Phylogenetic and Phenotypic Analyses of a Collection of Food and Clinical Listeria monocytogenes Isolates Reveal Loss of Function of Sigma B from Several Clonal Complexes.

To understand the molecular mechanisms that contribute to the stress responses of the important foodborne pathogen Listeria monocytogenes, we collected 139 strains (meat,  = 25; dairy,  = 10; vegetable,  = 8; seafood,  = 14; mixed food,  = 4; and food processing environments,  = 78), mostly isolated in Ireland, and subjected them to whole-genome sequencing. These strains were compared to 25 Irish clinical isolates and 4 well-studied reference strains. Core genome and pan-genome analysis confirmed a highly clonal and deeply branched population structure.

Listeria monocytogenes environmental sampling program in ready-to-eat processing facilities: A practical approach.

Listeria monocytogenes is a foodborne pathogen that is frequently found in the environment. It can easily enter food processing environments and contaminate food, potentially causing public health issues. Food business operators (FBOs) are responsible for the control of L.

Effect of different cleaning procedures on water use and bacterial levels in weaner pig pens.

Pork is one of the most globally eaten meats and the pig production chain contributes significantly to the water footprint of livestock production. However, very little knowledge is available about the on-farm factors that influence freshwater use in the pig production chain. An experiment was conducted to quantify the effect of three different washing treatments on freshwater use, bacterial levels [(total bacterial counts; TBC), Enterobacteriaceae and Staphylococcus] and cleaning time in washing of pens for weaning pigs.

High-Throughput Characterization of Listeria monocytogenes Using the OmniLog Phenotypic Microarray.

High-throughput biochemical screening techniques are an important tool in phenotypic analysis of bacteria. New methods, simultaneously measuring many phenotype responses, increase the output of such investigations and allow a more complete overview of the bacterial phenotype, facilitating large-scale correlation to related genotypes. This chapter describes the application of OmniLog phenotype microarray analysis, a high-throughput assay for the phenotypic characterization of bacterial strains across a variety of different traits such as nutrient utilization and antimicrobial sensitivity, to Listeria species.

Pulsed-Field Gel Electrophoresis (PFGE) Analysis of Listeria monocytogenes.

PFGE is a valuable tool for assessing L. monocytogenes strain interrelatedness. It is based on the study of total bacterial DNA restriction patterns.

The public health risk posed by in frozen fruit and vegetables including herbs, blanched during processing.

A multi-country outbreak of ST6 linked to blanched frozen vegetables (bfV) took place in the EU (2015-2018). Evidence of food-borne outbreaks shows that is the most relevant pathogen associated with bfV. The probability of illness per serving of uncooked bfV, for the elderly (65-74 years old) population, is up to 3,600 times greater than cooked bfV and very likely lower than any of the evaluated ready-to-eat food categories.

Effectiveness of current hygiene practices on minimization of in different mushroom production-related environments.

Background: The commercial production of is a three stage process: 1) production of compost, also called "substrate"; 2) production of casing soil; and 3) production of the mushrooms. Hygiene practices are undertaken at each stage: pasteurization of the substrate, hygiene practices applied during the production of casing soil, postharvest steam cookout, and disinfection at the mushroom production facilities. However, despite these measures, foodborne pathogens, including are reported in the mushroom production environment.

Prevalence, virulence characterization, and genetic relatedness of Listeria monocytogenes isolated from chicken retail points and poultry slaughterhouses in Turkey.

Listeria monocytogenes is one of the most important foodborne pathogens and is a causal agent of listeriosis in humans and animals. The aim of this study was to determine the prevalence, serogroups, antibiotic susceptibility, virulence factor genes, and genetic relatedness of L. monocytogenes strains isolated from 500 poultry samples in Turkey.

Whole-Genome Sequencing-Based Characterization of 100 Listeria monocytogenes Isolates Collected from Food Processing Environments over a Four-Year Period.

is frequently found in foods and processing facilities, where it can persist, creating concerns for the food industry. Its ability to survive under a wide range of environmental conditions enhances the potential for cross-contamination of the final food products, leading to possible outbreaks of listeriosis. In this study, whole-genome sequencing (WGS) was applied as a tool to characterize and track 100 isolates collected from three food processing environments.

Inhibition of Biofilm Formation by the Amidase Domain of the Phage vB_LmoS_293 Endolysin.

is a ubiquitous Gram-positive bacterium that is a major concern for food business operators because of its pathogenicity and ability to form biofilms in food production environments. Bacteriophages (phages) have been evaluated as biocontrol agents for in a number of studies and, indeed, certain phages have been approved for use as anti-listerial agents in food processing environments (ListShield and PhageGuard Listex). Endolysins are proteins produced by phages in the host cell.

Screening commercial teat disinfectants against bacteria isolated from bovine milk using disk diffusion.

Background And Aim: Teat disinfection is an important tool in reducing the incidence of bovine mastitis. Identifying the potential mastitis-causing bacterial species in milk can be the first step in choosing the correct teat disinfectant product. The objective of this study was to screen commercial teat disinfectants for inhibition against mastitis-associated bacteria isolated from various types of milk samples.

Microbiological quality of milk from farms to milk powder manufacture: an industrial case study.

The experiments reported in this research paper aimed to track the microbiological load of milk throughout a low-heat skim milk powder (SMP) manufacturing process, from farm bulk tanks to final powder, during mid- and late-lactation (spring and winter, respectively). In the milk powder processing plant studied, low-heat SMP was produced using only the milk supplied by the farms involved in this study. Samples of milk were collected from farm bulk tanks (mid-lactation: 67 farms; late-lactation: 150 farms), collection tankers (CTs), whole milk silo (WMS), skim milk silo (SMS), cream silo (CS) and final SMP.

Are some teat disinfectant formulations more effective against specific bacteria isolated on teat skin than others?

The use of pre- and post-milking teat disinfectants can reduce teat bacterial load and aid in the collection of high-quality milk. The objective of this study was to compare the reduction in bacteria populations on teat skin after the application of different commercial teat disinfectant products. Ten teat disinfectant products were applied to the teats of 10 Holstein-Friesian cows.

Challenge Studies to Determine the Ability of Foods to Support the Growth of Listeria monocytogenes.

is a foodborne pathogen that causes listeriosis, a relatively rare, but potentially fatal, disease, with a mortality rate of 20⁻30%. In general, European Regulations require the absence of in five samples of 25 g before the food has left the producer, but if the food has been demonstrated not to support the growth of , up to 100 cfu g are allowed in the food (except for foods for infants or medical purposes) during its shelf-life under reasonably foreseeable storage conditions. It is important for food producers to determine if their food supports the growth of The European Union Reference Laboratory for published a Technical Guidance document for conducting shelf-life studies on in ready-to-eat foods in June 2014.

A Comparative Study of the Susceptibility of Listeria Species to Sanitizer Treatments When Grown under Planktonic and Biofilm Conditions.

Listeria species are ubiquitous in nature and can adapt to survive in a variety of niches, including food processing environments. Listeria species that colonize these environments may also have the potential to persist. Food safety strategies designed to manage these niches include regular cleaning and disinfection with proven sanitizers containing biocide-active compounds.

Listeria monocytogenes in Foods.

Listeria monocytogenes causes listeriosis, a rare foodborne disease with a mortality rate of 20%-30%. The elderly and immunocompromised are particularly susceptible to listeriosis. L.

Virulence Gene Sequencing Highlights Similarities and Differences in Sequences in Serotype 1/2a and 4b Strains of Clinical and Food Origin From 3 Different Geographic Locations.

The -virulence gene cluster (VGC) is the main pathogenicity island in , comprising the , and genes. In this study, the VGC of 36 isolates with respect to different serotypes (1/2a or 4b), geographical origin (Australia, Greece or Ireland) and isolation source (food-associated or clinical) was characterized. The most conserved genes were and , with the lowest nucleotide diversity (π) among all genes ( < 0.

Genomic Characterization of Listeria monocytogenes Isolates Associated with Clinical Listeriosis and the Food Production Environment in Ireland.

is a major human foodborne pathogen that is prevalent in the natural environment and has a high case fatality rate. Whole genome sequencing (WGS) analysis has emerged as a valuable methodology for the classification of isolates and the identification of virulence islands that may influence infectivity. In this study, WGS was used to provide an insight into 25 isolates from cases of clinical infection in Ireland between 2013 and 2015.

The effect of different precooling rates and cold storage on milk microbiological quality and composition.

The objective of this study was to measure the effect of different milk cooling rates, before entering the bulk tank, on the microbiological load and composition of the milk, as well as on energy usage. Three milk precooling treatments were applied before milk entered 3 identical bulk milk tanks: no plate cooler (NP), single-stage plate cooler (SP), and double-stage plate cooler (DP). These precooling treatments cooled the milk to 32.

A Review on the Applications of Next Generation Sequencing Technologies as Applied to Food-Related Microbiome Studies.

The development of next generation sequencing (NGS) techniques has enabled researchers to study and understand the world of microorganisms from broader and deeper perspectives. The contemporary advances in DNA sequencing technologies have not only enabled finer characterization of bacterial genomes but also provided deeper taxonomic identification of complex microbiomes which in its genomic essence is the combined genetic material of the microorganisms inhabiting an environment, whether the environment be a particular body econiche (e.g.

Draft Genome Sequences of 25 Isolates Associated with Human Clinical Listeriosis in Ireland.

is a Gram-positive opportunistic pathogen that is the causative agent of listeriosis. Here, we report the draft genome sequences of 25 strains isolated from patients with clinical listeriosis in the Republic of Ireland between 2013 and 2015.

A 3-year multi-food study of the presence and persistence of Listeria monocytogenes in 54 small food businesses in Ireland.

The problem of assessing the occurrence of the food-borne pathogen Listeria monocytogenes in the food chain, and therefore the risk of exposure of the human population, is often challenging because of the limited scope of some studies. In this study the occurrence of L. monocytogenes in food from four major food groups, dairy products, meats, seafood and vegetables, and associated food processing environments in Ireland was studied over a three-year period.

Comparative Genomic Analysis of Two Serotype 1/2b Isolates from Analogous Environmental Niches Demonstrates the Influence of Hypervariable Hotspots in Defining Pathogenesis.

The vast majority of clinical human listeriosis cases are caused by serotype 1/2a, 1/2b, 1/2c, and 4b isolates of . The ability of to establish a systemic listeriosis infection within a host organism relies on a combination of genes that are involved in cell recognition, internalization, evasion of host defenses, and survival and growth. Recently, whole genome sequencing and comparative genomic analysis have proven to be powerful tools for the identification of these virulence-associated genes in .