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Abstract Purpose Invasive Listeria monocytogenes infection is rare, but can lead to life-threatening complications among high-risk patients. Our aim was to assess characteristics and follow-up of adults hospitalized with invasive L. monocytogenes infection. Methods A retrospective observational cohort study was conducted at a national referral center between 2004 and 2019. Patients with proven invasive listeriosis, defined by the European Centre for Disease Prevention and Control criteria, were included. Data collection and follow-up were performed using the hospital electronic system, up until the last documented visit. The primary outcome was in-hospital all-cause mortality, secondary outcomes included residual neurological symptoms, brain abscess occurrence, and requirement for intensive care unit (ICU) admission. Results Altogether, 63 cases were identified (57.1% male, median age 58.8 ± 21.7 years), and 28/63 developed a complicated disease course (44.4%). At diagnosis, 38/63 (60.3%) presented with sepsis, 54/63 (85.7%) had central nervous system involvement, while 9/63 (14.3%) presented with isolated bacteremia. Frequent clinical symptoms included fever (53/63, 84.1%), altered mental state (49/63, 77.8%), with immunocompromised conditions apparent in 56/63 (88.9%). L. monocytogenes was isolated from blood (37/54, 68.5%) and cerebrospinal fluid (48/55, 87.3%), showing in vitro full susceptibility to ampicillin and meropenem (100% each), gentamicin (86.0%) and trimethoprim/sulfamethoxazole (97.7%). In-hospital all-cause mortality was 17/63 (27.0%), and ICU admission was required in 28/63 (44.4%). At discharge, residual neurological deficits (11/46, 23.9%) and brain abscess formation (6/46, 13.0%) were common. Conclusion Among hospitalized adult patients with comorbidities, invasive L. monocytogenes infections are associated with high mortality and neurological complications during follow-up.

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

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

In this study, gas chromatography-mass spectrometry (GC-MS) was used to analyze the chemical components of the essential oil extracted from the fruits of Aipinia oxyhylla Miq. (AOEO) by steam distillation. To evaluate the antimicrobial activity of AOEO against Listeria monocytogenes, the inhibitory zone diameter, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined by means of filter paper and micro-double dilution methods. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were performed to observe the effect of AOEO on bacterial morphology. The antibacterial mechanism was investigated by measuring the growth curve, the change of electrical conductivity, the leakage of intracellular macromolecules, the activity of superoxide dismutase (SOD) and the content of malondialdehyde (MDA). The results showed that a total of 45 chemical components were identified in AOEO, mainly including terpenes, aromatic hydrocarbons and oxygen-containing derivatives. Among them, valencene, nootkatone, 2,6,10,10-tetramethylbicyclo[7.2.0]undeca-1,6-diene, (2S,4aR,8aR)-4a,8-dimethyl-2-(prop-1-en-2-yl)-1,2,3,4,4a,5,6,8a-octahydronaphthalene, (2R,8R,8aS)-8,8a-dimethyl-2-(prop-1-en-2-yl)-1,2,3,7,8,8a-hexahydronaphthalene and p-cymene were predominant. AOEO significantly inhibited the growth of L. monocytogenes with an inhibitory zone diameter of 14.20 mm. The MIC and MBC were 0.195 and 0.781 mg/mL, respectively. The growth curve showed that the antimicrobial activity of AOEO was concentration-dependent. SEM and TEM showed that AOEO destroyed the morphological structure of L. monocytogenes and changed the permeability of the cell membrane, thereby causing the leakage of a large number of electrolytes and macromolecular contents (nucleic acids and proteins) out of the cells. The dynamic balance of the SOD system was also destroyed by the oil while inducing the generation of a large number of free radicals, thus resulting in increased levels of lipid oxidation and MDA content in the cells. Therefore, AOEO inhibited the growth of L. monocytogenes and causes cell apoptosis by causing a series of cellular changes. This could be due to the synergistic action of multiple components and multiple targets of AOEO. Terpenes, aromatic hydrocarbons and ketones were tentatively identified as the major antibacterial substances of AOEO. This study provides a scientific theoretical basis for the development and utilization of Aipinia oxyhylla Miq. as a natural bacteriostatic agent in the food industry.

To investigate the effects of nitrogen source nutrients on the growth and metabolism of Lactobacillus rhamnosus GG (LGG), this study used soybean protein isolates (dSPI) and soybean peptides (dPEP) from simulated gastrointestinal digestion as raw materials. The number of viable cells and the production of lactic acid and acetic acid in LGG were measured through mono-culture. LGG was co-cultured with Listeria monocytogenes to determine its utilization of soybean protein isolates and soybean peptides in the presence of pathogens. The results of mono-culture showed that both dPEP and dSPI could increase the viable number of LGG (P

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

Abstract Background Leprosy is a chronic infectious disease caused by Mycobacterium leprae (M. leprae) that is responsible for deformities and irreversible peripheral nerve damage and has a broad spectrum of clinical and serological manifestations. Leprosy primarily affects the peripheral nerves and rarely presents with central nervous system involvement. Diagnosing leprosy can still be difficult in some cases, especially when the infection involves uncommon clinical manifestations and extracutaneous sites. Delayed diagnosis and treatment of leprosy may lead to irreversible damage and death. Case Presentation We report a case of a 30-year-old female presenting with “repeated high fever with symptoms of headache for 14 days”. On the day of admission, physical signs of lost eyebrows and scattered red induration patches all over her body were observed. The patient’s diagnosis was based on the clinical characteristics using a combination of metagenomic next-generation sequencing (mNGS) of cerebrospinal fluid (CSF) and slit-skin smear. After confirming Listeria meningitis and multibacillary leprosy with erythema nodosum leprosum (ENL), a type 2 reaction, she was treated with ampicillin sodium, dapsone, rifampicin, clofazimine, methylprednisolone, and thalidomide. At the 1-year follow-up, the frequency and severity of headaches have significantly decreased and a good clinical response with improved skin lesions was found. Conclusion This case highlights the importance of considering leprosy, which is a rare and underrecognized disease, in the differential diagnosis of skin rashes with rheumatic manifestations, even in areas where the disease is not endemic, and physicians should be alerted about the possibility of central nervous system infections. In addition, mNGS can be used as a complementary diagnostic tool to traditional diagnostic methods to enhance the diagnostic accuracy of leprosy.

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.

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

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.

ABSTRACT Transposon sequencing (Tn-seq) is a powerful genome-wide technique to assess bacterial fitness under varying growth conditions. However, screening via Tn-seq in vivo is challenging. Dose limitations and host restrictions create bottlenecks that diminish the transposon mutant pool being screened. Here, we have developed a murine model with a disruption in Akr1c13 that renders the resulting RECON−/− mouse resistant to high-dose infection. We leveraged this model to perform a Tn-seq screen of the human pathogen Listeria monocytogenes in vivo. We identified 135 genes which were required for L. monocytogenes growth in mice including novel genes not previously identified for host survival. We identified organ-specific requirements for L. monocytogenes survival and investigated the role of the folate enzyme FolD in L. monocytogenes liver pathogenesis. A mutant lacking folD was impaired for growth in murine livers by 2.5-log10 compared to wild type and failed to spread cell-to-cell in fibroblasts. In contrast, a mutant in alsR, which encodes a transcription factor that represses an operon involved in D-allose catabolism, was attenuated in both livers and spleens of mice by 4-log10 and 3-log10, respectively, but showed modest phenotypes in in vitro models. We confirmed that dysregulation of the D-allose catabolism operon is responsible for the in vivo growth defect, as deletion of the operon in the ∆alsR background rescued virulence. By undertaking an unbiased, genome-wide screen in mice, we have identified novel fitness determinants for L. monocytogenes host infection, which highlights the utility of the RECON−/− mouse model for future screening efforts.IMPORTANCEListeria monocytogenes is the gram-positive bacterium responsible for the food-borne disease listeriosis. Although infections with L. monocytogenes are limiting in healthy hosts, vulnerable populations, including pregnant and elderly people, can experience high rates of mortality. Thus, understanding the breadth of genetic requirements for L. monocytogenes in vivo survival will present new opportunities for treatment and prevention of listeriosis. We developed a murine model of infection using a RECON−/− mouse that is restrictive to systemic L. monocytogenes infection. We utilized this model to screen for L. monocytogenes genes required in vivo via transposon sequencing. We identified the liver-specific gene folD and a repressor, alsR, that only exhibits an in vivo growth defect. AlsR controls the expression of the D-allose operon which is a marker in diagnostic techniques to identify pathogenic Listeria. A better understanding of the role of the D-allose operon in human disease may further inform diagnostic and prevention measures.

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

Monitoring data submitted to the National Center for Biotechnology Information’s Pathogen Detection whole-genome sequence database, which includes the foodborne bacterial pathogens Listeria monocytogenes, Salmonella enterica, and Escherichia coli, has proven effective for detecting emerging outbreaks. As part of the submission process, new sequence data are typed using a whole-genome multi-locus sequence typing scheme and clustered with sequences already in the database. Publicly available text files contain the results of these analyses. However, contextualizing and interpreting this information is complex. We present the Rapid Intuitive Pathogen Surveillance (RIPS) tool, which shows the results of the NCBI Rapid Reports, along with appropriate metadata, in a graphical, interactive dashboard. RIPS makes the information in the Rapid Reports useful for real-time surveillance of genome sequence databases.

This study aimed to conduct a preliminary investigation in eight Sardinian fermented sausage (SFS) production plants to acquire knowledge about the differences in the applied technological process and their influence on the safety and sensory characteristics of the finished product. Two audits were conducted in each plant to evaluate structural characteristics and process technologies; 72 samples of SFS at the end of seasoning and 48 environmental samples were analyzed. Listeria monocytogenes, Listeria spp., Salmonella spp., and Yersinia enterocolitica were investigated, and chemical-physical analyses were also performed. A panel of consumers was subjected to the Check All That Apply test and acceptability test to determine the qualities perceived by consumers and assess the product acceptance rating. A water activity value of >0.941, permissive for the growth of L. monocytogenes, was detected in SFS produced by one producing plant; L. monocytogenes, Salmonella spp., and Y. enterocolitica were detected in 2.8% of SFS samples, and Listeria spp. in 20.8% of samples. Environmental samples tested positive for 45.8% of Listeria spp. and 16.7% of L. monocytogenes. Correct drying and ripening steps, applied for at least 20 days, are critical for the development of hurdles required to guarantee the safety of fermented sausages. The application of proper hygiene and cleaning procedures is required to reduce environmental contamination. Sensory analysis results show how the production processes applied determine the marketing of sensorially different products. The ideal profile suggested by consumers confirms that the attributes that allow for improved liking are “moderate spicing”, “moderate spiciness”, “seasoned product”, and “artisanal character”.

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

Listeria monocytogenes infection often leads to listeriosis in immunocompromised individuals, and screening for potential nutrients that improve immunity may be beneficial. Here, we found that pre-incubation with heptadecanoic acid (C17:0), an odd-chain saturated fatty acid, significantly inhibited L.monocytogenes replication in differentiated THP-1 and RAW264.7, as evidenced by comparison of listeriolysin expression and colony count. Mechanistically, the administration of C17:0 triggered the activation of the IFN and NF-κB signaling pathways. Furthermore, C17:0 upregulated ACOD1 expression and the generation of itaconate, an anti-bacterial metabolite in macrophages. Based on these results, our comparative analysis showed that sheep tail fat (STF), ruminant lipid rich in C17:0, had similar anti-L.monocytogenes effect. Collectively, our data highlighted the function of C17:0 in boosting the immune response, shedding light on the application of C17:0 and STF as potential candidates for strengthening anti-L.monocytogenes response.

Controlling Listeria in produce packinghouses can be challenging due to the large number of potential contamination routes. For example, repeated isolation of the same Listeria subtype in a packinghouse could indicate persistence in the packinghouse or reintroduction of the same Listeria from an upstream source. To improve understanding of Listeria transmission patterns in packinghouses, we performed a longitudinal study in four apple packinghouses, including testing of 1,339 environmental sponges and whole genome sequencing (WGS)-based characterization of 280 isolates. Root cause analysis and subsequent intervention implementation were also performed and assessed for effectiveness. Listeria prevalence among environmental sponges collected from the four packinghouses was 20% (range of 5–31% for individual packinghouses). Sites that showed high Listeria prevalence included drains, forklift tires and forks, forklift stops, and waxing area equipment frames. A total of 240/280 WGS-characterized isolates were represented in 41 clusters, each containing two or more isolates that differed by ≤50 high-quality single nucleotide polymorphisms (hqSNPs); 21 clusters were isolated from one packinghouse over ≥2 samplings (suggesting persistence or possibly reintroduction), while 11 clusters included isolates from >2 packinghouses, suggesting common upstream sources. Some interventions successfully (i) reduced Listeria detection on forklift tires and forks (across packinghouses) and (ii) mitigated packinghouse-specific Listeria issues (e.g., in catch pans). However, interventions that lacked enhanced equipment disassembly when persistence was suspected typically appeared to be unsuccessful. Overall, while our data suggest a combination of intensive environmental sampling with subtyping and root cause analysis can help identify effective interventions, implementation of effective interventions continues to be a challenge in packinghouses.

ABSTRACT Pathogenic bacteria rely on secreted virulence factors to cause disease in susceptible hosts. However, in Gram-positive bacteria, the mechanisms underlying secreted protein activation and regulation post-membrane translocation remain largely unknown. Using proteomics, we identified several proteins that are dependent on the secreted chaperone PrsA2. We followed with phenotypic, biochemical, and biophysical assays and computational analyses to examine the regulation of a detected key secreted virulence factor, listeriolysin O (LLO), and its interaction with PrsA2 from the bacterial pathogen Listeria monocytogenes (Lm). Critical to Lm virulence is internalization by host cells and the subsequent action of the cholesterol-dependent pore-forming toxin, LLO, which enables bacterial escape from the host cell phagosome. Since Lm is a Gram-positive organism, the space between the cell membrane and wall is solvent exposed. Therefore, we hypothesized that the drop from neutral to acidic pH as the pathogen is internalized into a phagosome is critical to regulating the interaction of PrsA2 with LLO. Here, we demonstrate that PrsA2 directly interacts with LLO in a pH-dependent manner. We show that PrsA2 protects and sequesters LLO under neutral pH conditions where LLO can be observed to aggregate. In addition, we identify molecular features of PrsA2 that are required for interaction and ultimately the folding and activity of LLO. Moreover, protein-complex modeling suggests that PrsA2 interacts with LLO via its cholesterol-binding domain. These findings highlight a mechanism by which a Gram-positive secretion chaperone regulates the secretion, stability, and folding of a pore-forming toxin under conditions relevant to host cell infection.IMPORTANCELm is a ubiquitous food-borne pathogen that can cause severe disease to vulnerable populations. During infection, Lm relies on a wide repertoire of secreted virulence factors including the LLO that enables the bacterium to invade the host and spread from cell to cell. After membrane translocation, secreted factors must become active in the challenging bacterial cell membrane-wall interface. However, the mechanisms required for secreted protein folding and function are largely unknown. Lm encodes a chaperone, PrsA2, that is critical for the activity of secreted factors. Here, we show that PrsA2 directly associates and protects the major Lm virulence factor, LLO, under conditions corresponding to the host cytosol, where LLO undergoes irreversible denaturation. Additionally, we identify molecular features of PrsA2 that enable its interaction with LLO. Together, our results suggest that Lm and perhaps other Gram-positive bacteria utilize secreted chaperones to regulate the activity of pore-forming toxins during infection.

Peritoneal dialysis (PD)-associated peritonitis is a major cause of peritoneal dysfunction and failure. The main issue regarding the treatment is whether to remove the catheter surgically or to treat with antibiotics alone. Notably, PD-associated peritonitis is commonly caused by gram-positive cocci, but rarely by Listeria monocytogenes and Burkholderia cepacia. Here, we report a patient diagnosed with PD-associated peritonitis caused by L. monocytogenes and B. cepacia who presented with a fever, abdominal pain, and turbid dialysate and had been receiving PD for over 20 years. After 2 weeks of antibiotic treatment, the catheter in the patient was surgically removed. Culture and pathology results revealed pathogen growth, foreign body granuloma with chronic inflammation, and inflammatory cells with fibroblast infiltration. The patient was switched to hemodialysis. She eventually recovered and was discharged. The patient presented fair health at the 3-month follow-up. In conclusion, sequential dialysate white blood cell count may help clinicians decide the course of treatment and guide the timing of surgical intervention.

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

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

ABSTRACT Bacterial genotyping through whole-genome sequencing plays a crucial role in disease surveillance and outbreak investigations in public health laboratories. This study assessed the effectiveness of Oxford Nanopore Technologies (ONT) sequencing in the genotyping of Listeria monocytogenes and Salmonella enterica serovar Enteritidis. Our results indicated that ONT sequences, generated with the R10.4.1 flow cell and basecalled using the Dorado 0.5.0 Super Accurate 4.3 model, exhibited comparable accuracy to Illumina sequences, effectively discriminating among bacterial strains from outbreaks. These findings suggest that ONT sequencing has the potential to be a promising tool for rapid whole-genome sequencing of bacterial pathogens in public health laboratories for epidemiological investigations.IMPORTANCEThis study unveils that Oxford Nanopore Technologies sequencing, by itself, holds the potential to serve as a whole-genome sequencing-based genotyping tool in public health laboratories, enabling routine subtyping of bacterial isolates for disease surveillance and outbreak investigations

Listeria monocytogenes are considered to be the major foodborne pathogen worldwide. To understand the prevalence and potential risk of L. monocytogenes in retail foods, a total of 1243 retail foods in 12 food categories were sampled and screened for L. monocytogenes from 2020 to 2022 in Huzhou, China. A total of 46 out of 1234 samples were confirmed to be L. monocytogenes positive with a total rate of 3.7%. The contamination rate of seasoned raw meat (15.2%) was the highest, followed by raw poultry meat and raw livestock meat (9.9%) and salmon sashimi (9.5%). The L. monocytogenes isolates belonged to four serotypes, 1/2a,1/2b, 1/2c, and 4b, with the most prevalent serotype being 1/2a (47.9%). All isolates were grouped into 15 sequence types (STs) belonging to 14 clonal complexes (CCs) via multilocus sequence typing (MLST). The most prevalent ST was ST9/CC9 (23.9%), followed by ST3/CC3 (19.6%) and ST121/CC121 (17.4%). Notably, 11 STs were detected from ready-to-eat (RTE) foods, some of them have been verified to be strongly associated with clinical origin listeriosis cases, such as ST3, ST2, ST5, ST8, and ST87. Listeria pathogenicity islands 1 (LIPI-1) and LIPI-2 were detected in approximately all L. monocytogenes isolates, whereas the distribution of both LIPI-3 genes and LIPI-4 genes exhibited association with specific ST, with LIPI-3 in ST3 and ST288, and LIPI-4 in ST87. The strains carrying LIPI-3 and LIPI-4 virulence genes in this study were all isolated from RTE foods. Antimicrobial susceptibility tests showed that >90% of isolates were susceptible to PEN, AMP, ERY, CIP, SXT, VAN, CHL, and GEN, indicating the antibiotic treatment might be still efficient for most of the L. monocytogenes strains. However, for the three clinical first-line antibiotics (PEN, AMP, and GEN), we also observed three and four strains showing MIC values greater than the susceptibility standards for PEN and AMP, respectively, and one strain showing resistance to GEN.

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 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.

ObjectiveTo utilize whole genome sequencing to comprehensively compare and analyze the genomic characteristics of Listeria monocytogenes （L. monocytogenes） and Listeria innocua （L. innocua） isolated from commercially available foods in Gansu Province.MethodsDuring 2021 and 2022， 25 strains of L. monocytogenes and 7 strains of L. innocua were isolated from commercially available food sources within Gansu Province and subjected to whole genome sequencing for phylogenetic lineage， clonal complex （CC）， sequence type （ST）， virulence gene， resistance gene， and pan-genome analyses.ResultsThe 32 Listeria strains examined could be classified into three distinct groups： L. monocytogenes lineages Ⅰ and Ⅱ and L. innocua. Considering their CC types， further subdivision into 10 subgroups was observed for L. monocytogenes， whereas L. innocua had 5 subgroups. Core genome multi-locus sequence typing effectively differentiated strains with different CC types within each lineage， with lineage Ⅰ showing a closer evolutionary relationship with L. innocua. All 25 L. monocytogenes strains carried Listeria pathogenicity island 1 （LIPI-1） and internalin genes； none carried LIPI-3， and 2 strains of ST87 carried LIPI-4. Conversely， none of the seven strains of L. innocua carried LIPI-1 or internalin genes； however， they all carried LIPI-4， and 5 carried LIPI-3. Among the L. monocytogenes strains， 16 carried surface sensory island 1 （SSI-1）， and 3 carried SSI-2； all 7 L. innocua strains did not carry SSI-1， but 6 of them carried SSI-2. The pan-genome size of L. monocytogenes increased linearly with the number of sequenced genomes. Upon reaching 15 strains， the number of core genes stabilized at 2 272， accounting for 46.2% of the pan-genome genes. Furthermore， 1 487 common core genes were shared between the 25 L. monocytogenes strains and 7 L. innocua strains， with the count tending to stabilize when the strain count reached 10.ConclusionMulti-locus sequence typing of the core genome can effectively distinguish among Listeria strains originating from different lineages and CCs. The similarity in the biochemical characteristics of L. monocytogenes and L. innocua is due to their close genetic relationship， while the differences in their pathogenicity can be attributed to the presence of certain virulence genes in L. monocytogenes.

This study assessed the extent of L. monocytogenes transfer from onions to the surface of a commercial dicer, from inoculated onions to uninoculated onions, and the efficacy of various sanitizers during the subsequent flume washing of diced onions. Spanish yellow onions (Allium cepa L.) were dip-inoculated in a 3-strain avirulent L. monocytogenes cocktail (5.9 or 4.2 log CFU/50 g) and air-dried. After dicing one 2.2 kg batch of onions inoculated at ~5.9 log CFU/50 g followed by ten uninoculated batches of 2.2 kg each, L. monocytogenes progressively decreased from 4.6 to 2.6 log CFU/50 g in baches 1 through 10, respectively. After onions inoculated at ~4.0 log CFU/g were diced and flume washed for 2 min in tap water, electrolyzed water containing 55 ppm free chlorine, 80 ppm free chlorine from a commercial sanitizer, or 80 ppm peroxyacetic acid and dewatered on a mechanical shaker table, L. monocytogenes populations decreased 0.4, 0.3, 1.4, and 1.0 log, respectively, with populations of ~1.2 log CFU/mL in water for all three sanitizers. These findings should be useful in future risk assessments and aid in the development of improved industry guidelines to better enhance the safety of diced onions.

Background: Listeria monocytogenes leads to listeriosis in humans through the consumption of ready-to-eat foods. Older adults, immunocompromised patients, pregnant women, and newborns are at the highest risk for this infection. To detect probiotic bacteria with an inhibitory activity against L. monocytogenes, we evaluated the inhibitory effect of Lactococcus lactis on the growth and invasion of L. monocytogenes. Materials and Methods: In this study, we used the L. monocytogenes ATCC 7644 strain and the L. lactis PTCC 1336 probiotic strain. To investigate the inhibitory effects of L. lactis on the growth of pathogenic L. monocytogenes, we employed the well diffusion agar method, and to investigate its inhibitory effect on invasion by this bacterium, we conducted a co-culture with Caco-2 human enterocyte cells. Results: The results showed that L. lactis in concentrations of 0.25, 0.5, and 1 had antimicrobial properties against L. monocytogenes. With increasing concentration, the inhibitory effect on this pathogen increased. In addition, L. lactis showed an inhibitory effect on the L. monocytogenes invasion of Caco-2 cells. Therefore, in the concentration of 1, L. lactis decreased the number of bacteria by reducing the invasion of the cells by Listeria from log 108 to log 102; in the concentration of 0.5, from log 108 to log 103; and in the concentration of 0.25, from log 108 to log 105. Conclusion: L. lactis has antimicrobial and inhibitory properties against the invasion of L. monocytogenes and can be considered an option to inhibit invasion and gastrointestinal infections caused by this bacterium.

Introduction: Reactive oxygen species cause disease by damaging the chemical compounds in our body. On the other hand, drug resistance is becoming a serious issue in infection treatment, globally. Ginkgo biloba has many therapeutically features. The objective of this study was to evaluate antioxidant and antibacterial activity of Iranian Ginkgo’s leaf extracts. Methods: In this experimental study, aqueous, ethanolic (%70) and methanolic (%80) extracts were made using Ginkgo. Total Phenolic and Flavonoids Content were measured by folin– ciocalteu reagent and Chloride Aluminum color assays. The extracts’ antioxidant activity was assessed by their potential in scavenging DPPH free radicals. Disc Diffusion assay was carried out to test antibacterial potency against two strains of bacteria (Enterococcus faecalis, Listeria monocytogenes). Data analysis was performed using factorial experiment within a completely randomized design. SPSS version 16 software and Duncan's multiple range tests were used to compare the means. Results: Based on results, all three extracts contained extensive amount of phenolic and especially flavonoid compounds with methanolic extract being the richest in phenolic and flavonoids while aqueous extract having the least of these compounds. The most antioxidant activity was found in methanolic extract of 300 mg/mL concentration with %84.73 (P

In order to improve the stability of vanillin by polysaccharide-protein interaction and to investigate the inhibitory effect of the composite nanocarrier on Listeria monocytogenes and E. coli, a vanillin-loaded composite nanocarrier of corn bran arabinoxylan (AX) and zein was prepared. Two crude polysaccharide fractions of corn bran were obtained by precipitating with 80% and 90% ethanol. Four fractions (F80-1, F80-2, F90-1, and F90-2) were subjected to anion-exchange chromatography purification. The monosaccharide composition of the fractions was determined using gas chromatography. It was found that the total content of arabinose and xylose in each fraction was 67.41%, 76.12%, 77.16%, and 84.89%, respectively, and the encapsulation rate of vanillin in the composite nanoparticles of the four fractions was 81.18%, 69.36%, 86.80%, and 88.48%, respectively. The vanillin encapsulation and the intermolecular interaction in the composite nanocarriers were verified by fluorescence spectrometry and differential scanning calorimetry (DSC). Bacterial inhibition experiments showed that F80-2 composite nanocarriers were most effective at inhibiting Listeria monocytogenes, and F90-2 composite nanocarriers were most effective at inhibiting E. coli.

ObjectiveTo analyze the contamination of Salmonella， Listeria monocytogenes （L. monocytogenes）， and Yersinia enterocolitica （Y. enterocolitica） in raw poultry meat and prepared meat products in Shanghai City.MethodsFrom January to August in 2022， 348 samples were collected from traditional markets， supermarkets， and restaurants in Shanghai City， including 240 raw poultry meat and 108 prepared meat products. The samples were evaluated for the presence of Salmonella， L. monocytogenes and Y. enterocolitica following national standard methods. All suspected isolates were further confirmed with the VITEK2 automatic biochemical identification method， and all Salmonella isolates were serotyped.ResultsThe detection rates of Salmonella， L. monocytogenes and Y. enterocolitica in raw poultry meat were 28.33% （68/240）， 5.00% （12/240）， and 0.83% （2/240）， respectively， and in prepared meat products were 5.56% （6/108）， 28.70% （31/108）， and 1.85% （2/108）， respectively. Serotyping results showed that 68 strains of Salmonella were distributed in 14 different serotypes in raw poultry meat， of which Salmonella Corvallis， Salmonella typhimurium， and Salmonella enteritidis accounted for 35.29%，16.18%， and 13.24%， respectively. Six strains of Salmonella in prepared meat products were distributed in three different serotypes. They were Salmonella enteritidis， Salmonella Kentucky， and Salmonella typhimurium accounted for 66.67%，16.67%， and 16.67%，respectively .ConclusionThe contamination rate of Salmonella and L. monocytogenes in raw poultry meat and prepared meat products in Shanghai City was high， which may cause foodborne diseases and more attention should be paid in the follow-up supervision.

Abstract Listeria monocytogenes is an important foodborne pathogen that incorporated into many serious infections in human especially immunocompromised individuals, pregnant women, the elderly, and newborns. The consumption of food contaminated with such bacteria is considered a source of potential risk for consumers. Therefore, a total of 250 poultry purchased in highly popular poultry stores besides 50 swabs from workers hands in the same stores, in Mansoura City had been tested for the L. monocytogenes prevalence, virulence genes, and antibiotic resistance profile illustrating the health hazards from such poultry. The L. monocytogenes were recovered from 9.6% of poultry samples while not detected from workers hand swabs. The antimicrobial susceptibility of 24 L. monocytogenes strains against 24 antibiotics of seven different classes revealed high susceptibility rates to erythromycin (79.17%), streptomycin (66.67%), gentamycin (66.67%), vancomycin (58.33%), chloramphenicol (58.33%) and cefotaxime (41.67%). The majority (79.2%) of L. monocytogenes were classified as multidrug resistant strains with high resistance to tetracyclines and β-lactams antibiotics while 16.7% of the strains were categorized as extensively resistant ones. The iap virulence-specific determination gene had been detected in all recovered L. monocytogenes isolates while 83.33 and 70.83% of the isolates harbored hylA and actA genes. In addition, the study confirmed the capability of most L. monocytogenes isolates for biofilm formation by moderate to strong production and the quantitative risk assessment illustrated the risk of developing listeriosis as the risk value exceeded 100. The current results illustrate that poultry meat can be a source of pathogenic antibiotic resistant strains that may cause infection with limited or no treatment in immunosuppressed consumers via the food chain.

Ligilactobacillus is a genus of Gram-positive lactobacilli commonly found in the intestinal tracts of vertebrates. It has been granted a Qualified Presumption of Safety (QPS) status from the European Food Safety Authority (EFSA). One specific strain, Ligilactobacillus salivarius B4311, was isolated from fecal samples of broiler chickens from a farm associated with Chung-Ang University (Anseong, Korea). This strain was observed to have inhibitory effects against Listeria monocytogenes. In this paper, we present the complete genome sequence of Lig. salivarius B4311. The whole genome of strain B4311 comprises 2,071,255 bp assembled into 3 contigs representing a chromosome, repA-type megaplasmid, and small plasmid. The genome contains 1,963 protein-coding sequences, 22 rRNA genes, and 78 tRNA genes, with a guanine + cytosine (GC) content of 33.1%. The megaplasmid of strain B4311 was found to contain the bacteriocin gene cluster for salivaricin P, a two-peptide bacteriocin belonging to class IIb.

Jingrui Zhang,1,&ast; Zengbin Liu,2,&ast; Zhirong Li,2 Caihong Xu,1 Hongbin Wang,3 Rugang Yang,1 Li Liu1 1Department of Clinical Laboratory, The Fourth Hospital of Shijiazhuang, Shijiazhuang, Hebei, People’s Republic of China; 2Department of Clinical Laboratory, The Second Hospital of Hebei Medical University, Shijiazhuang, Hebei, People’s Republic of China; 3Department of Gynecology and Obstetrics, The Fourth Hospital of Shijiazhuang, Shijiazhuang, Hebei, People’s Republic of China&ast;These authors contributed equally to this workCorrespondence: Jingrui Zhang; Li Liu, The Fourth Hospital of Shijiazhuang, Shijiazhuang, 050000, People’s Republic of China, Email jingrui20005@163.com; liuliok2012@163.comBackground: Maternal–fetal listeriosis, caused by Listeria monocytogenes, is a rare but serious infection. Herein, we report the clinical and genomic characteristics of a clinical L. monocytogenes ST120 isolate recovered from a pregnant woman.Methods: The clinical symptoms and treatment in pregnant woman were described in detail. Whole genome sequencing (WGS) was performed on the L. monocytogenes isolate SJZ_LM001, and the genomic characterization of the isolate was deeply analyzed.Results: The clinical symptoms in pregnant women were mainly fever, and the placenta experienced severe inflammation. The pregnant woman was treated with ampicillin for effective anti-infective therapy. Genomic analysis showed that isolate SJZ_LM001 is sequence type (ST) 120, belong to clonal complex (CC)8 and lineage II of L. monocytogenes. Additionally, the isolates SJZ_LM001 harbored a novel plasmid pSJZ_LM001, which carried arsenical resistance genes (arsACD and acr3), and cadmium resistance genes (cadAC). Drug susceptibility testing showed that the isolate SJZ-LM001 was susceptible to ampicillin, meropenem, penicillin, and cotrimoxazole.Conclusion: This is the first to identify a clinical case of infection in a pregnant woman caused by ST120 L. monocytogenes in China. These findings could benefit our understanding of the genomic characteristics of L. monocytogenes, and the pregnancy-related listeriosis and providing early diagnosis and effective targeted treatment.Keywords: Listeria monocytogenes, whole genome sequence, ST120, plasmid

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.

The safety of uncooked fermented, dried sausages relies upon controlled fermentation and drying that inactivates pathogenic bacteria. Current guidelines for the production of fermented sausages by the United States Department of Agriculture (USDA) Food Safety Inspection Services (FSIS) and related research highlight specific safety parameters. The confidence that processing steps, which do not include cooking, inherently mitigate microbial risks, is challenged by the resilience of pathogens in the dry and acidic environments of these food products. The aim of this work was to examine the length of drying required to achieve a target pathogen reduction across a range of sausage diameters. This study investigated the relationship between product diameter and time required to achieve target reductions of Escherichia coli O157:H7, Salmonella enterica, and Listeria monocytogenes, as well as the attainment of specific water activity (aw). The research utilized salami and summer sausage with diameters of 18 mm, 30 mm, 60 mm, 90 mm, and 110 mm. Sausage batter was inoculated with 5 strains each of E. coli O157:H7, L. monocytogenes, and S. enterica. Inoculated sausages were processed with fermentation and drying protocols for each sausage type. Smaller diameter sausages reached both the desired pathogen reduction and target aw of 0.85 sooner than larger ones. However, the time to achieve the target aw did not align with the time to achieve the pathogen reduction targets, suggesting that aw alone is not a reliable indicator of safety. Another finding was larger sausages achieved the target pathogen reduction without reaching the target aw, suggesting complex relationship between aw, diameter, and pathogen inactivation. These data support the need for food safety guidelines that consider drying duration, aw, and pathogen behavior for varying sausage diameters. This research contributes to developing more precise safety protocols for producing dry and semi-dry fermented sausages.

Field-packing of cantaloupes involves numerous food contact surfaces that can contamination melons with foodborne pathogens; the soil on these surfaces increases throughout the harvest day. Data are lacking on the cross-contamination risk from contaminated food contact surfaces under the dry conditions typical of cantaloupe field-packing operations. This study sought to evaluate the survival of Salmonella and Listeria monocytogenes on cantaloupe field-pack food contact surfaces using both a wet and dry inoculum to provide insights into managing foodborne pathogen contamination risks. Five clean or fouled materials (cotton gloves, nitrile gloves, rubber gloves, cotton rags, and stainless steel) were inoculated with a cocktail of either Salmonella or L. monocytogenes. A wet inoculum was spot inoculated (100 µL) onto coupons. A dry inoculum was prepared by mixing wet inoculum with 100 g of sterile sand and shaking the coupons with the inoculated sand for 2 min. Coupons were held at 35°C (35% RH) and enumerated at 0, 2, 4, 6, and 8 h. Significant differences in pathogen concentrations over time were calculated, and the GInaFiT add-in tool for Excel was used to build Log-linear, Weibull, and Biphasic die-off models. Depending on the material type, coupon condition, and inoculum type, Salmonella and L. monocytogenes reductions over 8 h ranged from 0.3 to 3.3 and −0.4 to 4.2 log10 CFU/coupon, respectively. For all material types, Salmonella reductions were highest on wet-inoculated clean coupons; L. monocytogenes varied by material type. Weibull and biphasic models were a better fit of respective pathogen die-off curves than linear models. Overall, faster die-off rates were seen for wet inoculated and clean materials. Since pathogen populations remained viable over the study duration and both inoculum type and coupon condition impacted survival, frequent sanitation or replacement of food contact surfaces during the operational day is needed to reduce the risk of cross-contamination.

The objective of this study was to reveal the antibacterial mode of action of garviecin LG34 against S. aureus CICC 21600 and L. monocytogenes CICC 21633 and measure the inhibitions on these two foodborne pathogenic bacteria in milk. Antibacterial mechanism of garviecin LG34 was ascertained by its effect on the efflux of Potassium (K+) ions, extracellular electrical conductivity, UV-absorbing substances, potential across the membrane (ΔΨ), and cell permeability. The inhibition of garviecin LG34 against S. aureus CICC 21600 and L. monocytogenes CICC 21600 in milk was studied by viable counting method. Supplementation with 160 AU/ml of garviecin LG34 had a bactericidal effect on S. aureus CICC 21600 and L. monocytogenes CICC 21633. A total of 80, 160, and 320 AU/ml of garviecin LG34 resulted in the effusion of potassium ion and UV-absorbing substances, the leakage of cellular electrolytes, and the dissipation of electrical potential across the membrane of these two food-borne bacteria and showed a dose-dependent. Moreover, the increase in cell permeability of both strains was observed by flow cytometer after cells treated with 160 AU/ml of garviecin LG34. Garviecin LG34 significantly inhibited the growth of these two food-borne bacteria in milk, especially in skimmed milk. Garviecin LG34 could cause pore formation, intracellular materials release, and permeability increase of S. aureus CICC 21600 and L. monocytogenes CICC 21633, and could be applied to milk as bio-preservative.

Listeria monocytogenes (Lm) is a Gram-positive bacterium causing listeriosis, a rare but severe foodborne infection, particularly impactful during pregnancy. Maternal-fetal transmission can lead to adverse fetal outcomes, yet symptoms in mothers may be nonspecific, delaying intervention. Despite the severity, the mechanisms of vertical transmission remain unclear. This report describes a case of rapid Lm diagnosis in a preterm newborn using cord blood and placental swabs. A 31-week pregnant woman presented with abdominal pain, diarrhea, and reduced fetal movements after consuming raw sushi. Laboratory findings indicated infection, and she vaginally delivered a live infant with placental and fetal abscesses. Cultures confirmed Lm, with swift diagnosis aided by molecular syndromic testing. The neonate received appropriate antibiotics and was asymptomatic by the end of treatment. This case underscores the need for the rapid diagnosis of maternal-fetal listeriosis, as it poses significant risks during pregnancy, including preterm birth and neonatal complications. Current diagnostic methods often delay treatment. This report emphasizes the use of innovative molecular techniques for early diagnosis, which is crucial in managing neonatal infections, especially in preterm newborns.

Listeria monocytogenes (L. monocytogenes) is a foodborne pathogen with high morbidity and mortality rates, necessitating rapid detection methods. Current techniques, while reliable, are labor-intensive and not amenable to on-site testing. We report the design and synthesis of a novel imprinted upconversion fluorescence probe through Pickering emulsion polymerization for the specific detection of L. monocytogenes. The probe employs trimethylolpropane trimethacrylate and divinylbenzene as cross-linkers, acryloyl-modified chitosan as a functional monomer, and the bacterium itself as the template. The developed probe demonstrated high specificity and sensitivity in detecting L. monocytogenes, with a limit of detection of 72 CFU/mL. It effectively identified the pathogen in contaminated salmon and chicken samples, with minimal background interference. The integration of molecular imprinting and upconversion fluorescence materials presents a potent and reliable approach for the rapid and specific detection of L. monocytogenes, offering considerable potential for on-site food safety testing.

ABSTRACT The placenta is a critical barrier against viral, bacterial, and eukaryotic pathogens. For most teratogenic pathogens, the precise molecular mechanisms of placental resistance are still being unraveled. Given the importance of understanding these mechanisms and challenges in replicating trophoblast-pathogen interactions using in vitro models, we tested an existing stem-cell-derived model of trophoblast development for its relevance to infection with Toxoplasma gondii. We grew human trophoblast stem cells (TSCT) under conditions leading to either syncytiotrophoblast (TSSYN) or cytotrophoblast (TSCYT) and infected them with T. gondii. We evaluated T. gondii proliferation and invasion, cell ultrastructure, as well as for transcriptome changes after infection. TSSYNs cells showed similar ultrastructure compared to primary cells and villous explants when analyzed by transmission electron microscopy and scanning electron microscopy (SEM), a resistance to T. gondii adhesion could be visualized on the SEM level. Furthermore, TSSYNs were highly refractory to parasite adhesion and replication, while TSCYTs were not. RNA-seq data on mock-treated and infected cells identified differences between cell types as well as how they responded to T. gondii infection. We also evaluated if TSSC-derived SYNs and CYTs had distinct resistance profiles to another vertically transmitted facultative intracellular pathogen, Listeria monocytogenes. We demonstrate that TSSYNs are highly resistant to L. monocytogenes, while TSCYTs are not. Like T. gondii, TSSYN resistance to L. monocytogenes was at the level of bacterial adhesion. Altogether, our data indicate that stem-cell-derived trophoblasts recapitulate resistance profiles of primary cells to T. gondii and highlight the critical importance of the placental surface in cell-autonomous resistance to teratogens.IMPORTANCECongenital toxoplasmosis can cause a devastating consequence to the fetus. To reach the fetus’s tissues, Toxoplasma gondii must cross the placenta barrier. However, how this parasite crosses the placenta and the precise molecular mechanisms of placental resistance to this parasite are still unknown. In this study, we aimed to characterize a new cellular model of human trophoblast stem cells to determine their resistance, susceptibility, and response to T. gondii. Syncytiotrophoblast derived from trophoblast stem cells recapitulate the resistance profile similarly to placenta cells. We also showed that these cells are highly resistant to Listeria monocytogenes, at the level of bacterial adhesion. Our results suggest that resisting pathogen adhesion/attachment may be a generalized mechanism of syncytiotrophoblast resistance, and trophoblast stem cells represent a promising model to investigate cell-intrinsic mechanisms of resistance to pathogen adhesion and replication.

As a common foodborne pathogen, infection with L. monocytogenes poses a significant threat to human life and health. The objective of this study was to employ comparative genomics to unveil the biodiversity and evolutionary characteristics of L. monocytogenes strains from different regions, screening for potential target genes and mining novel target genes, thus providing significant reference value for the specific molecular detection and therapeutic targets of L. monocytogenes strains. Pan-genomic analysis revealed that L. monocytogenes from different regions have open genomes, providing a solid genetic basis for adaptation to different environments. These strains contain numerous virulence genes that contribute to their high pathogenicity. They also exhibit relatively high resistance to phosphonic acid, glycopeptide, lincosamide, and peptide antibiotics. The results of mobile genetic elements indicate that, despite being located in different geographical locations, there is a certain degree of similarity in bacterial genome evolution and adaptation to specific environmental pressures. The potential target genes identified through pan-genomics are primarily associated with the fundamental life activities and infection invasion of L. monocytogenes, including known targets such as inlB, which can be utilized for molecular detection and therapeutic purposes. After screening a large number of potential target genes, we further screened them using hub gene selection methods to mining novel target genes. The present study employed eight different hub gene screening methods, ultimately identifying ten highly connected hub genes (bglF_1, davD, menE_1, tilS, dapX, iolC, gshAB, cysG, trpA, and hisC), which play crucial roles in the pathogenesis of L. monocytogenes. The results of pan-genomic analysis showed that L. monocytogenes from different regions exhibit high similarity in bacterial genome evolution. The PCR results demonstrated the excellent specificity of the bglF_1 and davD genes for L. monocytogenes. Therefore, the bglF_1 and davD genes hold promise as specific molecular detection and therapeutic targets for L. monocytogenes strains from different regions.