Biochemistry, Genetics and Molecular Biology › Biotechnology

Listeria monocytogenes in Food Safety

Works Count: 34273

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Description

This cluster of papers focuses on the pathogenesis, virulence determinants, and food safety implications of Listeria monocytogenes. It covers topics such as bacterial contamination of fresh produce, microbial inactivation methods, epidemiology of foodborne illness outbreaks, and the molecular mechanisms of Listeria pathogenicity.

Keywords

Listeria monocytogenes; foodborne illness; pathogenicity; fresh produce; virulence determinants; UV radiation; bacterial contamination; food safety; outbreaks; microbial inactivation

Listeria monocytogenes Virulence and Pathogenicity, a Food Safety Perspective

2002-11-01

Sophia Kathariou

Model for bacterial culture growth rate throughout the entire biokinetic temperature range

1983-06-01

David A. Ratkowsky , Robert K. Lowry , TA McMeekin +2 more

The "square-root" relationship proposed by Ratkowsky et al. (J. Bacteriol. 149:1-5, 1982) for modeling the growth rate of bacteria below the optimum growth temperature was extended to cover the full … The "square-root" relationship proposed by Ratkowsky et al. (J. Bacteriol. 149:1-5, 1982) for modeling the growth rate of bacteria below the optimum growth temperature was extended to cover the full biokinetic temperature range. Two of the four parameters of this new nonlinear regression model represent minimum and maximum temperature bounds, respectively, for the predicted growth of the culture. The new model is easy to fit and has other desirable statistical properties. For example, the least-squares estimators of the parameters of the model were almost unbiased and normally distributed. The model applied without exception to all bacterial cultures for which we were able to obtain data. Results for 30 strains are reported.

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Listeria, Listeriosis, and Food Safety

2007-03-27

Elliot T. Ryser , Elmer H. Marth

The genus listeria and listeria monocytogenes - phylogenetic position, taxonomy and identification listeria monocytogenes in the natural environment listeriosis in animals listeriosis in humans pathogenesis of listeria monocytogenes characteristics of … The genus listeria and listeria monocytogenes - phylogenetic position, taxonomy and identification listeria monocytogenes in the natural environment listeriosis in animals listeriosis in humans pathogenesis of listeria monocytogenes characteristics of listeria monocytogenes important to food processors conventional methods to detect and isolate listeria monocytogenes rapid methods for detection of listeria subtyping listeria monocytogenes foodborne listeriosis incidence and behaviour of listeria monocytogenes in unfermented dairy products incidence and behaviour of listeria monocytogenes in meat products incidence and behaviour of listeria monocytogenes in poultry and egg products incidence and behaviour of listeria monocytogenes in fish and seafood products incidence and behaviour of listeria monocytogenes in products of plant origin incidence and control of listeria in food processing facilities.

Listeria monocytogenes, a food-borne pathogen.

1991-01-01

Jeffrey M. Farber , Pearl I. Peterkin

Listeriosis, caused by Listeria monocytogenes, appears to be increasing in incidence worldwide. The disease is of great concern to the food industry. A recent outbreak in California was linked to … Listeriosis, caused by Listeria monocytogenes, appears to be increasing in incidence worldwide. The disease is of great concern to the food industry. A recent outbreak in California was linked to the consumption of Mexican-style soft cheese and involved more than 300 cases, 30% of which were fatal. L. monocytogenes can be found in a variety of dairy products, leafy vegetables, fish and meat products. It can grow in refrigerated foods and is more heat resistant than most vegetative microbes. The epidemiologic features of listeriosis are poorly understood, and the minimum infectious dose is unknown. Those predisposed to listeriosis include immunocompromised people and pregnant women and their fetuses. Meningitis, spontaneous abortion and septicemia are the primary manifestations of the disease. Early recognition is critical for successful treatment, and ampicillin is the preferred drug. Listeriosis should be considered in any febrile patient with neurologic symptoms of unknown origin, as well as in women with unexplained recurrent miscarriages, premature labour or fetal death. A food source should be the prime suspect if any isolated case or outbreak occurs.

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Fresh fruit and vegetables as vehicles for the transmission of human pathogens

2010-07-15

Cédric N. Berger , Samir V. Sodha , Robert K. Shaw +4 more

Summary Much research into food‐borne human pathogens has focused on transmission from foods of animal origin. However, recent investigations have identified fruits and vegetables are the source of many disease … Summary Much research into food‐borne human pathogens has focused on transmission from foods of animal origin. However, recent investigations have identified fruits and vegetables are the source of many disease outbreaks. Now believed to be a much larger contributor to produce‐associated outbreaks than previously reported, norovirus outbreaks are commonly caused by contamination of foods from hands of infected workers. Although infections with Shiga toxin‐producing E. coli O157 have been linked to beef more often than to any other food product, severe outbreaks have been traced to consumption of contaminated radish sprouts and pre‐packaged spinach. Similarly, while infections with Salmonella have mainly been linked to consumption of foods of animal origin, many outbreaks have been traced to contaminated fresh produce. E. coli O157 binds to lettuce leaves by alternative mechanisms involving the filamentous type III secretions system, flagella and the pilus curli. Association of Salmonella with fresh produce appears to be serovar‐specific involving flagella, curli, cellulose, and O antigen capsule. A better understanding of plant, microbiological, environmental, processing and food handling factors that facilitate contamination will allow development of evidence‐based policies, procedures and technologies aimed at reducing the risk of contamination of fresh produce.

In vitro model of penetration and intracellular growth of Listeria monocytogenes in the human enterocyte-like cell line Caco-2

1987-11-01

Jean‐Louis Gaillard , Patrick Berche , Joëlle Mounier +2 more

Penetration and replication of Listeria monocytogenes within intestinal epithelial cells were studied by infecting the human enterocyte-like cell line Caco-2. Entry was due to directed phagocytosis, as suggested by the … Penetration and replication of Listeria monocytogenes within intestinal epithelial cells were studied by infecting the human enterocyte-like cell line Caco-2. Entry was due to directed phagocytosis, as suggested by the inhibiting effect of cytochalasin D on bacterial entry and by electron microscopy showing bacteria inside membrane-limiting vacuoles at the early stage of infection. Only bacteria from pathogenic species (L. monocytogenes and Listeria ivanovii) were able to induce their own phagocytosis by Caco-2 cells, as opposed to Listeria seeligeri, Listeria welshimeri, and Listeria innocua. L. monocytogenes multiplied readily within Caco-2 cells, with an apparent generation time of about 90 min. Listeriolysin O was found to be a major factor promoting intracellular growth of L. monocytogenes. After being internalized at the same rate as that of its hemolytic revertant strain, a nonhemolytic mutant from L. monocytogenes failed to replicate significantly within Caco-2 cells. Electron microscopic study demonstrated that bacteria from the nonhemolytic mutant remained inside phagosomes during cellular infection, whereas hemolytic bacteria from L. monocytogenes were released free within the cytoplasm. This indicates that disruption of vacuole membranes by listeriolysin O-producing strains of L. monocytogenes might be a key mechanism allowing bacteria to escape from phagosomes and to multiply unrestricted within cell cytoplasm.

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Listeria monocytogenes and listeric infections

1966-06-01

M. L. Gray , A. H. Killinger

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Standardization of Pulsed-Field Gel Electrophoresis Protocols for the Subtyping ofEscherichia coliO157:H7,Salmonella, andShigellafor PulseNet

2006-03-01

Efrain M. Ribot , M. A. Lambert Fair , Romesh Gautom +4 more

Standardized rapid pulsed-field gel electrophoresis (PFGE) protocols for the subtyping of Escherichia coli O157:H7, Salmonella serotypes, and Shigella species are described. These protocols are used by laboratories in PulseNet, a … Standardized rapid pulsed-field gel electrophoresis (PFGE) protocols for the subtyping of Escherichia coli O157:H7, Salmonella serotypes, and Shigella species are described. These protocols are used by laboratories in PulseNet, a network of state and local health departments, and other public health laboratories that perform real-time PFGE subtyping of these bacterial foodborne pathogens for surveillance and outbreak investigations. Development and standardization of these protocols consisted of a thorough optimization of reagents and reaction conditions to ensure that the protocols yielded consistent results and high-quality PFGE pattern data in all the PulseNet participating laboratories. These rapid PFGE protocols are based on the original 3–4-day standardized procedure developed at Centers for Disease Control and Prevention that was validated in 1996 and 1997 by eight independent laboratories. By using these rapid standardized PFGE protocols, PulseNet laboratories are able to subtype foodborne pathogens in approximately 24 h, allowing for the early detection of foodborne disease case clusters and often aiding in the identification of the source responsible for the infections.

The growing burden of foodborne outbreaks due to contaminated fresh produce: risks and opportunities

2009-02-09

Michael Lynch , Robert V. Tauxe , Craig W. Hedberg

SUMMARY Foodborne outbreaks from contaminated fresh produce have been increasingly recognized in many parts of the world. This reflects a convergence of increasing consumption of fresh produce, changes in production … SUMMARY Foodborne outbreaks from contaminated fresh produce have been increasingly recognized in many parts of the world. This reflects a convergence of increasing consumption of fresh produce, changes in production and distribution, and a growing awareness of the problem on the part of public health officials. The complex biology of pathogen contamination and survival on plant materials is beginning to be explained. Adhesion of pathogens to surfaces and internalization of pathogens limits the usefulness of conventional processing and chemical sanitizing methods in preventing transmission from contaminated produce. Better methods of preventing contamination on the farm, or during packing or processing, or use of a terminal control such as irradiation could reduce the burden of disease transmission from fresh produce. Outbreak investigations represent important opportunities to evaluate contamination at the farm level and along the farm-to-fork continuum. More complete and timely environmental assessments of these events and more research into the biology and ecology of pathogen-produce interactions are needed to identify better prevention strategies.

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GInaFiT, a freeware tool to assess non-log-linear microbial survivor curves

2005-05-13

Annemie Geeraerd , Vasilis Valdramidis , Jan Van Impe

Disinfection of wastewater with peracetic acid: a review

2003-06-30

Mehmet Kitiş

Ecological factors influencing survival and growth of human pathogens on raw fruits and vegetables

2002-04-01

Larry R. Beuchat

A dynamic approach to predicting bacterial growth in food

1994-11-01

József Baranyi , T.A. Roberts

Listeria monocytogenes lineages: Genomics, evolution, ecology, and phenotypic characteristics

2010-08-14

Renato H. Orsi , Henk C. den Bakker , Martin Wiedmann

E-Cadherin Is the Receptor for Internalin, a Surface Protein Required for Entry of L. monocytogenes into Epithelial Cells

1996-03-01

J Mengaud , Hélène Ohayon , Pierre Gounon +2 more

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Produce Handling and Processing Practices

1997-12-01

Larry R. Beuchat , Jee-Hoon Ryu

In the past decade, outbreaks of human illness associated with the consumption of raw vegetables and fruits (or unpasteurized products produced from them) have increased in the United States. Changes … In the past decade, outbreaks of human illness associated with the consumption of raw vegetables and fruits (or unpasteurized products produced from them) have increased in the United States. Changes in agronomic, harvesting, distribution, processing, and consumption patterns and practices have undoubtedly contributed to this increase. Pathogens such as Listeria monocytogenes, Clostridium botulinum, and Bacillus cereus are naturally present in some soil, and their presence on fresh produce is not rare. Salmonella, Escherichia coli O157:H7, Campylobacter jejuni, Vibrio cholerae, parasites, and viruses are more likely to contaminate fresh produce through vehicles such as raw or improperly composted manure, irrigation water containing untreated sewage, or contaminated wash water. Contact with mammals, reptiles, fowl, insects, and unpasteurized products of animal origin offers another avenue through which pathogens can access produce. Surfaces, including human hands, which come in contact with whole or cut produce represent potential points of contamination throughout the total system of growing, harvesting, packing, processing, shipping, and preparing produce for consumption. Treatment of produce with chlorinated water reduces populations of pathogenic and other microorganisms on fresh produce but cannot eliminate them. Reduction of risk for human illness associated with raw produce can be better achieved through controlling points of potential contamination in the field; during harvesting; during processing or distribution; or in retail markets, food-service facilities, or the home.

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Review — Persistence of Listeria monocytogenes in food industry equipment and premises

2011-01-09

Brigitte Carpentier , O. Cerf

Epidemic Listeriosis — Evidence for Transmission by Food

1983-01-27

Walter F. Schlech , Pierre Lavigne , Robert Bortolussi +7 more

The bacterium Listeria monocytogenes is a motile, gram-positive coccobacillus that can frequently be isolated from soil, water, and vegetation. It is a common cause of meningoencephalitis and abortion in ruminants, … The bacterium Listeria monocytogenes is a motile, gram-positive coccobacillus that can frequently be isolated from soil, water, and vegetation. It is a common cause of meningoencephalitis and abortion in ruminants, but it is infrequently identified as a human pathogen. In adults, L. monocytogenes is an uncommon cause of bacterial meningitis and a rare cause of sepsis, endocarditis, peritonitis, or focal abscess. In neonates, it is the third most common cause of bacterial meningitis after Escherichia coli and Streptococcus agalactiae. In addition, perinatal infections can cause abortion, stillbirth, and a devastating septic illness termed "granulomatosis infantisepticum."The mode of acquisition . . .

Factors influencing the microbial safety of fresh produce: A review

2012-05-08

Amin N. Olaimat , Richard A. Holley

On calculating sterility in thermal preservation methods: application of the Weibull frequency distribution model

2002-01-01

Pierre Mafart , Olivier Couvert , Stéphane Gaillard +1 more

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The epidemiology of human listeriosis

2007-05-08

Bala Swaminathan , Peter Gerner‐Smidt

Foodborne Pathogens in Milk and the Dairy Farm Environment: Food Safety and Public Health Implications

2005-06-01

S.P. Oliver , B.M. Jayarao , R.A. Almeida

Milk and products derived from milk of dairy cows can harbor a variety of microorganisms and can be important sources of foodborne pathogens. The presence of foodborne pathogens in milk … Milk and products derived from milk of dairy cows can harbor a variety of microorganisms and can be important sources of foodborne pathogens. The presence of foodborne pathogens in milk is due to direct contact with contaminated sources in the dairy farm environment and to excretion from the udder of an infected animal. Most milk is pasteurized, so why should the dairy industry be concerned about the microbial quality of bulk tank milk? There are several valid reasons, including (1) outbreaks of disease in humans have been traced to the consumption of unpasteurized milk and have also been traced back to pasteurized milk, (2) unpasteurized milk is consumed directly by dairy producers, farm employees, and their families, neighbors, and raw milk advocates, (3) unpasteurized milk is consumed directly by a large segment of the population via consumption of several types of cheeses manufactured from unpasteurized milk, (4) entry of foodborne pathogens via contaminated raw milk into dairy food processing plants can lead to persistence of these pathogens in biofilms, and subsequent contamination of processed milk products and exposure of consumers to pathogenic bacteria, (5) pasteurization may not destroy all foodborne pathogens in milk, and (6) inadequate or faulty pasteurization will not destroy all foodborne pathogens. Furthermore, pathogens such as Listeria monocytogenes can survive and thrive in post-pasteurization processing environments, thus leading to recontamination of dairy products. These pathways pose a risk to the consumer from direct exposure to foodborne pathogens present in unpasteurized dairy products as well as dairy products that become re-contaminated after pasteurization. The purpose of this communication is to review literature published on the prevalence of bacterial foodborne pathogens in milk and in the dairy environment, and to discuss public health and food safety issues associated with foodborne pathogens found in the dairy environment. Information presented supports the model in which the presence of pathogens depends on ingestion of contaminated feed followed by amplification in bovine hosts and fecal dissemination in the farm environment. The final outcome of this cycle is a constantly maintained reservoir of foodborne pathogens that can reach humans by direct contact, ingestion of raw contaminated milk or cheese, or contamination during the processing of milk products. Isolation of bacterial pathogens with similar biotypes from dairy farms and from outbreaks of human disease substantiates this hypothesis.

Entry of L. monocytogenes into cells is mediated by internalin, a repeat protein reminiscent of surface antigens from gram-positive cocci

1991-06-01

Jean-Louis Gaillard , Patrick Berche , Claude Fréhel +2 more

Microbiological Aspects of Ozone Applications in Food: A Review

2001-11-01

M.A. Khadre , Ahmed E. Yousef , Jeongeun Kim

ABSTRACT: Ozone is a powerful antimicrobial agent that is suitable for application in food in the gaseous and aqueous states. Molecular ozone or its decomposition products (for example, hydroxyl radical) … ABSTRACT: Ozone is a powerful antimicrobial agent that is suitable for application in food in the gaseous and aqueous states. Molecular ozone or its decomposition products (for example, hydroxyl radical) inactivate microorganisms rapidly by reacting with intracellular enzymes, nucleic material and components of their cell envelope, spore coats, or viral capsids. Combination of ozone with appropriate initiators (for example, UV or H 2 O 2 ) results in advanced oxidation processes (AOPs) that are potentially effective against the most resistant microorganisms; however, applications of AOPs in food are yet to be developed. When applied to food, ozone is generated on‐site and it decomposes quickly, leaving no residues. Ozone is suitable for decontaminating produce, equipment, food‐contact surfaces, and processing environment.

Immune responses to Listeria monocytogenes

2004-10-01

Eric G. Pamer

Perspectives on the use of organic acids and short chain fatty acids as antimicrobials

2003-04-01

S. C. Ricke

Organic acids have a long history of being utilized as food additives and preservatives for preventing food deterioration and extending the shelf life of perishable food ingredients. Specific organic acids … Organic acids have a long history of being utilized as food additives and preservatives for preventing food deterioration and extending the shelf life of perishable food ingredients. Specific organic acids have also been used to control microbial contamination and dissemination of foodborne pathogens in preharvest and postharvest food production and processing. The antibacterial mechanism(s) for organic acids are not fully understood, and activity may vary depending on physiological status of the organism and the physicochemical characteristics of the external environment. An emerging potential problem is that organic acids have been observed to enhance survivability of acid sensitive pathogens exposed to low pH by induction of an acid tolerance response and that acid tolerance may be linked to increased virulence. Although this situation has implications regarding the use of organic acids, it may only apply to circumstances in which reduced acid levels have induced resistance and virulence mechanisms in exposed organisms. Evaluating effectiveness of organic acids for specific applications requires more understanding general and specific stress response capabilities of foodborne pathogens. Development and application of molecular tools to study pathogen behavior in preharvest and postharvest food production environments will enable dissection of specific bacterial genetic regulation involved in response to organic acids. This could lead to the development of more targeted strategies to control foodborne pathogens with organic acids.

Existing and potential applications of ultraviolet light in the food industry - a critical review

2000-05-01

Τhomas Bintsis , E. Litopoulou‐Tzanetaki , Richard K. Robinson

Short-wave ultraviolet light (UVC, 254 nm) can reduce dramatically the microbial load in air or on hard surfaces free from food residues, and can eliminate pathogens from potable water filtered … Short-wave ultraviolet light (UVC, 254 nm) can reduce dramatically the microbial load in air or on hard surfaces free from food residues, and can eliminate pathogens from potable water filtered to remove organic residues and 'clumps' of bacteria. More recently, approval of the Food and Drug Administration (USA) has been sought for a system for the destruction of pathogenic bacteria in fruit juices using UVC, and the same approach could perhaps be applied to remove spoilage organisms from cider or wines. In contrast, long-wave UV light (UVA, >320 nm) has limited microbiocidal properties, and for practical applications its effectiveness has to be enhanced by the presence of photosensitive compounds (eg furocoumarins) that will diffuse into a microbial cell prior to irradiation. The penetration of UVA into water is better than that of UVC, and its bacteriocidal action in the presence of photosensitisers can be rapid. However, pure furocoumarins are expensive and their addition to foodstuffs might be questioned on safety grounds. © 2000 Society of Chemical Industry

The Listeria transcriptional landscape from saprophytism to virulence

2009-05-17

Alejandro Toledo‐Arana , Olivier Dussurget , Georgios Nikitas +7 more

Differentiation of the Major Listeria monocytogenes Serovars by Multiplex PCR

2004-08-01

Michel Doumith , Carmen Buchrieser , Philippe Glaser +2 more

ABSTRACT A new multiplex PCR assay was developed to separate the four major Listeria monocytogenes serovars isolated from food and patients (1/2a, 1/2b, 1/2c, and 4b) into distinct groups. The … ABSTRACT A new multiplex PCR assay was developed to separate the four major Listeria monocytogenes serovars isolated from food and patients (1/2a, 1/2b, 1/2c, and 4b) into distinct groups. The PCR test, which constitutes a rapid and practical alternative to laborious classical serotyping, was successfully evaluated with 222 Listeria strains.

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Modeling of the Bacterial Growth Curve

1990-06-01

M.H. Zwietering , I. Jongenburger , F.M. Rombouts +1 more

Several sigmoidal functions (logistic, Gompertz, Richards, Schnute, and Stannard) were compared to describe a bacterial growth curve. They were compared statistically by using the model of Schnute, which is a … Several sigmoidal functions (logistic, Gompertz, Richards, Schnute, and Stannard) were compared to describe a bacterial growth curve. They were compared statistically by using the model of Schnute, which is a comprehensive model, encompassing all other models. The t test and the F test were used. With the t test, confidence intervals for parameters can be calculated and can be used to distinguish between models. In the F test, the lack of fit of the models is compared with the measuring error. Moreover, the models were compared with respect to their ease of use. All sigmoidal functions were modified so that they contained biologically relevant parameters. The models of Richards, Schnute, and Stannard appeared to be basically the same equation. In the cases tested, the modified Gompertz equation was statistically sufficient to describe the growth data of Lactobacillus plantarum and was easy to use.

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Actin filaments and the growth, movement, and spread of the intracellular bacterial parasite, Listeria monocytogenes.

1989-10-01

L G Tilney , Daniel A. Portnoy

Listeria monocytogenes was used as a model intracellular parasite to study stages in the entry, growth, movement, and spread of bacteria in a macrophage cell line. The first step in … Listeria monocytogenes was used as a model intracellular parasite to study stages in the entry, growth, movement, and spread of bacteria in a macrophage cell line. The first step in infection is phagocytosis of the Listeria, followed by the dissolution of the membrane surrounding the phagosome presumably mediated by hemolysin secreted by Listeria as nonhemolytic mutants remain in intact vacuoles. Within 2 h after infection, each now cytoplasmic Listeria becomes encapsulated by actin filaments, identified as such by decoration of the actin filaments with subfragment 1 of myosin. These filaments are very short. The Listeria grow and divide and the actin filaments rearrange to form a long tail (often 5 microns in length) extending from only one end of the bacterium, a "comet's tail," in which the actin filaments appear randomly oriented. The Listeria "comet" moves to the cell surface with its tail oriented towards the cell center and becomes incorporated into a cell extension with the Listeria at the tip of the process and its tail trailing into the cytoplasm behind it. This extension contacts a neighboring macrophage that phagocytoses the extension of the first macrophage. Thus, within the cytoplasm of the second macrophage is a Listeria with its actin tail surrounded by a membrane that in turn is surrounded by the phagosome membrane of the new host. Both these membranes are then solubilized by the Listeria and the cycle is repeated. Thus, once inside a host cell, the infecting Listeria and their progeny can spread from cell to cell by remaining intracellular and thus bypass the humoral immune system of the organism. To establish if actin filaments are essential for the spread of Listeria from cell to cell, we treated infected macrophages with cytochalasin D. The Listeria not only failed to spread, but most were found deep within the cytoplasm, rather than near the periphery of the cell. Thin sections revealed that the net of actin filaments is not formed nor is a "comet" tail produced.

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Listeria: A foodborne pathogen that knows how to survive

2006-09-29

Megha Gandhi , Michael L. Chikindas

Listeria monocytogenes, a food-borne pathogen

1991-09-01

Jeffrey M. Farber , Pearl I. Peterkin

The gram-positive bacterium Listeria monocytogenes is an ubiquitous, intracellular pathogen which has been implicated within the past decade as the causative organism in several outbreaks of foodborne disease. Listeriosis, with … The gram-positive bacterium Listeria monocytogenes is an ubiquitous, intracellular pathogen which has been implicated within the past decade as the causative organism in several outbreaks of foodborne disease. Listeriosis, with a mortality rate of about 24%, is found mainly among pregnant women, their fetuses, and immunocompromised persons, with symptoms of abortion, neonatal death, septicemia, and meningitis. Epidemiological investigations can make use of strain-typing procedures such as DNA restriction enzyme analysis or electrophoretic enzyme typing. The organism has a multifactorial virulence system, with the thiol-activated hemolysin, listeriolysin O, being identified as playing a crucial role in the organism's ability to multiply within host phagocytic cells and to spread from cell to cell. The organism occurs widely in food, with the highest incidences being found in meat, poultry, and seafood products. Improved methods for detecting and enumerating the organism in foodstuffs are now available, including those based on the use of monoclonal antibodies, DNA probes, or the polymerase chain reaction. As knowledge of the molecular and applied biology of L. monocytogenes increases, progress can be made in the prevention and control of human infection.

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Comparative Genomics of Listeria Species

2001-10-26

Philippe Glaser , Lionel Frangeul , Carmen Buchrieser +7 more

Listeria monocytogenes is a food-borne pathogen with a high mortality rate that has also emerged as a paradigm for intracellular parasitism. We present and compare the genome sequences of L. … Listeria monocytogenes is a food-borne pathogen with a high mortality rate that has also emerged as a paradigm for intracellular parasitism. We present and compare the genome sequences of L. monocytogenes (2,944,528 base pairs) and a nonpathogenic species, L. innocua (3,011,209 base pairs). We found a large number of predicted genes encoding surface and secreted proteins, transporters, and transcriptional regulators, consistent with the ability of both species to adapt to diverse environments. The presence of 270 L. monocytogenes and 149 L. innocua strain-specific genes (clustered in 100 and 63 islets, respectively) suggests that virulence in Listeria results from multiple gene acquisition and deletion events.

ListeriaPathogenesis and Molecular Virulence Determinants

2001-07-01

José A. Vázquez‐Boland , Michael Kuhn , Patrick Berche +6 more

The gram-positive bacterium Listeria monocytogenes is the causative agent of listeriosis, a highly fatal opportunistic foodborne infection. Pregnant women, neonates, the elderly, and debilitated or immunocompromised patients in general are … The gram-positive bacterium Listeria monocytogenes is the causative agent of listeriosis, a highly fatal opportunistic foodborne infection. Pregnant women, neonates, the elderly, and debilitated or immunocompromised patients in general are predominantly affected, although the disease can also develop in normal individuals. Clinical manifestations of invasive listeriosis are usually severe and include abortion, sepsis, and meningoencephalitis. Listeriosis can also manifest as a febrile gastroenteritis syndrome. In addition to humans, L. monocytogenes affects many vertebrate species, including birds. Listeria ivanovii, a second pathogenic species of the genus, is specific for ruminants. Our current view of the pathophysiology of listeriosis derives largely from studies with the mouse infection model. Pathogenic listeriae enter the host primarily through the intestine. The liver is thought to be their first target organ after intestinal translocation. In the liver, listeriae actively multiply until the infection is controlled by a cell-mediated immune response. This initial, subclinical step of listeriosis is thought to be common due to the frequent presence of pathogenic L. monocytogenes in food. In normal individuals, the continual exposure to listerial antigens probably contributes to the maintenance of anti-Listeria memory T cells. However, in debilitated and immunocompromised patients, the unrestricted proliferation of listeriae in the liver may result in prolonged low-level bacteremia, leading to invasion of the preferred secondary target organs (the brain and the gravid uterus) and to overt clinical disease. L. monocytogenes and L. ivanovii are facultative intracellular parasites able to survive in macrophages and to invade a variety of normally nonphagocytic cells, such as epithelial cells, hepatocytes, and endothelial cells. In all these cell types, pathogenic listeriae go through an intracellular life cycle involving early escape from the phagocytic vacuole, rapid intracytoplasmic multiplication, bacterially induced actin-based motility, and direct spread to neighboring cells, in which they reinitiate the cycle. In this way, listeriae disseminate in host tissues sheltered from the humoral arm of the immune system. Over the last 15 years, a number of virulence factors involved in key steps of this intracellular life cycle have been identified. This review describes in detail the molecular determinants of Listeria virulence and their mechanism of action and summarizes the current knowledge on the pathophysiology of listeriosis and the cell biology and host cell responses to Listeria infection. This article provides an updated perspective of the development of our understanding of Listeria pathogenesis from the first molecular genetic analyses of virulence mechanisms reported in 1985 until the start of the genomic era of Listeria research.

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Microtiter Plate Assay for Assessment of Listeria monocytogenes Biofilm Formation

2002-06-01

D. Djordjević , Martin Wiedmann , Lynne McLandsborough

ABSTRACT Listeria monocytogenes has the ability to form biofilms on food-processing surfaces, potentially leading to food product contamination. The objective of this research was to standardize a polyvinyl chloride (PVC) … ABSTRACT Listeria monocytogenes has the ability to form biofilms on food-processing surfaces, potentially leading to food product contamination. The objective of this research was to standardize a polyvinyl chloride (PVC) microtiter plate assay to compare the ability of L. monocytogenes strains to form biofilms. A total of 31 coded L. monocytogenes strains were grown in defined medium (modified Welshimer's broth) at 32°C for 20 and 40 h in PVC microtiter plate wells. Biofilm formation was indirectly assessed by staining with 1% crystal violet and measuring crystal violet absorbance, using destaining solution. Cellular growth rates and final cell densities did not correlate with biofilm formation, indicating that differences in biofilm formation under the same environmental conditions were not due to growth rate differences. The mean biofilm production of lineage I strains was significantly greater than that observed for lineage II and lineage III strains. The results from the standardized microtiter plate biofilm assay were also compared to biofilm formation on PVC and stainless steel as assayed by quantitative epifluorescence microscopy. Results showed similar trends for the microscopic and microtiter plate assays, indicating that the PVC microtiter plate assay can be used as a rapid, simple method to screen for differences in biofilm production between strains or growth conditions prior to performing labor-intensive microscopic analyses.

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Role of hemolysin for the intracellular growth of Listeria monocytogenes.

1988-04-01

P. Suzanne Portnoy , P S Jacks , David J. Hinrichs

Listeria monocytogenes insertion mutants defective in hemolysin production were generated using the conjugative transposons Tn916 and Tn1545. All of the nonhemolytic mutants (hly-) lacked a secreted 58-kD polypeptide, presumedly hemolysin, … Listeria monocytogenes insertion mutants defective in hemolysin production were generated using the conjugative transposons Tn916 and Tn1545. All of the nonhemolytic mutants (hly-) lacked a secreted 58-kD polypeptide, presumedly hemolysin, and were avirulent in a mouse model. An intracellular multiplication assay was established in monolayers of mouse bone marrow-derived macrophages, the J774 macrophage-like cell line, the CL.7 embryonic mouse fibroblast cell line, and the Henle 407 human epithelial cell line. The hly+ strain grew intracellularly in all of the tissue culture cells with a doubling time of approximately 60 min. In contrast, the hly- mutants failed to grow in the murine-derived tissue culture cells, but retained the ability to grow in the human tissue culture cells examined. Hemolytic-positive revertants were selected after passage of the hly- mutants through monolayers of J774 cells. In each case, the hemolytic revertants possessed the 58-kD polypeptide, were capable of intracellular growth in tissue culture monolayers and were virulent for mice.

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Klebsiellaspp. as Nosocomial Pathogens: Epidemiology, Taxonomy, Typing Methods, and Pathogenicity Factors

1998-10-01

Rainer Podschun , U. Ullmann

Bacteria belonging to the genus Klebsiella frequently cause human nosocomial infections. In particular, the medically most important Klebsiella species, Klebsiella pneumoniae, accounts for a significant proportion of hospital-acquired urinary tract … Bacteria belonging to the genus Klebsiella frequently cause human nosocomial infections. In particular, the medically most important Klebsiella species, Klebsiella pneumoniae, accounts for a significant proportion of hospital-acquired urinary tract infections, pneumonia, septicemias, and soft tissue infections. The principal pathogenic reservoirs for transmission of Klebsiella are the gastrointestinal tract and the hands of hospital personnel. Because of their ability to spread rapidly in the hospital environment, these bacteria tend to cause nosocomial outbreaks. Hospital outbreaks of multidrug-resistant Klebsiella spp., especially those in neonatal wards, are often caused by new types of strains, the so-called extended-spectrum-beta-lactamase (ESBL) producers. The incidence of ESBL-producing strains among clinical Klebsiella isolates has been steadily increasing over the past years. The resulting limitations on the therapeutic options demand new measures for the management of Klebsiella hospital infections. While the different typing methods are useful epidemiological tools for infection control, recent findings about Klebsiella virulence factors have provided new insights into the pathogenic strategies of these bacteria. Klebsiella pathogenicity factors such as capsules or lipopolysaccharides are presently considered to be promising candidates for vaccination efforts that may serve as immunological infection control measures.

Surviving the Acid Test: Responses of Gram-Positive Bacteria to Low pH

2003-09-01

Paul D. Cotter , Colin Hill

SUMMARY Gram-positive bacteria possess a myriad of acid resistance systems that can help them to overcome the challenge posed by different acidic environments. In this review the most common mechanisms … SUMMARY Gram-positive bacteria possess a myriad of acid resistance systems that can help them to overcome the challenge posed by different acidic environments. In this review the most common mechanisms are described: i.e., the use of proton pumps, the protection or repair of macromolecules, cell membrane changes, production of alkali, induction of pathways by transcriptional regulators, alteration of metabolism, and the role of cell density and cell signaling. We also discuss the reponses of Listeria monocytogenes , Rhodococcus , Mycobacterium , Clostridium perfringens , Staphylococcus aureus , Bacillus cereus , oral streptococci, and lactic acid bacteria to acidic environments and outline ways in which this knowledge has been or may be used to either aid or prevent bacterial survival in low-pH environments.

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Indices for performance evaluation of predictive models in food microbiology

1996-11-01

T Ross

Two complementary measures are proposed as simple indices of the performance of models in predictive food microbiology. The indices assess the level of confidence one can have in the predictions … Two complementary measures are proposed as simple indices of the performance of models in predictive food microbiology. The indices assess the level of confidence one can have in the predictions of the model and whether the model displays any bias which could lead to ‘fail‐dangerous’predictions. The use of the indices is demonstrated using data collated from independent and published literature. This analysis supports previous reports that evaluation of predictive models by comparison to published microbial growth rate data may be inappropriate because of limitations in that data. The indices may fail to reveal some forms of systematic deviation between observed and predicted behaviour. It is concluded, however, that the indices provide an objective and readily interpreted summary of model performance and may serve as a first step towards the development of an objective and useful definition of the term ‘validated model’in predictive food microbiology.

Control of Listeria monocytogenes in the Food-Processing Environment

2002-04-01

R. B. Tompkin

Fresh-cut product sanitation and wash water disinfection: Problems and solutions

2009-05-26

María I. Gil , María V. Selma , Francisco López‐Gálvez +1 more

Transmission of Escherichia coli O157:H7 from Contaminated Manure and Irrigation Water to Lettuce Plant Tissue and Its Subsequent Internalization

2002-01-01

Ethan B. Solomon , Sima Yaron , Karl R. Matthews

ABSTRACT The transmission of Escherichia coli O157:H7 from manure-contaminated soil and irrigation water to lettuce plants was demonstrated using laser scanning confocal microscopy, epifluorescence microscopy, and recovery of viable cells … ABSTRACT The transmission of Escherichia coli O157:H7 from manure-contaminated soil and irrigation water to lettuce plants was demonstrated using laser scanning confocal microscopy, epifluorescence microscopy, and recovery of viable cells from the inner tissues of plants. E. coli O157:H7 migrated to internal locations in plant tissue and was thus protected from the action of sanitizing agents by virtue of its inaccessibility. Experiments demonstrate that E. coli O157:H7 can enter the lettuce plant through the root system and migrate throughout the edible portion of the plant.

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The microbiology of minimally processed fresh fruits and vegetables

1994-07-01

C. Nguyen‐The , Frédéric Carlin

Abstract Minimally processed fresh (MPF) fruits and vegetables are good media for growth of microorganisms. They have been involved in outbreaks because of the consumption of products contaminated by pathogens. … Abstract Minimally processed fresh (MPF) fruits and vegetables are good media for growth of microorganisms. They have been involved in outbreaks because of the consumption of products contaminated by pathogens. They are also sensitive to various spoilage microorganisms such as pectinolytic bacteria, saprophytic Gram‐negative bacteria, lactic acid bacteria, and yeasts. Contamination of MPF fruits and vegetables occurs at every stage of the food chain, from cultivation to processing. Polluted environments during cultivation or poor hygienic conditions in processing increase the risk of contamination with foodborne pathogens. Although MPF fruits and vegetables may harbor psychrotrophic microorganisms such as fluorescent pseudomonads or Listeria monocytogenes, good control of refrigeration temperature limits growth of spoilage and pathogenic microorganisms. Modified atmospheres are often efficient to maintain or improve visual and organoleptic quality of MPF fruits and vegetables, but their effects on microorganisms are inconsistent. Chemical disinfection can partially reduce the initial bacterial contamination; irradiation seems to be more efficient. The applications of legislations and quality assurance systems to control contamination, survival, and growth of foodborne pathogens in MPF fruits and vegetables are discussed.

Epidemic Listeriosis Associated with Mexican-Style Cheese

1988-09-29

Michael Linnan , Laurene Mascola , Xiao Dong Lou +7 more

In Los Angeles County, California, 142 cases of human listeriosis were reported from January 1 through August 15, 1985. Ninety-three cases (65.5 percent) occurred in pregnant women or their offspring, … In Los Angeles County, California, 142 cases of human listeriosis were reported from January 1 through August 15, 1985. Ninety-three cases (65.5 percent) occurred in pregnant women or their offspring, and 49 (34.5 percent) in nonpregnant adults. There were 48 deaths: 20 fetuses, 10 neonates, and 18 nonpregnant adults. Of the nonpregnant adults, 98 percent (48 of 49) had a known predisposing condition. Eighty-seven percent (81 of 93) of the maternal/neonatal cases were Hispanic. Of the Listeria monocytogenes isolates available for study, 82 percent (86 of 105) were serotype 4b, of which 63 of 86 (73 percent) were the same phage type. A case-control study implicated Mexican-style soft cheese (odds ratio, 5.5; 95 percent confidence interval, 1.2 to 24.8) as the vehicle of infection; a second case-control study showed an association with one brand (Brand A) of Mexican-style soft cheese (odds ratio, 8.5; 95 percent confidence interval, 2.4 to 26.2). Laboratory study confirmed the presence of L. monocytogenes serogroup 4b of the epidemic phage type in Brand A Mexican-style cheese. In mid-June, all Brand A cheese was recalled and the factory was closed. An investigation of the cheese plant suggested that the cheese was commonly contaminated with unpasteurized milk. We conclude that the epidemic of listeriosis was caused by ingestion of Brand A cheese contaminated by one phage type of L. monocytogenes serotype 4b.

Growthcurver: an R package for obtaining interpretable metrics from microbial growth curves

2016-04-19

Kathleen Sprouffske , Andreas Wagner

Abstract Background Plate readers can measure the growth curves of many microbial strains in a high-throughput fashion. The hundreds of absorbance readings collected simultaneously for hundreds of samples create technical … Abstract Background Plate readers can measure the growth curves of many microbial strains in a high-throughput fashion. The hundreds of absorbance readings collected simultaneously for hundreds of samples create technical hurdles for data analysis. Results Growthcurver summarizes the growth characteristics of microbial growth curve experiments conducted in a plate reader. The data are fitted to a standard form of the logistic equation, and the parameters have clear interpretations on population-level characteristics, like doubling time, carrying capacity, and growth rate. Conclusions Growthcurver is an easy-to-use R package available for installation from the Comprehensive R Archive Network (CRAN). The source code is available under the GNU General Public License and can be obtained from Github (Sprouffske K, Growthcurver sourcecode, 2016).

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A review of Listeria monocytogenes : An update on outbreaks, virulence, dose-response, ecology, and risk assessments

2016-12-12

Robert L. Buchanan , L.G.M. Gorris , Melinda M. Hayman +2 more

Improved control measures starting in the 1990s have greatly reduced the prevalence of L. monocytogenes in many food categories, particularly in meats and meat products. However, the rate of listeriosis … Improved control measures starting in the 1990s have greatly reduced the prevalence of L. monocytogenes in many food categories, particularly in meats and meat products. However, the rate of listeriosis has remained constant during the last decade and the more severe, systemic (invasive) form of listeriosis is now recognized as occurring more frequently in small outbreaks than previously recognized. This review addresses the recent advances in epidemiology and virulence, in growth and modelling, and insights from the risk assessments. Recognition of recent outbreaks from food vehicles not traditionally associated with L. monocytogenes (celery, cantaloupe, mung bean sprouts, stone fruits, caramel apples and ice cream) was facilitated by PFGE and, increasingly, whole genome sequencing. The Key Events framework, an understanding of the key individual biochemical steps from ingestion to infection, provides a structure for relating new knowledge on strain variability, mutations, and host susceptibility to the probability of illness. Guidance for determination of the growth/no growth potential of a food has been issued by several regulatory authorities and the risk assessments indicate that prevention of growth remains a principle control element. The recognition of biofilm formation and the possible existence of dormant, non-dividing persister cells will require additional attention. The recent outbreaks underscored the individual characteristics of specific foods (melons vs all fruit; microenvironments in the caramel apples) and raised questions about the current understanding of infectivity of lower doses and the susceptibility of specific individuals. Advances have been made in these areas, but further research is clearly necessary to control this pathogen.

Pasteurized Milk as a Vehicle of Infection in an Outbreak of Listeriosis

1985-02-14

David W. Fleming , Stephen L. Cochi , Kristine L. MacDonald +7 more

Between June 30th and August 30th, 1983, 49 patients in Massachusetts acquired listeriosis. Seven cases occurred in fetuses or infants and 42 in immunosuppressed adults; 14 patients (29 per cent) … Between June 30th and August 30th, 1983, 49 patients in Massachusetts acquired listeriosis. Seven cases occurred in fetuses or infants and 42 in immunosuppressed adults; 14 patients (29 per cent) died. Of 40 Listeria monocytogenes isolates available for testing, 32 were serotype 4b. Two case-control studies, one matching for neighborhood of residence and the other for underlying disease, revealed that the illness was strongly associated with drinking a specific brand of pasteurized whole or 2 per cent milk (odds ratio = 9, P less than 0.01 for the neighborhood-matched study; odds ratio = 11.5, P less than 0.001 for the illness-matched study). The association with milk was further substantiated by four additional analyses that suggested the presence of a dose-response effect, demonstrated a protective effect of skim milk, associated cases with the same product in an independent study in another state, and linked a specific phage type with the disease associated with milk. The milk associated with disease came from a group of farms on which listeriosis in dairy cows was known to have occurred at the time of the outbreak. Multiple serotypes of L. monocytogenes were isolated from raw milk obtained from these farms after the outbreak. At the plant where the milk was processed, inspections revealed no evidence of improper pasteurization. These results support the hypothesis that human listeriosis can be a foodborne disease and raise questions about the ability of pasteurization to eradicate a large inoculum of L. monocytogenes from contaminated raw milk.

Listeria monocytogenes: towards a complete picture of its physiology and pathogenesis

2017-11-27

Lilliana Radoshevich , Pascale Cossart

Application of Ozone for Enhancing the Microbiological Safety and Quality of Foods: A Review

1999-09-01

Jin-Gab Kim , Ahmed E. Yousef , Sandhya Dave

Neonatal disseminated listeriosis in a premature infant

2025-06-25

D. M. Mushcherova , H.A. Sarkisyan , Yu. V. Zhirkova +7 more | CHILDREN INFECTIONS

Pregnant women and newborn infants are at risk of developing severe listeriosis infection. The time of development and the character of the clinical picture of neonatal listeriosis depend on the … Pregnant women and newborn infants are at risk of developing severe listeriosis infection. The time of development and the character of the clinical picture of neonatal listeriosis depend on the timing and mechanism of infection of the foetus. Intrauterine infection with this pathogen is one of the leading factors in the development of sepsis and meningitis in the neonatal period. Early laboratory diagnosis and prompt administration of antibiotic therapy are crucial to improve prognosis and reduce mortality in children. The aim of the work is to demonstrate the tactics of management of a premature infant with severe course of early neonatal listeriosis and favourable outcome according to the results of catamnestic observation. Materials and methods : The medical records of a child who was under inpatient treatment in a children's multidisciplinary hospital in January—February 2025 due to laboratory-confirmed neonatal disseminated listeriosis were analysed; the outcome of this patient was assessed based on the result of a second planned hospitalisation in April 2025; the world medical literature on neonatal listeriosis was studied using search engines and databases elibrary, PubMed, Google Scholar, Scopus.

Advances and Future Challenges in Microbial Food Safety: Volume I

2025-06-24

María Lavilla , Félix Amárita | Foods

Consumers’ growing demand for products with adequate nutritional, physicochemical, and sensory characteristics has challenged both the food industry (including the food production sector) and researchers, necessitating a constant effort in … Consumers’ growing demand for products with adequate nutritional, physicochemical, and sensory characteristics has challenged both the food industry (including the food production sector) and researchers, necessitating a constant effort in the development of innovative strategies to manufacture new products with optimal characteristics that ensure food safety at the same time [...]

A Quantitative Risk Assessment Model for Listeria monocytogenes in Ready-to-Eat Cantaloupe

2025-06-23

Laurent Guillier , Úrsula Gonzales-Barrón , Régis Pouillot +7 more | Foods

This study introduces a farm-to-fork quantitative risk assessment (QRA) model for invasive listeriosis from ready-to-eat diced cantaloupe. The modular model comprises seven stages—preharvest (soil and irrigation contamination), harvest (cross-contamination and … This study introduces a farm-to-fork quantitative risk assessment (QRA) model for invasive listeriosis from ready-to-eat diced cantaloupe. The modular model comprises seven stages—preharvest (soil and irrigation contamination), harvest (cross-contamination and survival), pre-processing (brushing), processing (flume tank washing, dicing and equipment cross-contamination), lot testing, cold-chain transport and retail growth, and consumer storage/handling. Each stage employs stochastic functions to simulate microbial prevalence and concentration changes (growth, inactivation, removal, partitioning, cross-contamination) using published data. In a reference scenario—good agricultural practices (soil barriers, no preharvest irrigation), hygienic processing and proper cold storage—the model predicts low lot- and pack-level contamination, with few packs >10 CFU/g and most servings below detection; the mean risk per serving is very low. “What-if” analyses highlight critical control points: the absence of soil barriers with preharvest irrigation can increase the risk by 10,000-fold; flume tank water contamination has a greater impact than harvest-stage cross-contamination; and poor consumer storage can raise the risk by up to 500-fold. This flexible QRA framework enables regulators and industry to evaluate and optimize interventions—from improved agricultural measures to targeted sampling plans and consumer guidance—to mitigate listeriosis risk from RTE diced cantaloupe.

Combined UV and Formic Acid Treatment Suppresses Aspergillus flavus and Aflatoxin B1 on Dried Red Chili Powder

2025-06-23

Xiaoman Chen , Gang Yang , Yi Zhang +7 more | Foods

Aflatoxin contamination poses a significant food safety risk, particularly during the storage of dried chili peppers. This study evaluated the efficacy of formic acid treatment, ultraviolet (UV) treatment, and combined … Aflatoxin contamination poses a significant food safety risk, particularly during the storage of dried chili peppers. This study evaluated the efficacy of formic acid treatment, ultraviolet (UV) treatment, and combined UV-formic acid treatment in both preventing and controlling Aspergillus flavus in dried red chili powder. Efficacy was assessed by measuring the growth diameter of A. flavus colonies on un-colonized and already colonized dried red chili powder. The optimal treatment conditions for the UV-formic acid combination were determined through single-factor experiments, orthogonal experiments, and quality assessment. Finally, the effects of the UV-formic acid combination on the cell membrane, antioxidant system, and energy metabolism of A. flavus were investigated. The results revealed that fumigation of un-colonized dried red chili powder with 5% formic acid for 24 h inhibited A. flavus growth by 93.29% and toxin synthesis by 99.41%. In contrast, treatment of already colonized chili powder with 10% formic acid inhibited A. flavus colony growth by 50%. Through a three-factor, three-level orthogonal experiment followed by quality testing, the optimal conditions were determined to be 8% formic acid concentration, a UV irradiation distance of 15 cm, and a treatment time of 75 min. This optimized combined treatment reduced the required fumigation time from 24 h to 1.25 h. This technique achieved complete suppression of aflatoxin B1 synthesis on un-colonized dried red chili powder. On already colonized chili powder, the mycelial growth inhibition rate was 48.05 ± 6.68%, and aflatoxin B1 synthesis was inhibited by 91.32 ± 3.15%. Quality assessment revealed that the UV-formic acid co-treatment parameters did not significantly affect key quality indicators including color, capsaicin content, total phenolic content (p > 0.05). Furthermore, UV-formic acid treatment disrupt the cell membrane structure of A. flavus, impairs its antioxidant and energy metabolism systems, and induces mitochondrial dysfunction. The study confirmed the synergistic antifungal effect of formic acid and UV, providing a potential industrialized solution for enhancing the safety and storage stability of dried chili products.

Emerging Technologies and Integrated Strategies for Microbial Detection and Control in Fresh Produce

2025-06-21

Ayman Elbehiry , Eman Marzouk , Feras Alzaben +5 more | Microorganisms

The global consumption of fresh and ready-to-eat (RTE) fruits and vegetables has surged due to increasing awareness of their nutritional benefits. However, this trend has been accompanied by a rise … The global consumption of fresh and ready-to-eat (RTE) fruits and vegetables has surged due to increasing awareness of their nutritional benefits. However, this trend has been accompanied by a rise in foodborne illness outbreaks linked to microbial contamination. This narrative review synthesizes current knowledge on the prevalence and diversity of foodborne pathogens in fresh produce, including bacterial, viral, and fungal agents. It critically evaluates both conventional and emerging detection methods, ranging from culture-based techniques and immunoassays to advanced molecular diagnostics, biosensors, flow cytometry (FC), and hyperspectral imaging (HSI). Additionally, this review discusses cutting-edge control strategies, such as natural antifungal agents, essential oils, biocontrol methods, and non-thermal technologies like cold plasma and UV-C treatment. Emphasis is placed on sampling methodologies, sustainability, One Health perspectives, and regulatory considerations. By highlighting recent technological advances and their limitations, this review aims to support the development of integrated, effective, and safe microbial control approaches for the fresh produce supply chain.

Evaluation of Washing with Sodium Hypochlorite, Ultraviolet Irradiation, and Storage Temperature on Shell Egg Quality During Storage

2025-06-20

Huichuan Yu , I.C. Chen , Fa‐Jui Tan | Foods

Shell eggs are susceptible to fecal contamination, facilitating the adhesion of microorganisms to the eggshell surface. The consumption of such eggs, especially when unwashed or raw, poses potential health risks … Shell eggs are susceptible to fecal contamination, facilitating the adhesion of microorganisms to the eggshell surface. The consumption of such eggs, especially when unwashed or raw, poses potential health risks to consumers. This study aimed to evaluate the effects of unwashed control, sodium hypochlorite (NaOCl) sanitization (150 ppm), and the combination of NaOCl and ultraviolet (UV) sanitization on the quality of eggs stored at varying temperatures over a four-week period. The findings demonstrated that NaOCl sanitization alone reduced surface bacterial counts by 1.23 log10 CFU/mL, while the combination of NaOCl and UV-C irradiation achieved a greater reduction of 1.48 log10 CFU/mL compared to the unwashed group. After two weeks of storage, unwashed egg groups (UC and UR) exhibited higher eggshell strength compared to NaOCl-sanitized groups (p < 0.05); however, this did not significantly influence internal contamination. Prolonged storage, particularly under refrigeration, led to increased hydroxyl (OH) group peak intensities on the eggshell, indicating dehydration and the formation of fissures in the cuticle. Elevated storage temperatures and extended durations adversely affected egg quality, whereas UV treatment did not have a detrimental impact. In conclusion, to ensure the safety and quality of shell eggs, it is recommended that they undergo NaOCl sanitization, UV irradiation, and be stored under refrigerated conditions.

Influence of UV-C Radiation on the Treatment of Minas Frescal Cheese Inoculated with Escherichia coli and Staphylococcus aureus

2025-06-18

Laura Ribeiro Cerqueira de Oliveira , Gabriel Cicalese Bevilaqua , Marina Maria Barbosa de Oliveira +5 more | International Dairy Journal

Sub-lethal stress-induced cross-protection against ultraviolet-C in Salmonella enterica on raw whole almonds and fresh-cut leafy greens

2025-06-18

Zhao Chen , Jie Zheng , Shirley A. Micallef +1 more | Frontiers in Microbiology

Pre-exposure to sub-lethal stress can increase the resistance of foodborne pathogens to inactivation processes, posing potential risks to food safety. This study examined how sub-lethal stress influences the resistance of … Pre-exposure to sub-lethal stress can increase the resistance of foodborne pathogens to inactivation processes, posing potential risks to food safety. This study examined how sub-lethal stress influences the resistance of Salmonella enterica to ultraviolet-C (UV-C) treatments on raw whole almonds (RWAs) and fresh-cut leafy greens (FCLGs), investigated the role of rpoS in stress-induced cross-protection, and evaluated Enterococcus faecium NRRL B-2354 as a surrogate for S. enterica . Additionally, we assessed the survival of sub-lethally stressed cells on FCLGs under cold or temperature abuse condition post-UV-C treatment. A cocktail of three S. enterica strains, along with S. Typhimurium ATCC 14028 and its Δ rpoS mutant (IB43), were exposed to desiccation stress, heat shock, oxidation stress, or acid stress. Afterward, stressed and unstressed cells were inoculated onto RWAs and FCLGs, and treated with UV-C (500 μW/cm 2 , 60 min). Treated FCLGs were then stored under cold or temperature abuse condition for 7 days. Results showed that acid-stressed S. enterica exhibited greater UV-C resistance on RWAs, while oxidation-stressed cells had increased survival on FCLGs ( p &lt; 0.05). Under temperature abuse, unstressed, oxidation-stressed, or acid-stressed S. enterica were inactivated faster, whereas heat-shocked cells persisted until Day 7. Desiccation-stressed cells rebounded temporarily before inactivation by Day 7. IB43 was more susceptible to UV-C ( p &lt; 0.05) than the wild-type strain and lacked cross-protection from prior sub-lethal stress exposure, confirming the crucial role of rpoS in UV-C resistance and stress adaptation. NRRL B-2354 demonstrated comparable or greater survival than S. enterica , supporting its use as a suitable surrogate. These findings highlight the influence of sub-lethal stress on UV-C resistance in S. enterica and emphasize the importance of including stress-adapted pathogens in challenge studies to improve food safety.

Peracetic Acid (PAA) Exhibits Higher Antimicrobial Efficacy Compared to Chlorine-Based Disinfectants against Salmonella Typhimurium on Chicken Skin and Food-Contact Surfaces

2025-06-17

A.G.M.Sofi Uddin Mahamud , Shamsun Nahar Begum , Sang‐Do Ha | Poultry Science

Outbreaks of Salmonella, especially in the poultry industry, pose significant food safety and public health challenges. These outbreaks are often intensified by the limited effectiveness of widely used disinfectants, including … Outbreaks of Salmonella, especially in the poultry industry, pose significant food safety and public health challenges. These outbreaks are often intensified by the limited effectiveness of widely used disinfectants, including chlorine-based agents like chlorine dioxide (ClO2) and sodium hypochlorite (NaOCl), particularly against bacterial biofilms. Biofilm formation on food-contact surfaces shields Salmonella from sanitizers, leading to persistent contamination and increased resistance, emphasizing the need for more effective disinfection strategies. This study aimed to evaluate and compare the bactericidal and antibiofilm efficacy of peroxyacetic acid (PAA) with ClO2 and NaOCl against Salmonella enterica serovar Typhimurium (S. Typhimurium) on various food-contact surfaces, including stainless steel, plastic, silicon rubber, and chicken skin. PAA demonstrated the highest bactericidal and antibiofilm effectiveness, requiring lower concentrations than ClO2 and NaOCl, even in organic load-rich environments. Confocal microscopy and protein leakage assays demonstrated that PAA induces significant cell wall disruption of S. Typhimurium planktonic cells, unlike ClO2 and NaOCl, which were less effective under similar conditions. These findings suggest that PAA is a superior alternative for controlling Salmonella in poultry processing facilities, offering greater applicability for sanitation in processing facilities to enhance overall food safety.

Genetic diversity and the prevalence of Listeria monocytogenes in food in Shanghai, China: Insights during 2020–2023 surveillance and the Apriori algorithm approach

2025-06-17

Hongzhi Zhang , Xin Dou , Tian‐Wei Shi +7 more | International Journal of Food Microbiology

Impact of c-di-AMP Accumulation, L-cysteine, and Oxygen on Catalase Activity and Oxidative Stress Resistance of Listeria monocytogenes 10403S

2025-06-16

Mahide Muge Yilmaz Topcam , Dimitrios P. Balagiannis , Kimon‐Andreas G. Karatzas | Microorganisms

Listeria monocytogenes is a foodborne pathogen frequently exposed to oxidative stress in diverse environmental conditions. Cyclic di-AMP (c-di-AMP) is a second messenger that plays a key role in stress resistance. … Listeria monocytogenes is a foodborne pathogen frequently exposed to oxidative stress in diverse environmental conditions. Cyclic di-AMP (c-di-AMP) is a second messenger that plays a key role in stress resistance. This study investigates the role of pdeA (degrades c-di-AMP) and how c-di-AMP accumulation affects catalase activity and oxidative stress response and gene expression. Survival and catalase activity assays were conducted under oxidative stress, and c-di-AMP levels were quantified in L. monocytogenes 10403S under aerobic, anaerobic, and L-cysteine-supplemented conditions. ΔpdeA, which accumulates c-di-AMP, exhibited greater sensitivity to oxidative stress (4.6 log reduction for the wild type (WT) vs 7.34 log reduction for ΔpdeA at 10 h) and lower catalase activity than the WT in the early stationary phase. However, in the late stationary phase, while the catalase activity levels of ΔpdeA remained stable (~6.33 cm foam height), it became resistant to oxidative stress (5.85 log reduction). These findings indicate that pdeA contributes to catalase activity in L. monocytogenes. Transcriptomic analysis revealed differential expression of pathways mainly including pentose phosphate pathway, carbon metabolism, O-antigen nucleotide sugar biosynthesis and ABC transporters in ΔpdeA compared to WT. Our transcriptomic data provided promising insights into the molecular mechanisms underlying c-di-AMP regulation, which may enhance stress resistance. Moreover, oxidative stress led to increased intracellular c-di-AMP levels. Under L-cysteine supplementation, catalase activity levels in WT were similar to ΔpdeA (~1.86 cm foam height for both), but the latter showed enhanced oxidative stress resistance and c-di-AMP levels. Anaerobic conditions also elevated c-di-AMP levels in WT and ΔpdeA but resulted in greater oxidative stress sensitivity. Understanding these regulatory mechanisms provides valuable insights into oxidative stress resistance, with potential implications for food safety and pathogen control.

Antibiofilm effect of caffeine against Listeria monocytogenes and Escherichia coli in grape and apple fruit juices

2025-06-16

André Ricardo Peron dos Santos , Bruna Camila Souza Lima , Gabriel José Couto +7 more | Biofouling

This study evaluated the antibiofilm activity of caffeine against Listeria monocytogenes and Escherichia coli within grape and apple juice matrices. Caffeine, a purine alkaloid recognized for its antimicrobial properties, was … This study evaluated the antibiofilm activity of caffeine against Listeria monocytogenes and Escherichia coli within grape and apple juice matrices. Caffeine, a purine alkaloid recognized for its antimicrobial properties, was tested at the minimum inhibitory concentration (MIC) against planktonic and sessile cells. MIC values were established at 9.37 mM for E. coli and 37.5 mM for L. monocytogenes. Biofilm formation was evaluated through crystal violet staining, both when bacterial cells were exposed to caffeine during the initial stages of biofilm development (co-treatment) and after the biofilm had been established (post-treatment). The extracellular polymeric substances (EPS) produced within the biofilms were quantitatively measured. Bacterial viability was assessed by time-kill kinetics assays and further visualized by scanning electron microscopy (SEM). Caffeine treatment significantly inhibited biofilm formation by 98.1% for E. coli and 98.7% for L. monocytogenes, and by 98.8 and 99.0%, in co-treatment and post-treatment, respectively. No consistent correlation was observed between EPS quantity and biofilm inhibition. SEM analysis confirmed caffeine-induced structural disruption of the biofilm matrix and damage to bacterial cell integrity. This investigation introduces a novel application of caffeine as an anti-biofilm agent in unpreserved fruit juice systems and demonstrates, for the first time, its efficacy against foodborne pathogens.

1295-P: The Association between Elevated A1C and ASCVD Risk Scores in a Food Insecure Population in Chicago

2025-06-13

Camden Richter , Ethan Belnap , Andrew M. McIntosh +6 more | Diabetes

Introduction and Objective: Studies show diabetes is a strong predictor of cardiovascular disease (CVD). Diabetes-related complications include coronary heart disease, cerebrovascular disease, heart failure and peripheral vascular disease. Food insecurity … Introduction and Objective: Studies show diabetes is a strong predictor of cardiovascular disease (CVD). Diabetes-related complications include coronary heart disease, cerebrovascular disease, heart failure and peripheral vascular disease. Food insecurity poses key barriers to glycemic management, potentially resulting in worse CVD outcomes. The goal of this study is to examine the association between elevated A1c and ASCVD risk scores in a food insecure population in West Chicago. Methods: The Cardiometabolic Health Initiative (CHI) is a mobile screening clinic that performs comprehensive cardiometabolic health screenings at food pantries in West Chicago. Between August 2023 and December 2024, patients received point of care A1c measurements, lipid panels, and blood pressure readings. Results were used to calculate 10-year Atherosclerotic Cardiovascular Disease (ASCVD) risk scores and provide individualized health coaching, focused on confronting social determinants of health (SDoH). Results: Out of 153 patients, 82 (54%) had a normal A1c (&lt;5.7%), 51 (33%) had a prediabetic A1c (5.7%-6.4%) and 20 (13%) had a diabetic A1c (&gt;6.4%) (Figure 1). The average ASCVD risk score for the total population was 9.1% (SD=11.3; Figure 2). Among patients with a normal A1c, the average ASCVD risk score was 6.6% (SD=7.9), among prediabetic patients, the average ASCVD risk score was 9.8% (SD=10.8) and among diabetic patients, the average ASCVD risk score was 17.6% (SD=18.4, p=0.000; Figure 2). Conclusion: These findings suggest a high prevalence of prediabetes and diabetes within this food insecure population with 46% of screened patients having an elevated A1c. Consistent with previous literature, elevated A1c values may directly correlate with increased ASCVD risk. Community-based preventative screenings and health education programs, like CHI, can help identify these high-risk individuals, address SDoH, and combat disease burden in disadvantaged populations. Disclosure C. Richter: None. E. Belnap: None. A. McIntosh: None. I. Khosla: None. W. Cohen: None. E. Sullivan: None. R. Garcia: None. A. DeMeo: None. D. Luger: None.

Peracetic acid-based advanced oxidation processes for disinfection: Unveiling mechanism of protein spatial structure disordering

2025-06-13

Rui‐Cheng Ji , Tongcai Liu , Longlong Zhang +7 more | Chemical Engineering Journal

Prevalence of Listeria monocytogenes in Raw Milk and Karish Cheese: Implications for Public Health in Egypt

2025-06-12

Engku Hasmah Engku Abdullah , Eman Ariny , Mohamed Abdel-Haleem +1 more | Bulletin of Faculty of Science Zagazig University

Evaluation of commercially available produce antimicrobial washes to improve the quality and microbial safety of fresh produce

2025-06-12

Hansel A. Mina , D. A. H. Buckley , Jack Burnett +1 more | International Journal of Food Microbiology

Antibiofilm effects of bacteriocin PCM7-4 on Listeria monocytogenes

2025-06-05

Haotian Ma , Jinju Peng , Yang Li +5 more | PLoS ONE

Listeria monocytogenes is a significant zoonotic pathogen capable of forming biofilms on food and other materials, representing a considerable risk to human health and animal husbandry. The use of bacteriocins … Listeria monocytogenes is a significant zoonotic pathogen capable of forming biofilms on food and other materials, representing a considerable risk to human health and animal husbandry. The use of bacteriocins as potential new antibacterial and antibiofilm reagents has attracted considerable interest. This study aimed to determine the inhibitory effects of bacteriocin PCM7−4 on L. monocytogenes biofilm formation. In this study, bacteriocin PCM7−4 of SICs (1/16 × MIC, 1/8 × MIC) significantly inhibited the formation of L. monocytogenes biofilm. Bacteriocin PCM7−4 of SICs significantly reduced the production of bacterial extracellular polysaccharides, and could decrease the bacterial motility, meanwhile, PCM7−4 significantly reduced the number and viability of bacteria within the biofilm. RT-qPCR results showed that bacteriocin PCM7−4 significantly reduced the expression of flagella, community sensing and virulence factor genes associated with biofilm formation. The results demonstrated the considerable potential of bacteriocin PCM7−4 as a therapeutic agent for the prevention and treatment of L. monocytogenes biofilms.

Fluoroquinolone susceptibility of wild-type Listeria monocytogenes isolates and the role of FepR and ParC mutations in conferring fluoroquinolone tolerance

2025-06-03

Andrea Domen , John R. Porter , Lorraine McIntyre +2 more | International Journal of Food Microbiology

Fluoroquinolone response and associated genotypic variants were characterized in a set of 88 Listeria monocytogenes strains isolated from Canadian dairy facilities over a span of 10 years. All strains were … Fluoroquinolone response and associated genotypic variants were characterized in a set of 88 Listeria monocytogenes strains isolated from Canadian dairy facilities over a span of 10 years. All strains were susceptible to ciprofloxacin (CIP), moxifloxacin (MOX), and levofloxacin (LEV) using the VITEK GP-AST75 assay. However, CIP minimum inhibitory concentrations (MICs) varied in the broth dilution assay, with 47 isolates exhibiting MICs of 1 ppm and 41 isolates at ≤0.5 ppm (detection limit). Isolates with elevated MICs to one fluoroquinolone showed correlated increases in MICs to other fluoroquinolones (Spearman's correlation; p < 0.0001). MICs were confirmed using a broth dilution assay (0.125-8 ppm; two-fold dilution in MHB), with variable growth observed among replicates at sublethal CIP concentrations. After two passages in 0.5 ppm CIP, WRLP81 exhibited increased fitness (reduced lag phase duration) and MIC increases in CIP (4 ppm), LEV (2 ppm), and MOX (1 ppm). Whole genome sequencing of descendants (81.2B; 81.2C) revealed two unique frameshift mutations in fepR: V114fs and Glu139fs. Molecular modeling predicted conformational defects likely impairing FepA dimerization and efflux pump repression. Similarly, after two passages in 0.5 ppm CIP, a WRLP86 descendant (86.2C_2) exhibited increased MICs for CIP (2 ppm), LEV (4 ppm), and MOX (1 ppm), linked to a parC missense mutation that altered the winged helix domain. This amino acid change likely creates steric interference near the fluoroquinolone binding pocket and represents the first report of a parC mutation identified in L. monocytogenes in response to sublethal CIP exposure. This research highlights the rapid and varied adaptation of reduced fluoroquinolone susceptibility in L. monocytogenes.

Simultaneous Study of the Combined Effect of Gliding Arc Plasma and Zataria multiflora Essential Oil on Pathogens Inactivation and Quality Changes in Sliced Iranian White Cheese

2025-06-01

Mahdieh Raoofi Asl Soofiani , Negin Noori , Afshin Akhondzadeh Basti +3 more | Food Science & Nutrition

ABSTRACT This study aimed to inactivate Escherichia coli O 111 , Listeria monocytogenes , and Aspergillus flavus on sliced Iranian white cheese by using the combination of gliding arc nonthermal … ABSTRACT This study aimed to inactivate Escherichia coli O 111 , Listeria monocytogenes , and Aspergillus flavus on sliced Iranian white cheese by using the combination of gliding arc nonthermal plasma (GAP) and Zataria multiflora essential oil (ZEO). The cheese samples were exposed to different levels of GAP (0, 2, and 5 min) and ZEO (0 and 100 ppm) and stored at 4°C for 60 days. The extraction yield of ZEO based on dry weight was 1.66%. Carvacrol (33.85%) was the most important compound in ZEO. During the storage period, E. coli and L. monocytogenes counts increased in all samples. However, the most effective inhibition of E. coli and L. monocytogenes was observed in samples treated with 100 ppm ZEO combined with 2 min of GAP, and 100 ppm ZEO combined with 5 min of GAP, respectively, resulting in increases of only 1.35 and 1.8 log CFU/g over the storage period. In terms of the growth inhibition percentage of A. flavus , the lowest inhibition was detected in the presence of essential oil alone, while the highest inhibitory effect resulted from 5 min of plasma treatment combined with essential oil. GAP treatment also reduced the pH value of the cheese while increasing thiobarbituric acid reactive substances (TBARS). The control sample showed the lowest pH and the highest TBARS during storage. The highest overall acceptance sensory properties score was observed in cheese samples treated with 2 min of GAP and 100 ppm ZEO. According to the results of microbial, chemical, and sensory tests, Iranian white cheese samples treated with 2 min of GAP and 100 ppm ZEO can be used as a novel technique for sterilization and extending the shelf life of white cheese.

Exposure assessment of Staphylococcus aureus in fluid milk

2025-06-01

Yingying Lin , Mengjia Pan , Yunfeng Yang +4 more | International Dairy Journal

Regression Models Used in Food Science: Linearity, Reparameterization, and Rescaling

2025-06-01

Sencer Buzrul | Journal of Food Process Engineering

ABSTRACT Models can be linear or nonlinear; however, the linearity of a model refers to its parameters. Although linear regression has several advantages over nonlinear regression such as having an … ABSTRACT Models can be linear or nonlinear; however, the linearity of a model refers to its parameters. Although linear regression has several advantages over nonlinear regression such as having an analytical solution and symmetric confidence intervals, most regression models used in food science are nonlinear. Therefore, nonlinear regression should be used to obtain the parameters and their uncertainties. Reparameterization can be useful to have interpretable parameters, and sometimes it is better to perform nonlinear regression instead of simple linear regression even if there is a linear relationship between the dependent and independent variable. Rescaling is a desirable method to have statistically significant parameters. The aim of this paper is to discuss the linearity of the models and to show some useful reparameterization and rescaling by using some published data. Examples are given from food microbiology (microbial inactivation kinetics) and degradation kinetics of foods.

Effectiveness of UVC-Assisted Fenton Reaction Wash-Based System to Inactivate Salmonella Typhimurium, Escherichia coli O157:H7, and Listeria monocytogenes on Cherry Tomatoes

2025-06-01

Xuetong Fan , Joshua B. Gurtler , Jessica Baik +2 more | Journal of Food Protection

The Fenton reaction results when hydrogen peroxide (H2O2) interacts with the ferrous ion, producing highly antimicrobial hydroxyl free radicals (·OH). In this study, a UVC-assisted Fenton reaction was tested against … The Fenton reaction results when hydrogen peroxide (H2O2) interacts with the ferrous ion, producing highly antimicrobial hydroxyl free radicals (·OH). In this study, a UVC-assisted Fenton reaction was tested against cocktails of Salmonella Typhimurium, E. coli O157:H7, and Listeria monocytogenes, inoculated onto cherry tomatoes. Inoculated cherry tomatoes were subjected to 2% H2O2 wash, 1 mM Fe3+ wash, or exposed to UVC during washing, and simultaneously in the following combinations: H2O2 + Fe3+, H2O2 + UVC, or H2O2 + Fe3+ + UVC for 2 min at ambient temperature (∼20°C). In addition, ·OH were measured using the methylene blue dye test, after combining Fenton reaction components in water. Results revealed that H2O2 alone, or in combination, reduced significantly higher populations of the three bacterial pathogens, when compared with water wash alone. The H2O2 + Fe3+ + UVC treatment inactivated 5.24±1.17 log CFU Salmonella/fruit, which was significantly (P<0.05) greater than those reduced by Fe3+ or UVC alone. However, the reduction was not statistically significant when compared to H2O2, H2O2 + Fe3+ or H2O2 + UVC. Similarly, the combinations did not inactivate significantly (P>0.05) more E. coli O157:H7 and L. monocytogenes than individual H2O2 or UVC treatments with reductions of 2.31-3.20 and 1.96-3.17 log CFU/fruit, respectively, although ·OH were produced in water during the H2O2 + Fe3+ + UVC treatments. Overall, our results demonstrate that UVC-assisted Fenton washing does not consistently exhibit advantages over individual H2O2 or UVC treatments during cherry tomato washing to inactivate foodborne pathogens, presumably due to inability of short-lived hydroxyl radicals to reach the bacteria on tomatoes.

Modeling the Inactivation Kinetics of Salmonella Typhimurium and Pseudomonas aeruginosa on Eggshell Surfaces Using Gaseous Ozone

2025-06-01

Izadora Martina de Freitas Meireles , Amanda Mattos Dias Martins , Wilson José Fernandes Lemos +3 more | Food Microbiology

" Listeria monocytogenes infection ": A report detailing multiple diagnostic approaches

2025-06-01

Shujuan Zheng , Yunyan Yu , Jiumei Zhao +4 more | New Microbes and New Infections

Impact of blue-LED as a non-thermal preservation technology on bio-active compounds, quality parameters, microbial and enzymatic spoilage of guava juice

2025-06-01

Marwa Rashad Ali , Manar Hassan , Mohamed M. El-Mogy +1 more | Innovative Food Science & Emerging Technologies

Quantitative risk assessment of Listeria monocytogenes in cooked meat products from retail to consumption in China

2025-06-01

Xiang Wang , Lisha Liu , Xiao Liu +7 more | Food Control

Curcumin-mediated photodynamic treatment efficiently inhibits Bacillus cereus and extends the shelf-life of flat rice noodles

2025-06-01

H Ji , Jiajun Yan , Zihui Chen +7 more | Food Research International

Navigating listeriosis: a case report highlighting swift diagnosis and management in a high-risk patient

2025-06-01

Muhammad Salman , Ahmed Khan Jadoon , Syed Ahmed Nadeem +1 more | Journal of the Pakistan Medical Association

Listeriosis is a serious foodborne bacterial infection with potentially severe consequences, particularly for pregnant women. A 38-year-old primigravida presented with fever and malaise during her third trimester of pregnancy and … Listeriosis is a serious foodborne bacterial infection with potentially severe consequences, particularly for pregnant women. A 38-year-old primigravida presented with fever and malaise during her third trimester of pregnancy and a diagnosis of listeriosis was confirmed through blood culture. An emergency caesarean section was performed, and a healthy baby was delivered. The patient had consumed a significant number of dairy products before the onset of fever, highlighting the importance of dietary history. This case report emphasises the need for healthcare providers to maintain a high index of suspicion, especially in high-risk patients. This also shows that swift diagnosis and empirically targeted management are essential in combatting listeriosis in pregnancy, and lead to better maternal and foetal outcomes. It also underscores the necessity of raising awareness among pregnant women about safe dietary practices to reduce the risk of listeria infection. Keywords: Listeria monocytogenes, Listeriosis, Pregnancy, Outcomes.

Survival of Escherichia coli O157:H7 and Listeria monocytogenes on spinach and blueberries treated with aqueous chlorine dioxide and muscadine (Vitis rotundifolia) extract

2025-06-01

Adel R. A. Abd‐Allah , Juan L. Silva , Wes Schilling +2 more | Journal of Food Protection

The antimicrobial effect of various concentrations of chlorine dioxide (ClO2) and muscadine extract (ME) were investigated on Escherichia coli O157:H7 and Listeria monocytogenes under in vitro conditions and on treated … The antimicrobial effect of various concentrations of chlorine dioxide (ClO2) and muscadine extract (ME) were investigated on Escherichia coli O157:H7 and Listeria monocytogenes under in vitro conditions and on treated spinach and blueberries. Tryptic soy broth (TSB) and produce were inoculated with a 3-strain cocktail of each pathogen. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined using either 96-well plates incubated in a microplate reader for ClO2 or test tubes incubated in a conventional incubator at 37°C for 24 h for the ME. Pathogen reduction on inoculated produce (inoculation levels were 5.6-7.0 log CFU/g for spinach and 4.5-5.1 log CFU/g for blueberries) was evaluated after exposure to various antimicrobial treatments for 10 min + 30-45 min dry time + storage at 8°C for up to six days. Under in vitro, L. monocytogenes was more susceptible than E. coli O157:H7 to ClO2 and ME. On spinach, 300 mg/ml ME and 3 ppm ClO2 + 300 mg/ml ME treatments resulted in the maximum reduction of E. coli O157:H7 (4.6 log CFU/g reduction at day 1) and L. monocytogenes (5.6 log CFU/g reduction at day 2), respectively. On blueberries, all the treatments significantly decreased E. coli O157:H7 counts (≤1.7 log CFU/g), and no differences (P>0.05) were detected from day 1 to 6. The treatment 3 ppm ClO2 + 300 mg/ml ME led to non-detectable (P≤0.05) L. monocytogenes levels on blueberries at days 1, 2, 4, and 6, leading to surface reductions >4.1 log CFU/g. Based on the study, ME combined with ClO2 could be a potential candidate as postharvest treatment to reduce the presence of E. coli O157:H7 and L. monocytogenes on blueberries. Both pathogens were less susceptible to these combined treatments on spinach.

Agricultural biowaste based disinfectant formulation mitigates drug resistant nosocomial pathogens

2025-06-01

Srividhya Krishnan , V. Ponnusami , P. Kavitha +2 more | Microbial Pathogenesis

Understanding the Role of Pyruvate Dehydrogenase in Listeria monocytogenes Virulence

2025-05-29

Matthew J. Freeman , Noah J Eral , Abigail M. Debrine +3 more | bioRxiv (Cold Spring Harbor Laboratory)

To survive within restrictive host niches, bacterial pathogens must possess finely tuned physiological adaptations. One such niche inhabited by Listeria monocytogenes (L. monocytogenes) is the host cell cytosol, a compartment … To survive within restrictive host niches, bacterial pathogens must possess finely tuned physiological adaptations. One such niche inhabited by Listeria monocytogenes (L. monocytogenes) is the host cell cytosol, a compartment characterized by significant barriers to entry, metabolic limitation, and immune surveillance. Previously, we identified L. monocytogenes transposon mutants defective for intracellular survival due to disruptions in key metabolic pathways, including cell wall biosynthesis, menaquinone production, and pyruvate metabolism. One of these mutants mapped to a central component of the pyruvate dehydrogenase (PDH) complex, pdhC::Tn. Notably, this mutant exhibits pronounced survival defects during infection, despite retaining robust growth and survival in nutrient-rich media. We go on to show that disruption of pdhA::Tn and pdhD::Tn similarly led to virulence attenuation during intra-macrophage growth, plaquing assays, and murine infections. Respiro-fermentative metabolic profiling revealed that pdhC::Tn mutants have an altered respiro-fermentative metabolism with more prominent secretion of lactate. Further, unbiased metabolomic profiling revealed a global starvation phenotype with lower levels of upper glycolytic intermediates and TCA cycle intermediates coupled with elevated intra-bacterial levels of pyruvate and lactate. We then demonstrate that PDH mutants are unable to efficiently utilize phosphotransferase (PTS)-dependent carbon sources and that their growth can be rescued using non-PTS-mediated carbon sources such as hexose phosphates. To identify genetic suppressors of PDH deficiency, we performed an EMS mutagenesis screen using fructose - a PTS-transported carbon source - as the sole carbon source. Five suppressors each contained a single independent mutation in the redox sensing regulator rex. Subsequently, we show that loss of rex restores pdhC::Tn mutant ability to consume PTS-mediated carbon sources through the alleviation of fermentative repression. Further, pdhC::Tn suppressor mutants show restored intracellular growth, but not virulence in vivo. Together, these findings indicate that a key defect in PDH mutants is the inability to import and metabolize PTS-dependent carbon sources in the host cytosol. We posit this impairment leads to disruptions in redox balance and a shift in respiro-fermentative metabolism, ultimately contributing to the loss of intracellular fitness and virulence.