Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

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    Explanatory Variables Associated with Campylobacter and Escherichia coli Concentrations on Broiler Chicken Carcasses during Processing in Two Slaughterhouses
    Pacholewicz, Ewa ; Swart, Arno ; Wagenaar, Jaap A. ; Lipman, Len J.A. ; Havelaar, Arie H. - \ 2016
    Journal of Food Protection 79 (2016)12. - ISSN 0362-028X - p. 2038 - 2047.
    This study aimed at identifying explanatory variables that were associated with Campylobacter and Escherichia coli concentrations throughout processing in two commercial broiler slaughterhouses. Quantative data on Campylobacter and E. coli along the processing line were collected. Moreover, information on batch characteristics, slaughterhouse practices, process performance, and environmental variables was collected through questionnaires, observations, and measurements, resulting in data on 19 potential explanatory variables. Analysis was conducted separately in each slaughterhouse to identify which variables were related to changes in concentrations of Campylobacter and E. coli during the processing steps: scalding, defeathering, evisceration, and chilling. Associations with explanatory variables were different in the slaughterhouses studied. In the first slaughterhouse, there was only one significant association: poorer uniformity of the weight of carcasses within a batch with less decrease in E. coli concentrations after defeathering. In the second slaughterhouse, significant statistical associations were found with variables, including age, uniformity, average weight of carcasses, Campylobacter concentrations in excreta and ceca, and E. coli concentrations in excreta. Bacterial concentrations in excreta and ceca were found to be the most prominent variables, because they were associated with concentration on carcasses at various processing points. Although the slaughterhouses produced specific products and had different batch characteristics and processing parameters, the effect of the significant variables was not always the same for each slaughterhouse. Therefore, each slaughterhouse needs to determine its particular relevant measures for hygiene control and process management. This identification could be supported by monitoring changes in bacterial concentrations during processing in individual slaughterhouses. In addition, the possibility that management and food handling practices in slaughterhouses contribute to the differences in bacterial contamination between slaughterhouses needs further investigation.
    Influence of food handlers' compliance with procedures of poultry carcasses contamination : A case study concerning evisceration in broiler slaughterhouses
    Pacholewicz, Ewa ; Sura Barus, Sri Aika ; Swart, Arno ; Havelaar, Arie H. ; Lipman, Len J.A. ; Luning, Pieternel A. - \ 2016
    Food Control 68 (2016). - ISSN 0956-7135 - p. 367 - 378.
    Campylobacter - Compliance with procedures - Food handler - Processing hygiene

    Campylobacter remains the most commonly reported zoonotic agent worldwide. Reducing the concentration of Campylobacter on chicken meat is seen as the most efficient strategy to diminish the number of human campylobacteriosis cases. Analysis of risk factors related to characteristics of broiler batches and processing conditions could, however, not fully explain differences in impact of processing on contamination levels between slaughterhouses. Our study aimed at investigating whether compliance of food handlers with procedures on setting and controlling evisceration process parameters could explain differences in microbial concentrations on carcasses between slaughterhouses. The study was conducted in two commercial broiler chicken slaughterhouses. Analysis of documentation provided insight in the adequacy of procedures, and observational studies revealed insight in compliance with procedures by using a set of criteria for evisceration control. The frequency of carcasses with visible faecal contamination was counted and Escherichia coli concentrations on carcasses classified based on visible contamination was analysed. E. coli was found to be a valid indicator for Campylobacter during evisceration. Food handlers' knowledge, attitude and practices related to evisceration control tasks were analysed based on a validated questionnaire. Documentation analysis revealed obvious differences in the procedures between slaughterhouses. The observation study revealed that in the slaughterhouse with advanced procedures, the food handlers more often complied with these procedures and a lower frequency of carcasses with visible faecal contamination was observed. Carcasses contaminated with visible faecal spots, even at a low level, carried significantly higher concentrations of E. coli than visibly clean carcasses. Food handlers in both slaughterhouses revealed a good knowledge level. The attitude of food handlers differed between slaughterhouses. In one slaughterhouse, where food handlers complied more frequently with procedures their attitude was at a good level, and practices at good and moderate levels. In the other slaughterhouse the attitude of food handlers was at moderate level and practices at moderate and poor levels. In conclusion, the results from our case study suggest that management factors like availability of adequate monitoring procedures and food handlers' compliance with these procedures may influence the bacterial concentrations on carcasses. Our study demonstrated that compliance with procedures differed between slaughterhouses, and might be associated with faecal contamination of carcasses and thus with higher bacterial concentrations. These results suggest that managerial improvements, supervising and motivating food handlers could be an important control point. To validate the observed relation between compliance with procedures and contamination of carcasses, an intervention study is needed.

    A comparison of fluctuations of Campylobacter and Escherichia coli concentrations on broiler chicken carcasses during processing in two slaughterhouses
    Pacholewicz, Ewa ; Swart, Arno ; Schipper, Maarten ; Gortemaker, B.G.M. ; Wagenaar, J.A. ; Havelaar, A.H. ; Lipman, L.J.A. - \ 2015
    International Journal of Food Microbiology 205 (2015). - ISSN 0168-1605 - p. 119 - 127.
    Poultry - Process Hygiene Criteria - Slaughter hygiene

    The causes of differences in Campylobacter and Escherichia coli concentrations on broiler chicken carcasses after chilling between slaughterhouses are not fully identified. Therefore, it is a challenge for slaughterhouses to comply with Process Hygiene Criteria for broiler meat.The aim of the study was to identify which processing steps contribute to increases or decreases in Campylobacter and E. coli concentrations within and between two slaughterhouses. Identifying the processing steps with variable performance could explain the differences in bacterial concentrations after chilling between slaughterhouses.Thermotolerant Campylobacter and E. coli concentrations on carcasses during broiler processing were measured during the summer period in 21 trials after bleeding, scalding, defeathering, evisceration and chilling.In two slaughterhouses with comparable Campylobacter and E. coli concentrations in the incoming batches (after bleeding), the mean log10 concentrations are found to be significantly different after chilling. Campylobacter concentrations decreased by 1.40 log10 in Slaughterhouse 1 and by 1.86 log10 in Slaughterhouse 2, whereas E. coli decreased by 2.19 log10 in Slaughterhouse 1 and by 2.84 log10 in Slaughterhouse 2. Higher concentrations of Campylobacter and E. coli on carcasses after chilling were observed in Slaughterhouse 1 in which an increase in concentrations was observed after evisceration. The effect of processing on Campylobacter and E. coli concentrations in Slaughterhouse 1 did not differ between batches. In Slaughterhouse 2, the effect of processing on the concentrations of both bacteria varied over batches. Changes in E. coli concentration levels during processing were similar to Campylobacter except for defeathering. E. coli concentration significantly decreased after defeathering in both slaughterhouses, whereas Campylobacter increased in Slaughterhouse 2 and in Slaughterhouse 1 no significant changes were observed.The patterns of increases and decreases in bacterial concentrations during processing are specific for each slaughterhouse. Inhomogeneous patterns potentially explain the differences in concentrations after chilling between slaughterhouses. Critical processing steps should be validated in each slaughterhouse by longitudinal studies and potentially based on E. coli. E. coli has a potential to be used as an indicator of processing hygiene, because the impact of most of the studied processing steps was similar as for Campylobacter.

    Availability of wild Brassica sect. Brassica accessions in genebanks
    Maggioni, L. ; Bas, N. ; Poulsen, G. ; Branca, F. ; Ralli, P. ; Bothmer, R. von; Lipman, E. - \ 2013
    Report of a Working Group on Solanaceae : first meeting of the Working group and ad hoc meeting of the database managers, 14-17 Februari 2012, Menemen, Turkey
    Dooijeweert, W. van; Maggioni, L. ; Daunay, M.C. ; Lipman, E. - \ 2012
    Menemen, Turkey : Biodiversity International - 38
    solanaceae - genenbanken - genetische bronnen van plantensoorten - gewassen - databanken - genetische diversiteit - plantenverzamelingen - solanaceae - gene banks - plant genetic resources - crops - databases - genetic diversity - plant collections
    The Solanaceae Working Group (WG) of the European Cooperative Programme for Plant Genetic Resources (ECPGR) has established six databases for the crops that form its mandate. These include three major crops (Eggplant, Pepper and Tomato) and three minor crops (Cyphomandra, Pepino and Physalis). The ad hoc meeting of the Solanaceae Database (DB) Managers took place on 14 February 2012, prior to the meeting of the whole Solanaceae WG from 15 to 17 February. Willem van Dooijeweert, Chair of the WG, welcomed the DB Managers and explained the objectives of the meeting. The idea of the ad hoc meeting of DB Managers was brought up at an ad hoc meeting of the Vegetables Network Coordinating Group (18 April 2008, Wageningen, The Netherlands), as a response to the requirement of the initiative for “A European Genebank Integrated System” (AEGIS) that each WG submit lists of accessions for inclusion in the European Collection. The meeting was seen as an opportunity for the five attending DB Managers to exchange knowledge and discuss problems related to the management of the databases and, in particular, to prepare for AEGIS. After the one-day meeting, the DB Managers would propose a common vision of the selection process of European Accessions at the WG meeting that was to follow. Ahead of their meeting, the DB Managers had compiled Excel working files containing all data of each crop, which were extracted from the European Plant Genetic Resources Catalogue (or European Internet Search Catalogue, EURISCO) and the Central Crop Databases (CCDBs).
    Clostridium difficile infections in the community: a zoonotic disease?
    Hensgens, M.P.M. ; Keessen, A.M. ; Squire, M.M. ; Riley, T.V. ; Koene, M.G.J. ; Boer, E. de; Lipman, L.J. ; Kuijper, E.J. - \ 2012
    Clinical Microbiology and Infection 18 (2012)7. - ISSN 1198-743X - p. 635 - 645.
    retail ground meat - general-practice - food animals - antimicrobial susceptibility - fatal enterocolitis - neonatal diarrhea - intestinal flora - north-america - pcr ribotypes - prevalence
    Clostridium difficile infections (CDIs) are traditionally seen in elderly and hospitalized patients who have used antibiotic therapy. In the community, CDIs requiring a visit to a general practitioner are increasingly occurring among young and relatively healthy individuals without known predisposing factors. C. difficile is also found as a commensal or pathogen in the intestinal tracts of most mammals, and various birds and reptiles. In the environment, including soil and water, C. difficile may be ubiquitous; however, this is based on limited evidence. Food products such as (processed) meat, fish and vegetables can also contain C. difficile, but studies conducted in Europe report lower prevalence rates than in North America. Absolute counts of toxigenic C. difficile in the environment and food are low, however the exact infectious dose is unknown. To date, direct transmission of C. difficile from animals, food or the environment to humans has not been proven, although similar PCR ribotypes are found. We therefore believe that the overall epidemiology of human CDI is not driven by amplification in animals or other sources. As no outbreaks of CDI have been reported among humans in the community, host factors that increase vulnerability to CDI might be of more importance than increased exposure to C. difficile. Conversely, emerging C. difficile ribotype 078 is found in high numbers in piglets, calves, and their immediate environment. Although there is no direct evidence proving transmission to humans, circumstantial evidence points towards a zoonotic potential of this type. In future emerging PCR ribotypes, zoonotic potential needs to be considered
    Gefermenteerde producten
    Ruiter, A. ; Nout, M.J.R. - \ 2011
    In: Inleiding tot de levensmiddelenhygiëne - Achtergronden en feiten, 2e druk / Lipman, L.J.A., Ruiter, A., Amsterdam : Reed Business Information - ISBN 9789035233423 - p. 129 - 141.
    Report of a Vegetables Network : Second Meeting, 26–28 June 2007, Olomouc, Czech Republic
    Astley, D. ; Bas, N. ; Branca, F. ; Daunay, M.C. ; Keller, J. ; Dooijeweert, W. van; Treuren, R. van; Maggioni, L. ; Lipman, E. - \ 2009
    Olomouc, Czech Republic : Bioversity International
    genetische bronnen van plantensoorten - groenten - genenbanken - europa - databanken - conservering - plant genetic resources - vegetables - gene banks - europe - databases - conservation
    The Second Meeting of the Vegetables Network (VEGNET) of the European Cooperative Programme for Plant Genetic Resources (ECPGR) was held on 26-28 June 2007 in Olomouc, Czech Republic. The meeting was organized jointly with the Third Meeting of the ECPGR Working Group on Medicinal and Aromatic Plants (MAP WG), which had been formally included in the VEGNET from January 2004 to September 2006. The local organization of the meetings was arranged by the Crop Research Institute, Prague-Ruzyne, Division of Plant Genetics, Breeding and Product Quality, and its local Department of Vegetables and Special Crops in Olomouc. The first introductory session was attended jointly by the VEGNET and MAP Working Groups.
    Overview of studies on wild crop relatives of lettuce carried out within the framework of the EU project GENE-MINE
    Treuren, R. van; Lebeda, A. ; Krístková, E. ; Dehmer, K.J. ; Pink, D.A. ; Wiel, C.C.M. van de; Doležalová, I. ; Sretenovic-Rajicic, T. ; Astley, D. ; Spence, N. ; Hintum, T.J.L. van - \ 2008
    In: Report of a Working Group on Leafy Vegetables, First Meeting, Olomouc, Czech Republic, 13 - 14 October, 2005. - Rome, Italy : Bioversity International - ISBN 9789290437819 - p. 41 - 44.
    Report of a Working Group on Fibre Crops (Flax and Hemp)
    Bas, N. ; Pavelek, M. ; Maggioni, L. ; Lipman, E. - \ 2007
    Rome, Italy : Bioversity International - 28
    genenbanken - vezelgewassen - vlas - hennep - databanken - plantenverzamelingen - gene banks - fibre plants - flax - hemp - databases - plant collections
    Members of the newly established ECPGR Working Group on Fibre Crops (Flax and Hemp), in the framework of Sugar, Starch and Fibre Crops Network, met for the first time at Wageningen, the Netherlands on 14–16 June 2006. Fifteen participants from the Czech Republic, Germany, Hungary, Italy, Latvia, Lithuania, the Netherlands, Poland, Portugal and Romania took part in the meeting to discuss flax and hemp national collection status reports as well as flax and hemp international databases development.
    Gefermenteerde producten
    Ruiter, A. ; Nout, M.J.R. - \ 2007
    In: Inleiding tot de Levensmiddelenhygiëne - Achtergronden en feiten / Lipman, L.J.A., Ruiter, A., Maarssen, NL : Reed Business Information bv, Elsevier gezondheidszorg - ISBN 9789035228863 - p. 123 - 136.
    Proef in de praktijk met decontamineren van vleeskuikens: Het mag wel, maar het werkt niet
    Bolder, N.M. ; Lipman, L.J. - \ 2006
    De Pluimveehouderij 36 (2006)29. - ISSN 0166-8250 - p. 14 - 15.
    decontaminatie - pluimveevlees - pluimveeproducten - vleeskuikens - voedselbesmetting - voedselveiligheid - salmonella - campylobacter - decontamination - poultry meat - poultry products - broilers - food contamination - food safety - salmonella - campylobacter
    Decontamineren van pluimvee is toegestaan, maar het wachten is op de lijst met middelen die daarvoor kunnen worden gebruikt. ASG-Lelystad en IRAS/V&V Utrecht voerden proeven uit onder praktijkomstandigheden in een slachterij en testten enkele middelen op hun effectiviteit tegen Salmonella en Campylobacter
    Potential routes of acquisition of Acrobacter species by piglets
    Ho, T.K. ; Lipman, L.J.A. ; Graaf, L. van der; Bergen, M.A.P. van; Gaastra, W. - \ 2006
    Veterinary Microbiology 114 (2006)1-2. - ISSN 0378-1135 - p. 123 - 133.
    retail meats - pig fetuses - sp-nov. - spp. - prevalence - campylobacter - butzleri - diversity - cryaerophilus - skirrowii
    The aim of this study was to determine the prevalence and the transmission routes of Arcobacter spp. in sows and their offspring on a breeding farm. Twelve Arcobacter-positive sows and their litters were studied for this purpose. Analysis of rectal samples showed a high prevalence of Arcobacter spp. among the sows (approximately 42% of the sows carried one or more Arcobacter species). Intermittent excretion of one particular species and shifts in excretion from one species to another were observed in individual animals over time. The detection of Arcobacter spp. in amniotic fluid of the sows and in rectal samples from newborn piglets (ranging from 38.5-83.3% per litter), as well as the high similarity between PFGE profiles of Arcobacter isolates from sows and their respective newborns indicated the existence of an intra-uterine transmission route for Arcobacter spp. Specific antibodies against Arcobacter spp. were detected in colostrum by Western blot. At 2 weeks of age, only a few piglets were positive for Arcobacter. The reappearance of Arcobacter in these piglets at Week 3 and the shift in the Arcobacter species detected (from a prominent presence of A. cryaerophilus at birth to the presence of A. skirrowii and A. butzleri at 3 weeks after birth) showed that a post-natal infection route from their mothers, newcomers or the environment to the piglets existed. Thus, in this manuscript the transmission of Arcobacter spp. (both vertical and horizontal) from carrying sows to their offspring is demonstrated.
    Genetic resources activities on forages in the Netherlands
    Soest, L.J.M. van; Bas, N. ; Treuren, R. van - \ 2005
    In: Proceedings of the 8th meeting, 10-12 April 2003, Linz, Austria. - Rome, Italy : International Plant Genetic Resources Institute - p. 70 - 74.
    Survival and resuscitation of ten strains of Campylobacter jejuni and Campylobacter coli under acid conditions
    Chaveerach, P. ; Huurne, A.A.H.M. ter; Lipman, L.J.A. ; Knapen, F. van - \ 2003
    Applied and Environmental Microbiology 69 (2003)1. - ISSN 0099-2240 - p. 711 - 714.
    non-culturable campylobacter - broiler-chickens - drinking-water - cells - recovery - colonization - salmonella - forms - contamination - maintenance
    The culturability of 10 strains of Campylobacter jejuni and Campylobacter coli was studied after the bacteria were exposed to acid conditions for various periods of time. Campylobacter cells could not survive 2 h under acid conditions (formic acid at pH 4). The 10 Campylobacter strains could not be recovered, even when enrichment media were used. Viable cells, however, could be detected by a double-staining (5-cyano-2,3-ditolyl tetrazolium chloride [CTC]-4',6'-diamidino-2-phenylindole [DAPI]) technique, demonstrating that the treated bacteria changed into a viable but nonculturable (VBNC) form; the number of VBNC forms decreased over time. Moreover, some VBNC forms of Campylobacter could be successfully resuscitated in specific-free-pathogen fertilized eggs via two routes, amniotic and yolk sac injecting.
    Current status of the CGN Linum collection
    Soest, L.J.M. van; Bas, N. - \ 2002
    In: Flax Genetic Resources in Europe Ad hoc meeting, 7-8 December 2001, Prague, Czech Republic / Maggioni, L., Pavelek, M., Soest, L.J.M, Lipman, E., Rome : IPGRI - ISBN 9789290435358 - p. 44 - 48.
    Flax Genetic Resources in Europe. Ad Hoc meeting, 7-8 December 2001, Prague, Czech Republic
    Maggioni, L. ; Pavelek, M. ; Soest, L.J.M. van; Lipman, E. - \ 2002
    Rome : IPGRI - ISBN 9789290435358 - 79
    linum usitatissimum - vlas - vezelgewassen - genetische bronnen van plantensoorten - genenbanken - germplasm - plantenverzamelingen - europa - linum usitatissimum - flax - fibre plants - plant genetic resources - gene banks - germplasm - plant collections - europe
    Effect of fermented feed on shedding of Enterobacteriaceae by fattening pigs
    Winsen, R.L. van; Keuzenkamp, D. ; Urlings, B.A.P. ; Lipman, L.J.A. ; Snijders, J.A.M. ; Verheijden, J.H.M. ; Knapen, F. van - \ 2002
    Veterinary Microbiology 87 (2002). - ISSN 0378-1135 - p. 267 - 276.
    In vitro study on the effect of organic acids on Campylobacter jejuni/coli populations in mixtures of water and feed
    Chaveerach, P. ; Keuzenkamp, D.A. ; Urlings, H.A.P. ; Lipman, L.J.A. ; Knapen, F. van - \ 2002
    Poultry Science 81 (2002)5. - ISSN 0032-5791 - p. 621 - 628.
    Gastroenteritis caused by Campylobacter spp. infection has been recognized as one of the important public health problems in the developed countries. Outbreaks mostly originate from the consumption of contaminated poultry or infected water. The aim of this study was to determine the bactericidal activity on Campylobacter spp. of organic acids individually and in combinations at different pH levels and times and to compare bactericidal activities with activities of commercially available products. Ten strains of Campylobacter spp. were added in a mixture of water with commercial broiler feed, separately adjusted by four acids: formic, acetic, propionic, and hydrochloric acids, into pH 4.0, 4.5, 5.0, and 5.5. A combination of three organic acids was used in two different formulation ratios: formic:acetic:propionic at 1:2:3 and 1:2:5, at pH 4.0, 4.5, 5.0, and 5.5. All organic acids showed the strongest bactericidal effect on Campylobacter at pH 4.0. In contrast, at pH 5.0 and 5.5, the bactericidal activity of the four acids was low. The combination of organic acids showed a synergistic bactericidal activity at pH 4.5. Interestingly, the effect of the combined organic acids was stronger than the commercial products. Morphological cell changes were studied by transmission electron microscopy to determine the effect of the organic acids on the cell structure of Campylobacter. Some loss of outer membranes of the bacteria could be found in treated groups. Therefore, it can be concluded that organic acids, individually or in combination, have a strong bactericidal effect on Campylobacter spp. Routine application of organic acids to the water supply on poultry farms could prevent or diminish Campylobacter transmission.
    Effect of fermented feed on the microbial population of the gastrointestinal tracts of pigs
    Winsen, R.L. van; Urlings, B.A.P. ; Lipman, L.J.A. ; Snijders, J.M.A. ; Keuzenkamp, D. ; Verheijden, J.H.M. ; Knapen, F. van - \ 2001
    Applied and Environmental Microbiology 67 (2001). - ISSN 0099-2240 - p. 3071 - 3076.
    An in vivo experiment was performed with pigs to study the inhibitory effect of fermented feed on the bacterial population of the gastrointestinal tract. Results demonstrated a significant positive correlation between pH and lactobacilli in the stomach contents of pigs in dry feed as well as in the stomach contents of pigs fed fermented feed. Furthermore, a significant positive correlation between the pH and the numbers of bacteria in the family Enterobacteriaceae in the contents of the stomach of pigs fed dry feed was found. In the stomach contents of pigs fed fermented feed, a significant negative correlation was found between the concentration of the undissociated form of lactic acid and the numbers of Enterobacteriaceae. The numbers of Enterobacteriaceae in the contents of the stomach, ileum, cecum, colon, and rectum of pigs fed fermented feed were significantly lower compared with the contents of the stomach, ileum, caecum, colon, and rectum of pigs fed dry feed. The numbers of total lactobacilli were significantly higher in the stomach contents of pigs fed fermented feed and in the ileum contents of one pig group fed fermented feed compared with the contents of pigs fed dry feed. However, the influence of lactobacilli on numbers of Enterobacteriaceae could not be demonstrated. It was concluded that fermented feed influences the bacterial ecology of the gastrointestinal tract and reduces the levels of Enterobacteriaceae in the different parts of the gastrointestinal tract.
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