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

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

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

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

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

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

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

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

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

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

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

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

Foodborne illnesses can be infectious and dangerous, and most of them are caused by bacteria. Some common food-related bacteria species exist widely in nature and pose a serious threat to both humans and animals; they can cause poisoning, diseases, disabilities and even death. Rapid, reliable and cost-effective methods for bacterial detection are of paramount importance in food safety and environmental monitoring. Polymerase chain reaction (PCR), lateral flow immunochromatographic assay (LFIA) and electrochemical methods have been widely used in food safety and environmental monitoring. In this paper, the recent developments (2013–2023) covering PCR, LFIA and electrochemical methods for various bacterial species (Salmonella, Listeria, Campylobacter, Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli)), considering different food sample types, analytical performances and the reported limit of detection (LOD), are discussed. It was found that the bacteria species and food sample type contributed significantly to the analytical performance and LOD. Detection via LFIA has a higher average LOD (24 CFU/mL) than detection via electrochemical methods (12 CFU/mL) and PCR (6 CFU/mL). Salmonella and E. coli in the Pseudomonadota domain usually have low LODs. LODs are usually lower for detection in fish and eggs. Gold and iron nanoparticles were the most studied in the reported articles for LFIA, and average LODs were 26 CFU/mL and 12 CFU/mL, respectively. The electrochemical method revealed that the average LOD was highest for cyclic voltammetry (CV) at 18 CFU/mL, followed by electrochemical impedance spectroscopy (EIS) at 12 CFU/mL and differential pulse voltammetry (DPV) at 8 CFU/mL. LOD usually decreases when the sample number increases until it remains unchanged. Exponential relations (R2 > 0.95) between LODs of Listeria in milk via LFIA and via the electrochemical method with sample numbers have been obtained. Finally, the review discusses challenges and future perspectives (including the role of nanomaterials/advanced materials) to improve analytical performance for bacterial detection. [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]

Background: The in-depth understanding of the role of lateral genetic transfer (LGT) in phage-prophage interactions is essential to rationalizing phage applications for human and animal therapy, as well as for food and environmental safety. This in silico study aimed to detect LGT between phages of potential industrial importance and their hosts. Methods: A large array of genetic recombination detection algorithms, implemented in SplitsTree and RDP4, was applied to detect LGT between various Escherichia, Listeria, Salmonella, Campylobacter, Staphylococcus, Pseudomonas, and Vibrio phages and their hosts. PHASTER and RAST were employed respectively to identify prophages across the host genome and to annotate LGT-affected genes with unknown functions. PhageAI was used to gain deeper insights into the life cycle history of recombined phages. Results: The split decomposition inferences (bootstrap values: 91.3–100; fit: 91.433-100), coupled with the Phi (0.0-2.836E-12) and RDP4 (P being well below 0.05) statistics, provided strong evidence for LGT between certain Escherichia, Listeria, Salmonella, and Campylobacter virulent phages and prophages of their hosts. The LGT events entailed mainly the phage genes encoding for hypothetical proteins, while some of these genetic loci appeared to have been affected even by intergeneric recombination in specific E. coli and S. enterica virulent phages when interacting with their host prophages. Moreover, it is shown that certain L. monocytogenes virulent phages could serve at least as the donors of the gene loci, involved in encoding for the basal promoter specificity factor, for L. monocytogenes. In contrast, the large genetic clusters were determined to have been simultaneously exchanged by many S. aureus prophages and some Staphylococcus temperate phages proposed earlier as potential therapeutic candidates (in their native or modified state). The above genetic clusters were found to encompass multiple genes encoding for various proteins, such as e.g., phage tail proteins, the capsid and scaffold proteins, holins, and transcriptional terminator proteins. Conclusions: It is suggested that phage-prophage interactions, mediated by LGT (including intergeneric recombination), can have a far-reaching impact on the co-evolutionary trajectories of industrial phages and their hosts especially when excessively present across microbially rich environments. [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]

Introduction: Foodborne diseases constitute one of the significant public health problems worldwide. There needs to be knowledge about the microbiological quality of raw bovine milk in Paipa and surrounding areas in Colombia. Objective: To determine the microbiological quality of raw bovine milk from a farm in Paipa, Boyacá. Method: A descriptive cross-sectional study was conducted, collecting raw bovine milk samples to be microbiologically analyzed. This analysis included counting mesophilic aerobes, coagulase-positive Staphylococcus aureus, total and fecal coliforms, molds, and yeasts, as well as detecting the presence/absence of pathogenic bacteria such as Listeria sp. and Salmonella sp. Results: Twenty-five raw milk samples were analyzed, revealing that most of the samples did not meet the permissible limits set by the standard. The prevalence of Salmonella sp. was 24%, contrary to Listeria sp., which was 0%. Conclusions: The raw milk samples did not comply with the permissible limits of the regulations governing Colombia. More studies are recommended to understand the microbiological reality of milk in the region. [ABSTRACT FROM AUTHOR]

Listeria monocytogenes (L. monocytogenes) is a food-borne pathogenic bacteria that frequently contaminates animal-derived food and low-temperature preserved food. Listeriosis caused by its infection has a high mortality rate and poses a serious threat to human health. Therefore, it is crucial to establish a sensitive, rapid and easy-to-operate technique. In this study, a Recombinase Aided Amplification (RAA) assisted CRISPR/Cas12a (RAA-CRISPR/Cas12a) fluorescence platform was established for highly sensitive nucleic acid detection of L. monocytogenes. The established RAA-CRISPR/Cas12a showed high sensitivity and high specificity, with the sensitivity of 350 CFU/mL and 5.4 × 10−3 ng/μL for pure bacterial solution and genomic DNA, and good specificity for 5 strains of Listeria spp. and 14 strains of other common pathogenic bacteria. L. monocytogenes could be detected at an initial concentration of 2.3 CFU/25g within 2 h of enriching the beef in the food matrix, and this method could be applied to food samples that were easily contaminated with L. monocytogenes The results of RAA-CRISPR/Cas12a could be observed in 5 min, while the amplification was completed in 20–30 min. The speed and sensitivity of RAA-CRISPR/Cas12a were significantly higher than that of the national standard method. In conclusion, the RAA-CRISPR/Cas12a system established in this study has new application potential in the diagnosis of food-borne pathogens. [ABSTRACT FROM AUTHOR]

Objective To observe the effect of deubiquitinase Abraxas brother 1 (ABRO1) on the release of interleu‐ kin (IL)-1β from monocyte macrophage J774A. 1 in mice induced by listeriolysin O (LLO), and to explore the relevant mechanisms. Methods J774A. 1 cells were cultured and infected with wild-type Listeria monocytogenes (LM) strains with LLO (wild-type group), hly gene deficient (Δhly) LM strains with LLO knockout (gene deficient group), and Δhly strains supplemented with hly gene LM strains (replenishment group), respectively. Western blotting was used to detect ABRO1 protein, and ELISA was used to detect IL-1β in the supernatant of cell culture medium. We divided J774A. 1 cells into NI group (uninfected LM strain), WT group (infected WT LM strain), and Δhly group (infected Δhly LM strain), and cells in each group were transfected with NCsiRNA and ABRO1siRNA, respectively. The IL-1β in the super‐ natant of the cell culture medium was detected by ELISA, and Western blotting was used to detect inflammasome-related molecules Caspase-1, p20, and IL-1β, and p17. Results Over the infection time, the expression of ABRO1 and IL-1β levels gradually increased in the wild-type group and the replenishment group, reaching their highest levels at 120 minutes of infection, and both were higher than those in the gene deficient group (all P<0. 05). There were no significant changes in ABRO1 expression or IL-1β levels at different time points in the gene deficient group. The level of IL-1β and expression of p20 and p17 in the supernatant of cells transfected with ABRO1 siRNA in the WT group were lower than those in cells transfected with NC siRNA （all P<0. 05）. The level of IL-1β and expression of p20 and p17 in the supernatant of cells transfected with NC siRNA in the WT group were higher than those in the NI group （all P<0. 05）. The level of IL-1β and expression of p20 and p17 in the supernatant of cells transfected with NC siRNA in the Δhly group were lower than those in the WT group （all P<0. 05）. Conclusions Under the induction of LLO， the expression of ABRO1 increased in J774A. 1 cells. After down-regulating ABRO1 expression， the release of IL-1β in LLO-induced J774A. 1 cells decreased； LLO may promote LLO-mediated IL-1β release by activating inflammasomes. [ABSTRACT FROM AUTHOR]

Listeria monocytogenes is a pathogenic foodborne bacterium that is a significant cause of mortality associated with foodborne illness and causes many food recalls attributed to a bacteriological cause. Their ability to form biofilms contributes to the persistence of Listeria spp. in food processing environments. When growing as biofilms, L. monocytogenes are more resistant to sanitizers used in the food industry, such as benzalkonium chloride (BAC), as well as to physical stresses like desiccation and starvation. Lytic phages of Listeria are antagonistic to a broad range of Listeria spp. and may, therefore, have utility in reducing the occurrence of Listeria-associated food recalls by preventing food contamination. We screened nine closely related Listeria phages, including the commercially available Listex P100, for host range and ability to degrade microtiter plate biofilms of L. monocytogenes ATCC 19111 (serovar 1/2a). One phage, CKA15, was selected and shown to rapidly adsorb to its host under conditions relevant to applying the phage in dairy processing environments. Under simulated dairy processing conditions (SDPC), CKA15 caused a 2-log reduction in Lm19111 biofilm bacteria. This work supports the biosanitation potential of phage CKA15 and provides a basis for further investigation of phage-bacteria interactions in biofilms grown under SDPC. IMPORTANCE Listeria monocytogenes is a pathogenic bacterium that is especially dangerous for children, the elderly, pregnant women, and immune-compromised people. Because of this, the food industry takes its presence in their plants seriously. Food recalls due to L. monocytogenes are common with a high associated economic cost. In food-processing plants, Listeria spp. typically reside in biofilms, which are structures produced by bacteria that shield them from environmental stressors and are often attached to surfaces. The significance of our work is that we show a bacteriophage—a virus-infecting bacteria—can reduce Listeria counts by two orders of magnitude when the bacterial biofilms were grown under simulated dairy processing conditions. This work provides insights into how phages may be tested and used to develop biosanitizers that are effective but are not harmful to the environment or human health. [ABSTRACT FROM AUTHOR]

Objectives: This study aimed to assess the antibacterial activity of the crude venom of Pseudocerastes persicus against some Gram-negative and Gram-positive bacteria using an antimicrobial susceptibility test. Methods: The susceptibility of Methicillin-Resistant Staphylococcus aureus (MRSA), Listeria monocytogenes, Bacillus subtilis, Salmonella typhimurium, and E. coli O157:H7 to the crude venom of Pseudocerastes persicus was investigated at a concentration of 100 pg/ml. Standard antibiotic disks were utilized as positive controls. Furthermore, the minimum inhibitory concentration (MIC) against Staphylococcus aureus and MRSA was determined through the dilution method (160-1.25 pg/ml). These MIC values were compared with those of conventional drugs such as streptomycin (25 pg), tetracycline (30 pg), and neomycin (25 pg). Results: The crude venom exhibited significant antibacterial activity against Staphylococcus aureus, MRSA, Listeria monocytogenes, and E. coli O157:H7. It displayed moderate effects on Salmonella typhimurium but showed no significant impact on Bacillus subtilis. The MIC values against these bacteria ranged from 160 to 80 pg/ml. Conclusion: The venom from Pseudocerastes persicus demonstrates antibacterial properties and shows potential therapeutic value. Further investigations involving fractionation are necessary to fully explore its therapeutic potential. [ABSTRACT FROM AUTHOR]

Even though differences in methodology (e.g., sample volume and detection method) have been shown to affect observed microbial water quality, multiple sampling and laboratory protocols continue to be used for water quality monitoring. Research is needed to determine how these differences impact the comparability of findings to generate best management practices and the ability to perform metaanalyses. This study addresses this knowledge gap by compiling and analyzing a data set representing 2,429,990 unique data points on at least one microbial water quality target (e.g., Salmonella presence and Escherichia coli concentration). Variance partitioning analysis was used to quantify the variance in likelihood of detecting each pathogenic target that was uniquely and jointly attributable to non-methodological versus methodological factors. The strength of the association between microbial water quality and select methodological and non-methodological factors was quant ified using conditional forest and regression analysis. Fecal indicator bacteria concentrations were more strongly associated with non-methodological factors than methodological factors based on conditional forest analysis. Variance partitioning analysis could not disentangle non-methodological and methodological signals for pathogenic Escherichia coli, Salmonella, and Listeria. This suggests our current perceptions of foodborne pathogen ecology in water systems are confounded by methodological difference s between studies. For example, 31% of total variance in likelihood of Salmonella detection was explained by methodological and/or non-methodological factors, 18% was jointly attributable to both methodological and non-methodological factors. Only 13% of total variance was uniquely attributable to non-methodological factors for Salmonella, highlighting the need for standardization of methods for microbiological water quality testing for comparison across studies. [ABSTRACT FROM AUTHOR]

Introduction: Foodborne diseases are caused by the ingestion of food contaminated with infectious agents that can cause damage to the consumer's health. Objective: To microbiologically characterize fresh artisanal cheeses from Hoya del Río Suárez, Colombia. Method: Stratified convenience sampling was performed, and pathogenic and non-pathogenic microorganisms were identified. Results: 211 samples were analyzed in the period 2021-2022 the presence of Salmonella sp. was determined in 38.3% (n=81) and Listeria sp. in 42.6% (n=90). Additionally, 12.3% (n=26), 1.8% (n=4) and 11.8% (n=25) of the samples presented Staphylococcus aureus, total Coliforms and fecal Coliforms counts respectively. Conclusions: The isolation of highly pathogenic microorganisms such as Salmonella sp. and Listeria sp. It is of relevance in public health. The results obtained will allow the standards of good manufacturing practices to be socialized to producers and marketers, to optimize the quality of fresh cheese and thus improve food security in the region. It is recommended to carry out future studies to expand knowledge of the microbiology of this type of food. [ABSTRACT FROM AUTHOR]

Background: Listeriosis is a severe foodborne infection caused by Listeria monocytogenes, an important foodborne pathogen of animals and humans. Listeriosis is a rare disease in cats. Objective: To describe the clinical, diagnostic imaging, histological, and microbiological features of L. monocytogenes‐associated mesenteric lymphadenitis in a cat. Animals: Listeria monocytogenes‐associated mesenteric lymphadenitis was confirmed in a cat by histology and microbiology. Results: Two distinct isolates of L. monocytogenes were cultured from the affected mesenteric lymph node and whole genome sequencing was performed. Conclusion and Clinical Importance: This report should alert veterinary clinicians and microbiologists to the syndrome, which may have implications for health and food safety in animals and humans. [ABSTRACT FROM AUTHOR]

The common gastrointestinal commensal Akkermansia muciniphila is a mucin-degrading bacterium that is greatly reduced in individuals consuming a high-fat diet. Increasing evidence from a variety of clinical and pre-clinical studies suggests that oral supplementation with Akkermansia can improve metabolic health and moderate systemic inflammation. We and others have demonstrated a role for Akkermansia administration in protection against infectious disease and the outcome from sepsis. Very recent studies have indicated the molecular mechanisms by which A. muciniphila may interact with the host to influence systemic immune-regulation and control of microbial pathogenesis. Here we consider recent studies which demonstrate the efficacy of this potential next-generation probiotic in animal models of Salmonella Typhimurium, Listeria monocytogenes and Clostridioides difficile as well as influenza virus and phlebovirus. The potential mechanisms by which A. muciniphila may influence local and systemic immune responses are discussed. [ABSTRACT FROM AUTHOR]

This study was aimed to find out how common Listeria monocytogenes in a group of Iraqi women who had miscarriages. Also, investigates the dependability of molecular diagnosis, specifically evaluating the target hlyA gene as an alternate solution tool for identification. A total of 200 specimens comprising cervical swabs were collected from 176 women suffered from miscarriage and 24 women as control. The detection of L. monocytogenes in miscarriages women by using HiCrome™ Listeria Agar Base as both a selective and differential agar medium for quick and direct recognition of Listeria species. The biochemical tests were achieved for confirmation identification. In addition, virulenceassociated genes (hlyA gene) isolates were identified using a Real-time PCR approach. Results show out of the 200 (patients and control) specimens, 176 women with miscarriages were analyzed and it was found that 117 (66.5%) specimens from abortion cases were negative for L. monocytogenes, while 59 (33.5%) specimens were positive for Listeria species. All 24 women of control give negative result. Seventy-five (32.4%) isolates from the 59 positive women showed the presence of the hlyA gene in Real-time PCR. We found that molecular diagnostic through Real-Time PCR is a quick and accurate diagnostic method that can help minimize the time it takes to start a specific treatment and track its success. [ABSTRACT FROM AUTHOR]

The present study was undertaken to investigate the difference in carbohydrate metabolization between Listeria ivanovii wild-type strain and a pediocin-resistant variant. The growth and organic acid production of both L. ivanovii strains under different carbohydrate conditions in the presence or absence of pediocin were investigated. At the genetic level, the mannose phosphotransferase system (Man-PTS) related genes were analysed at the transcriptional level. In contrast to the rapid growth of wild-type strain cultured in mannose and glucose, cellobiose appeared to be the most efficiently utilized carbohydrate for the resistant variant. Pediocin addition caused a decline in OD600, which for the resistant variant was especially pronounced in the mannose medium. The resistant variant cultured in cellobiose displayed the highest lactic acid production in the presence of pediocin. Upregulation of mptA, mptC and mptD was detected in the L. ivanovii resistant cells cultured in glucose and mannose media, while downregulation of these genes was observed when cultured in the presence of cellobiose and fructose. These results suggested that there were inherent connection between carbohydrate metabolism and L. ivanovii sensitivity to pediocin, which may provide clue for unraveling mechanism of resistance development. [ABSTRACT FROM AUTHOR]

The foodborne pathogen Listeria monocytogenes can grow in a wide range of environmental conditions. For the study of the physiology of this organism, several chemically defined media have been developed over the past decades. Here, we examined the ability of L. monocytogenes wildtype strains EGD‐e and 10403S to grow under salt and pH stress in Listeria synthetic medium (LSM). Furthermore, we determined that a wide range of carbon sources could support the growth of both wildtype strains in LSM. However, for hexose phosphate sugars such as glucose‐1‐phosphate, both L. monocytogenes strains need to be pre‐grown under conditions, where the major virulence regulator PrfA is active. In addition, growth of both L. monocytogenes strains was observed when LSM was supplemented with the amino acid sugar N‐acetylmannosamine (ManNAc). We were able to show that some of the proteins encoded in the operon lmo2795‐nanE, such as the ManNAc‐6‐phosphate epimerase NanE, are required for growth in the presence of ManNAc. The first gene of the operon, lmo2795, encodes a transcriptional regulator of the RpiR family. Using electrophoretic mobility shift assays and quantitative real‐time PCR analysis, we were able to show that Lmo2795 binds to the promoter region of the operon lmo2795‐nanE and activates its expression. [ABSTRACT FROM AUTHOR]

This report by the European Food Safety Authority and the European Centre for Disease Prevention and Control presents the results of the zoonoses monitoring and surveillance activities carried out in 2022 in 27 Member States (MSs), the United Kingdom (Northern Ireland) and 11 non‐MSs. Key statistics on zoonoses and zoonotic agents in humans, food, animals and feed are provided and interpreted historically. In 2022, the first and second most reported zoonoses in humans were campylobacteriosis and salmonellosis, respectively. The number of cases of campylobacteriosis and salmonellosis remained stable in comparison with 2021. Nineteen MSs and the United Kingdom (Northern Ireland) achieved all the established targets in poultry populations for the reduction of Salmonella prevalence for the relevant serovars. Salmonella samples from carcases of various animal species, and samples for Campylobacter quantification from broiler carcases, were more frequently positive when performed by the competent authorities than when own checks were conducted. Yersiniosis was the third most reported zoonosis in humans, followed by Shiga toxin‐producing Escherichia coli (STEC) and Listeria monocytogenes infections. L. monocytogenes and West Nile virus infections were the most severe zoonotic diseases, with the most hospitalisations and highest case fatality rates. In 2022, reporting showed an increase of more than 600% compared with 2021 in locally acquired cases of human West Nile virus infection, which is a mosquito‐borne disease. In the EU, the number of reported foodborne outbreaks and cases, hospitalisations and deaths was higher in 2022 than in 2021. The number of deaths from outbreaks was the highest ever reported in the EU in the last 10 years, mainly caused by L. monocytogenes and to a lesser degree by Salmonella. Salmonella and in particular S. Enteritidis remained the most frequently reported causative agent for foodborne outbreaks. Norovirus (and other calicivirus) was the agent associated with the highest number of outbreak human cases. This report also provides updates on brucellosis, Coxiella burnetii (Q fever), echinococcosis, rabies, toxoplasmosis, trichinellosis, infection with Mycobacterium tuberculosis complex (focusing on Mycobacterium bovis and Mycobacterium caprae) and tularaemia. This publication is linked to the following EFSA Journal article: https://efsa.onlinelibrary.wiley.com/doi/10.2903/j.efsa.2023.p211202 [ABSTRACT FROM AUTHOR]

The objective of this study is to stochastically assess the inactivation probabilities of four common foodborne pathogens (Listeria, Salmonella, Escherichia coli, and Campylobacter) in chicken meat during ohmic heating (OH) in a salt solution. A mechanistic model was used to accomplish this, coupling heat transfer, laminar fluid flow, and the electric field, and solved numerically using COMSOL Multiphysics® v5.6. The 3D model represented 1000 particles randomly placed on the meat's surface to determine the 7-log reduction of bacterial load probability. These particles are virtual representatives of bacterial colonies in the model. The influence of uncertain input parameters (specific heat capacity and electrical conductivity) and OH conditions (salt concentration of the heating medium, applied voltage, and heating time) was explained using logistic regression. The same analysis was repeated for the slowest heating point of chicken meat, as well. According to the findings, cold spots are observed at the corners of the meat piece during OH, requiring additional attention to the meat surface temperature to prevent under-processing. Sensitivity analysis revealed that the applied voltage and brine concentration are the main factors affecting the inactivation probabilities of pathogenic bacterial cells on the chicken meat surface. Salmonella and Listeria may require higher electrical conductivity of chicken meat and longer processing times. The developed model enables predicting inactivation probabilities of microorganisms that can be found on the outer surface by measuring the core temperature of the meat. However, especially for bacteria with higher heat resistance, it is better to consider the cold spot temperature found in the corners of the food material during OH. [ABSTRACT FROM AUTHOR]

The accuracy of Oxford Nanopore Technology (ONT) sequencing has significantly improved thanks to new flowcells, sequencing kits, and basecalling algorithms. However, novel modification types untrained in the basecalling models can seriously reduce the quality. Here we reports a set of ONT-sequenced genomes with unexpected low quality due to novel modification types. Demodification by whole-genome amplification significantly improved the quality but lost the epigenome. We also developed a reference-based method, Modpolish, for correcting modification-mediated errors while retaining the epigenome when a sufficient number of closely-related genomes is publicly available (default: top 20 genomes with at least 95% identity). Modpolish not only significantly improved the quality of in-house sequenced genomes but also public datasets sequenced by R9.4 and R10.4 (simplex). Our results suggested that novel modifications are prone to ONT systematic errors. Nevertheless, these errors are correctable by nucleotide demodification or Modpolish without prior knowledge of modifications. The authors report excessive amounts of modification-mediated errors in Listeria strains during Nanopore sequencing that are due to novel modifications that were untrained in the Nanopore basecalling model. A whole-genome amplification and a reference-based computational methods (Modpolish) can correct these modification-mediated errors without the need for demodification. [ABSTRACT FROM AUTHOR]

The present study was aimed to find the prevalence of Listeria monocytogenes in raw chicken meat purchased across the Nagpur city. Cultural examination of 100 raw poultry meat samples revealed 35.0 % prevalence of Listeria spp. Among them, L. grayi was predominant (15 %) followed by L. monocytogenes (12 %), L. welshimeri (5 %), L. innocua (2 %) and L. seeligeri (1 %). A typical β-haemolysis clear zone was exhibited by 18 listeriae isolates. Of these, 12 isolates with characteristic biochemical pattern and showing haemolytic zone. All 12 L. monocytogenes isolates expressed the PI PLC activity. Multiplex PCR study of Listeria spp. revealed that four L. monocytogenes isolates were positive for plcA, actA, hlyA and iap genes. Amplified products of three virulence-associated genes namely, actA, hlyA and iap were detected in five L. monocytogenes and three L. monocytogenes isolates were positive for hlyA and iap genes. L. grayi isolates revealed the amplified product of iap gene. Two isolate of L. innocua were positive for actA and iap genes, Five L. welshimeri isolates and one L. seeligeri isolate were positive for iap gene, lacking plcA, actA and hlyA genes. As actA and iap genes were detected in a two isolate of L. innocua. It is clear that actA and iap genes are shared by L. monocytogenes and L. innocua. It is concluded that genes in three different combinations were recorded in Listeria spp. and that prfA and hlyA detected by PCR distinctively in L. monocytogenes suggest the usefulness of PCR amplification from various food samples. [ABSTRACT FROM AUTHOR]

Typically, short‐ and long‐chain lipids from oils exhibit different antimicrobial activities and therefore have been used in agriculture and aquaculture, biomedical therapeutic and antibacterial fields. However, these fatty acids have limitations in terms of bioactive efficacy, thermostability and aqueous solubility. In this study, water‐soluble iso‐fatty acid arginate hydrochloride derivatives with antimicrobial properties were produced by introducing branched (iso‐) chain and other linear‐ (n‐) chain fatty acids to the "arginine" amino acid molecule. The two‐step synthetic route was straightforward and provided an efficient 88% and 76% product yields for ethyl n‐oleoyl arginate hydrochloride and ethyl iso‐oleoyl arginate hydrochloride, respectively. ATR‐FT‐IR, NMR, and LC‐MS‐Q‐TOF techniques were used to thoroughly characterize and confirm the products. These arginate products had strong antimicrobial activities against Listeria innucua, a Gram‐positive bacterium with minimum inhibitory concentrations and minimum bactericidal concentrations ranging from 1.8 µg mL−1 to 29.1 µg mL−1. Therefore, the study demonstrated the development of a novel class of antimicrobial compounds from iso‐fatty acids and arginates. [ABSTRACT FROM AUTHOR]

Listeria monocytogenes is a facultative intracellular foodborne pathogen and the causative agent of the severe disease listeriosis. It is found ubiquitously in the environment and exhibits innate resistance to certain antimicrobials, but acquired antimicrobial resistance remains relatively uncommon. Given the potentially dire health outcomes associated with listeriosis, acquisition of antimicrobial resistance (AMR) by this pathogen is of considerable public health concern. AMR in L. monocytogenes has been surveyed frequently in strains of clinical and food origin, but much less commonly in wildlife. We analyzed 158 strains of L. monocytogenes and 27 of non-pathogenic Listeria spp. isolated from wild black bears (Ursus americanus) for resistance to a panel of antimicrobials. AMR was uncommon and noted mostly for tetracycline. Tetracycline resistance was more common in Listeria innocua than in L. monocytogenes. All tetracycline-resistant L. monocytogenes strains belonged to sequence type ST1039 and harbored the Tn916-like tet(M) transposon Tn916.1039 in a conserved chromosomal location. In contrast, three different tetracycline resistance elements, i.e., the tet(M) elements Tn5801.UAM and Tn5801.551 and the tet(S) element Tn6000.205, were ident ified among tetracycline-resistant strains of L. innocua. The greater prevalence and diversity of tetracycline resistance elements among bear-derived non-pathogenic Listeria strains suggest the potential of the latter to serve as reservoirs for retention and dive rsification of AMR determinants in this wildlife host and warrant their further monitoring and study. IMPORTANCE Listeria monocytogenes causes severe foodborne illness and is the only human pathogen in the genus Listeria. Previous surveys of AMR in Listeria focused on clinical sources and food or food processing environments, with AMR in strains from wildlife and other natural ecosystems remaining under-explored. We analyzed 185 sequenced strains from wild black bears (Ursus americanus) from the United States, including 158 and 27 L. monocytogenes and L. innocua, respectively. Tetracycline resistance was the most prevalent resistance trait. In L. monocytogenes, it was encountered exclusively in serotype 4b strains with the novel Tn916-like element Tn916.1039. In contrast, three distinct, novel tetracycline resistance elements (Tn5801.UAM, Tn5801.551, and Tn6000.205) were identified in L. innocua. Interestingly, Tn5801.551 was identical to elements in L. monocytogenes from a major foodborne outbreak in the United States in 2011. The findings suggest the importance of wildlife and non-pathogenic Listeria species as reservoir for resistance elements in Listeria. [ABSTRACT FROM AUTHOR]

"Chouriço de carne" is a Portuguese ready-to-eat dry fermented sausage which relies on effective spontaneous fermentation to ensure its microbial safety and desired organoleptic properties. This study aimed to assess selected microbiological and physicochemical characteristics of artisanal chouriço produced by 14 different regional producers. Aerobic mesophilic bacteria, lactic acid bacteria, Staphylococcus aureus, Clostridium spp., Listeria spp. and Salmonella spp., in addition to pH, water activity and moisture, were evaluated for each of 70 samples. Principal Component Analysis of all these attributes was performed to build quality maps of the analyzed lots. The results showed great variability between sausages of different producers within the same geographic region, and S. aureus, Clostridium spp., Salmonella spp. and Listeria spp. were identified in sausages of several producers, highlighting the need for stricter microbiological control and standardization of production processes among artisanal producers of chouriço. [ABSTRACT FROM AUTHOR]

This study determined the prevalence, risk factors, and molecular characteristics of Listeria species detected in beef and beef products sampled in Mpumalanga province, South Africa. Four hundred beef and beef products were collected from 30 retail outlets in three districts (Bronkhorstspruit, Emalahleni, and Middelburg) within the province. Standard bacteriological and polymerase chain reaction (PCR) assays were used in the study. The overall prevalence of L. monocytogenes and other Listeria spp. in the samples was 8.3% (33/400) and 30% (120/400) (p <.05), respectively. For the five variables investigated, statistically significant effects were evident only for the region (p <.001) and type of product (p <.0001) for L. monocytogenes, the type of outlet (p =.011) and the type of product (p <.0001) for Listeria spp. Of the 20 types of beef and beef products tested, 15 (75%) and 17 (85%) were contaminated by L. monocytogenes and Listeria spp., respectively (p =.429). Among the four categories of products tested, the prevalence of L. monocytogenes was 7.3% (8/109), 10.6% (11/104), 7.5% (8/106), and 7.4% (6/81) for raw beef, ready‐to‐eat (RTE) products, milled beef, and offal & organs, respectively (p >.799). Among the 33 L. monocytogenes isolates, PCR genoserogroup IIa (42.4%, 1/2a‐3a) was most frequently detected. All (100%) of the isolates carried one or more of the eight virulence‐associated genes assessed, with genes inlC and inlJ detected in all the isolates. The overall prevalence of L. monocytogenes (8.3%) and the high frequency of virulent serogroups of L. monocytogenes commonly associated with human listeriosis pose a food safety risk to consumers of beef and beef‐based products contaminated by L. monocytogenes. [ABSTRACT FROM AUTHOR]

Key Clinical Message: Listeria can cause neurological symptoms in immunocompromised and older patients. Additionally, it is impossible to rule out meningitis by the absence of typical meningeal irritation signs. Therefore, patients with fever and neurological impairments should be rapidly examined for blood and cerebrospinal fluid cultures to rule out Listeria meningitis. A woman in her 90s developed fever, dysarthria, and transient disturbance of consciousness. Physical examination revealed no meningeal irritation signs. Listeria monocytogenes were detected in her blood culture the following day. Because of an increased number of cells in cerebrospinal fluid, she was diagnosed with Listeria meningitis. [ABSTRACT FROM AUTHOR]

Urine and tissues samples were collected for bacteriological examination from 50 apparently diseased sheep of different ages and sexes which were clinically suspected suffering from renal infection and from slaughtered animals. We were collected samples from many locations at Matrouh Governorate and sent for laboratory. Post mortem examination of the renal system of affected cases revealed different investigations. kidneys appeared swollen, its surface was mottled red. Some kidneys were pale and greatly enlarged. Cut section of the kidney showed areas of hemorrhage and abscess formation. The results indicated that 80% (40) sheep were positive for bacterial infection however 10 show negative results of bacterial renal infection. Bacteriological investigations revealed that the isolated organisms were: Escherichia coli (20%), Staphyolcoccus aureus (25%), Pseudomonas aeruginosa (5.0%), Streptococcus spp. (7.5%), Enterococcus faeclis (7.5%), Corynebaeterium spp. (17.5%), Klebseilla pneumoniae (2.5%). and. Listeria monocytogene (2.5%). Moreover, mixed infection found in 12.5% of the examined samples. A total of eight isolates of E coli from renal examined samples were serologically positive to O111, O104, O26, O113, O91, O103 and O126. PCR results showed that two strains for Listeria isolates were Listeria monocytogenes and some of them have InI B gene. Antibiogram was applied upon the isolated bacterial pathogens and found that Garamycine was the drug of choice for treatment of infected animals. [ABSTRACT FROM AUTHOR]

Bacteriophages are viruses that infect and kill bacteria. Currently, phage products are available for the control of the pathogen Listeria monocytogenes in food products in the United States. In this study, we explore whether experimental evolution can be used to generate phages with improved abilities to function under specific food-relevant conditions. Ultra-pasteurized oat and whole milk were chosen as test matrices as they represent different food groups, yet have similar physical traits and macronutrient composition. We showed that (i) wild-type phage LP-125 infection kinetics are different in the two matrices and (ii) LP-125 has a significantly higher burst size in oat milk. From this, we attempted to evolve LP-125 to have improved infection kinetics in whole milk. Ancestral LP-125 was passaged through 10 rounds of amplification in milk conditions. Plaquepurified DNA samples from milk-selected phages were isolated and sequenced, and mutations present in the isolated phages were identified. We found two nonsynonymous substitutions in LP125_108 and LP125_112 genes, which encode putative baseplate-associated glycerophosphoryl diester phosphodiesterase and baseplate protein, respectively. Protein structural modeling showed that the substituted amino acids in the mutant phages are predicted to localize to surface-exposed helices on the corresponding structures, which might affect the surface charge of proteins and their interaction with the bacterial cell. The phage containing the LP125_112 mutation adsorbed significantly faster than the ancestral phage in both oat and whole milk. Follow-up experiments suggest that fat content may be a key factor for the expression of the phenotype of this mutation. [ABSTRACT FROM AUTHOR]

Antimicrobial blue light (aBL) in the 400-470 nm wavelength range has been reported to kill multiple bacteria. This study assessed its potential for mitigating an important foodborne pathogen, Listeria monocytogenes (Lm), focusing on surface decontamination. Three wavelengths were tested, with gallic acid as a photosensitizing agent (Ps), against dried cells obtained from bacterial suspensions, and biofilms on stainless-steel (SS) coupons. Following aBL exposure, standard microbiological analysis of inoculated coupons was conducted to measure viability. Statistical analysis of variance was performed. Confocal laser scanning microscopy was used to observe the biofilm structures. Within 16 h of exposure at 405 nm, viable Lm dried cells and biofilms were reduced by approx. 3 log CFU/cm2 with doses of 2,672 J/cm2. Application of Ps resulted in an additional 1 log CFU/cm2 at 668 J/cm2, but its effect was not consistent. The highest dose (960 J/cm2) at 420 nm reduced viable counts on the biofilms by 1.9 log CFU/cm2. At 460 nm, after 800 J/cm2, biofilm counts were reduced by 1.6 log CFU/cm2. The effect of material composition on Lm viability was also investigated. Irradiation at 405 nm (668 J/cm2) of cells dried on polystyrene resulted in one of the largest viability reductions (4.0 log CFU/cm2), followed by high-density polyethylene (3.5 log CFU/cm2). Increasing the dose to 4,008 J/cm2 from 405 nm (24 h), improved its efficacy only on SS and polyvinyl chloride. Biofilm micrographs displayed a decrease in biofilm biomass due to the removal of biofilm portions from the surface and a shift from live to dead cells suggesting damage to biofilm cell membranes. These results suggest that aBL is a potential intervention to treat Lm contamination on typical material surfaces used in food production. [ABSTRACT FROM AUTHOR]

Seal populations in Canadian waters provide sustenance to coastal communities. There is potential for pathogenic and/or antimicrobial‐resistant bacteria to transfer to humans through inadvertent faecal contamination of seal products. The objective of this study was to investigate the occurrence and potential antimicrobial resistance of Salmonella spp., Escherichia coli and Listeria monocytogenes in faecal samples collected from grey seals (Halichoerus grypus) in the Gulf of St. Lawrence and from ringed seals (Pusa hispida) in Frobisher Bay and Eclipse Sound, Nunavut, Canada. Grey seals were harvested during commercial hunts or during scientific sampling; ringed seals were collected by Inuit hunters during subsistence harvests. Virulence genes defining pathogenic E. coli were identified by PCR, and antimicrobial susceptibility testing was performed on recovered isolates. In grey seals, E. coli was detected in 34/44 (77%) samples, and pathogenic E. coli (extraintestinal E. coli [ExPEC], enteropathogenic E. coli [EPEC] or ExPEC/EPEC) was detected in 13/44 (29%) samples. Non‐susceptibility to beta‐lactams and quinolones was observed in isolates from 18 grey seals. In ringed seals from Frobisher Bay, E. coli was detected in 4/45 (9%) samples; neither virulence genes nor antimicrobial resistance was detected in these isolates. In ringed seals from Eclipse Sound, E. coli was detected in 8/50 (16%) samples and pathogenic E. coli (ExPEC and ExPEC/EPEC) in 5/50 (10%) samples. One seal from Eclipse Sound had an E. coli isolate resistant to beta‐lactams. A monophasic Salmonella Typhimurium was recovered from 8/50 (16%) seals from Eclipse Sound. All Salmonella isolates were resistant to ampicillin, streptomycin, sulfisoxazole and tetracycline. L. monocytogenes was not detected in any sample. These findings suggest that seals may act as important sentinel species and as reservoirs or vectors for antimicrobial‐resistant and virulent E. coli and Salmonella species. Further characterization of these isolates would provide additional insights into the source and spread of antimicrobial resistance and virulence genes in these populations of free‐living seals. [ABSTRACT FROM AUTHOR]

This article describes a rare case of Listeria rhombencephalitis, a central nervous system infection caused by Listeria monocytogenes. The patient, a 66-year-old woman with pancreatic cancer, presented with symptoms such as unsteadiness, dysarthria, and left arm weakness. The diagnosis was made through a cerebrospinal fluid analysis and confirmed by a multiplex polymerase chain reaction test. The patient's condition rapidly deteriorated, and she ultimately died. The article highlights the challenges in diagnosing and treating this condition and emphasizes the importance of prompt intervention. [Extracted from the article]

Comprehending bacterial genomic variation linked to distinct environments can yield novel insights into mechanisms underlying differential adaptation and transmission of microbes across environments. Gaining such insights is particularly crucial for pathogens as it benefits public health surveillance. However, the understanding of bacterial genomic variation is limited by a scarcity of investigations in genomic variation coupled with different ecological contexts. To address this limitation, we focused on Listeria, an important bacterial genus for food safety that includes the human pathogen L. monocytogenes, and analyzed a large-scale genomic dataset collected by us from natural and food-associated environments across the United States. Through comparative genomics analyses on 449 isolates from the soil and 390 isolates from agricultural water and produce processing facilities representing L. monocytogenes, L. seeligeri, L. innocua, and L. welshimeri, we find that the genomic profiles strongly differ by environments within each species. This is supported by the environment-associated subclades and differential presence of plasmids, stress islands, and accessory genes involved in cell envelope biogenesis and carbohydrate transport and metabolism. Core genomes of Listeria species are also strongly associated with environments and can accurately predict isolation sources at the lineage level in L. monocytogenes using machine learning. We find that the large environment-associated genomic variation in Listeria appears to be jointly driven by soil property, climate, land use, and accompanying bacterial species, chiefly representing Actinobacteria and Proteobacteria. Collectively, our data suggest that populations of Listeria species have genetically adapted to different environments, which may limit their transmission from natural to food-associated environments. [ABSTRACT FROM AUTHOR]

Listeria outbreaks and food recalls is on the raise globally. Milk particularly is highly susceptible to Listeria as its production and storage adequately support Listeria growth. The extent of milk contamination with Listeria monocytogenes (Lm) and preventative actions to halt milk associated outbreaks in Africa are unknown. Hence, this study aimed at assessing the national and subregional prevalence of Lm in milk in Africa and identify impacting factors via generalized logistic mixed-effects (GLMEs) and meta-regression modelling. Lm-milk-specific data acquired from primary studies according to standard protocol were fitted using a GLMEs. The GLMEs was subjected to leave-one-study-out-cross-validation (LOSOCV). Factors impacting Lm prevalence in milk were assayed via a 1000-permutation-assisted meta-regression-modelling. The pooled prevalence of Lm in milk in Africa was 4.35% [2.73–6.86] with a prediction interval (PI) of 0.14–59.86% and LOSOCV value of 2.43% [1.62–3.62; PI: 0.32–16.11%]. Western Africa had the highest prevalence [20.13%, 4.13–59.59], then Southern Africa [5.85%, 0.12–75.72], Northern Africa [4.67%, 2.82–7.64], Eastern Africa [1.91%, 0.64–5.55], and there was no record from Central Africa. In term of country, Lm prevalence in milk significantly (p < 0.01) varied from 0.00 to 90.00%. Whereas the Lm prevalence was negligibly different (p = 0.77) by milk type, raw-milk had the highest prevalence [5.26%], followed by fermented-milk [4.76%], boiled-milk [2.90%], pasteurized-milk [1.64%], and powdered-milk [1.58%]. DNA extraction approach did not significantly (p = 0.07) affect Lm prevalence (Boiling [7.82%] versus Kit [7.24%]) as well as Lm detection method (p = 0.10; (ACP [3.64%] vs. CP [8.92%] vs. CS [2.27%] vs. CSP [6.82%]). Though a bivariate/multivariate combination of all tested variables in meta-regression explained 19.68–68.75% (R2) variance in Lm prevalence in milk, N, nation, and subregion singly/robustly accounted for 17.61% (F1;65 = 7.5994; p = 0.005), 63.89% (F14;52 = 4.2028; p = 0.001), and 16.54% (F3;63 = 3.4743; p = 0.026), respectively. In conclusion, it is recommended that adequate sample size should be prioritized in monitoring Lm in milk to prevent spuriously high or low prevalence to ensure robust, plausible, and credible estimate. Also, national efforts/interests and commitments to Lm monitoring should be awaken. [ABSTRACT FROM AUTHOR]

Listeria monocytogenes sometimes causes central nervous system infections. However, rhombencephalitis is a rare form of L. monocytogenes infection. Its clinical symptoms and magnetic resonance imaging (MRI) findings are often similar to those of vertebrobasilar stroke. We present the case of a 79-year-old woman with Listeria rhombencephalitis presenting with rhinorrhea and productive cough. She had giant cell arteritis (GCA) treated with prednisolone and methotrexate. She was admitted for loss of appetite, rhinorrhea, and productive cough. These symptoms were alleviated without specific treatment; however, she suddenly developed multiple cranial nerve palsies, and MRI showed hyperintense signals on diffusion-weighted imaging and hypointense signals on apparent diffusion coefficient in the brainstem. Ischemic stroke due to exacerbation of GCA was suspected, and treatment with intravenous methylprednisolone was initiated; however, seizures occurred, and a lumbar puncture was performed. Cerebrospinal fluid and blood cultures revealed L. monocytogenes , and she was diagnosed with Listeria rhombencephalitis. Although antibiotic treatment was continued, the patient died. Thus, when patients with rhinorrhea or productive cough develop sudden cranial nerve palsy, Listeria rhombencephalitis should be considered as a differential diagnosis, and lumbar puncture should be performed. [ABSTRACT FROM AUTHOR]

Intracellular bacterial pathogens remodel the plasma membrane of eukaryotic cells in order to establish infection. A common and well‐studied mechanism of plasma membrane remodelling involves bacterial stimulation of polymerization of the host actin cytoskeleton. Here, we discuss recent results showing that several bacterial pathogens also exploit the host vesicular trafficking pathway of 'polarized exocytosis' to expand and reshape specific regions in the plasma membrane during infection. Polarized exocytosis is mediated by an evolutionarily conserved octameric protein complex termed the exocyst. We describe examples in which the bacteria Listeria monocytogenes, Salmonella enterica serovar Typhimurium, and Shigella flexneri co‐opt the exocyst to promote internalization into human cells or intercellular spread within host tissues. We also discuss results showing that Legionella pneumophila or S. flexneri manipulate exocyst components to modify membrane vacuoles to favour intracellular replication or motility of bacteria. Finally, we propose potential ways that pathogens manipulate exocyst function, discuss how polarized exocytosis might promote infection and highlight the importance of future studies to determine how actin polymerization and polarized exocytosis are coordinated to achieve optimal bacterial infection. [ABSTRACT FROM AUTHOR]

Polymerase chain reaction (PCR) is commonly used to detect Listeria monocytogenes , foodborne pathogen. This study conducted in silico genomic analysis to investigate the specificity and binding efficacy of four published pairs of PCR primers targeting Listeria prfA -virulence gene cluster (pVGC) based on Listeria sequences available. We first performed comprehensive genomic analyses of the pVGC, the main pathogenicity island in Listeria spp. In total, 2961 prfA , 642 plcB , 629 mpl , and 1181 hlyA gene sequences were retrieved from the NCBI database. Multiple sequence alignments and phylogenetic trees were generated using unique (non-identical or not-shared) sequences of each represented genes, targeting four pairs of PCR primers published previously, namely 202 prfA , 82 plcB , 150 mpl , and 176 hlyA unique gene sequences. Only the hlyA gene showed strong (over 94%) primer mapping results, while prfA, plcB , and mpl genes showed weak (<50%) matching results. In addition, nucleotide variations were observed at the 3′ end of the primers, indicating non-binding to the targets could potentially cause false-negative results. Thus, we propose designing degenerate primers or multiple PCR primers based on as many isolates as possible to minimize the false-negative risk and reach the aim of low tolerable limits of detection. [ABSTRACT FROM AUTHOR]

The integration of bacteriophages, a particular class of viruses that specifically infect bacteria and archaea, in biosensors for the monitoring of pathogens in foods and beverages is highly desirable. To this end, an increasing focus has been set on the exploration of covalent and physical methods for the immobilization of phages on solid surfaces. This work investigates the electrostatic assembly of tailed phages, specifically anti-Listeria monocytogenes P100 phages, on an ultrathin self-assembled monolayer (SAM) of 11-amino-1-undecanethiol (AUT). The cationic properties of AUT may allow for the electrostatic capture of P100 in a capsid-down fashion, thereby exposing the specific receptor-binding proteins on their tails to the corresponding pathogens in the analytical samples. The morphology and charge transfer behavior of the assembled films were studied with atomic force microscopy, scanning electron microscopy and electrochemical techniques. These methods provided valuable insights into the orientation of the phages and the relevant role of the pH. Biological plaque assays revealed that the immobilized phages remain active towards the target bacterium. Overall, this research portrays SAMs of amino-akylthiols as a valid platform for the oriented immobilization of bacteriophages on surfaces for electroanalytical purposes. [ABSTRACT FROM AUTHOR]

Due to the complexity of tumor microenvironment，traditional cancer therapies have serious limitations，such as poor drug responsiveness，toxic side effects，difficulty in reaching deeper tumors，and tumors prone to recurrence. In recent years，bacterial ⁃ mediated cancer immunotherapy is attracting attention with its unique advantages. These bacteria preferentially colonize the hypoxic zone of tumors and kill tumor cells through various mechanisms，such as reshaping the tumor immune microenvironment and activating anti⁃tumor immunity. Based on this，genetic engineering techniques to construct recombinant antitumor strains that target tumors and secrete therapeutic proteins or nucleic acid drugs in the tumor core or in combination with other anticancer therapies are promising as a new cancer treatment strategy. This paper introduces the research progress of different antitumor bacteria and their clinical application status，and provides new ideas for bacterial immunotherapy of tumors. Due to the complexity of tumor microenvironment，traditional cancer therapies have serious limitations，such as poor drug responsiveness，toxic side effects，difficulty in reaching deeper tumors，and tumors prone to recurrence. In recent years，bacterial ⁃ mediated cancer immunotherapy is attracting attention with its unique advantages. These bacteria preferentially colonize the hypoxic zone of tumors and kill tumor cells through various mechanisms，such as reshaping the tumor immune microenvironment and activating anti⁃tumor immunity. Based on this，genetic engineering techniques to construct recombinant antitumor strains that target tumors and secrete therapeutic proteins or nucleic acid drugs in the tumor core or in combination with other anticancer therapies are promising as a new cancer treatment strategy. This paper introduces the research progress of different antitumor bacteria and their clinical application status，and provides new ideas for bacterial immunotherapy of tumors. [ABSTRACT FROM AUTHOR]

Listeria monocytogenes virulence factor InlB specifically interacts with the receptors c-Met and gC1q-R. Both receptors are present in non-professional and professional phagocytes, including macrophages. Phylogenetically defined InlB isoforms differently support invasion into non-professional phagocytes. This work deals with the effects of InlB isoforms on L. monocytogenes uptake and intracellular proliferation in human macrophages. Three isoforms of the receptor binding domain (idInlB) were derived from phylogenetically distinct L. monocytogenes strains belonging to the highly virulent CC1 (idInlBCC1), medium-virulence CC7 (idInlBCC7), and low-virulence CC9 (idInlBCC9) clonal complexes. The constant dissociation increased in the order idInlBCC1 << idInlBCC7 < idInlBCC9 for interactions with c-Met, and idInlBCC1 ≈ idInlBCC7 < idInlBCC9 for interactions with gC1q-R. The comparison of uptake and intracellular proliferation of isogenic recombinant strains which expressed full-length InlBs revealed that the strain expressing idInlBCC1 proliferated in macrophages twice as efficiently as other strains. Macrophage pretreatment with idInlBCC1 followed by recombinant L. monocytogenes infection disturbed macrophage functions decreasing pathogen uptake and improving its intracellular multiplication. Similar pretreatment with idInlBCC7 decreased bacterial uptake but also impaired intracellular multiplication. The obtained results demonstrated that InlB impaired macrophage functions in an idInlB isoform-dependent manner. These data suggest a novel InlB function in L. monocytogenes virulence. [ABSTRACT FROM AUTHOR]