| 1. |
- Mogren, Lars, et al.
(författare)
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The hurdle approach-A holistic concept for controlling food safety risks associated with pathogenic bacterial contamination of leafy green vegetables. A review
- 2018
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Ingår i: Frontiers in Microbiology. - : Frontiers Media SA. - 1664-302X. ; 9:AUG
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Forskningsöversikt (refereegranskat)abstract
- Consumers appreciate leafy green vegetables such as baby leaves for their convenience and wholesomeness and for adding a variety of tastes and colors to their plate. In Western cuisine, leafy green vegetables are usually eaten fresh and raw, with no step in the long chain from seed to consumption where potentially harmful microorganisms could be completely eliminated, e.g., through heating. A concerning trend in recent years is disease outbreaks caused by various leafy vegetable crops and one of the most important foodborne pathogens in this context is Shiga toxin-producing Escherichia coli (STEC). Other pathogens such as Salmonella, Shigella, Yersinia enterocolitica and Listeria monocytogenes should also be considered in disease risk analysis, as they have been implicated in outbreaks associated with leafy greens. These pathogens may enter the horticultural value network during primary production in field or greenhouse via irrigation, at harvest, during processing and distribution or in the home kitchen/restaurant. The hurdle approach involves combining several mitigating approaches, each of which is insufficient on its own, to control or even eliminate pathogens in food products. Since the food chain system for leafy green vegetables contains no absolute kill step for pathogens, use of hurdles at critical points could enable control of pathogens that pose a human health risk. Hurdles should be combined so as to decrease the risk due to pathogenic microbes and also to improve microbial stability, shelf-life, nutritional properties and sensory quality of leafy vegetables. The hurdle toolbox includes different options, such as physical, physiochemical and microbial hurdles. The goal for leafy green vegetables is multi-target preservation through intelligently applied hurdles. This review describes hurdles that could be used for leafy green vegetables and their biological basis, and identifies prospective hurdles that need attention in future research.
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| 2. |
- Andersson, Cecilia K., et al.
(författare)
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Impaired airway epithelial cell wound-healing capacity is associated with airway remodelling following RSV infection in severe preschool wheeze
- 2020
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Ingår i: Allergy: European Journal of Allergy and Clinical Immunology. - : Wiley. - 0105-4538. ; 75:12, s. 3195-3207
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Tidskriftsartikel (refereegranskat)abstract
- Background: Respiratory syncytial virus (RSV) causes exacerbations of asthma and preschool wheeze (PSW). However, the anti-viral and repair responses of the bronchial epithelium in children with severe therapy-resistant asthma (STRA) and PSW are poorly understood. Methods: Children with STRA (age 12 [6-16] years), PSW (age 2 [1-5] years) and non-asthmatic controls (age 7 [2-14] years) underwent bronchoscopy with endobronchial brushings and biopsies. Anti-viral, wound injury responses were quantified in biopsies and primary bronchial epithelial cells (PBECs) in response to RSV, poly(I:C), house dust mite (HDM) or IL-33 using RT-qPCR, Luminex and live cell imaging. Collagen deposition and tissue expression of epithelial growth factor receptor (EGFR), IL-33 and receptor ST2 were investigated in bronchial biopsies. Results: PBECs from STRA and PSW had increased TLR3 gene expression and increased secretion of anti-viral and pro-inflammatory cytokines (IFN-γ, IL-6 and IL-13) in response to RSV compared to controls. Exposure of PBECs to concomitant TLR3 agonist poly(I:C) and HDM resulted in a significant reduction in epithelial cell proliferation in PSW compared to controls. Wound-healing was also impaired in PSW compared to controls at baseline and following IL-33 stimulation. In addition, tissue EGFR expression was significantly reduced in PSW and correlated with collagen deposition in endobronchial biopsies. Conclusions: Despite increased anti-viral responses, preschool children with severe wheeze had impaired airway epithelial proliferative responses following damage. This might be connected to the low expression of EGFR in PSW which may affect epithelial function and contribute to asthma pathogenesis.
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| 3. |
- Berg, Lars-Erik, et al.
(författare)
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Introduktion av värmekameror i undervisningen vid Lillerudsgymnasiet
- 2020
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Vi har bedrivit en forskningscirkel med syfte att utvärdera värmekameran som visualiseringsteknik i olika ämnen på naturbruksprogrammet genom att planera, genomföra och reflektera kring lektionsupplägg, där elever har fått möjlighet att använda värmekameror med olika grad av styrning. Resultatet visar att värmekameran har många skilda tillämpningsområden inom lantbruk och djurhållning och kan användas i undervisningen som ett verktyg för elevers praktiska undersökningar av t.ex. djurs fysiologi, eller som ett mätinstrument då tillfälle ges, t.ex. för att studera juverbölder hos suggor eller temperaturökning när en skruv tar fel gäng. En utmaning i undervisningen är att finna en balans mellan öppenhet och styrning, där eleverna upplever att de har möjlighet att undersöka fenomen de själva är intresserade av, men utifrån ett etablerat, systematiskt arbetssätt. Sammanfattningsvis har vi upplevt användning av värmekameror som ett effektivt och intresseväckande sätt att konkretisera och individanpassa undervisningen på naturbruksprogrammet, vilket vi kan rekommendera andra lärare att prova.
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| 4. |
- Berlin, Frida, et al.
(författare)
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Mast Cell Proteases Tryptase and Chymase Induce Migratory and Morphological Alterations in Bronchial Epithelial Cells
- 2021
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Ingår i: International Journal of Molecular Sciences. - : MDPI AG. - 1422-0067. ; 22:10
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Tidskriftsartikel (refereegranskat)abstract
- Chronic respiratory diseases are often characterized by impaired epithelial function and remodeling. Mast cells (MCs) are known to home into the epithelium in respiratory diseases, but the MC-epithelial interactions remain less understood. Therefore, this study aimed to investigate the effect of MC proteases on bronchial epithelial morphology and function. Bronchial epithelial cells were stimulated with MC tryptase and/or chymase. Morphology and epithelial function were performed using cell tracking analysis and holographic live-cell imaging. Samples were also analyzed for motility-associated gene expression. Immunocytochemistry was performed to compare cytoskeletal arrangement. Stimulated cells showed strong alterations on gene, protein and functional levels in several parameters important for maintaining epithelial function. The most significant increases were found in cell motility, cellular speed and cell elongation compared to non-stimulated cells. Also, cell morphology was significantly altered in chymase treated compared to non-stimulated cells. In the current study, we show that MC proteases can induce cell migration and morphological and proliferative alterations in epithelial cells. Thus, our data imply that MC release of proteases may play a critical role in airway epithelial remodeling and disruption of epithelial function.
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| 5. |
- Berlin, Frida, et al.
(författare)
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Mast Cell Tryptase Promotes Airway Remodeling by Inducing Anti-Apoptotic and Cell Growth Properties in Human Alveolar and Bronchial Epithelial Cells
- 2023
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Ingår i: Cells. - 2073-4409. ; 12:10
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Tidskriftsartikel (refereegranskat)abstract
- Bronchial and alveolar remodeling and impaired epithelial function are characteristics of chronic respiratory diseases. In these patients, an increased number of mast cells (MCs) positive for serine proteases, tryptase and chymase, infiltrate the epithelium and alveolar parenchyma. However, little is known regarding the implication of intraepithelial MCs on the local environment, such as epithelial cell function and properties. In this study, we investigated whether MC tryptase is involved in bronchial and alveolar remodeling and the mechanisms of regulation during inflammation. Using novel holographic live cell imaging, we found that MC tryptase enhanced human bronchial and alveolar epithelial cell growth and shortened the cell division intervals. The elevated cell growth induced by tryptase remained in a pro-inflammatory state. Tryptase also increased the expression of the anti-apoptotic protein BIRC3, as well as growth factor release in epithelial cells. Thus, our data imply that the intraepithelial and alveolar MC release of tryptase may play a critical role in disturbing bronchial epithelial and alveolar homeostasis by altering cell growth–death regulation.
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| 6. |
- Callesen, Katrine T., et al.
(författare)
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Characterization of Mast Cells from Healthy and Varicose Human Saphenous Vein
- 2022
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Ingår i: Biomedicines. - : MDPI AG. - 2227-9059. ; 10:5
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Tidskriftsartikel (refereegranskat)abstract
- Mast cells (MCs) are distributed in tissues throughout the body and are highly involved in many physiological and pathophysiological processes. The potential and involvement of different MC phenotypes are still not well understood. MCs are present in blood vessel walls, but their specific phenotypic features are unknown. We aimed at characterizing MCs from human saphenous veins for localization, mediator content, and receptor expression. This was done in MCs from both healthy and varicose human saphenous veins (hSV and vSV, respectively). For both vSV and hSV, we found that vein MCs are mainly present in the tunica adventitia (99% MCs in adventitia) and that the population consists of both MCT and MCTC phenotypes (vSV: 55% MCT, hSV: 64% MCT). The vein MCs contained high levels of histamine (vSV: 27 pg/MC, hSV: 55 pg/MC) and tryptase (vSV: 98 pg/MC, hSV: 111 pg/MC), indicating a strong potential for regulatory effects on blood vessels. The receptor expression of FcɛRI, MRGPRX2, PTAFR, C3aR, and C5aR was found, even though the percentage of positive cells differed between vSV and hSV MCs. We conclude that vein MCs from the blood vessel wall have a high potential to affect the tissue around them.
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| 7. |
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| 8. |
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| 9. |
- Finnveden, Göran, et al.
(författare)
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Evaluation of integration of sustainable development in higher education in Sweden
- 2020
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Ingår i: International Journal of Sustainability in Higher Education. - : Emerald Group Publishing Limited. - 1467-6370 .- 1758-6739. ; 21:4, s. 685-698
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Tidskriftsartikel (refereegranskat)abstract
- Purpose Since 2006, higher education institutions (HEIs) in Sweden, should according to the Higher Education Act, promote sustainable development (SD). In 2016, the Swedish Government asked the Swedish higher education authority to evaluate how this study is proceeding. The authority chose to focus on education. This paper aims to produce a report on this evaluation. Design/methodology/approach All 47 HEIs in Sweden were asked to write a self-evaluation report based on certain evaluation criteria. A panel was appointed consisting of academics and representatives for students and working life. The panel wrote an evaluation of each HEI, a report on general findings and recommendations, and gave an overall judgement of each HEI in two classes as follows: the HEI has well-developed processes for integration of SD in education or the HEI needs to develop their processes. Findings Overall, a mixed picture developed. Most HEIs could give examples of programmes or courses where SD was integrated. However, less than half of the HEIs had overarching goals for integration of SD in education or had a systematic follow-up of these goals. Even fewer worked specifically with pedagogy and didactics, teaching and learning methods and environments, sustainability competences or other characters of education for SD. Overall, only 12 out of 47 got a higher judgement. Originality/value This is a unique study in which all HEIs in a country are evaluated. This provides unique possibilities for identifying success factors and barriers. The importance of the leadership of the HEIs became clear.
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| 10. |
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| 11. |
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| 12. |
- Holmlund, Sofia, et al.
(författare)
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Health professionals' experiences and views of obstetric ultrasound in Rwanda
- 2017
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Ingår i: European Journal of Public Health. - : OXFORD UNIV PRESS. - 1101-1262 .- 1464-360X. ; 27:Suppl_3, s. 367-
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Background: The World Health Organizatiońs new recommendations for antenatal care (ANC) include one ultrasound examination before 24 weeks of gestation. Implementation of ultrasound in ANC in low resource countries has been shown to increase pregnant women’s compliance to ANC visits, and facilitate detection of high-risk pregnancies. The aim of this study was to explore Rwandan health professionals’ experiences and views of obstetric ultrasound in relation to clinical management, resources and skills.Methods: A cross-sectional questionnaire study involving physicians (n = 222), obstetricians (n = 29), nurses (n = 387) and midwives (n = 269) managing pregnant women in RWANDA was performed, as part of the CROss Country Ultrasound Study (CROCUS). Data were collected at 106 health facilities from November 2016 – March 2017.Preliminary results: One third of the participants performed ultrasound examinations (32.3%) and the majority on a daily basis (60.1%). The ultrasound examination where most participants reported high level skills was evaluation of the fetal heart rate (69.0%). A majority reported no skills or low level skills (79.9%) for ultrasound examination of the fetal heart, aorta and pulmonary artery. A majority (65.0%) reported that lack of ultrasound training of the ultrasound operator sometimes led to suboptimal pregnancy management. Almost all participants (91.3%) agreed that ANC would be improved if midwives were qualified to perform basic ultrasound examinations.Conclusions: The vast majority of health professionals in the study believed that maternity care can be improved if midwives learn to perform basic ultrasound examinations. Additional training of physicians performing obstetric ultrasound was also suggested to increase the quality of obstetric ultrasound surveillance and to further improve maternal and fetal health outcomes.Key messages:Physicians managing pregnant women need more training in obstetric ultrasound.Midwives need to be educated in performing obstetric ultrasounds.
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| 13. |
- Lindblom, Tobias, et al.
(författare)
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Processing of leafy vegetables matters: Damage and microbial community structure from field to bag
- 2021
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Ingår i: Food Control. - : Elsevier BV. - 0956-7135 .- 1873-7129. ; 125
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Tidskriftsartikel (refereegranskat)abstract
- Leafy vegetables undergo abiotic and biotic stresses, and a series of processing steps that cause mechanical injury. Breaching the epidermis alters phyllosphere structural and nutrient conditions, resulting in successional shifts in leaf microbiota and entry of human pathogens. This study examined damage during processing of baby leaves (Swiss chard, spinach) and concomitant microbial successional events. Machine-harvesting, washing, and packaging caused major phyllosphere perturbations, with increasing levels of leaf damage. Older leaves showed most damage, but plant species was influential. Diversity estimates of bacterial and fungal communities revealed shifts in microbiota post-harvest, particularly after the washing step. Relative abundance of Pseudomonadaceae and Enterobacteriaceae increased from field to bag. Bacterial species specific to different harvesting and processing steps replaced core microbiota species. While processing is unavoidable, procedures that mitigate leaf damage can enhance shelf-life and food safety.
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| 14. |
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| 15. |
- Mogren, Sofia, et al.
(författare)
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Mast Cell Proteases Promote Diverse Effects on the Plasminogen Activation System and Wound Healing in A549 Alveolar Epithelial Cells
- 2022
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Ingår i: Cells. - : MDPI AG. - 2073-4409. ; 11:18
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Tidskriftsartikel (refereegranskat)abstract
- Tissue damage, epithelial alterations, and intraepithelial presence of mast cells (MCs) are characteristics of asthma pathogenesis. Increased alveolar infiltration of MC populations has also been identified as a feature of asthma and other chronic respiratory diseases. The asthma associated receptor, urokinase plasminogen activator receptor (uPAR), has been shown to regulate bronchial epithelial repair responses. However, the impact of MC tryptase and chymase on functional properties and expression of uPAR in alveolar epithelial cells have not been fully investigated. Alveolar epithelial cell migration and wound healing were investigated using holographic live cell imaging of A549 cells in a wound scratch model post stimulation with tryptase or chymase. The expression of uPAR was investigated on the protein and gene level from cellular supernatants and in bronchoalveolar lavage fluid fractions from allergic asthmatics. We found that tryptase improved wound healing capacity, cellular migration and membrane bound uPAR expression. Chymase reduced gap closure capacity, cellular migration and membrane bound uPAR expression but increased soluble uPAR release. Our data suggest a dual regulatory response from the MC proteases in events related to uPAR expression and wound healing which could be important features in asthmatic disease.
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| 16. |
- Mogren, Sofia, et al.
(författare)
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Mast cell tryptase enhances wound healing by promoting migration in human bronchial epithelial cells
- 2021
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Ingår i: Cell Adhesion and Migration. - : Informa UK Limited. - 1933-6918 .- 1933-6926. ; 15:1, s. 202-214
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Tidskriftsartikel (refereegranskat)abstract
- Epithelial damage and increase of intraepithelial mast cells (MC) are characteristics of asthma. The role of MC mediator tryptase and the protease-activated receptor-2 (PAR2) on epithelial wound healing is not fully investigated. Stimulation of bronchial epithelial cells (BECs) with tryptase promoted gap closure, migration and cellular speed compared to controls. Stimulated BECs had higher expression of migration marker CD151 compared to controls. Proliferation marker KI67 was upregulated in tryptase-stimulated BECs compared to controls. Treatment with PAR2 antagonist I-191 reduced gap closure, migration and cell speed compared to BECs stimulated with tryptase. We found that tryptase enhances epithelial wound healing by increased migration and proliferation, which is in part regulated via PAR2. Our data suggest that tryptase might be beneficial in tissue repair under baseline conditions. However, in a pathological context such as asthma with increased numbers of activated MCs, it might lead to epithelial remodeling and loss of function.
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| 17. |
- Naznin, Most Tahera, et al.
(författare)
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Bridging technique failure through low-tech improvisation: A case study of food microbiology
- 2020
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Ingår i: African Journal of Microbiology Research. - 1996-0808. ; 14:7, s. 361-365
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Tidskriftsartikel (refereegranskat)abstract
- Modern technology for food safety studies includes standardized protocols and equipment. However, appropriate technology needs to step in to bridge technology dys- or malfunctioning. We examined different low-tech methods for extraction of bacteria from fresh vegetables. Standard equipment including stomacher and filter bags were compared to extraction using bread stick and alternative filter material (nylon stocking, mosquito net). Comparison of microspheres’ (ø: 53-63 µm; ø: 63-75 µm) passage through filter bags, nylon stockings with different densities (15 DEN, 20 DEN, 25 DEN, 40 DEN) and mosquito net showed no significant difference between filter bag and nylon stocking. A significantly higher number of both size microspheres (ø: 53-63 and ø: 63-75 µm) passed through the mosquito net than filter bag and nylon stocking. Manual extraction of romaine lettuce leaf was performed by three technicians. Viable counts of leaf associated bacteria were influenced by the technician and choice of filter material. Viable bacterial counts obtained from breadstick with filter bag manual extraction did not show any significant difference from standard method. We conclude that standard procedures can be replaced by low-tech approaches in the event of malfunctioning equipment. However, method validation is imperative.
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| 18. |
- Ramos-Ramirez, Patricia, et al.
(författare)
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House Dust Mite and Cat Dander Extract Induce Asthma-Like Histopathology with an Increase of Mucosal Mast Cells in a Guinea Pig Model
- 2023
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Ingår i: Journal of Immunology Research. - : Hindawi Publishing Corporation. - 2314-8861 .- 2314-7156. ; 2023
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Tidskriftsartikel (refereegranskat)abstract
- Background. Asthma is a chronic inflammatory disease with structural changes in the lungs defined as airway remodelling. Mast cell responses are important in asthma as they, upon activation, release mediators inducing bronchoconstriction, inflammatory cell recruitment, and often remodelling of the airways. As guinea pigs exhibit anatomical, physiological, and pharmacological features resembling human airways, including mast cell distribution and mediator release, we evaluated the effect of extracts from two common allergens, house dust mite (HDM) and cat dander (CDE), on histopathological changes and the composition of tryptase- and chymase-positive mast cells in the guinea pig lungs. Methods. Guinea pigs were exposed intranasally to HDM or CDE for 4, 8, and 12 weeks, and airway histology was examined at each time point. Hematoxylin and eosin, Picro-Sirius Red, and Periodic Acid-Schiff staining were performed to evaluate airway inflammation, collagen deposition, and mucus-producing cells. In addition, Astra blue and immunostaining against tryptase and chymase were used to visualize mast cells. Results. Repetitive administration of HDM or CDE led to the accumulation of inflammatory cells into the proximal and distal airways as well as increased airway smooth muscle mass. HDM exposure caused subepithelial collagen deposition and mucus cell hyperplasia at all three time points, whereas CDE exposure only caused these effects at 8 and 12 weeks. Both HDM and CDE induced a substantial increase in mast cells after 8 and 12 weeks of challenges. This increase was primarily due to mast cells expressing tryptase, but not chymase, thus indicating mucosal mast cells. Conclusions. We here show that exposure to HDM and CDE elicits asthma-like histopathology in guinea pigs with infiltration of inflammatory cells, airway remodelling, and accumulation of primarily mucosal mast cells. The results together encourage the use of HDM and CDE allergens for the stimulation of a clinically relevant asthma model in guinea pigs.
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| 19. |
- Ramu, Sangeetha, et al.
(författare)
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Direct effects of mast cell proteases, tryptase and chymase, on bronchial epithelial integrity proteins and anti-viral responses
- 2021
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Ingår i: BMC Immunology. - : Springer Science and Business Media LLC. - 1471-2172. ; 22:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: Mast cells (MCs) are known to contribute to both acute and chronic inflammation. Bronchial epithelial cells are the first line of defence against pathogens and a deficient anti-viral response has been suggested to play a role in the pathogenesis of asthma exacerbations. However, effects of MC mediators on bronchial epithelial immune response have been less studied. The aim of this study is to investigate the direct effects of stimulation with MC proteases, tryptase and chymase, on inflammatory and anti-viral responses in human bronchial epithelial cells (HBECs). Method: Cultured BEAS-2b cells and primary HBECs from 3 asthmatic patients were stimulated with tryptase or chymase (0.1 to 0.5 μg/ml) for 1, 3, 6 and 24 h. To study the effects of MC mediators on the anti-viral response, cells were stimulated with 10 μg/ml of viral mimic Poly (I:C) for 3 and 24 h following pre-treatment with 0.5 μg/ml tryptase or chymase for 3 h. Samples were analysed for changes in pro-inflammatory and anti-viral mediators and receptors using RT-qPCR, western blot and Luminex. Results: Tryptase and chymase induced release of the alarmin ATP and pro-inflammatory mediators IL-8, IL-6, IL-22 and MCP-1 from HBECs. Moreover, tryptase and chymase decreased the expression of E-cadherin and zonula occludens-1 expression from HBECs. Pre-treatment of HBECs with tryptase and chymase further increased Poly (I:C) induced IL-8 release at 3 h. Furthermore, tryptase significantly reduced type-I and III interferons (IFNs) and pattern recognition receptor (PRR) expression in HBECs. Tryptase impaired Poly (I:C) induced IFN and PRR expression which was restored by treatment of a serine protease inhibitor. Similar effects of tryptase on inflammation and anti-viral responses were also confirmed in primary HBECs from asthmatic patients. Conclusion: MC localization within the epithelium and the release of their proteases may play a critical role in asthma pathology by provoking pro-inflammatory and alarmin responses and downregulating IFNs. Furthermore, MC proteases induce downregulation of epithelial junction proteins which may lead to barrier dysfunction. In summary, our data suggests that mast cells may contribute towards impaired anti-viral epithelial responses during asthma exacerbations mediated by the protease activity of tryptase.
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| 20. |
- Söderqvist, Karin, et al.
(författare)
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Fate of Listeria monocytogenes, Pathogenic Yersinia enterocolitica, and Escherichia coli O157:H7 gfpþ in Ready-to-Eat Salad during Cold Storage: What Is the Risk to Consumers?
- 2017
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Ingår i: Journal of Food Protection. - 0362-028X. ; 80, s. 204-212
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Tidskriftsartikel (refereegranskat)abstract
- In this study, we investigated the fate of Listeria monocytogenes, pathogenic Yersinia enterocolitica, and Escherichia coli O157:H7 gfp(+) inoculated in low numbers into ready-to-eat baby spinach and mixed-ingredient salad (baby spinach with chicken meat). Samples were stored at recommended maximum refrigerator temperature (8 degrees C in Sweden) or at an abuse temperature (15 degrees C) for up to 7 days. Mixed-ingredient salad supported considerable growth when stored at 15 degrees C during shelf life (3 days), with populations of L. monocytogenes, pathogenic Y. enterocolitica, and E. coli O157:H7 gfp(+) increasing from less than 2.0 log CFU/g on day 0 to 7.0, 4.0, and 5.6 log CFU/g, respectively. However, when mixed-ingredient salad was stored at 8 degrees C during shelf life, only L. monocytogenes increased significantly, reaching 3.0 log CFU/g within 3 days. In plain baby spinach, only pathogenic Y. enterocolitica populations increased significantly during storage for 7 days, and this was exclusively at an abuse temperature (15 degrees C). Thus, mixing ready-to-eat leafy vegetables with chicken meat strongly influenced levels of inoculated strains during storage. To explore the food safety implications of these findings, bacterial numbers were translated into risks of infection by modeling. The risk of listeriosis (measured as probability of infection) was 16 times higher when consuming a mixed ingredient salad stored at 8 degrees C at the end of shelf life, or 200,000 times higher when stored at 15 degrees C, compared with when consuming it on the day of inoculation. This indicates that efforts should focus on preventing temperature abuse during storage to mitigate the risk of listeriosis. The storage conditions recommended for mixed-ingredient salads in Sweden (maximum 8 degrees C for 3 days) did not prevent growth of L. monocytogenes in baby spinach mixed with chicken meat. Manufacturers preparing these salads should be aware of this, and recommended storage temperature should be revised downwards to reduce the risk of foodborne disease.
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| 21. |
- Söderqvist, Karin, et al.
(författare)
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Season and Species: Two Possible Hurdles for Reducing the Food Safety Risk of Escherichia coli O157 Contamination of Leafy Vegetables
- 2019
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Ingår i: Journal of Food Protection. - 0362-028X. ; 82, s. 247-255
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Tidskriftsartikel (refereegranskat)abstract
- The food safety risk of Shiga toxin-producing Escherichia coli (STEC) infection per serving of leafy vegetables was investigated using a quantitative microbial risk assessment (QMRA) approach. The estimated level of E. coli O157 contamination was based on observed numbers of Enterobacteriaceae and E. coli on leafy vegetables grown and processed in southern Sweden from 2014 to 2016. Samples were collected before harvest, after washing, and at the end of shelf life. The observed counts were combined with data on the ratio of E. coli to E. coli O157 taken from earlier studies to estimate the probability of illness. The risks of STEC infection associated with species, either spinach (Spinacia oleracea) or rocket (Diplotaxis tenuifolia), growing season (spring or autumn), and washing (washed or not washed) were then evaluated. The results indicated that leafy vegetable species and growing season could be possible hurdles for reducing the food safety risk of STEC infection. At harvest, the probability of infection was 87% lower when consuming rocket compared with spinach and 90% lower when consuming leafy vegetables grown in spring compared with autumn. These relative risk reductions remained consistent even with other serving sizes and dose-response models. The lowest risk of STEC infection was associated with leafy vegetables early in the production chain, i.e., before harvest, while the risk increased during storage and processing. Consequently, the highest risk was observed when leafy vegetables were consumed at the end of shelf life. Washing had no effect on the food safety risk of STEC infection in this study. To improve the quality of QMRA, there is a need for additional data on the relationship between indicator organisms that can be easily enumerated (e.g., E. coli and Enterobacteriaceae) and E. coli strains that can cause STEC infection (e.g., E. coli O157) but are difficult to identify in food samples such as leafy vegetables.
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