Monocytogenes In Foods Research Articles

Rapid detection of nitrite and Listeria monocytogenes in food based on multiple simulated enzyme activities of Fe3O4-ZnO-MnO2 nanocomposites

Food safety has emerged as a paramount concern in global health, prompting innovative approaches to ensure the safety of people's sustenance. In this study, a novel strategy was devised to fabricate Fe3O4-ZnO-MnO2 hybrid nanobiocatalysts, which exhibited remarkable enzymatic activity surpassing that of Horseradish peroxidase (HRP) catalysis. It demonstrated exceptional proficiency in decomposing 3,3′,5,5′-tetramethylbenzidine (TMB) without the need for harsh reaction conditions or the aid of H2O2. We established colorimetric detection systems based on Fe3O4-ZnO-MnO2-TMB both for nitrite (NO2−) and Listeria monocytogenes (LM) in food. Impressively, the detection limit of nitrite reached an astonishingly low level of 0.022 mg L−1, and the detection limit for LM was determined to be 3.5 cfu mL−1. These compelling results unequivocally validate the potential of these hybrid nanobiocatalysts to fortify food safety measures. Moreover, they serve as a valuable reference for the colorimetric detection of diverse analytes and the simultaneous detection of multiple targets.

Exploring the genetic variability, virulence factors, and antibiotic resistance of Listeria monocytogenes from fresh produce, ready-to-eat hummus, and food-processing environments.

Listeria monocytogenes is ubiquitous in nature and persistent in food-processing facilities, farms, retail stores, and home and restaurant kitchens. Current research suggests ready-to-eat (RTE) products (including RTE hummus and fresh produce) to be of increasing interest and concern. These foods are typically stored at refrigeration temperatures suited to the survival of L. monocytogenes and are consumed without further processing. Since L. monocytogenes is ubiquitous in agricultural environments, the cultivation of fresh produce predisposes it to contamination. The contamination of RTE foods originates either from raw ingredients or, more commonly, from cross-contamination within food-processing facilities. Research on the food-processing environment has been recommended to reduce the incidence of L. monocytogenes in foods. The consumption of contaminated foods by immunocompromised individuals causes invasive listeriosis, with a 20% to 30% fatality rate despite treatment. The emergence of antibiotic-resistant strains has reduced the effectiveness of modern medicine and may increase morbidity and mortality. Without epidemiological surveillance and identifying trends in disease determinants, no action can be taken to improve food safety and mitigate the risk of such outbreaks.

Colorimetric aptasensor for Listeria monocytogenes detection using dual functional Fe3O4@MIL-100(Fe) with magnetic separation and oxidase-like activities in food samples.

A novel colorimetric aptasensor assay based on the excellent magnetic responsiveness and oxidase-like activity of Fe3O4@MIL-100(Fe) was developed. Fe3O4@MIL-100(Fe) absorbed with aptamer and blocked by BSA served as capture probe for selective isolation and enrichment of Listeria monocytogenesone of the most common and dangerous foodborne pathogenic bacteria. The aptamer absorbed on Fe3O4@MIL-100(Fe) was further used as signal probe that specifically binds with target bacteria conjugation of capture probe for colorimetric detection of Listeria monocytogenes, taking advantages of its oxidase-like activity. The linear range of the detection of Listeria monocytogenes was from 102 to 107CFUmL-1, with the limit of detection as low as 14CFUmL-1. The approach also showed good feasibility for detection of Listeria monocytogenes in milk and meat samples. The spiked recoveries were in the range 81-114% with relative standard deviations ranging from 1.28 to 5.19%. Thus, this work provides an efficient, convenient, and practical tool for selective isolation and colorimetric detection of Listeria monocytogenes in food.

Is the persistence of Listeria monocytogenes in food processing facilities and its resistance to pathogen intervention linked to its phylogeny?

The foodborne pathogen Listeria monocytogenes is differentiated into four distinct lineages which differ in their virulence. It remains unknown, however, whether the four lineages also differ with respect to their ability to persist in food processing facilities, their resistance to high pressure, a preservation method that is used commercially for Listeria control on ready-to-eat meats, and their ability to form biofilms. This study aimed to determine differences in the pressure resistance and biofilm formation of 59 isolates of L. monocytogenes representing lineages I and II. Furthermore, the genetic similarity of 9 isolates of L. monocytogenes that were obtained from a meat processing facility over a period of 1 year and of 20 isolates of L. monocytogenes from food processing facilities was analyzed to assess whether the ability of the lineages of L. monocytogenes to persist in these facilities differs. Analysis of 386 genomes with respect to the source of isolation revealed that genomes of lineage II are over-represented in meat isolates when compared with clinical isolates. Of the 38 strains of Lm. monocytogenes that persisted in food processing facilities (this study or published studies), 31 were assigned to lineage II. Isolates of lineage I were more resistant to treatments at 400 to 600 MPa. The thickness of biofilms did not differ between lineages. In conclusion, strains of lineage II are more likely to persist in food processing facilities while strains of lineage I are more resistant to high pressure.IMPORTANCEListeria monocytogenes substantially contributes to the mortality of foodborne disease in developed countries. The virulence of strains of four lineages of L. monocytogenes differs, indicating that risks associated with the presence of L. monocytogenes are lineage specific. Our study extends the current knowledge by documentation that the lineage-level phylogeny of L. monocytogenes plays a role in the source of isolation, in the persistence in food processing facilities, and in the resistance to pathogen intervention technologies. In short, the control of risks associated with the presence of L. monocytogenes in food is also lineage specific. Understanding the route of contamination L. monocytogenes is an important factor to consider when designing improved control measures.

Listeria monocytogenes from Food Products and Food Associated Environments: Antimicrobial Resistance, Genetic Clustering and Biofilm Insights.

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

Contamination of Food Products by Listeria monocytogenes in Iran during 2010-2023

Introduction: Mortality rate of Listeria infection is high and has been reported to be up to 30%. In this regard, the present study aimed to provide more information about food sources contaminated with the Listeria monocytogenes and offer suitable strategies to control this pathogen in supply centers, slaughterhouses, and processing centers. Method: Results of investigations on the prevalence of L. monocytogenes in food (seafood and aquatic products, red meat, poultry, and dairy products) during 2010-2023 were reviewed. In total, 61 acceptable studies were involved in the present research. After the selection of papers, their key results were extracted, including the prevalence of Listeria monocytogenes, cultivation method, sample type, and sampling location. Results: Listeria monocytogenes is prevalent in all types of seafood products, red meat, poultry, dairy products, and vegetables, as well as ready-to-eat and ready-to-cook foods. Consuming raw and undercooked foods contaminated with animal and human feces and direct contact with feces can cause Listeria infection in humans. L. monocytogenes is sensitive to amoxicillin, ampicillin, penicillin, and gentamicin antibiotics; therefore, these antibiotics can be used for listeriosis treatment. Conclusion: In previous studies, the importance of traditional meat and dairy supply centers in L. monocytogenes transmission has been addressed to a lesser extent. It can be concluded that appropriate standards should be developed and applied to control this food pathogen by regulatory systems. In addition, regular and periodic monitoring of food products and providing necessary training to people about how to prevent food poisoning can play an effective role in reducing listeriosis.

A novel electrochemical biosensor based on SRCA-NEMA-G-quadruplex for sensitive detection of Listeria monocytogenes in food

Listeria monocytogenes (L. monocytogenes), as one of the most common foodborne pathogens, has caused many foodborne diseases, posing a major threat to food and public health safety. Therefore, a novel electrochemical biosensor was proposed based on the combination of saltatory rolling circle amplification (SRCA) and nicking enzyme mediated amplification (NEMA) for detecting Listeria monocytogenes. When L. monocytogenes was present, abundant double-stranded DNA (dsDNA) were produced by SRCA reaction. SRCA products could be specifically recognized and cleaved by Nb.BsmI. SRCA-NEMA was performed to generate abundant single-stranded DNA (ssDNA) with the action of Bst DNA polymerase and Nb.BsmI. The hydrosulfuryl-modified hairpin DNA (HS-hpDNA) was immobilized on the electrode surface and G-quadruplex was used as signaling molecule. The current signal increased with target DNA concentration and the ratio of the current could be calculated as the result. Subsequently, the detection linear range for L. monocytogenes genomic DNA was 5.4 × 100-5.4 × 107 fg/μL, with the detection limit of 2.13 fg/μL. In comparison with ISO 11290-1:2017 method, the relative sensitivity, relative specificity and relative accuracy of the developed method were 100 %, 97.8 % and 98 %, respectively. Overall, the developed method provides an outstanding platform for sensitive detection of L. monocytogenes in food.

Detection of Listeria monocytogenes in Food Using the Proofman-LMTIA Assay.

Microbial factors, including bacteria, viruses, and other pathogens, are significant contributors to foodborne illnesses, posing serious food safety risks due to their potential for rapid growth and contamination. Listeria monocytogenes is one of the most common types of foodborne bacteria that can cause serious foodborne diseases or even fatalities. In this study, a novel nucleic acid amplification method called Proofman-LMTIA was employed to detect Listeria monocytogenes contamination in food. This method combines proofreading enzyme-mediated probe cleavage with ladder-shape melting temperature isothermal amplification. A positive recombinant plasmid was used as a control to ensure the accuracy of the detection results, and primers and Proofman probes were specifically designed for the LMTIA. Genomic DNA was extracted, the reaction temperature was optimized, and the primers' specificity was verified using foodborne pathogens like Staphylococcus aureus, Escherichia coli O157:H7, and Salmonella. The sensitivity was assessed by testing serial dilutions of genomic DNA, and the method's applicability was confirmed by detecting artificially contaminated fresh pork. The established LMTIA method exhibited both high specificity and sensitivity. At the optimal reaction temperature of 63 °C, the primers specifically identified Listeria monocytogenes contamination in pork at a concentration of 8.0 ± 0.7 colony-forming units (CFUs) per 25 g. Furthermore, the Proofman-LMTIA method was applied to test Listeria monocytogenes DNA in 30 food samples purchased from a Chinese retail market, and reassuringly, all results indicated no contamination. Proofman-LMTIA can serve as a reliable and rapid method for detecting Listeria monocytogenes in food, contributing to public health by safeguarding consumers from foodborne illnesses, and strengthening food safety regulations.

Identification by High-Throughput Real-Time PCR of 30 Major Circulating Listeria monocytogenes Clonal Complexes in Europe.

Listeria monocytogenes is a ubiquitous bacterium that causes a foodborne illness, listeriosis. Most strains can be classified into major clonal complexes (CCs) that account for the majority of outbreaks and sporadic cases in Europe. In addition to the 20 CCs known to account for the majority of human and animal clinical cases, 10 CCs are frequently reported in food production, thereby posing a serious challenge for the agrifood industry. Therefore, there is a need for a rapid and reliable method to identify these 30 major CCs. The high-throughput real-time PCR assay presented here provides accurate identification of these 30 CCs and eight genetic subdivisions within four CCs, splitting each CC into two distinct subpopulations, along with the molecular serogroup of a strain. Based on the BioMark high-throughput real-time PCR system, our assay analyzes 46 strains against 40 real-time PCR arrays in a single experiment. This European study (i) designed the assay from a broad panel of 3,342 L. monocytogenes genomes, (ii) tested its sensitivity and specificity on 597 sequenced strains collected from 24 European countries, and (iii) evaluated its performance in the typing of 526 strains collected during surveillance activities. The assay was then optimized for conventional multiplex real-time PCR for easy implementation in food laboratories. It has already been used for outbreak investigations. It represents a key tool for assisting food laboratories to establish strain relatedness with human clinical strains during outbreak investigations and for helping food business operators by improving their microbiological management plans. IMPORTANCE Multilocus sequence typing (MLST) is the reference method for Listeria monocytogenes typing but is expensive and takes time to perform, from 3 to 5 days for laboratories that outsource sequencing. Thirty major MLST clonal complexes (CCs) are circulating in the food chain and are currently identifiable only by sequencing. Therefore, there is a need for a rapid and reliable method to identify these CCs. The method presented here enables the rapid identification, by real-time PCR, of 30 CCs and eight genetic subdivisions within four CCs, splitting each CC into two distinct subpopulations. The assay was then optimized on different conventional multiplex real-time PCR systems for easy implementation in food laboratories. The two assays will be used for frontline identification of L. monocytogenes isolates prior to whole-genome sequencing. Such assays are of great interest for all food industry stakeholders and public agencies for tracking L. monocytogenes food contamination.

Detection of Listeria monocytogenes in foods with a textile organic electrochemical transistor biosensor

Foods contaminated by pathogens are responsible for foodborne diseases which have socioeconomic impacts. Many approaches have been extensively investigated to obtain specific and sensitive methods to detect pathogens in food, but they are often not easy to perform and require trained personnel. This work aims to propose a textile organic electrochemical transistor-based (OECT) biosensor to detect L. monocytogenes in food samples. The analyses were performed with culture-based methods, Listeria Precis™ method, PCR, and our textile OECT biosensor which used poly(3,4-ethylenedioxythiophene) (PEDOT):polystyrene sulfonate (PSS) (PEDOT:PSS) for doping the organic channel. Atomic force microscopy (AFM) was used to obtain topographic maps of the gold gate. The electrochemical activity on gate electrodes was measured and related to the concentration of DNA extracted from samples and hybridized to the specific capture probe immobilized onto the gold surface of the gate. This assay reached a limit of detection of 1.05 ng/μL, corresponding to 0.56 pM of L. monocytogenes ATCC 7644, and allowed the specific and rapid detection of L. monocytogenes in the analyzed samples.Keypoints• Textile organic electrochemical transistors functionalized with a specific DNA probe• AFM topographic and surface potential maps of a functionalized gold gate surface• Comparison between the Listeria monocytogenes Precis™ method and an OECT biosensor

LISTERIA MONOCYTOGENES BACTERIUM IN THE AREA OF MOSTAR: OCCURRENCE IN VEGETABLES AND HEALTH RISKS

This research focuses on the bacterium Listeria monocytogenes and its occurrence in vegetables, specifically, tomatoes and peppers, and the risks this bacterium poses to health. The research included laboratory analysis of 16 samples of tomatoes and peppers, as well as survey research in the area of the City of Mostar. Based on the survey questionnaire, the respondents showed their knowledge about the occurrence of the bacteria Listeria monocytogenes in food and their general knowledge about listeriosis. Laboratory analysis consists of two parts. The first part refers to the laboratory analysis of the samples conducted in the Federal Agro-Mediterranean Institute laboratory in collaboration with its employees. The second part refers to an additional laboratory analysis conducted in the Veterinary Institute of Herzegovina–Neretva Canton laboratory in Mostar. This laboratory research aimed to establish whether the bacterium Listeria monocytogenes was present in the samples of vegetables examined in the analysis. All the vegetable samples were chosen randomly from four different locations in the area of Mostar. Also, the analysis included the examination of the washed and unwashed tomatoes and peppers. After conducting the laboratory research, it was established that the bacterium Listeria monocytogenes was not found in the samples used, which means all the examination results were negative.

Effective combination of nisin and sesamol against Listeria monocytogenes

Nisin (NS) has been considered as a food preservative against Listeria monocytogenes, an important foodborne pathogen that causes serious public health problems. However, the effectiveness of NS is also affected due to its instability and resistance of L. monocytogenes to NS. Combining NS with other antimicrobial substances is an excellent strategy to improve the effect. Sesamol (SE) has been reported to have the ability to inhibit the growth of L. monocytogenes. Thus, in this study, based on the determination of the fractional inhibitory concentration indices, the in vitro synergistic antibacterial activity of NS and SE was confirmed using standard L. monocytogenes ATCC19112 and L. monocytogenes isolated from food and clinical sources. The inhibition of NS and SE combination on the growth of L. monocytogenes was higher than that of NS or SE alone in tryptic soy yeast extract broth (TSB-YE) and pasteurized milk. The changes and damages of the cell structure and the cell morphology in the combination group were more significant than those in the single use of NS or SE. These results indicate that the combined application of NS and SE may be a promising alternative to NS for controlling the contamination of L. monocytogenes in food.

Diagnostic capabilities of modern methods of determination pathogenic listeria in meat products

Annual reports on the morbidity of the adult population report outbreaks of listeriosis caused by Listeria monocytogenes with clinically pronounced febrile gastroenteritis. The main transmission route to humans is believed to be through consumption of contaminated food, especially ready-to-eat meat products. Rapid and specific detection of L. monocytogenes in food is critical for ensuring the safety of consumers. The aim of this work was to study the occurrence of L. monocytogenes in vacuum-packed meat products using modern diagnostic methods. In total, 60 vacuum-packed meat products were studied using real-time PCR (iQ-Check™ realtime PCR kit), immunoassay (VIDAS LMO2 test) and culturing. Thirty-two of 60 (53%) vacuum-packed meat products were L. monocytogenes positive by real-time PCR. The occurrence was especially high in heat-treated sausages (80%). Only two products (two bacons) were VIDAS and culture positive. Additionally, L. monocytogenes was isolated from one heat-treated sausage, which was VIDAS negative. All VIDAS and culture-positive samples were also PCR positive. In two (12%) out of 17 vacuum-packed ready-to-eat products, the number of L. monocytogenes was over 100 cfu/g demonstrating that the shelf life assigned to some vacuum-packed products is not appropriate. Real-time PCR based on iQ-Check™ realtime PCR kit was shown to be very sensitive to detect L. monocytogenes in foods and thus a useful tool for screening.

Application of a Loop-Mediated Isothermal Amplification (LAMP) Assay for the Detection of Listeria monocytogenes in Cooked Ham

Changing eating habits and rising demand of food have increased the incidence of foodborne diseases, particularly in industrialized countries. In this context, contaminated ready-to-eat food (RTE) may be a vehicle for the transmission of Listeria monocytogenes (L. monocytogenes), a foodborne pathogen responsible of listeriosis, a severe infectious disease involving humans and animals. It would be useful to have rapid detection methods to screen the presence of L. monocytogenes in food. In this study, a colorimetric Loop-mediated isothermal amplification (LAMP) assay was applied to the detection of L. monocytogenes in 37 experimentally contaminated RTE meat samples. The LAMP primers consisted of a set of six primers targeting eight regions on the hlyA gene; the assay was carried out in 30 min at 65 °C in a water bath. Amplification products were visualized by color change assessment. The results of colorimetric LAMP assays based on the hly gene obtained in this study were compared to microbiological cultural methods, real-time PCR and real-time LAMP PCR, which show 100% specificity and sensitivity. These data suggest that colorimetric LAMP assays can be used as a screen to detect L. monocytogenes in ready-to-eat meat food.

Listeria monocytogenes isolated from raw milk: phenotypic and molecularcharacterization, pathogenicity testing, and multidrug resistance profiling

Foodborne infections are a worldwide public health emergency that actually impact a variety of disorders. In the current research, a total of 300 samples comprising raw milk (100),milk products (100), and chicken (100) were screened for detection of pathogenic Listeria species by using the USDA method. On conventional biochemical characterization, three isolates were identified as Listeria monocytogenes (from raw milk samples)indicating an overall prevalence of Listeria monocytogenes to the tune of 1%. All other samples comprising milk products and chicken samples (100) showed negativity for the presence of any of the Listeria species. Further, all three isolates were subjected to polymerase chain reaction (PCR) targeting genus-specific (prsA and iap) and species-specific gene (isp) in which all three were turn out positive for both the genes, endorsing their identification as Listeria monocytogenes. All three confirmed Listeria monocytogenes isolates were phenotypically assessed for in-vitro pathogenicity tests like hemolysis on 7% sheep blood agar, CAMP test, and PI-PLC assay. The results revealed their highly pathogenic nature. Subsequently, all these isolates were also assessed for their virulent nature by PCR, targeting the array ofmarkers including virulence-associated genes viz. hlyA, actA, plcA. The results endorsed pathogenic nature of all isolates showing amplification of all targeted virulence genes. The antibiotic resistance profiling revealed occurrence of multidrug-resistant pathogenic L. monocytogenes in foods of animal origin with maximum multiple antibiotic resistance (MAR) index of 0.6and a minimum MAR index of 0.48 in MDR, which is a matter of concern from public health point of view.

Comparison between qPCR, VIDAS immunoassays, and agar streaking for the detection of Listeria monocytogenes from food and environmental surfaces containing and not containing Listeria innocua

Comparisons among a qPCR assay, VIDAS® assays and a conventional agar streaking method following the same enrichment for the detection of Listeria monocytogenes were performed under two challenging conditions. In the first comparison, L. innocua and L. monocytogenes were coinoculated into sausages at ratios (L. innocua-to-L. monocytogenes) of 10, 100, 1000, and 10 000. qPCR provided the most sensitive detection at all ratios after both 24-h and 48-h enrichments. A modified VIDAS® LMO2 assay (i.e., replacement of the kit-specified enrichment scheme with the enrichment scheme used in this study) and agar streaking yielded equivalent results when the ratio was 10 and 100; agar streaking was more sensitive when the ratio was 1000; neither method could detect L. monocytogenes at the ratio of 10 000. Enrichment duration of 48 h was needed for modified VIDAS® to detect L. monocytogenes when the ratio was 1000. Agar streaking after 24-h enrichment isolated L. monocytogenes better than after 48-h enrichment when the ratio was 100 and 1000. In the second comparison, we followed the validation guidelines of AOAC International and inoculated L. monocytogenes, without any L. innocua, onto lettuce and stainless-steel surfaces at low levels. The numbers of positive samples detected by qPCR, VIDAS® LIS assay, modified VIDAS® LMO2 assay, and agar streaking after 48-h enrichment were not statistically different. Our data showed that qPCR was the most sensitive method, while agar streaking and VIDAS® performed reasonably well. Streaking after 24-h enrichment was needed when background flora could overgrow L. monocytogenes during prolonged enrichment, and this is critical for confirming rapid screening assays. Appropriate selection of enrichment duration and rapid assays will enhance the testing of L. monocytogenes in food and environmental samples.

Portable sensor based on magnetic separation and enzyme-mediated immune nanomaterials for point-of-care testing of Listeria monocytogenes in food

Listeria monocytogenes (L. monocytogenes), a typical foodborne pathogen, poses a serious threat to public health safety. This stimulates to develop a point-of-care testing (POCT) method to achieve rapid, sensitive detection of L. monocytogenes. In this study, polyethylene glycol (PEG) mediated ampicillin functionalized magnetic beads (Amp-PEG-MBs) was prepared successfully and it achieved high efficiency (>90%) and rapid (5 min) capture for L. monocytogenes at room temperature. The innovative combination of antibody (Ab), glucose oxidase (GOD) and graphene oxide (GO) prepared Ab@GO@GOD for the specific recognition of L. monocytogenes. Finally, Amp-PEG-MBs and Ab@GO@GOD were successfully assembled into Amp-PEG-MBs@L. monocytogenes-Ab@GO@GOD sandwich structure which could catalyze the glucose, and the final detection results were recorded by a blood glucose meter (BGM). Magnetic separation (MS) combined with enzyme-catalyzed sensor (MS-Ab@GO@GOD-BGM) was successfully established to achieve the detection of L. monocytogenes in artificially contaminated juice within 66 min with the limit of detection was 101 CFU/mL. This sensor has potential for other pathogens detection by modifying specific antibodies.

Essential Oils as Potential Tools to Control Listeria Monocytogenes in Foods

Foodborne diseases are indisputable risks to human health, as they are directly affected by the consumption of food and beverages exposed to spoiling and pathogenic microorganisms. A commonly confronted issue by the food industry is the use of synthetic additives to control microbial growth on food products. Alternatively, plant essential oils (EOs) are natural compounds with antimicrobial effects against pathogens in edible and drinkable products. Based on bacteriostatic and bactericidal activities, this review describes the antimicrobial effects of plant EOs on Listeria monocytogenes, also indicating their potential applicability in different food products. Conclusively, it is determined that the Gram-positive bacteria have more susceptibilities to the EOs. In addition, the antibacterial efficacy of the EOs reported in the literature varied according to several parameters, including the seasonal harvest of plants, well-settled methodologies for extraction of EOs, experimental conditions for testing the antibacterial effect on L. monocytogenes, and matrix effects considering several types of foodstuffs. This later represents the main challenge to be addressed in future research aiming at specific applications of EOs in food products.

Rapid detection of Listeria monocytogenes in dairy products by a novel chemilumonogenic approach

Routine monitoring of foodborne pathogens such as Listeria monocytogenes in food processing environments are time-consuming necessities to ensure food safety. Alternative rapid diagnostic methods for pathogen detection are increasingly used, but often demand specialized equipment, making them unsuitable for on-site testing. This short communication describes the successful demonstration of combining the sample preparation method Matrix-Lysis with a chemiluminescent based detection platform (AquaSpark™) for detection of L. monocytogenes in milk and yogurt. The proposed method was evaluated against qPCR resulting in 100% relative specificity for both foodstuffs and a relative sensitivity of 100% for milk as well as 96% for yogurt for bacterial levels >1 CFU/ml. Only at very low initial bacterial concentrations (<1 CFU/ml) diverging results were found highlighting the advantages and limitations of both methods. While being less susceptible to contamination and false positive results from non-growing or dead cells, qPCR had a slightly lower overall detection limit. However, it has to be pointed out that qPCR has an increased analytical cost and also requires an additional 24 h analysis time. This study demonstrates the first successful application of a chemilumonogenic detection approach for L. monocytogenes in food that has a high potential for on-site testing.

Establishment of droplet digital PCR for quantitative detection of Listeria monocytogenes in food

Establishment of droplet digital PCR for quantitative detection of Listeria monocytogenes in food