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BackgroundListeria monocytogenes is a Gram-positive bacterium transmitted to humans through contaminated food, water, and animal faeces, posing a public health risk. Listeria monocytogenes is difficult to isolate and is not sensitive to first-line treatment with broad-spectrum cephalosporins for bacterial meningitis. Listeria meningitis is rare but can progress rapidly and may be accompanied by serious complications (hydrocephalus, ventricular inflammation, cerebral palsy, and brain abscess) and a high mortality rate.Case presentationIt is a retrospective analysis of the clinical characteristics and treatment of a rare case of Listeria monocytogenes infection. Using laboratory indicators such as white blood cells (WBC), C-reactive protein (CRP), and procalcitonin (PCT), three detection methods (cerebrospinal fluid/blood culture), Targeted gene sequencing technology (tNGS), and Metagenomic next-generation sequencing technology (mNGS) combined with clinical manifestations of patients, analyze the use plan and prognosis of antibiotics in patients. The patient in this case initially had neurological symptoms such as fever, headache, unclear consciousness, and vomiting; laboratory indicators include elevated WBC, CRP, and PCT. Listeria monocytogenes was cultured in both the patient’s cerebrospinal fluid and blood samples. After treatment with penicillin and meropenem, the patient recovered and was discharged without any sequelae.ConclusionDue to the rarity of Listeria monocytogenes, there may be deficiencies and difficulties in clinical differential diagnosis, making it difficult to achieve targeted antibiotic treatment. Therefore, accurate identification of Listeria monocytogenes and relevant laboratory inflammation indicator testing, combined with traditional culture methods and NGS testing, through empirical coverage of Listeria monocytogenes, targeted antibiotic treatment ultimately impacts clinical outcomes significantly.

Listeria monocytogenes is a foodborne pathogen that lives in nature as a saprophyte. Two of the three most common serotypes that cause foodborne listeriosis are 1/2a and 4b. Within serotype 4b, there is a variant called 4bv-1. In the last decade, several produce-related outbreaks (linked to leafy salad, caramel apples, and stone fruit) were linked to 4bv-1 strains, specifically those of Sequence Type 382. This study assessed the fitness of ST 382 strains on lettuce leaf sections to determine if they are more fit on produce than strains of other serotypes. Strains of serotypes 1/2a, 4b, and ST 382 were inoculated as mixtures onto lettuce and incubated at 4 °C for 7 days or 25 °C for 24 h. Thirty L. monocytogenes colonies resulting from the growth on each lettuce piece were characterized for serotype by multiplex PCR, and the percentages of each serotype recovered were compared. In the individual mixtures with three strains, none of the ST 382 strains showed better fitness for growth on lettuce at either 4 °C or 25 °C. Overall, ST 382 strains showed better recovery from lettuce sections grown at 4 °C than at 25 °C. Statistical analysis of the recovery of twelve strains tested in competition experiments indicated that ST 382 strains were less fit for lettuce growth when competing against the other serotypes. The data indicate that ST 382 strains do not have a competitive fitness advantage on cut lettuce sections.

Listeria monocytogenes and Cronobacter sakazakii are two important foodborne bacterial pathogens. Bacterial endophytes, which reside in plant cells, can produce antimicrobial compounds to protect the host organism or inhibit pathogens. This study investigated the bacterial community of tropical fruits for their potential to inactivate L. monocytogenes or C. sakazakii in cantaloupe and liquid infant formula, respectively. Tropical fruits including papayas, dragon fruits, and sugar apples, were sourced from several countries. Candidate bacterial endophytes were recovered from these tropical fruits using blood agar and Reasoner’s 2A (R2A) agar and tested for potential inhibition against L. monocytogenes and C. sakazakii. A total of 196 bacterial endophytes were recovered from papayas, dragon fruits, and sugar apples. Among these bacterial endophytes, 33 (16.8%) and 13 (6.6%) of them demonstrated an inhibition zone against L. monocytogenes and C. sakazakii, respectively. The inhibitory strains were identified using 16S rRNA sequencing as Bacillus spp., Enterobacter spp., Klebsiella spp., Microbacterium spp., Pantoea spp., and Pseudomonas spp. A cocktail of Pantoea spp. and Enterobacter spp. was used in challenge studies with cantaloupe and significantly reduced the number of L. monocytogenes by approximately 2.5 log10 CFU/g. In addition, P. stewartii demonstrated antagonistic activity against C. sakazakii in liquid infant formula, i.e., it significantly decreased the number of C. sakazakii by at least 1 log10 CFU/mL. Thus, the use of bacterial endophytes recovered from fruits and vegetables could be a promising area of research. Their use as potential biocontrol agents to control bacterial pathogens in ready-to-eat foods warrants further investigation.

We traced back a nationwide outbreak of human listeriosis in Switzerland to a persisting production line contamination of a factory producing baker's yeast with Listeria monocytogenes serotype 1/2a sequence type 3141. We used whole-genome sequencing to match clinical isolates to isolates from product samples. [ABSTRACT FROM AUTHOR]

We describe the case of an immunocompromised patient in whom a severe infection with meningoencephalitis was detected. Listeria monocytogenes was the pathogen. Invasive listeriosis is a rare infectious disease that is notifiable in Switzerland and can be lethal. The most common route of contamination for the ubiquitous bacteria is the consumption of foods such as dairy products, raw vegetables or meat. Antibiotic treatment can lead to a complete cure. [ABSTRACT FROM AUTHOR]

Food irradiation can reduce foodborne illnesses but is rarely used in the United States. We determined whether outbreaks related to Campylobacter, Salmonella, Escherichia coli, and Listeria monocytogenes were linked to irradiation-eligible foods. Of 482 outbreaks, 155 (32.2%) were linked to an irradiation-eligible food, none of which were known to be irradiated.

ObjectiveTo analyze Salmonella， Listeria monocytogenes and diarrheagenic Escherichia coli in vegetables in Yunnan Province， the antibiotic susceptibilities and whole genome sequencing （WGS） were determined to characterize the antimicrobial resistance and virulence genotypes of these isolates.MethodsSalmonella， Listeria monocytogenes and diarrheagenic Escherichia coli of 180 samples of vegetables that can be eaten raw were isolated and identified by National food safety standard Food GB 4789.4—2016， GB 4789.30—2016， GB 4789.6—2016. The susceptibilities of isolates were determined by broth microdilution. The whole genome of isolates was then sequenced. The corresponding genomes were assembled and further analysis was carried out using appropriate bioinformatics pipelines.ResultsTwelve of 180 samples of vegetables that can be eaten raw had isolates of pathogenic bacteria from Lactuca sativa， cilantro and Houttuynia cordata Thunb and so on. A total of 13 isolates were detected， including 7 strains of Salmonella which contain 7 serotypes， 4 strains of multi-drug resistance （drug resistance phenotype and drug resistance genes were well correlated）， 5 strains carrying IncHI and IncF plasmids related to multi-drug resistance， 4 strains of Listeria monocytogenes which contain 1 strain of multi-drug resistance and 2 strains carrying the virulence island LIPI-3. 2 strains of enteroaggregative Escherichia coli in which 1 strain of multi-drug resistance.ConclusionMore attention should be paid to vegetables that can be eaten raw with regional characteristics， such as Houttuynia cordata Thunb. Some strains of Listeria monocytogenes can be a potential public health risk due to high harboring rate of virulence genes. It is serious that of multidrug resistance of Salmonella and diarrheagenic Escherichia coli isolated from raw vegetables.

Abstract Current knowledge about effects of disturbance on the fate of invaders in complex microbial ecosystems is still in its infancy. In order to investigate this issue, we compared the fate of Klebsiella pneumoniae (Kp) and Listeria monocytogenes (Lm) in soil microcosms. We then used environmental disturbances (freeze–thaw or heat cycles) to compare the fate of both invaders and manipulate soil microbial diversity. Population dynamics of the two pathogens was assessed over 50 days of invasion while microbial diversity was measured at times 0, 20 and 40 days. The outcome of invasion was strain-dependent and the response of the two invaders to disturbance differed. Resistance to Kp invasion was higher under the conditions where resident microbial diversity was the highest while a significant drop of diversity was linked to a higher persistence. In contrast, Lm faced stronger resistance to invasion in heat-treated microcosms where diversity was the lowest. Our results show that diversity is not a universal proxy of resistance to microbial invasion, indicating the need to properly assess other intrinsic properties of the invader, such as its metabolic repertoire, or the array of interactions between the invader and resident communities.

Abstract Introduction Listeriosis is a severe food-borne disease caused by Listeria monocytogenes infection. The data of listeriosis in Xi’an population are limited. The aim of this study is to evaluate the clinical features and fatality risk factors for listeriosis in three tertiary-care hospitals in Xi’an, China Methods The characteristics of demographic data, underlying diseases, clinical manifestations, laboratory indicators, cranial imaging examination, antibiotics therapeutic schemes, and clinical outcomes were collected between 2011 and 2023. Logistic regression analysis was performed. Results Seventy-one etiologically confirmed listeriosis patients were enrolled, including 12 neonatal and 59 non-neonatal cases. The majority of neonatal listeriosis presented as preterm (50%) and fetal distress (75%). The main clinical manifestations of non-neonatal listeriosis included fever (88%), headache (32%), disorder of consciousness (25%), vomiting (17%), abdominal pain (12%), and convulsions (8%). The fatality rate in neonatal cases was higher than in non-neonatal listeriosis (42 vs. 17%). Although no deaths were reported in maternal listeriosis, only two of 23 patients had an uneventful obstetrical outcome. Five maternal listeriosis delivered culture-positive neonates, three of whom decreased within 1 week post-gestation due to severe complications. Twenty-eight cases were neurolisteriosis and 43 cases were bacteremia. Neurolisteriosis had a higher fatality rate compared with bacteremia listeriosis (36 vs. 12%). The main neuroradiological images were cerebral edema/hydrocephalus, intracranial infection, and cerebral hernia. Listeria monocytogenes showed extremely low resistance to ampicillin (two isolates) and penicillin (one isolate). The fatality risk factors were the involvement of the central nervous system, hyperbilirubinemia, and hyponatremia for all enrolled subjects. Hyperuricemia contributed to the elevation of fatality risk in non-neonatal listeriosis. Conclusions When the patients suffered with symptoms of fever and central nervous system infection, they should be alert to the possibility of listeriosis. Early administration of ampicillin- or penicillin-based therapy might be beneficial for recovery of listeriosis.

ObjectiveTo analyze the distribution characteristics of virulence genes and drug resistance of foodborne Listeria monocytogenes （Lm） in Liaoning Province， 2020—2021.MethodsThe 19 virulence genes of Lm including 6 loci （prfA， plcA， plcB， hlyA， mpl and actA） and 10 loci of virulence island Ⅱ （inlA， inlB， inlC， inlD， inlE， inlF， inlG， inlH/C2， inlI and inlJ）， and the other 3 virulence related loci （iap， fbpA， hpt） were detected by PCR.ResultsAmong 91 Lm strains， the detection rate of 19 virulence genes was 39.6%. All 19 virulence genes of 36 Lm strains were detected， and 55 Lm strains showed different deletions of two or more virulence genes. inlG and inlF were the most seriously deficient， with a deletion rate of 41.8%（38/91） and 52.7%（48/91）. According to the virulence gene deletion， 91 strains could be divided into 13 genotypes， and the dominant virulence genotype was type Ⅰ with all 19 virulence genes. The 91 Lm strains were divided into four PCR serotypes， namely， 1/2a （3a）， 1/2b （3b）， 1/2c （3c） and 4b （4d， 4e）， with the proportions of each serum 59.3% （54/91）， 34.1%（31/91）， 3.3% （3/91） and 3.3% （3/91）， respectively. The 3 strains of serotype 4b were all from meat and meat products.ConclusionThe virulence gene carrying rate of foodborne Lm in Liaoning Province is high， and the virulence gene deletion has diversity and sample differences.

In recent years， food poisoning caused by Listeria monocytogenes contamination in meat products at home and abroad has occurred frequently. Diseases caused by Listeria monocytogenes contamination have become a hidden danger to people’s health. As a traditional country in the production and consumption of meat products， China should be vigilant. Meat product manufacturers need to develop monitoring programs to prevent Listeria monocytogenes contamination and control potential risks. Based on the microbial characteristics of Listeria monocytogenes， the possible ways of contamination by Listeria monocytogenes in the production process of meat products are analyzed， and the monitoring and disinfection plan of Listeria monocytogenes in the production process of meat products is put forward， which provides direction and help for the risk control measures of meat product manufacturers.

ObjectiveIn order to find out the contamination situation and potential risk of Listeria monocytogenes in refrigerated ready-to-eat prepackaged foods. This study carried out a quantitative contamination risk survey of L. monocytogenes for ready-to-eat cooked meat products with short shelf life.MethodsWe collected 64 samples of ready-to-eat cooked meat from Chengdu， and carried out qualitative and quantitative detection of L. monocytogenes according to traditional culture method and RT-PCR molecular detection method. Additionally， the second generation of the whole genome sequencing was performed after DNA extraction of the isolated strains， and relevant epidemiological characteristics were analyzed.ResultsThe results showed that L. monocytogenes were isolated from 6 samples of cooked meat （6/64）. All 6 L. monocytogenes positive samples were produced by the same manufactory， of which 5 were three platters of marinated meat. The results of quantitative detection showed that the contamination level of L. monocytogenes in three platters of marinated meat was 30-200 CFU/g， and the contamination level of cooked pork samples with positive L. monocytogenes was lower as

Listeria monocytogenes, which causes human listeriosis after consumption of contaminated food, can adapt and survive under a wide range of physiological and chemical stresses. In this study, the overall proteomic response of the L. monocytogenes strain F2365—a strain with mutations limiting its ability to tolerate acidic conditions—to progressive non-thermal acidic inactivation was investigated. The challenge process was investigated in the early stationary growth phase where F2365 cultures were acidified (pH 3.0, HCl) at 5 min, 1 h, and 2 h, generating pH 4.8, pH 4.1, and pH 3.5, respectively, with protein abundance measured using iTRAQ. Approximately 73 proteins increased in abundance and 8 declined when acidic stress became non-growth-permissive (pH < 4.1) and inactivation accelerated to approximately 2 log units/h. The functional categories of responding proteins were broad but the proteins involved were specific in nature and did not include whole pathways. Many responses likely accentuate energy conservation and compensate vital metabolic processes. For example, further repression of FlaA, normally repressed under acidic stress, occurs accompanied by an increase in quinol oxidase subunit QoxA and glycerol kinase GlpK. Proteins maintaining cell wall integrity, such as Iap and CwlO, manifested the overall largest abundance increase trend. Virulence proteins were also induced, including InlA, InlC, Hyl, Mpl, PlcA, and PlcB, suggesting that acidification may have mimicked conditions inducing some host survival traits. The overall suite of proteins affected appears to be the "last ditch" responses to non-thermal inactivation above and beyond the standard protections afforded in the stationary-growth phase. The array of proteins found here may provide a deeper understanding of the physiological responses of this pathogen during non-thermal inactivation.

This work aimed to investigate the inactivation mechanism of lauroyl arginate ethyl (LAE) against Listeria monocytogenes. The antibacterial activity of LAE against L. monocytogenes was evaluated by measuring the minimum antibacterial concentration (MIC). Then, the antibacterial mechanism of LAE against L. monocytogenes was investigated by measuring the cell morphology, cell membrane integrity, intracellular ATP level, cell membrane potential, cell surface hydrophobicity, and intracellular reactive oxygen species (ROS) level. The results showed that LAE could effectively inhibit the growth of L. monocytogenes with a MIC value of 10 μg/mL. After LAE treatment at a final concentration of 40 μg/mL for 10 min, the cell morphology of L. monocytogenes shrank obviously, the levels of extracellular nucleic acid and protein significantly (P

ObjectiveTo use whole genome sequencing （WGS） to analysis the genomic characteristics， the antimicrobial resistance and virulence genotypes of 64 Listeria monocytogenes strains isolated from commercial food in Xianyang City.MethodsSixty four Listeria monocytogenes were isolated and the susceptibilities were determined by broth microdilution. After the whole genome sequencing， using bioinformatics software for genome annotation， phylogenetic tree construction， genome features and genetic components analysis.ResultsAll isolates were found to be susceptible to ampicillin， Penicillin， meropenem， trimethoprim-sulfamethoxazole， vancomycin. 2 isolates were resistant to tetracycline and erythromycin at the same time. All isotates were categorized into three different lineages and 15 CCs， Lineage Ⅰ and Ⅱ were the predominant types. The genotypes of 2 resistant isolates correlated well with its resistant phenotype. Up and down stream analysis of the genetic context， in which these resistant genes were found， suggested that they may have been acquired from Erysipelothrix rhusiopathiae， Enterococcus and plasmid. All the isolates harboured the LIPI-1 and LIPI-2， subset of lineage Ⅰ isotates harboured LIPI-3 or LIPI-4 with potential pathogenicity. Lineage Ⅱ isotates harboured more plasmids and genes linked to stress adaptation . The premature stop codon （PMSC） mutation in inlA more frequently happened in lineage Ⅱ and may reduce virulence.ConclusionThe genome of Listeria monocytogenes in commercial food in Xianyang City is stable. Acquires resistance existed in this bacterium， and can be a potential public health risk due to its high harboring rate of virulence genes. Lineage Ⅰ and Lineage Ⅱ isolates were differ in virulence genes， stress adaptation genes and plasmids harboring， indicating differences among subtypes. This findings would be helpful to the surveillance and control of this foodborne pathogen in Xianyang City.

Pediocin (Ped) is a 4.6kDa bacteriocin effective against Listeria monocytogenes and several Gram-positive bacteria. To produce purified Ped with high yield and apply it to food preservation, this study expresses and purifies recombinant Ped (rPed) from Pichia pastoris X33::ped, and preliminary applies it in shrimp preservation. The results showed that methanol 1% is optimal for inducing the expression of rPed from P. pastoris X33::ped, achieving 6,400 AU/ml of rPed after 72 hours of yeast culture on a BSM medium. The rPed purification process was successfully established with a sample loading rate of 155.9 cm/h. This process yielded rPed with 91.7% purity and 11.0 mg per liter of culture. This rPed could preserve shrimp at 4°C for 07 days. Therefore, these results demonstrate the potential of producing rPed from Pichia pastoris X33::ped and applying it in food preservation.

Listeria monocytogenes bacilli are a known cause of non-invasive gastrointestinal listeriosis with diarrhea, less frequently they cause invasive infections: meningitis and encephalitis, bacteremia and its complications: endocarditis, intraocular inflammation of the eye and others. The risk of human infection is mainly associated with consuming food contaminated with these bacteria. According to the European Food Safety Authority (EFSA), infections with L. monocytogenes etiology caused the highest hospitalizations and deaths among zoonotic diseases reported in 2022. A report by the European Center for Disease Prevention and Control (ECDC) reported 0.44 cases of listeriosis per 100,000 population in 2021, with the highest incidence rate for people over 64 years old at 1.7.

Abstract Background Listeria monocytogenes is a foodborne pathogen, which can cause a severe illness, especially in people with a weakened immune system or comorbidities. The interactions between host and pathogens and between pathogens and tumor cells have been debated in recent years. However, it is still unclear how bacteria can interact with tumor cells, and if this interaction can affect tumor progression and therapy. Methods In this study, we evaluated the involvement of L. monocytogenes in pre-neoplastic and colorectal cancer cell proliferation and tumorigenic potential. Results Our findings showed that the interaction between heat-killed L. monocytogenes and pre-neoplastic or colorectal cancer cells led to a proliferative induction; furthermore, by using a three-dimensional cell culture model, the obtained data indicated that L. monocytogenes was able to increase the tumorigenic potential of both pre-neoplastic and colorectal cancer cells. The observed effects were then confirmed as L. monocytogenes-specific, using Listeria innocua as negative control. Lastly, data suggested the Insulin Growth Factor 1 Receptor (IGF1R) cascade as one of the possible mechanisms involved in the effects induced by L. monocytogenes in the human colorectal adenocarcinoma cell line. Conclusions These findings, although preliminary, suggest that the presence of pathogenic bacterial cells in the tumor niches may directly induce, increase, and stimulate tumor progression.

The Association for Dressings and Sauces’ (ADS) members have conducted challenge studies on salad dressing products to assess pathogen survival. Data from 79 different challenge studies provided by ADS were used in this analysis. The acid-moisture ratio, pH, incubation temperature, and ingredient details were provided for each study. Linear regression models were used to predict the time to 3-log, 4-log, and 5-log reduction as a function of study parameters. A statistically based approach also was used to estimate the concentration of pathogens in ingredients based on testing history. This was combined with decline modeling to estimate pathogen concentration over time. The time-to-five log reduction for each of the target pathogens were highly skewed. A logarithmic transformation of time to 5 log reduction resulted in approximately normal distributions. Incubation temperature and formulation pH were highly significant (p

The tight and coordinated regulation of virulence gene expression is crucial to ensure the survival and persistence of bacterial pathogens in different contexts within their hosts. Considering this, bacteria do not express virulence factors homogenously in time and space, either due to their associated fitness cost or to their detrimental effect at specific infection stages. To efficiently infect and persist into their hosts, bacteria have thus to monitor environmental cues or chemical cell-to-cell signaling mechanisms that allow their transition from the external environment to the host, and therefore adjust gene expression levels, intrinsic biological activities, and appropriate behaviors. Listeria monocytogenes (Lm), a major Gram-positive facultative intracellular pathogen, stands out for its adaptability and capacity to thrive in a wide range of environments. Because of that, Lm presents itself as a significant concern in food safety and public health, that can lead to potentially life-threatening infections in humans. A deeper understanding of the intricate bacterial virulence mechanisms and the signals that control them provide valuable insights into the dynamic interplay between Lm and the host. Therefore, this review addresses the role of some crucial signals behind Lm pathogenic virulence mechanisms and explores how the ability to assimilate and interpret these signals is fundamental for pathogenesis, identifying potential targets for innovative antimicrobial strategies.

AbstractListeria monocytogenes is a food-borne bacterial pathogen known to cause a burden on human health and food safety globally. Regardless of the few available studies on Listeria monocytogenes, there is no comprehensive evidence of its prevalence and antimicrobial susceptibility in Ethiopia. We conducted to estimate the pooled prevalence and antimicrobial susceptibility profile of Listeria monocytogenes from various sources in Ethiopia. The study was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) Checklist. The quality of the studies was assessed based on the Newcastle–Ottawa scale. We found 18 studies that fit our inclusion criteria. Results were synthesized with random-effects meta-analyses and meta-regressions to evaluate heterogeneity between studies. The pooled prevalence of Listeria monocytogenes from various sources in Ethiopia was 4.2% (95% CI, 2.13, 6.22). The pooled prevalence was higher in human subjects 6.4% (95% CI, 0.27–15.6) when compared to animals 4.7% (95% CI, −0.40 to 9.1) and foods of animal origin 5.1% (95% CI, 0.42–10.6). Higher rate of resistance of Listeria monocytogenes against tetracycline (72.7%), amoxicillin (63.7%), nalidixic acid (63.6%), penicillin (63.6%), and cephalothin (54.5%) was observed. The prevalence of Listeria monocytogenes and the occurrence of resistant isolates in different source populations warn of a potential future threat to public health. Hence, increasing public awareness and designing effective policies and disease control measures are strongly recommended.

A variety of electron transfer mechanisms link bacterial cytosolic electron pools with functionally diverse redox activities in the cell envelope and extracellular space. In Listeria monocytogenes, the ApbE-like enzyme FmnB catalyzes extracytosolic protein flavinylation, covalently linking a flavin cofactor to proteins that transfer electrons to extracellular acceptors. L. monocytogenes uses an energy-coupling factor (ECF) transporter complex that contains distinct substrate-binding, transmembrane, ATPase A, and ATPase A' subunits (RibU, EcfT, EcfA, and EcfA') to import environmental flavins, but the basis of extracytosolic flavin trafficking for FmnB flavinylation remains poorly defined. In this study, we show that the EetB and FmnA proteins are related to ECF transporter substrate-binding and transmembrane subunits, respectively, and are essential for exporting flavins from the cytosol for flavinylation. Comparisons of the flavin import versus export capabilities of L. monocytogenes strains lacking different ECF transporter subunits demonstrate a strict directionality of substrate-binding subunit transport but partial functional redundancy of transmembrane and ATPase subunits. Based on these results, we propose that ECF transporter complexes with different subunit compositions execute directional flavin import/export through a broadly conserved mechanism. Finally, we present genomic context analyses that show that related ECF exporter genes are distributed across members of the phylum Firmicutes and frequently colocalize with genes encoding flavinylated extracytosolic proteins. These findings clarify the basis of ECF transporter export and extracytosolic flavin cofactor trafficking in Firmicutes. IMPORTANCE Bacteria import vitamins and other essential compounds from their surroundings but also traffic related compounds from the cytosol to the cell envelope where they serve various functions. Studying the foodborne pathogen Listeria monocytogenes, we find that the modular use of subunits from a prominent class of bacterial transporters enables the import of environmental vitamin B2 cofactors and the extracytosolic trafficking of a vitamin B2-derived cofactor that facilitates redox reactions in the cell envelope. These studies clarify the basis of bidirectional small-molecule transport across the cytoplasmic membrane and the assembly of redox-active proteins within the cell envelope and extracellular space.

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

The microbiological quality of dairy products from small-scale producers in Serbia was analysed. A total of 302 dairy products [raw (n = 111) and pasteurized milk cheeses (n = 79) and kajmak (n = 112)], were collected and tested for the presence of pathogens, Listeria monocytogenes and Salmonella spp., and enumerated for Coagulase-positive staphylococci (CPS), Escherichia coli, and yeasts and moulds. None of the samples tested positive for Salmonella spp., while L. monocytogenes was recovered from one raw milk cheese and five kajmak samples. Raw milk cheese and kajmak also had higher levels of indicator microorganisms, namely E. coli and yeast and moulds. Molecular serotyping grouped L. monocytogenes isolates into serogroups 1 (1/2a and 3a) and 3 (1/2b, 3b, and 7). When exposed to eight antibiotics, L. monocytogenes isolates were mostly sensitive, with the exception of oxacillin and reduced susceptibility to clindamycin, penicillin G, and trimethoprim/sulfamethoxazole, emphasizing the importance of continuous surveillance for antimicrobial resistance. Samples that tested positive for Listeria spp. also had higher loads of indicator microorganisms, namely E. coli and yeast and moulds, suggesting lapses in hygiene practices during production. Collectively, these data emphasize the need for improved food safety and hygiene practices among small-scale dairy producers. This is crucial to reduce the microbial contamination and improve both the quality and safety of dairy products in the Serbian market. [ABSTRACT FROM AUTHOR]

We report a very rare case of Listeria multiple brain abscesses manifested as delirium, which represented diagnostic and therapeutic challenges overcome only by the close cooperation between Infectious Diseases and Neuroradiology, without which a satisfactory outcome would not be achieved. An elderly man presented with confusion and drowsiness with a background of type-II diabetes mellitus. Although computed tomography of the brain only showed frontal lobe oedema, contrast magnetic resonance (MR) imaging showed numerous irregular rim-enhancing lesions containing central diffusion restriction, suggesting multiple pyogenic cerebral abscesses of unclear aetiology. Thereafter, Listeria monocytogenes was isolated from blood cultures, suggesting this as the causative organism. Deemed unsuitable for neurosurgical drainage, the patient received medical management with a protracted course of antibiotics. This case was extremely challenging, due to 1) the impossibility of source control, 2) the small number of effective antibiotics available to treat this condition, and 3) the inevitable antibiotic side-effects, derived from long-term exposure. A successful outcome was only possible thanks to strict close multidisciplinary follow up, requiring frequent MR imaging and a judicious antibiotic choice, including monitoring of their side-effects. Due to the rarity of this condition, there is lack of guidance on its management, hence the importance of multidisciplinary involvement with very close imaging and antibiotic monitoring. [ABSTRACT FROM AUTHOR]

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

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

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

A fast and accurate identification of Listeria monocytogenes. A new quartz crystal microbalance (QCM) aptasensor was designed for the specific and rapid detection of L. monocytogenes. Before detection of the target bacterium from samples in the QCM aptasensor, a magnetic pre-enrichment system was used to eliminate any contaminant in the samples. The prepared magnetic system was characterized using ATR-FTIR, SEM, VSM, BET, and analytical methods. The saturation magnetization values of the Fe3O4, Fe3O4@PDA, and Fe3O4@PDA@DAPEG particles were 57.2, 40.8, and 36.4 emu/g, respectively. The same aptamer was also immobilized on the QCM crystal integrated into QCM flow cell and utilized to quantitatively detect L. monocytogenes cells from the samples. It was found that a specific aptamer-magnetic pre-concentration system efficiently captured L. monocytogenes cells in a short time (approximately 10 min). The Fe3O4@PDA@DA-PEG-Apt particles provided selective isolation of L. monocytogenes from the bacteria-spiked media up to 91.8%. The immobilized aptamer content of the magnetic particles was 5834 µg/g using 500 ng Apt/mL. The QCM aptasensor showed a very high range of analytical performance to the target bacterium from 1.0 × 102 and 1.0 × 107 CFU/mL. The limit of detection (LOD) and limit of quantitation (LOQ) were 148 and 448 CFU/mL, respectively, from the feeding of the QCM aptasensor flow cell with the eluent of the magnetic pre-concentration system. The reproducibility of the aptasensor was more than 95%. The aptasensor was very specific to L. monocytogenes compared to the other Listeria species (i.e., L. ivanovii, L. innocua, and L. seeligeri) or other tested bacteria such as Staphylococcus aureus, Escherichia coli, and Bacillus subtilis. The QCM aptasensor was regenerated with NaOH solution, and the system was reused many times. [ABSTRACT FROM AUTHOR]

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

This study aimed to generate low molecular weight peptides (LMWP) from fish collagen type I hydrolysed by increasing activity of Alcalase® from 0.0 to 12.0 (AU-A per 100 g) at 55 °C and 7.4 of pH for 3 h 40 min. The results showed that all enzyme activity levels caused 34–55 % reductions in protein recovery, 1.0–3.0 folds' increase in free α-amino groups and 1.7–3.2 folds' increase in carboxyl groups. Degree of hydrolysis ranged from 20 to 30 % with increasing enzyme activity. The number average molecular weight significantly reduced from 3200 g/mol in 0.0 AU-A per 100 g enzyme activity to 1151, 1398, 1175, 1040 and 1246 g/mol in 2.4, 4.8, 7.2, 9.6 and 12.0 AU-A per 100 g enzyme activities, respectively. Depending upon enzyme activity level, the produced LMWP with reactive carboxyl and amino end-groups exhibited 2.5- to 4.0-fold increases in antioxidant capacity and 1.0–3.5 log cfu/ml inhibition of four pathogen bacteria. Highest inhibition of 2.5 log cfu/ml in Escherichia coli was obtained from 2.4 AU-A per 100 g enzyme activity and 3.5 log cfu/ml in Listeria monocytogenes from 9.6 and 12.0 AU-A per 100 g enzyme activity levels. Infrared spectroscopy clearly identified reactive end-groups and showed remarkably differences in molar absorptivity of various molecular regions between non-enzyme and enzyme treated collagen type I molecule. A 9.6 and 12.0 AU-A per 100 g enzyme activity levels were found optimally effective to generate LMWP. In conclusion, LMWP exhibited high antioxidant and antibacterial activity due to increased functional reactive end-groups, and these bio-active peptides may have greater potentialities in various food and pharmaceutical applications. [ABSTRACT FROM AUTHOR]

Copyright of Mustafa Kemal University Journal of Agricultural Sciences / Mustafa Kemal Üniversitesi Tarım Bilimleri Dergisi is the property of Mustafa Kemal University, Faculty of Agriculture 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.)

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

The study used whole-genome sequencing (WGS) and bioinformatics analysis for the genomic characterization of 60 isolates of Listeria monocytogenes obtained from the beef production chain (cattle farms, abattoirs, and retail outlets) in Gauteng province, South Africa. The sequence types (STs), clonal complexes (CCs), and the lineages of the isolates were determined using in silico multilocus sequence typing (MLST). We used BLAST-based analyses to identify virulence and antimicrobial genes, plasmids, proviruses/prophages, and the CRISPR-Cas system. The study investigated any association of the detected genes to the origin in the beef production chain of the L. monocytogenes isolates. Overall, in 60 isolates of Listeria monocytogenes, there were seven STs, six CCs, forty-four putative virulence factors, two resistance genes, one plasmid with AMR genes, and three with conjugative genes, one CRISPR gene, and all 60 isolates were positive for proviruses/prophages. Among the seven STs detected, ST204 (46.7%) and ST2 (21.7%) were the most prominent, with ST frequency varying significantly (p < 0.001). The predominant CC detected were CC2 (21.7%) and CC204 (46.7%) in lineages I and II, respectively. Of the 44 virulence factors detected, 26 (across Listeria Pathogenicity Islands, LIPIs) were present in all the isolates. The difference in the detection frequency varied significantly (p < 0.001). The two AMR genes (fosX and vga(G)) detected were present in all 60 (100%) isolates of L. monocytogenes. The only plasmid, NF033156, was present in three (5%) isolates. A CRISPR-Cas system was detected in six (10%), and all the isolates carried proviruses/prophages. The source and sample type significantly affected the frequencies of STs and virulence factors in the isolates of L. monocytogenes. The presence of fosX and vga(G) genes in all L. monocytogenes isolates obtained from the three industries of the beef production chain can potentially cause therapeutic implications. Our study, which characterized L. monocytogenes recovered from the three levels in the beef production chain, is the first time genomics was performed on this type of data set in the country, and this provides insights into the health implications of Listeria. [ABSTRACT FROM AUTHOR]

Listeria monocytogenes (L. monocytogenes) poses a significant threat to food safety due to its ability to cause severe human illness and its resistance to various antibiotics and environmental conditions. This study investigated the prevalence, serotype distribution, virulence gene profiles, and antimicrobial resistance patterns of L. monocytogenes in ready-to-eat (RTE) food products from Romania. A total of 8151 samples were analyzed, including various processed dairy, bovine, poultry, pork, and fish products. Bacterial isolation was conducted using the classical standard method, followed by confirmation through biochemical and molecular testing. Among the isolated strains, serotypes 1/2a, 1/2b, and 1/2c were identified, with a prevalence of 75% for serotype 1/2a. Additionally, virulence genes specific to listeriolysin O (hlyA) and regulatory factor A (prfA) were detected in all isolates. Antimicrobial susceptibility testing revealed varying resistance patterns among the L. monocytogenes strains. Trimethoprim-sulfamethoxazole and oxacillin showed the highest prevalence of resistance at 26.92% and 23.07%, respectively. However, all strains remained susceptible to ciprofloxacin, levofloxacin, and moxifloxacin. Notably, 23.07% of the isolates exhibited multidrug resistance, with the most common pattern being resistance to oxacillin, penicillin, and tetracycline. Analysis of antimicrobial resistance genes identified tetracycline resistance genes, particularly tet(C), tet(M), and tet(K), in a significant proportion of isolates. The presence of ampC and dfrD genes was also notable, indicating potential mechanisms of resistance. These results emphasize the necessity for ongoing surveillance of L. monocytogenes in RTE foods and emphasize the importance of thorough monitoring of antimicrobial resistance to guide public health strategies within the European Union. [ABSTRACT FROM AUTHOR]

The search for natural food additives makes propolis an exciting alternative due to its known antimicrobial activity. This work aims to investigate propolis' behavior as a nitrite substitute ingredient in cooked ham (a ready-to-eat product) when confronted with pathogenic microorganisms of food interest. The microbial evolution of Listeria monocytogenes, Staphylococcus aureus, Bacillus cereus, and Clostridium sporogenes inoculated at known doses was examined in different batches of cooked ham. The design of a challenge test according to their shelf life (45 days), pH values, and water activity allowed the determination of the mesophilic aerobic flora, psychotropic, and acid lactic bacteria viability. The test was completed with an organoleptic analysis of the samples, considering possible alterations in color and texture. The cooked ham formulation containing propolis instead of nitrites limited the potential growth (δ < 0.5 log10) of all the inoculated microorganisms until day 45, except for L. monocytogenes, which in turn exhibited a bacteriostatic effect between day 7 and 30 of the storage time. The sensory analysis revealed the consumer's acceptance of cooked ham batches including propolis as a natural additive. These findings suggest the functionality of propolis as a promising alternative to artificial preservatives for ensuring food safety and reducing the proliferation risk of foodborne pathogens in ready-to-eat products. [ABSTRACT FROM AUTHOR]

The aim of using minimal food processing technologies is to preserve the raw material or to achieve a special technological goal with the least possible impact. When several technologies are used together, the intensity of each treatment can be reduced according to Leistner's hurdle principle. Does the order of application of the treatments result in a detectable difference? This research focuses on the effect of the combination of the sous-vide technology and the high hydrostatic pressure (HHP) treatment. The effect of the pressure level (300 and 600 MPa) and the influence of the treatment order was investigated on pork (longissimus thoracis and lumborum muscles (LTL)). Physico-chemical and microbiological measurements were carried out on day 0 and after 21-day storage at 2 °C and 8 °C. Significant differences were found for both the order of treatment and pressure level in weight loss (p < 0.001), CIELab color parameters a* and b* (p < 0.001), and denaturation enthalpy (p < 0.01). The texture (p < 0.001) and lipid oxidation TBARS values (p < 0.05) were only influenced by the pressure level. In the challenge test, the initial count of 105 CFU/g Listeria monocytogenes dropped below detection limit in all cases. Total aerobic and anaerobic viable numbers were below/near the detection limit in all combined-treated samples on day 0 and showed only slight or more notable growth after 21-day storage at 2 °C and 8 °C, respectively. An additional 300 MPa pressure treatment can increase the safety of sous-vide cooked pork samples while having only a minor effect on physicochemical properties. The 600 MPa pressure treatment results in a stable, albeit not shelf-stable product, but it also affects a considerable number of quality parameters such as color, texture, weight loss, and TBARS values. [ABSTRACT FROM AUTHOR]

Traditional and regional foods have been increasing in popularity among consumers in Poland for many years. The observed trend of searching for natural and authentic taste encourages many producers to craft products from raw milk, including Koryciński cheeses. The aim of this study was to assess the microbiological hazards resulting from the presence of pathogenic bacteria in Koryciński cheeses available in retail trade. The tests were carried out using accredited methods, including the detection of the presence of Salmonella spp., the enumeration of Listeria monocytogenes, the enumeration of coagulase-positive staphylococci, and the detection of staphylococcal enterotoxins in food when the number of coagulase-positive staphylococci in the sample exceeded the limit of 105 cfu/g. The research material consisted of 45 Koryciński cheeses. The tests conducted revealed that Salmonella spp. was not detected in any of the examined cheeses. However, coagulase-positive staphylococci were present in 68.9% of the samples. In as many as 15 tested cheeses, the level of S. aureus contamination was above 105 cfu/g; therefore, these samples were tested for the presence of staphylococcal enterotoxins. The presence of staphylococcal enterotoxins was found in one Koryciński cheese. In four cheeses, the number of L. monocytogenes exceeded the level of 102 cfu/g, the limit specified in Regulation 2073/2005 on microbiological criteria for foodstuffs. The obtained research results confirm the validity of monitoring the microbiological quality of Koryciński cheeses and the need to increase awareness of ensuring proper hygienic conditions of production, including the increased risk associated with unpasteurized milk products. [ABSTRACT FROM AUTHOR]

Listeria monocytogenes is the causative agent of listeriosis, a severe foodborne illness characterized by septicemia, meningitis, encephalitis, abortions, and occasional death in infants and immunocompromised individuals. L. monocytogenes is composed of four genetic lineages (I, II, III, and IV) and fourteen serotypes. The aim of the current study was to identify proteins that can serve as biomarkers for detection of genetic lineage III strains based on simple antibody-based methods. Liquid chromatography (LC) with electrospray ionization tandem mass spectrometry (ESI MS/MS) followed by bioinformatics and computational analysis were performed on three L. monocytogenes strains (NRRL B-33007, NRRL B-33014, and NRRL B-33077), which were used as reference strains for lineages I, II, and III, respectively. Results from ESI MS/MS revealed 42 unique proteins present in NRRL B-33077 and absent in NRRL B-33007 and NRRL B-33014 strains. BLAST analysis of the 42 proteins against a broader panel of >80 sequenced strains from lineages I and II revealed four proteins [TM2 domain-containing protein (NRRL B-33077_2770), DUF3916 domain-containing protein (NRRL B-33077_1897), DNA adenine methylase (NRRL B-33077_1926), and protein RhsA (NRRL B-33077_1129)] that have no homology with any sequenced strains in lineages I and II. The four genes that encode these proteins were expressed in Escherichia coli strain DE3 and purified. Polyclonal antibodies were prepared against purified recombinant proteins. ELISA using the polyclonal antibodies against 12 L. monocytogenes lineage I, II, and III isolates indicated that TM2 protein and DNA adenine methylase (Dam) detected all lineage III strains with no reaction to lineage I and II strains. In conclusion, two proteins including TM2 protein and Dam are potentially useful biomarkers for detection and differentiation of L. monocytogenes lineage III strains in clinical, environmental, and food processing facilities. Furthermore, these results validate the approach of using a combination of proteomics and bioinformatics to identify useful protein biomarkers. [ABSTRACT FROM AUTHOR]

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

We present an unusual case of Listeria monocytogenes rhomboencephalitis in a young, healthy patient. Although L. monocytogenes meningitis is usually associated with immunodeficiency, rhomboencephalitis is more commonly seen in immunocompetent patients. The wide differential for rhomboencephalitis can create a diagnostic challenge. Without prompt pathogen identification and appropriate antibiotic regimen, L. monocytogenes central nervous system infections can be fatal. Cerebro-Spinal Fluid (CSF) Polymerase Chain Reaction (PCR) aided a prompt diagnosis and adjustment of therapy to achieve a good patient outcome. [ABSTRACT FROM AUTHOR]

Listeria monocytogenes, a foodborne pathogen, exhibits high adaptability to adverse environmental conditions and is common in the food industry, especially in ready-to-eat foods. L. monocytogenes strains pose food safety challenges due to their ability to form biofilms, increased resistance to disinfectants, and long-term persistence in the environment. The aim of this study was to evaluate the presence and genetic diversity of L. monocytogenes in food and related environmental products collected from 2014 to 2022 and assess antibiotic susceptibility and biofilm formation abilities. L. monocytogenes was identified in 13 out of the 227 (6%) of samples, 7 from food products (meat preparation, cheeses, and raw milk) and 6 from food-processing environments (slaughterhouse-floor and catering establishments). All isolates exhibited high biofilm-forming capacity and antibiotic susceptibility testing showed resistance to several classes of antibiotics, especially trimethoprim-sulfamethoxazole and erythromycin. Genotyping and core-genome clustering identified eight sequence types and a cluster of three very closely related ST3 isolates (all from food), suggesting a common contamination source. Whole-genome sequencing (WGS) analysis revealed resistance genes conferring resistance to fosfomycin (fosX), lincosamides (lin), fluoroquinolones (norB), and tetracycline (tetM). In addition, the qacJ gene was also detected, conferring resistance to disinfecting agents and antiseptics. Virulence gene profiling revealed the presence of 92 associated genes associated with pathogenicity, adherence, and persistence. These findings underscore the presence of L. monocytogenes strains in food products and food-associated environments, demonstrating a high virulence of these strains associated with resistance genes to antibiotics, but also to disinfectants and antiseptics. Moreover, they emphasize the need for continuous surveillance, effective risk assessment, and rigorous control measures to minimize the public health risks associated to severe infections, particularly listeriosis outbreaks. A better understanding of the complex dynamics of pathogens in food products and their associated environments can help improve overall food safety and develop more effective strategies to prevent severe health consequences and economic losses. [ABSTRACT FROM AUTHOR]

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

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