accounted for the remaining 9%. Two groups accounted for about 76% of the recalls: biological contamination and allergens. The FDA classifies recalls by the potential severity of the health impact. Over half of the F&B recalls were Class I recalls, and biological contamination and allergens accounted for 96% of those recalls. Listeria monocytogenes was the largest cause of all of the recalls accounting for 7,844 recalls: 22% of the total recalls and 45% of the biological contamination recalls. Salmonella serovars were responsible for 6,597 recalls, including 18% of the total recalls and 38% of the biological recalls. Listeria and Salmonella serovars together resulted in 40% of all of the F&B recalls.

This study investigated the impact of irrigation sources (pond, stream, and well) in high tunnel-dripline systems on the dissemination and persistence of foodborne pathogens (Escherichia coli O157, Listeria monocytogenes, Campylobacter spp., Salmonella spp., and the ‘big six’ Shiga toxin-producing E. coli [STEC]) in small specialty crop farms (SSCFs). Ten SSCF-growing fresh tomatoes using high tunnel-dripline systems were sampled between January and November 2022. Selective enrichment combined with PCR was used to detect the selected foodborne pathogens in the irrigation water (n = 240), soil (n = 240), and tomato fruits (n = 120). Overall, surface-originated water sources (streams and ponds) having potential contact with farm animals or wildlife harbored higher pathogen burden (cumulative prevalence of all the pathogens) compared to subsurface water source (well and underground spring water). STEC O26, O45, and O103 were detected at high frequency (up to 88% per SSCF per time point) in the water source and associated dripline irrigation system of 4/6 SSCFs using stream and pond water. Other foodborne pathogens (especially, L. monocytogenes) were detected in 6/10 SSCFs, but at low frequency (

Study’s Novelty/Excerpt • This study investigates the phenotypic and genotypic antibiotic resistance of Listeria monocytogenes isolated from food samples in Yola, revealing significant multi-drug resistance (MDR) in 72.72% of the isolates. • The research highlights alarming resistance rates to commonly used antibiotics, including 100% resistance to ceftriaxone and the presence of resistance genes blaCTX-M, blaTEM, and sul1 in all MDR isolates. • These findings underscore a potential public health crisis, indicating that future outbreaks of L. monocytogenes in the area may be difficult to control with the current antibiotic treatments. Full Abstract Listeria monocytogenes is an opportunistic bacterial pathogen implicated in several lethal illness outbreaks. Future outbreaks may be more complicated to manage because of the surfacing of antibiotic resistance among L. monocytogenes strains in food products. Accordingly, this study aimed to determine the phenotypic and genotypic antibiotic resistance of L. monocytogenes previously isolated from different food samples in Yola. Antibiotic resistance of L. monocytogenes was determined via disc diffusion and polymerase chain reaction (PCR). Exactly 72.72% of the isolates were multi-drug resistant (MDR) with high resistance to Beta-Lactams and sulfonamides. Percentage resistance to ceftriaxone, ampicillin, augmentin, cefuroxime, and sulfamethoxazole/trimethoprim were 100%, 72.7%, 64.0%, 64.0%, and 54.5% respectively. The MDR isolates were subjected to PCR, and antibiotic resistance genes blaCTX-M, 7(100%), blaTEM, 7(100%), and sul1 7(100%) were detected in (72.72%) i.e. all the MDR isolates. L. monocytogenes isolates from food samples in this study area exhibited phenotypic and genotypic resistance to multiple antibiotics. This implies that future outbreaks of L. monocytogenes in the study area may be complicated to manage using the commonly used antibiotics tested in this study, representing a major public health concern.

Background: Food-borne pathogen Listeria monocytogenes is abundantly present in nature and accountable for sporadic and epidemic cases of listeriosis in humans. The objective of this study was to screen common food sources for L. monocytogenes using biochemical and molecular methods to detect and characterise its toxin genes as well as for biofilm formation. Methods: A total of 92 samples, comprising dairy and street food products, were randomly collected from various sources for this investigation. The collected samples were processed for biochemical and molecular methods to detect L. monocytogenes. Additionally, virulence factors associated genes, antibiogram profiles and biofilm formation related assays were determined. Results: L. monocytogenes presence was confirmed using molecular detection methods targeting prs and lmo1030 genes, along with MALDI-TOF MS. Following 16 S rRNA sequencing, the identified Listeria species were further categorised into two groups. L. monocytogenes was detected in two (2.17%) food samples tested (L-23 and L-74). Multiplex PCR indicated the presence of seven virulence-related genes in L. monocytogenes isolates, i.e., inlA, inlB, prfA, iap, actA, plcB, and hlyA. In addition, 17 antibiotics were tested, whereby two isolates showed resistance to clindamycin and azithromycin, while one isolate (L-74) was also resistant to nalidixic acid, co-trimoxazole, ampicillin, norfloxacin, and cefotaxime. L-23 and L-74 isolates showed biofilm formation, especially at pH 8.6 and 37°C. Conclusions: Besides the demonstration of the presence of L. monocytogenes in some dairy and street food products, this study underscores the need to increase the standards of hygiene on the one hand and the importance of the surveillance of food-borne pathogens on the other.

As the interest in plant-based alternative food products has increased significantly in the last years, it is also important to investigate these products regarding microbiological aspects. The aim of this study was to assess the microbiological quality and the occurrence of selected foodborne pathogens in plant-based meat alternative products (PBMA) collected at retail level in Switzerland. A total of 100 PBMA (84 vegan and 16 vegetarian products) was analyzed qualitatively for the presence of Salmonella, Listeria monocytogenes and quantitatively for Staphylococcus aureus, Bacillus cereus group members, Enterobacteriaceae, and the total viable count. Furthermore, pH measurements were carried out and the aw-value was determined. Isolates were further analyzed with Whole Genome Sequencing. The total viable count before the expiration date was between

Proper activation of cytotoxic T cells via the T cell receptor and the costimulatory receptor CD28 is essential for adaptive immunity against viruses, intracellular bacteria, and cancers. Through biochemical analysis of RNA:protein interactions, we uncovered a non-coding RNA circuit regulating activation and differentiation of cytotoxic T cells composed of the long non-coding RNA Malat1 (Metastasis Associated Lung Adenocarcinoma Transcript 1) and the microRNA family miR-15/16. miR-15/16 is a widely and highly expressed tumor suppressor miRNA family important for cell proliferation and survival. miR-15/16 play important roles in T cell responses to viral infection, including the regulation of antigen-specific T cell expansion and memory. Comparative Argonaute-2 high-throughput sequencing of crosslinking immunoprecipitation (AHC) combined with gene expression profiling in normal and miR-15/16-deficient mouse T cells revealed a large network of hundreds of direct miR-15/16 target mRNAs, many with functional relevance for T cell activation, survival and memory formation. Among these targets, Malat1 contained the largest absolute magnitude miR-15/16-dependent AHC peak. This binding site was among the strongest lncRNA:miRNA interactions detected in the T cell transcriptome. We used CRISPR targeting with homology directed repair to generate mice with a 5-nucleotide mutation in the miR-15/16-binding site in Malat1. This mutation interrupted Malat1:miR-15/16 interaction, and enhanced the repression of other miR-15/16 target genes, including CD28. Interrupting Malat1 interaction with miR-15/16 decreased cytotoxic T cell activation, including the expression of interleukin 2 (IL-2) and a broader CD28-responsive gene program. Accordingly, Malat1 mutation diminished memory cell persistence in mice following LCMV Armstrong and Listeria monocytogenes infection. This study marks a significant advance in the study of long non-coding RNAs in the immune system by ascribing cell-intrinsic, sequence-specific in vivo function to Malat1. These findings have implications for T cell-mediated autoimmune diseases, antiviral and anti-tumor immunity, as well as lung adenocarcinoma and other malignancies where Malat1 is overexpressed.

Listeria monocytogenes causes listeriosis, an infectious and potentially fatal disease of animals and humans. A diverse network of transcriptional regulators, including LysR-type catabolite control protein C (CcpC), is critical for the survival of L. monocytogenes and its ability to transition into the host environment. In this study, we explored the physiological and genetic consequences of deleting ccpC and the effects of such deletion on the ability of L. monocytogenes to cause disease. We found that ccpC deletion did not impact hemolytic activity, whereas it resulted in significant reductions in phospholipase activities. Western blotting revealed that the ΔccpC strain produced significantly reduced levels of the cholesterol-dependent cytolysin LLO relative to the wildtype F2365 strain. However, the ΔccpC mutant displayed no significant intracellular growth defect in macrophages. Furthermore, ΔccpC strain exhibited reduction in plaque numbers in fibroblasts compared to F2365, but plaque size was not significantly affected by ccpC deletion. In a murine model system, the ΔccpC strain exhibited a significantly reduced bacterial burden in the liver and spleen compared to the wildtype F2365 strain. Interestingly, the deletion of this gene also enhanced the survival of L. monocytogenes under conditions of H2O2-induced oxidative stress. Transcriptomic analyses performed under H2O2- induced oxidative stress conditions revealed that DNA repair, cellular responses to DNA damage and stress, metalloregulatory proteins, and genes involved in the biosynthesis of peptidoglycan and teichoic acids were significantly induced in the ccpC deletion strain relative to F2365. In contrast, genes encoding internalin, 1-phosphatidylinositol phosphodiesterase, and genes associated with sugarspecific phosphotransferase system components, porphyrin, branched-chain amino acids, and pentose phosphate pathway were significantly downregulated in the ccpC deletion strain relative to F2365. This finding highlights CcpC as a key factor that regulates L. monocytogenes physiology and responses to oxidative stress by controlling the expression of important metabolic pathways. [ABSTRACT FROM AUTHOR]