• Assessment and Control of Foodborne Pathogens in Ireland

      Ross, R.Paul; Hill, Colin; Murphy, P.; Jordan, Kieran; Arendt, Elke; Van Sinderen, D.; Morgan, S.; Hickey, Rita; Maher, M.; Kelly, J.; Galvin, M.; Scannell, A. (Teagasc, 2001-05-01)
      Consumers are increasingly demanding food that is free from pathogens, but with less preservatives and additives. As a response to these conflicting demands, current trends in the food industry include minimal processing, and the investigation of alternative inhibitors for use in foods. Additionally, the manufacture of an increasing range of novel foods, and the inclusion of non-dairy ingredients into dairy products, and vice versa, poses additional dangers with respect to safety. Furthermore, the dramatic increase in incidence of food-borne illness internationally, as a result of contamination with food-borne pathogens such as Listeria monocytogenes, is a cause of considerable consumer concern. Bacteriocins are inhibitory peptides produced by a number of Lactic Acid Bacteria which are capable of killing other bacteria. These natural inhibitors have widespread applications in the preservation of foods, since they can kill a number of pathogenic and spoilage bacteria. The broad spectrum bacteriocin Lacticin 3147 (discovered in a previous project and patented - see DPRC No. 3) is produced by Lactococcus lactis subsp. lactis DPC3147, a food-grade strain, similar to strains used for commercial cheese manufacture. Lacticin 3147 is effective in the inhibition of all Gram positive bacteria tested including the food pathogens Listeria monocytogenes and Staphylococcus aureus and food spoilage bacteria such as Clostridia and Bacillus species. As part of this project the bacteriocin Lacticin 3147 was assessed as a food preservative for improving food safety via inhibition of pathogenic organisms. Thus the project plan followed a "twin-track" approach to assessing and controlling the food safety aspects of Irish food. The first of these was designed to investigate the current safety status of Irish dairy products. The second approach involved an attempt to exploit natural antimicrobial substances, including Lacticin 3147, to protect foods from pathogenic bacteria.
    • A case of bovine raw milk contamination with Listeria monocytogenes

      Hunt, Karen; Drummond, Niall; Murphy, Mary; Butler, Francis; Buckley, Jim; Jordan, Kieran (Biomed Central, 2012-07-06)
      During routine sampling of bulk raw milk on a dairy farm, the pathogenic bacteria Listeria monocytogenes was found to be a contaminant, at numbers < 100 cfu/ml. A strain with an indistinguishable pulsed-field gel electrophoresis pattern was isolated from the bulk milk two months later. Environmental swabs taken at the dairy environment were negative for the presence of L. monocytogenes, indicating a possible case of excretion of the L. monocytogenes directly into the milk. Milk samples were collected from the individual cows and analysed, resulting in the identification of L. monocytogenes excretion (at 280 cfu/ml) from one of the 4 mammary quarters of one dairy cow out of 180. When the infected cow was isolated from the herd, no L. monocytogenes was detected from the remaining herd. The pulsed-field gel electrophoresis pattern of the strain from the individual cow was indistinguishable from that originally isolated from the bulk milk. The infected cow did not show any clinical signs of disease, nor did the appearance of the milk have any physical abnormalities. Antibiotic treatment of the infected mammary quarter was found to be ineffective. This study shows that there can be risks associated with direct contamination of raw milk with L. monocytogenes.
    • Identification of existing and emerging chemical residue contamination concerns in milk

      Danaher, Martin; Jordan, Kieran (Teagasc (Agriculture and Food Development Authority), Ireland, 2013)
      In order to maintain the quality of Irish milk and meet increasingly demanding specifications, it is necessary to focus on chemical residues in milk, in addition to other quality issues. The objective of the work was to assess the current status of chemical contaminant analysis and to identify technological and knowledge needs. This was achieved through a review of literature with respect to chemical contaminants. Quaternary ammonium compounds (QACs) have been identified as an area of concern for the dairy industry because of the recent reports of QAC residues in dairy products internationally. Analytical support to analyse QAC residues in milk and dairy products on an ongoing basis is required. Furthermore, the source of QAC residues along the milk production chain needs to be identified. Similarly, analytical support and research is needed in the area of phthalates, to support the development of intervention strategies to reduce contamination, if present. Cephalosporin antibiotics have been a concern for the dairy industry because of the lack of suitable chemical tests to measure these substances.
    • Iodine concentrations in milk

      O'Brien, Bernadette; Gleeson, David E; Jordan, Kieran (Teagasc (Agriculture and Food Development Authority), Ireland, 2013)
      Iodine tends to be supplemented at farm level in the expectation of increasing cow health and fertility. There is concern that such practices may result in high milk iodine, which could affect ingredients for infant formula and, thus, dairy export markets. The objective of this study was to quantify the effect of iodine fortified feed and teat disinfection practices of dairy cows on milk iodine concentration. Thirty lactating cows were fed 7 kg, 3 kg (10 mg iodine/kg) and 0 kg of concentrate feed during 3 periods of 35 days each. During the first 14 days of each period, cows were on dietary iodine treatments only; during days 15–21, one of three teat disinfection treatments (n = 10) was applied (in addition to the dietary iodine treatments): non-iodine (chlorhexidine) post-milking spray; 0.5% iodine spray post-milking; 0.5% iodine spray pre- and post-milking. Cow milk yield was 21.3 kg/day. Individual cow milk samples were analysed for iodine concentration on 2 days at the end of each treatment period. Dietary supplementation of iodine at both 30 mg and 70 mg/day, when compared to the diet with no supplement, increased milk iodine concentrations significantly (P < 0.001) from 449 to 1034 and 915 μg/kg, respectively. Teat disinfection both pre- and post-milking increased milk iodine concentration at each of the dietary supplementation levels of 0, 30 and 70 mg/day compared with a non-iodine teat disinfectant (P < 0.001). In conclusion, both dietary iodine supplementation and teat disinfection iodine increased milk iodine concentrations in an additive manner, exceeding common target values of 250 μg/kg. As both iodine treatments can occur simultaneously on farm, supplementation strategies should be monitored.
    • Listeria monocytogenes in Milk Products

      Jordan, Kieran; Hunt, Karen; Dalmasso, Marion (Springer International Publishing, 2016-04-13)
      Milk and milk products are frequently identified as vectors for transmission of Listeria monocytogenes. Milk can be contaminated at farm level either by indirect external contamination from the farm environment or less frequently by direct contamination of the milk from infection in the animal. Pasteurisation of milk will kill L. monocytogenes, but post-pasteurisation contamination, consumption of unpasteurised milk and manufacture of unpasteurised milk products can lead to milk being the cause of outbreaks of listeriosis. Therefore, there is a concern that L. monocytogenes in milk could lead to a public health risk. To protect against this risk, there is a need for awareness surrounding the issues, hygienic practices to reduce the risk and adequate sampling and analysis to verify that the risk is controlled. This review will highlight the issues surrounding L. monocytogenes in milk and milk products, including possible control measures. It will therefore create awareness about L. monocytogenes, contributing to protection of public health.
    • A note on challenge trials to determine the growth of Listeria monocytogenes on mushrooms (Agaricus bisporus)

      Leong, Dara; Alvarez-Ordonez, Avelino; Jordan, Kieran (Teagasc (Agriculture and Food Development Authority), Ireland, 2015-12-30)
      In the EU, food is considered safe with regard to Listeria monocytogenes if the number of micro-organisms does not exceed 100 colony forming units (cfu)/g throughout its shelf-life. Therefore, it is important to determine if a food supports growth of L. monocytogenes. Guidelines for conducting challenge tests for growth assessment of L. monocytogenes on foods were published by the European Union Reference Laboratory (EURL) in 2014. The aim of this study was to use these guidelines to determine if refrigerated, fresh, whole, closed-cap, prepackaged mushrooms (Agaricus bisporus) support the growth of L. monocytogenes. Three batches of mushrooms were artificially inoculated at approximately 100 cfu/g with a three-strain mix of L. monocytogenes and incubated for 2 days at 8°C followed by 4 days at 12°C. L. monocytogenes numbers were determined (in triplicate for each batch) on days 0, 2 and 6. Water activity, pH and total bacterial counts were also determined. There was no increase in the number of L. monocytogenes above the threshold of 0.5 log cfu/g in any of the replicates. In 8 of 9 replicates, the numbers decreased indicating that A. bisporus do not support the growth of L. monocytogenes. As the EU regulations allow < 100 cfu/g if the food cannot support growth of L. monocytogenes, the significance of this study is that mushrooms with < 100 cfu/g may be within the regulations and therefore, quantitative rather than qualitative determination may be required.
    • Process environment sampling can help to reduce the occurrence of Listeria monocytogenes in food processing facilities

      Dalmasso, Marion; Jordan, Kieran (Teagasc (Agriculture and Food Development Authority), Ireland, 2013)
      The occurrence and persistence of Listeria monocytogenes strains in food processing environments pose a risk of cross-contamination to food. The control of these strains is thus essential to ensure food safety. In the present study, 205 samples were collected from a food processing facility between May 2012 to February 2013 and analysed for the presence of L. monocytogenes by the ISO11290 standard method. L. monocytogenes isolates were differentiated using pulsed field gel electrophoresis. Up to 55% of the samples were positive for L. monocytogenes until October 2012. Advice was given on the implementation of corrective actions regarding cleaning and disinfection procedures and workflows. This resulted in a decrease in the number of positive samples, reflecting the reduction of L. monocytogenes in the processing environment. Eight pulsotypes were found in the food processing facility environment, mainly on non-food contact surfaces. One type was identified as persistent as it was isolated on each sampling occasion and constituted more than 71% of the isolates collected. It was the only type found in the processing environment after the implementation of corrective actions. This work demonstrates that processing environment sampling plans are effective to assess hygiene and implement corrective actions. This contributes to prevention of contamination events and consequently to assuring the safety of the food product.
    • Protocols and strategies to study the migration of veterinary drug residues into milk and dairy products in licensed trials

      Power, C.; Sayers, Riona; O'Brien, Bernadette; Furey, A.; Danaher, Martin; Jordan, Kieran (Teagasc (Agriculture and Food Development Authority), Ireland, 2013)
      In the interest of animal welfare, and in order that the results from animal trials are considered valid for inclusion in the development of regulations, it is necessary that such trials are undertaken in accordance with the appropriate licensing arrangements. In January 2013, new licensing arrangements were introduced in the European Union. The aim of this paper is to outline the legislative strategy required for obtaining licences for animal trials and based on live animal trials with flukicides, establishes a blueprint for obtaining the appropriate licences and undertaking the experiments.
    • Protocols and strategies to study the migration of veterinary drug residues into milk and dairy products in licensed trials – Corrigendum

      Power, C.; Sayers, Riona; O'Brien, Bernadette; Furey, A.; Danaher, Martin; Jordan, Kieran (Teagasc (Agriculture and Food Development Authority), Ireland, 2014)
      Corrigendum
    • Review of potential sources and control of thermoduric bacteria in bulk-tank milk

      Gleeson, David E; O'Connell, Aine; Jordan, Kieran (Teagasc (Agriculture and Food Development Authority), Ireland, 2013)
      Bacteria that contaminate milk include thermoduric bacteria that can survive pasteurisation and subsequently grow in the pasteurised milk or contaminate product. Elimination of thermodurics at milking is not feasible. Therefore, knowledge of their source and strategies for their reduction are important. The major sources of thermodurics in milk are contamination of the teat skin from soil and bedding, and subsequent contamination from deposits that can build up on milking equipment surfaces. Hygiene at milking can reduce the number of bacteria contaminating milk. Teat preparation at milking and a recommended plant cleaning procedure are critical to the prevention of the contamination of milk with thermoduric bacteria.
    • A Review on the Applications of Next Generation Sequencing Technologies as Applied to Food-Related Microbiome Studies

      CaoYu; Fanning, Seamus; Proos, Sinead; Jordan, Kieran; Srikumar, Shabarinath; Department of Agriculture, Food and the Marine; SMART-PIF; 13/F/423 (Frontiers, 2017)
      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., human intestinal contents) or a food manufacturing facility econiche (e.g., floor drain). To date, 16S rDNA sequencing, metagenomics and metatranscriptomics are the three basic sequencing strategies used in the taxonomic identification and characterization of food-related microbiomes. These sequencing strategies have used different NGS platforms for DNA and RNA sequence identification. Traditionally, 16S rDNA sequencing has played a key role in understanding the taxonomic composition of a food-related microbiome. Recently, metagenomic approaches have resulted in improved understanding of a microbiome by providing a species-level/strain-level characterization. Further, metatranscriptomic approaches have contributed to the functional characterization of the complex interactions between different microbial communities within a single microbiome. Many studies have highlighted the use of NGS techniques in investigating the microbiome of fermented foods. However, the utilization of NGS techniques in studying the microbiome of non-fermented foods are limited. This review provides a brief overview of the advances in DNA sequencing chemistries as the technology progressed from first, next and third generations and highlights how NGS provided a deeper understanding of food-related microbiomes with special focus on non-fermented foods.
    • Transcriptome analysis of Listeria monocytogenes exposed to biocide stress reveals a multi-system response involving cell wall synthesis, sugar uptake, and motility

      Casey, Aidan; Fox, Edward M.; Schmitz-Esser, Stephan; Coffey, Aidan; McAuliffe, Olivia; Jordan, Kieran (Frontiers Media SA, 2014-02-28)
      Listeria monocytogenes is a virulent food-borne pathogen most often associated with the consumption of “ready-to-eat” foods. The organism is a common contaminant of food processing plants where it may persist for extended periods of time. A commonly used approach for the control of Listeria monocytogenes in the processing environment is the application of biocides such as quaternary ammonium compounds. In this study, the transcriptomic response of a persistent strain of L. monocytogenes (strain 6179) on exposure to a sub-lethal concentration of the quaternary ammonium compound benzethonium chloride (BZT) was assessed. Using RNA-Seq, gene expression levels were quantified by sequencing the transcriptome of L. monocytogenes 6179 in the presence (4 ppm) and absence of BZT, and mapping each data set to the sequenced genome of strain 6179. Hundreds of differentially expressed genes were identified, and subsequent analysis suggested that many biological processes such as peptidoglycan biosynthesis, bacterial chemotaxis and motility, and carbohydrate uptake, were involved in the response of L. monocyotogenes to the presence of BZT. The information generated in this study further contributes to our understanding of the response of bacteria to environmental stress. In addition, this study demonstrates the importance of using the bacterium's own genome as a reference when analysing RNA-Seq data.