Search

Copyright of Afyon Kocatepe University Journal of Science & Engineering / Afyon Kocatepe Üniversitesi Fen Ve Mühendislik Bilimleri Dergisi is the property of Afyon Kocatepe University, Faculty of Science & Literature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

We investigate the relationship between the level of food safety risk in retail food establishments and average incomes in surrounding communities. Building on the environmental justice literature, we hypothesize that there is a relationship between community income levels and levels of food safety risk. Using data on the prevalence of Listeria monocytogenes (Lm) obtained from grocery store delis, we find that stores located in census tracts whose residents are in lower income quartiles have greater Lm prevalence. An indicator for American Indian and Alaskan Native residents also has a positive statistically significant relationship with food safety risk. [ABSTRACT FROM AUTHOR]

The aim of this study was to describe the pathology in seals from which Listeria monocytogenes was isolated and investigate if the lesions' nature and severity were related to the phylogeny of isolates. L. monocytogenes was isolated from 13 of 50 (26%) dead grey seal (Halichoerus grypus) pups, six (12%) in systemic distribution, on the Isle of May, Scotland. Similar fatal L. monocytogenes -associated infections were found in a grey seal pup from Carnoustie, Scotland, and a juvenile harbour seal (Phoca vitulina) in the Netherlands. Whole genome sequencing of 15 of the L. monocytogenes isolates identified 13 multilocus sequence types belonging to the L. monocytogenes lineages I and II, but with scant phenotypic and genotypic antimicrobial resistance and limited variation in virulence factors. The phylogenetic diversity present suggests there are multiple sources of L. monocytogenes , even for seal pups born in the same colony and breeding season. This is the first description of L. monocytogenes isolated from, and detected in lesions in, pinnipeds and indicates that infection can be systemic and fatal. Therefore, listeriosis may be an emerging or overlooked disease in seals with infection originating from contamination of the marine environment. [ABSTRACT FROM AUTHOR]

Relatively few studies have focused on mortality risk factors for listeriosis in the literature. Information on the mortality of populations with listeriosis is needed. We aimed to explore the mortality risk factors related to listeriosis in this meta-analysis. The studies were considered eligible for inclusion only if they directly compared the mortality risk factors for listeriosis between dead patients and surviving patients. The mortality risk factors included clinical predisposing factors and predisposing comorbidities. Thirteen studies were included in this study. There were 12,265 listeriosis patients, including 2863 (23.3%) dead patients. The meta-analysis provided evidence that the mortality risk factors related to listeriosis were as follows: 1. Clinical predisposing factors included age ≥ 60 years, primary bacteremia and central nervous system involvement; 2. Predisposing comorbidities included non-hematological malignancies, alcoholism, chronic kidney disease, cardiovascular disease, and pulmonary disease. In addition, autoimmune disease comorbidity had a protective effect against listeriosis. The presence of older patients, primary bacteremia, central nervous system involvement, non-hematological malignancies, alcoholism, chronic kidney disease, cardiovascular disease, and pulmonary disease should alert physicians to the higher risk of mortality. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Journal of Veterinary Research / Revue Canadienne de Recherche Vétérinaire is the property of Canadian Veterinary Medical Association and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Shewanella putrefaciens and Listeria monocytogenes are concerned by scientists and consumers due to their ability to produce dense biofilms to contaminate and cause food spoilage. The object of this study was to investigate the antimicrobial and anti-biofilm activities of octyl gallate (OG) against the two food-related bacteria. Results showed that the antimicrobial activities of OG were in a dose-dependent manner and the minimum inhibitory concentration (MIC) of S. putrefaciens and L. monocytogenes were 0.2 mmol/L and 0.1 mmol/L, respectively. OG can rapidly penetrate the bacteria and produce reactive oxygen species (ROS). Then, OG and ROS can lead to membrane damage and cell rupture, causing DNA and protein leakage. Our data also strongly suggested that OG not only can inhibit biofilms formation, but also eradicate the performed biofilms. Furthermore, it was shown that OG, as an additive, has great potential in antimicrobial application to prolong the shelf life of large yellow croakers. These prove that OG can combat bacteria and eradicate biofilm against S. putrefaciens and L. monocytogenes. • Octyl gallate (OG) can lead to membrane disruption and then bacterial lysis. • The cellular functions were inhibited by OG with reactive oxygen species (ROS) generation. • OG not only can inhibit biofilms formation, but also eradicate the performed biofilms. • OG can be applied as an attractive antibacterial additive to prolong the shelf life of large yellow croakers. [ABSTRACT FROM AUTHOR]

Gibberellic acid-stimulated Arabidopsis (GASA) proteins, also known as Snakin proteins, have emerged as key players in plant development and stress tolerance. The investigation of the role of TdGASA2 in host defense responses revealed dynamic expression patterns under different stress conditions. TdGASA2 expression showed a consistent increase after wounding, methyl jasmonate (MeJA), and ethylene (ETP) treatments, peaking after 12–24 h for MeJA and ETP and after 1 h for pathogen elicitor (PA) treatment. Optimal expression conditions were determined, and the protein was successfully purified with a molecular weight of approximately 10 kDa. In vitro experiments demonstrated the potent antimicrobial activity of TdGASA2 against a range of pathogens, surpassing the efficacy of kanamycin. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values confirmed its bactericidal and bacteriostatic activity against various bacteria. Time-kill assays also highlighted its efficacy against Listeria monocytogenes and Salmonella enterica , underscoring its potential as a therapeutic agent. Additionally, TdGASA2 exhibited superior DPPH radical-scavenging activity compared to ascorbic acid, indicating its potential as a natural antioxidant. In situ experiments revealed dose-dependent effects of TdGASA2 treatment on microbial growth in cheese, suggesting its efficacy as a preservative to extend shelf life and enhance food safety. These findings underscore TdGASA2's multifaceted potential in both antimicrobial and antioxidant applications, positioning it as a promising candidate for food preservation and health promotion. [ABSTRACT FROM AUTHOR]

Currently, there is a high demand for fresh, minimally processed foods. Therefore, the search for natural compounds that can be used to increase the quality and shelf life of food, as well as to control or eliminate the development of pathogens has been increasing. The general objective was to determine the simultaneous production, at a controlled pH 6, of bacteriocin and bioemulsifier by the Enterococcus mundtii Tw278 strain and evaluate the conservation capacity in a food model. The pH control did not affect the production of the compounds when the optimal production media were used (LAPTg for bacteriocin and LAP LW for bioemulsifier), respectively. The values obtained for bacteriocin were 819,200 AU/mL at 9 h in the batch, while this value was obtained at 12 h in the reactor. The highest emulsification index (E24) was 60.97 at 24 h in the batch, while in the reactor, it was 54.3 at 12 h. The bioemulsifier produced would be a glyprotein, according to FTIR analysis, with the capacity to form polydisperse oil-in-water emulsions with particles with an average diameter of 50 μm. Finally, it was found that E. mundtii Tw278 strain, as well as its antilisteria extract, were able to control and reduce the initial population of 3.4 log CFU/mL of Listeria monocytogenes Scott A to undetectable values in a yogurt model, with production at 42 °C for 8 h and storage at 4 °C for 15 days and bacteriocinogenic strain and its extract did not alter the physicochemical properties inherent to yogurt. [ABSTRACT FROM AUTHOR]

Listeria monocytogenes is a prominent cause of foodborne illnesses and public health concerns worldwide. Naturally active compounds have been extensively explored for their potential to reduce foodborne pathogenic contamination. This work is designed to study the chemical composition, antibacterial effect, and inhibition mechanism of Citrus bergamia essential oil (CB-EO) against L. monocytogenes. The CB-EO composition revealed the major components of the total account are d -limonene (23.2%), linalyl acetate (14.01%), and linalool (9.96%). The inhibitory effect was examined at different concentrations of CB-EO, and the MIC value was 1.5 mg/mL against L. monocytogenes. The CB-EO concentration of 1.5 mg/mL significantly disturbed the membrane permeability and fluidity, leading to leakage of intracellular protein and DNA constituents, as revealed by the BCA protein assay and UV–Vis spectrophotometric analysis, respectively. However, a decrease in concentration to 0.75 mg/mL indicated a significant decline in intracellular macromolecule leakage as well as membrane disruption. Moreover, SEM and CLSM observations provided extensive insight into the inhibition mechanism of CB-EO against L. monocytogenes. Finally, while investigating the anti-hemolysis activity, CB-EO and its major compounds, limonene, linalool, and linalyle acetate, have been found to be effective against the virulence agent listeriolysin O (LLO). Thus, it was proposed that CB-EO could act on L. monocytogenes cells through multiple mechanisms of action, with EO concentration providing a crucial role in determining the mode of action. This work offers deep insight into the inhibition mechanisms of natural substances, expanding the potential uses of CB-EO as a natural antimicrobial. [ABSTRACT FROM AUTHOR]

Nowadays, as the interest in natural preservatives increases, research on bioprotective cultures that produce bacteriocins and studies on the use of these cultures in foods are also increasing day by day. Present study aimed to investigate bacteriocin characterization and safety of Enterococcus faecium H108, H206 isolates and their potential utilization in the reduction of Listeria monocytogenes ATCC7644 in Beyaz cheese. Enterocin producing E. faecium H108 and H206 strains were isolated from raw cow's milk and identified by 16S rRNA sequencing. Enterocin containing supernatants of E. faecium H108 and H206 were found to be stable to heat various chemicals used in food industry, wide pH range, lysozyme and catalase enzymes. On the other hand, activity of enterocins were inactivated by proteolytic enzymes. Maximum activity of E. faecium H108 was 6400 AU/mL, while that of H206 was 12800 AU/mL, and the activities remained stable for 24 h. Supernatant of both E. faecium H108 and H206 inhibited L. monocytogenes growth in vitro. E. faecium H108 and H206 did not show haemolytic and DN-ase activities and were susceptible to most of the antibiotics tested. The isolates were used in Beyaz cheese and were found to significantly, but not completely inhibit L. monocytogenes growth. The findings of this research suggest that E. faecium H108 and H206 isolates, after a detailed safety assessment, might be employed as bioprotective cultures in Beyaz cheese with starter culture or hurdle technologies. [ABSTRACT FROM AUTHOR]

The present study evaluates and models the efficacy of three different disinfectants-sodium hypochlorite (SH), peracetic acid (PAA), and chlorine dioxide (ClO 2) solution in inactivating biofilm formation of Listeria monocytogenes on stainless steel (SS) surfaces. The nonlinear survival curves of L. monocytogenes biofilm cells treated with different disinfectants were fitted using the Weibull model and four supervised machine learning models (Artificial Neural Networks (ANN), Random Forest (RF), Support Vector Regression (SVR), and Gradient Boosting Decision Tree (GBDT)). RF model exhibited superior predictive ability compared to other methods (RMSE: 0.12, MAE: 0.10, MAPE: 2.38, and R2: 0.99). Both RF and ANN showed better predictive effectiveness than the Weibull model. This research quantifies and models the efficacy of three disinfectants on L. monocytogenes biofilm on SS surfaces, providing valuable insights into the disinfection process of equipment surfaces in food processing. [Display omitted] • Listeria monocytogenes biofilm is very important in the food industry. • The efficacy of SH, PAA, and ClO 2 to inactivate L. M biofilm on SS was evaluated. • The Weibull and ML models fit the survival curves of biofilm disinfection well. • Random Forest model exhibited superior predictive ability compared to other methods. [ABSTRACT FROM AUTHOR]

In this study, we employed a novel encapsulation approach to develop a stable eugenol oil-in-water (O/W) emulsion by using Lactobacillus plantarum ATCC 8014 isolated exopolysaccharide (EPS) as a natural emulsifier. The emulsion was optimized and analyzed for physical stability, microstructure, rheology, and chemical behavior using fourier-transform infrared analysis (FTIR). The eugenol emulsion consisting of a 40:60 O/W ratio with 3 % w/v EPS exhibited a desired droplet size of 192 ± 1.89 nm with multimodal size distribution, polydispersity index of 0.362 ± 0.01 and zeta-potential of −32 ± 1.90 mV. Scanning electron microscopy (SEM) revealed porous and granulated structures with profound consistency. EPS maintained its emulsifying activity across processing conditions (−20 to 70 °C, pH 3–9, salinity 1 %–30 %), with stability over 90 days. Both EPS and eugenol synergistically enhanced the antimicrobial activity of emulsion against Listeria monocytogenes B600 and Salmonella Poona 36. The practical application of optimized emulsion was assessed by demonstrating a reduction in microbial load on the lettuce surface. Microbial load was determined by immersion and sprayed treatment methods which resulted in more than 3.0 log reduction. This potential application of lactobacillus– derived EPS as a natural emulsifier for encapsulating bioactive essential oils will enable its future applications for food safety. [Display omitted] • Lactobacillus -derived exopolysaccharide (EPS) stabilizes oil-in-water emulsion. • Encapsulated eugenol acquired a desirable droplet size of d < 200 nm. • Rheological behavior explains the extended stability in future processing. • Emulsion tends to stabilize at a lower pH (4.0) and higher salt concentrations. • Emulsion usage significantly reduced microbial load on fresh lettuce surfaces. [ABSTRACT FROM AUTHOR]

The objective of this study was to investigate the effects of Lactiplantibacillus plantarum fermentation on the bioactive compounds, volatile compounds, rheological properties and bacteriostatic activities of fig juices supplemented with oligosaccharides, namely fructooligosaccharides (FOS), galactooligosaccharides (GOS), isomaltooligosaccharides (IMO), xylooligosaccharides (XOS), stachyose (SOE) and mannanoligosaccharides (MOS). Results showed that SOE, FOS and IMO supplementations stimulated the proliferation of Lactiplantibacillus plantarum , especially for SOE, exhibiting the highest viable bacterial counts (9.84 log CFU/mL). Oligosaccharides supplementation accelerated the conversion of carbohydrates to organic acids, and increased the total contents of flavonoid (TFC) and carotenoid (TCC) during fermentation, of which FOS exhibited the greatest increases in TFC (66.28 mg RE/L) and TCC (0.032 mg/L). Furthermore, the highest levels of DPPH RSA (65.88%) and ABTS RSA (66.24%) were found in fermented fig juice supplemented with MOS, while the highest level of FRAP (0.97 mmol Trolox/L) and protocatechuic acid (6.97 mg/L) was observed in that with GOS. The total contents of alcohols and esters were significantly increased, while aldehyde content was decreased by oligosaccharides supplementation. In addition, oligosaccharides supplementation decreased the apparent viscosity of fermented juices. Fermented juices supplemented with FOS exhibited dramatically effective inhibition against Escherichia coli , Staphylococcus aureus and Listeria monocytogenes , due to the ruptures of cell surfaces and collapse of cellular structure. According to Pearson's correlation analysis, protocatechuic acid content was significantly and positively correlated with bacteriostatic activities. It was suggested that FOS should be a better probiotic additive for the preparation of fermented fig juice. [Display omitted] • Oligosaccharides stimulated the proliferation of Lactiplantibacillus plantarum. • Galactooligosaccharide improved protocatechuic acid content in fermented fig juice. • Antioxidant activities of fermented juice were enhanced by oligosaccharides. • Oligosaccharides improved flavor characteristics of fermented fig juice. • Fermented juice with fructooligosaccharide showed excellent bacteriostatic effect. [ABSTRACT FROM AUTHOR]

Biosurfactants play a very important role in the fresh produce industry, especially as anti-microbial agents. This study aimed to investigate the anti-oxidant and anti-bacterial activities of a glycolipoprotein biosurfactant (BSF) produced by Lactobacillus plantarum MGL-8, as well as its anti-bacterial mechanism of action against Listeria monocytogenes DMST17303. Its application as a sanitizer for fresh Chinese kale was investigated at different storage temperatures and exposure times. Its safety was monitored by cytotoxic effect to human skin HaCaT keratinocyte cells. The BSF exhibited high anti-oxidant capacities, with ferric-reducing from the FRAP assay of 15.96 μgVCEA/mg and ABTS scavenging activities with an IC 50 of 877.00 μg/mL. BSF demonstrated anti-bacterial activity against L. monocytogenes through decreasing the fluidity and increasing permeability of the cell membrane, resulting in reducing membrane function and leakage of intracellular components. The study revealed that the appropriate washing procedures of W2 (BSF 400 μg/mL for 20 min) and W3 (BSF 450 μg/mL for 10 min) efficiently inhibited the growth of L. monocytogenes in fresh Chinese kale stored at 5 °C for 7 and 14 days. BSF did not exhibit any cytotoxic effects on HaCaT cells at concentrations of up to 1,000 μg/mL, suggesting using BSF for disinfect L. monocytogenes in fresh Chinese kale at 450 μg/mL is safe for human. Therefore, it is recommended to wash fresh Chinese kale with BSF at 400 or 450 μg/mL for 20 or 10 min, respectively, to reduce food safety risks such as L. monocytogenes before storing at 5 °C for 14 days. [Display omitted] • BSF exhibited anti-oxidants through FRAP and ABTS radical scavenging activities. • BSF increased membrane permeability along with decreased membrane fluidity in L. monocytogenes. • BSF at concentrations of 400 and 450 μg/mL could control survival rate of L. monocytogenes. • BSF at concentrations of up to 1,000 μg/mL did not exhibit toxicity against HaCaT cells. [ABSTRACT FROM AUTHOR]

Listeria monocytogenes is a bacterium that can cause disease in many species, including humans, livestock, and wildlife. Increased interactions via shared habitats may promote pathogen transmission among these groups. Our objectives were to evaluate the Southeastern Cooperative Wildlife Disease Study diagnostic data to characterize and compare L. monocytogenes –induced lesions and comorbidities in gray foxes and wild turkeys, and to describe cases of listeriosis in 2 cervids. From 1991–2020, 8 gray foxes, 8 wild turkeys, a neonatal elk, and a white-tailed deer fawn from several eastern states in the United States were diagnosed with listeriosis. All 8 foxes had hepatitis and/or hepatic necrosis with intralesional gram-positive bacilli, and concurrent canine distemper virus (CDV) infection; 2 of the foxes had been vaccinated recently for CDV. L. monocytogenes was cultured from the liver (6 of 8) or lung (2 of 8) of foxes. Lesions in wild turkeys included hepatocellular necrosis (3 of 8), heterophilic hepatitis (1 of 8), heterophilic granulomas (1 of 8), intrasinusoidal gram-positive bacilli without hepatic lesions (1 of 8), granulomatous dermatitis (1 of 8), and/or granulomatous myocarditis (2 of 8). Lymphoproliferative disease viral DNA was detected in 5 of 6 turkeys tested; reticuloendotheliosis viral DNA was detected in 2 of 3 turkeys tested. Both cervids had systemic listeriosis, with L. monocytogenes isolated from liver. Immunohistochemistry for Listeria spp. on select cases revealed immunolabeling in affected organs. Listeriosis was thus established as a cause of morbidity and mortality in 3 wildlife species, which often suffered from concurrent infections and likely immunosuppression. [ABSTRACT FROM AUTHOR]

Scavenging constitutes an understudied energy pathway in terrestrial ecosystems, with important connections to disease ecology. A prevailing null hypothesis in scavenging ecology is that carcasses serve as a risk-free meal for whatever animal first encounters them on the landscape. We tested this hypothesis by focusing on a suspected risk that scavengers would face at carcasses: the risk of pathogen exposure. We conducted field trials with mouse carcasses in which we manipulated potential cues to pathogen risk and then monitored scavenger foraging decisions. Separately, we studied pathogen and commensal bacteria dynamics within mouse carcasses through time in the laboratory to better understand how carcass age might impact pathogen risk to scavengers. A visual cue to pathogen risk in the field (carcasses deployed in groups of 7 in 1 m2) caused facultative vertebrate scavengers to pass on the opportunity to feed at a rate six-times higher than for carcasses deployed singly (46.9% vs. 7.7%), suggesting an ability to perceive cues to pathogen risk at carcasses. The cues to carcass age, however, produced no effect on facultative scavenger behavior in our field trials. Laboratory trials demonstrated that both commensal enteric bacteria and a known pathogen (Listeria monocytogenes) increased at least through bloat and active decay stages in carcasses, suggesting that cues to carcass age may not help scavengers reduce pathogen risk early in decomposition. In providing evidence counter to the free meal hypothesis, our results support the continued formation of an alternative risk-based framework to understand scavenger behavior at carcasses. [ABSTRACT FROM AUTHOR]

Listeria monocytogenes (L. monocytogenes) is a common foodborne pathogen that has been responsible for many foodborne illness outbreaks in recent years. Currently, Listeria contamination in food products is identified only through molecular tests conducted in diagnostic laboratories. No established phage based diagnostic methods for L. monocytogenes during food production or processing are used. Here we report a potentially disruptive rapid diagnostic method based on electrochemical biosensing principles that use bacteriophages as bioreceptors for selective identification and quantification of L. monocytogenes. Electrochemical biosensors are good alternatives to molecular detection methods due to their ease of use, high specificity, sensitivity, and low cost. Bacteriophages can serve as excellent biorecognition elements in biosensors due to their robust stability in a range of environmental conditions and their ability to distinguish between live and dead bacterial cells. The impedimetric biosensing platform for L. monocytogenes detection was developed by immobilizing P100 bacteriophage onto quarternized polyethylenimine modified carbon nanotubes using an in-house developed molecular tethering method. The resulting sensor showed high selectivity and sensitivity toward L. monocytogenes with a limit of detection of 8.4 CFU/ml. Initial results demonstrate that the biosensing platform is highly reliable in its selectivity towards its target analyte, L. monocytogenes. [ABSTRACT FROM AUTHOR]

A 27-year-old female white-faced saki (Pithecia pithecia) died following an onset of vomiting and ptyalism. Necropsy revealed lesions of suppurative ventriculitis, choroid plexitis, periventricular encephalitis and meningitis with intralesional gram-positive coccobacilli and paired rods. The saki also had suppurative to mononuclear hepatitis, mild intestinal crypt necrosis, proliferative glomerulonephritis, aortic arteriosclerosis, pulmonary interstitial fibrosis, chronic mild epicarditis, ovarian medullary arteriopathy and a focal superficial cerebral fibrotic nodule with surrounding chronic mixed cell inflammation. Listeria monocytogenes was cultured from liver and spinal cord. Intralesional Listeria bacteria were immunolabelled in brain sections and real-time polymerase chain reaction of brain tissue detected L. monocytogenes. Whole genome multilocus sequence typing characterized the cultured bacterial isolates as sequence type 6 and clonal complex 6. A database search for related clinical and food listerial outbreaks identified genetically related isolates but, because these isolates were more than 20 alleles distant from the saki isolates, they were not a related cluster. Reports of listeriosis in non-human primates are infrequent, and when infections do occur, they tend to be haematogenous with the propensity to cause meningoencephalitis. This saki likely ingested environmental L. monocytogenes , which resulted in disease that may have been facilitated by pre-existing co-morbidities and age. [ABSTRACT FROM AUTHOR]

[Display omitted] • C17:0 significantly inhibits L.monocytogenes replication in macrophages. • C17:0 triggers the IFN and NF-κB signaling pathways. • C17:0 uniquely upregulates the ACOD1/itaconate axis. • Sheep tail fat rich in C17:0 performs similar anti- L.monocytogenes effect. 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. [ABSTRACT FROM AUTHOR]

Phenyllactic acid (PLA) exhibits antibacterial activity against Listeria monocytogenes which is a significant foodborne pathogen. In this study, effects of PLA on the cell survival, cell morphology, cell wall thickness, extraction of cell wall peptidoglycan and expression levels of genes involved in the synthesis of cell wall peptidoglycan were investigated using L. monocytogenes 10403S, which were either PLA shocked for 30 min (PLA shock) or grown in medium with PLA (PLA growth). Flow cytometry analysis demonstrated that at the same concentration, PLA shock resulted in a higher proportion of dead and injured cells than those from PLA growth. Images of field emission scanning electron microscopy showed that PLA growth had almost no effect on cell morphology, while damages on L. monocytogenes cells were observed after PLA shock. Results from transmission electron microscopy showed that the cell walls became thinner after PLA shock while PLA growth resulted in thicker cell walls. Coincidently, lower extraction yields were obtained after PLA shock while PLA growth led to higher extraction yields compared to the corresponding control group. PLA shock inhibited expression of genes associated with the production of lipid II and polymerization of peptidoglycan, while PLA growth induced expression of genes responsible for the production and translocation of lipid II. Our results suggest that L. monocytogenes responds differently to PLA shock and PLA growth. PLA affects the cell wall thickness of L. monocytogenes through regulating the synthesis of peptidoglycan. • L. monocytogenes responds differently to PLA shock and PLA growth. • The cell walls became thinner after PLA shock. • PLA growth resulted in thicker cell walls. • PLA affects cell wall thickness by regulating peptidoglycan synthesis. [ABSTRACT FROM AUTHOR]

Ensuring food safety is a significant challenge in the processed meat industry. Listeria monocytogenes represents a persistent threat due to its ability to grow in adverse conditions. Nowadays, there's a growing interest in natural preservatives to inhibit its proliferation in foods. Accordingly, the aim of the present study was to preliminarily evaluate the in vitro inhibitory activity of various natural antimicrobial agents against Listeria innocua , used as a surrogate for L. monocytogenes. Thyme essential oil (EO) emerged as the most effective candidate for further in vivo testing in pork minced meat with 40% fat and no additional fat, deliberately contaminated with L. innocua. The samples were stored for 20 days under two different temperature conditions, mimicking common procedures used to produce salami with short ripening periods and high fat content, such as the Italian Ciauscolo PGI salami, either through spontaneous fermentation or with the use of starter cultures. In vivo , the inhibitory effect of thyme EO was minimal or absent, regardless of fat content. Statistically significant decreases in L. innocua counts (<2%) were sporadic and observed solely in samples stored under temperature conditions mimicking the typical procedure for spontaneously fermented salami production. However, this effect was not sustained until the end of the experiment. While thyme EO demonstrated potential as an antilisterial agent in vitro , our findings highlight the complex interaction between antimicrobial agents and food matrices, revealing challenges in practical applications. This underscores the importance of further investigation elucidating the effectiveness of antimicrobial agents in real food systems. [ABSTRACT FROM AUTHOR]

Thymoquinone (TQ), a monoterpene isolated from the Nigella sativa L. seeds using the oil expeller method, gave about 40% of the total oil. Clevenger hydrodistillation of the obtained oil yielded volatile oil (0.55%) with 30% of TQ. Subsequent purification through silica gel column chromatography resulted in the isolation of pure TQ. The microwave assisted reduction of TQ with zinc and acetic acid resulted in the formation of thymohydroquinone within 5 min (THQ, yield 85%). The conventional reduction method gives 42% - 60% yield and is found to be time-consuming (4–12 h). The prepared THQ was tested at various concentrations for the inhibition of planktonic as well as biofilm of Listeria monocytogenes Scott A and Salmonella typhi FB231 bacterial cultures. Minimum inhibitory concentration (MIC) using MTT assay showed 50 μg/mL and 100 μg/mL for L. monocytogenes and S. typhi , respectively. Further, the biofilm growth inhibition and development were assessed using a crystal violet (CV) assay, which confirmed that THQ and TQ significantly eradicated biofilm formed after 6 h and 24 h, as evidenced by bright field microscopy. Thus, the results provide scope on the quicker microwave assisted synthesis, which is considered a greener method and the THQ showed potential antimicrobial and antibiofilm activities against common food borne pathogens. [ABSTRACT FROM AUTHOR]

Ultrasensitive and simultaneous quantitative detection of Listeria monocytogenes (L. monocytogenes) that can survive in vacuum packaging and frozen food is critical to public health. Herein, teamed boronate affinity (TBA) magnetically functionalized materials combined with biomass fluorescent probe for L. monocytogenes detection in a sandwich-like strategy was established. Firstly, we prepared new TBA magnetically functionalized materials by reducing the pKa value of phenylboronic acid through the TBA strategy in the form of self-assembled intermolecular B-N coordination bonding. To our knowledge, this is the first study where TBA magnetically functionalized materials were utilized for the identification and capture of bacteria, with a high capture efficiency of over 90.8% in spiked lettuce samples for L. monocytogenes (within 35 min), showing superior capture ability. Then, Anti- L. monocytogenes monoclonal antibody was labeled in biomass-derived fluorescent probe with the help of biotin-streptavidin system to achieve specific and sensitive detection of L. monocytogenes. The sandwich-like strategy shows high sensitivity of designed fluorescence sensing platform for L. monocytogenes with a wide linear range (2.2 × 101–2.2 × 106 CFU/mL), a low limit of detection (2.2 × 101 CFU/mL), and a satisfactory recovery rate (85.19%–106.69%) spiked lettuce sample. Notably, the method was low-cost, general and had strong application prospects in the field of food safety. • The binding pH of APBA was lowered by the TBA strategy. • Provides dual identification of L. monocytogenes with LOD as low as 22 CFU/mL. • Efficient capture and detection in actual food samples is still possible. [ABSTRACT FROM AUTHOR]

We report the case of a 72-year old man previously treated with an aortic endograft for an abdominal aortic aneurysm. After 3 years the patient developed a sepsis. Imaging and blood exams detected an endograft infection related to Listeria monocytogenes. Patients underwent endograft removal and in-situ aortic reconstruction with a cryopreserved allograft. A continuous antibacterial therapy has been established. One-month follow-up revealed the absence of clinically relevant infection with patency of the graft and absence of biochemical inflammatory markers. [ABSTRACT FROM AUTHOR]

Background: The 2017–2018 listeriosis outbreak in South Africa warranted testing for Listeria monocytogenes in food products and processing environments. Diagnostic tests are needed to accurately differentiate L. monocytogenes from other Listeria species. Objective: The study assessed the performance of the commonly used tests in our setting to accurately identify L. monocytogenes. Methods: The study was conducted in a public health laboratory in South Africa. Cultured isolates from food and environmental samples were tested both prospectively and retrospectively between August 2018 and December 2018. Isolates were phenotypically identified using tests for detecting β-haemolysis, Christie-Atkins-Munch-Peterson, alanine arylamidase (AlaA), mannosidase, and xylose fermentation. Listeria monocytogenes isolates were identified using automated systems, Microscan Walkaway Plus 96, Vitek® MS, Vitek® 2 and Surefast Listeria monocytogenes PLUS PCR. All results were compared to whole-genome sequencing results. Results: β-haemolysis and Christie-Atkins-Munch-Peterson tests gave delayed positivity or were negative for L. monocytogenes and falsely positive for one strain of Listeria innocua. The AlaA enzyme and Colorex Listeria agar lacked specificity for L. monocytogenes identification. Based on a few phenotypic test results, an aberrant L. monocytogenes strain and Listeria seeligeri strain were reported. All automated platforms overcalled L. monocytogenes in place of other Listeria species. Conclusion: No test was ideal in differentiating Listeria species. This is an issue in resource-limited settings where these tests are currently used. Newer technologies based on enzyme-linked immunosorbent assay and other molecular techniques specific to L. monocytogenes detection need to be investigated. [ABSTRACT FROM AUTHOR]

Bacterial phospholipases and sphingomyelinases are lipolytic esterases that are structurally and evolutionarily heterogeneous. These enzymes play crucial roles as virulence factors in several human and animal infectious diseases. Some bacterial phospholipases C (PLCs) have both phosphatidylcholinesterase and sphingomyelinase C activities. Among them, Listeria monocytogenes PlcB, Clostridium perfringens PLC, and Pseudomonas aeruginosa PlcH are the most deeply understood. In silico predictions of substrates docking with these three bacterial enzymes provide evidence that they interact with different substrates at the same active site. This review discusses structural aspects, substrate specificity, and the mechanism of action of those bacterial enzymes on target cells and animal infection models to shed light on their roles in pathogenesis. [ABSTRACT FROM AUTHOR]

Copyright of Biomédica: Revista del Instituto Nacional de Salud is the property of Instituto Nacional de Salud of Colombia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Introduction and objective. The ability of L. monocytogenes to create biofilm results in the higher resistance to disinfectants and determines the need to search for effective methods of eradication. The aim of the study was to assess the level of L. monocytogenes contamination in the environment of a meat processing plant. The sensitivity of tested isolates to various antimicrobials used for disinfection purposes was also estimated. Materials and method. The samples were taken from raw materials, semi-finished and final products, as well as food contact surfaces inthe production hall and deli meat packaging department. The number of L. monocytogenes and the effect of eight different biocides on bacteria planktonic forms and biofilm formed on stainless steel and polypropylene was investigated. The effect of blood and albumin on L. monocytogenes resistance to disinfectants was also analysed. Results. The prevalence of L. monocytogenes on food contact surfaces was estimated at 2.93% (10 of 340 swabs taken). The samples of raw and processed products were not contaminated. Various disinfectants reduced the growth of planktonic L. monocytogenes forms at both tested concentrations 0.5% and 0.1% (irrespective of time exposure). The highest efficacy against L. monocytogenes biofilm was reported for agents containing hydrogen peroxide. The reduction of bacteria number ranged from 6.93-7.21 log CFU x cm-2, and was dependent on the surface type and time of agent application. Conclusions. In this study, the effectiveness of various disinfectants against planktonic bacteria and Listeria biofilm was observed. For the majority of disinfectants, the extension of time exposure increased bacteria elimination from the biofilm. The presence of blood resulted in reduction of the antilisterial action of most of the disinfectants applied at low concentrations. [ABSTRACT FROM AUTHOR]

Nationwide group B Streptococcus agalactiae (GBS) antepartum screening was instituted in Taiwan in 2012. The impact of the policy on early-onset sepsis (EOS) has not been evaluated. This study aimed to examine the impact of the policy on the incidence of neonatal EOS. This was a retrospective study conducted at MacKay Children's Hospital. Patients with culture-proven neonatal EOS were enrolled and divided by birth year in relation to the implementation of GBS prevention policy: Epoch 1, 2001–2004 pre-GBS screening; Epoch 2, 2005–2011 elective GBS screening; and Epoch 3, 2012–2018 universal GBS screening. The pathogens and antimicrobial resistance patterns were reviewed and analyzed. The incidence was modeled using Poisson regression. A total of 128 neonates met the enrollment criteria. The observed incidence of EOS was 1.52‰. The incidence rates of EOS, GBS, and Escherichia coli (E. coli) sepsis were similar in Epoch 1 and Epoch 3. E. coli and non-Enterococcal group D Streptococcus (GDS) infection increased significantly in term infants, whereas the EOS-related mortality rate declined in preterm infants. Approximately 72% of the isolated E. coli were ampicillin-resistant, and the antimicrobial sensitivity remained unaltered during the studied period. The overall EOS incidence has not changed from 2001 to 2018. However, changes in the causative pathogens were observed in both term and preterm infants. Clinicians should be aware of this evolving epidemiology to provide prompt appropriate perinatal management. [ABSTRACT FROM AUTHOR]