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.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    Description and determinants of the faecal resistome and microbiome of farmers and slaughterhouse workers : A metagenome-wide cross-sectional study
    Gompel, Liese Van; Luiken, Roosmarijn E.C. ; Hansen, Rasmus B. ; Munk, Patrick ; Bouwknegt, Martijn ; Heres, Lourens ; Greve, Gerdit D. ; Scherpenisse, Peter ; Jongerius-Gortemaker, Betty G.M. ; Tersteeg-Zijderveld, Monique H.G. ; García-Cobos, Silvia ; Dohmen, Wietske ; Dorado-García, Alejandro ; Wagenaar, Jaap A. ; Urlings, Bert A.P. ; Aarestrup, Frank M. ; Mevius, Dik J. ; Heederik, Dick J.J. ; Schmitt, Heike ; Bossers, Alex ; Smit, Lidwien A.M. - \ 2020
    Environment International 143 (2020). - ISSN 0160-4120
    Antimicrobial resistance - Farmers - Microbiome - Occupational exposure - Resistome - Slaughterhouse workers

    Background: By studying the entire human faecal resistome and associated microbiome, the diversity and abundance of faecal antimicrobial resistance genes (ARGs) can be comprehensively characterized. Prior culture-based studies have shown associations between occupational exposure to livestock and carriage of specific antimicrobial resistant bacteria. Using shotgun metagenomics, the present study investigated 194 faecal resistomes and bacteriomes from humans occupationally exposed to ARGs in livestock (i.e. pig and poultry farmers, employees and family members and pig slaughterhouse workers) and a control population (Lifelines cohort) in the Netherlands. In addition, we sought to identify determinants for the human resistome and bacteriome composition by applying a combination of multivariate (NMDS, PERMANOVA, SIMPER and DESeq2 analysis) and multivariable regression analysis techniques. Results: Pig slaughterhouse workers and pig farmers carried higher total ARG abundances in their stools compared to broiler farmers and control subjects. Tetracycline, β-lactam and macrolide resistance gene clusters dominated the resistome of all studied groups. No significant resistome alpha diversity differences were found among the four populations. However, the resistome beta diversity showed a separation of the mean resistome composition of pig and pork exposed workers from broiler farmers and controls, independent of their antimicrobial use. We demonstrated differences in resistome composition between slaughter line positions, pig versus poultry exposed workers, as well as differences between farmers and employees versus family members. In addition, we found a significant correlation between the bacteriome and resistome, and significant differences in the bacteriome composition between and within the studied subpopulations. Finally, an in-depth analysis of pig and poultry farms – of which also farm livestock resistomes were analysed – showed positive associations between the number of on-farm working hours and human faecal AMR loads. Conclusion: We found that the total normalized faecal ARG carriage was larger in persons working in the Dutch pork production chain compared to poultry farmers and controls. Additionally, we showed significant differences in resistome and bacteriome composition of pig and pork exposed workers compared to a control group, as well as within-population (farms, slaughterhouse) compositional differences. The number of on-farm working hours and the farm type (pig or broiler) that persons live or work on are determinants for the human faecal resistome. Overall, our results may suggest direct or indirect livestock contact as a determinant for human ARG carriage. Future studies should further focus on the connection between the human and livestock resistome (i.e. transmission routes) to substantiate the evidence for livestock-associated resistome acquisition.

    Identification of potential risk factors for Toxoplasma gondii in fattening pigs in the Netherlands using a Bayesian approach
    Eppink, D.M. ; Bouwknegt, M. ; Oorburg, D. ; Urlings, H.A.P. ; Asseldonk, Marcel van; Wagenberg, Coen van; Krijger, Inge ; Giessen, J.W.P. van der; Swanenburg, M. ; Wisselink, H.J. - \ 2019
    Introduction
    Toxoplasma gondii is a relevant foodborne pathogen,it is estimated that up to one third of the worldpopulation has been exposed to the parasite (Tenteret al. 2000). In the Netherlands toxoplasmosis rankssecond on a list of prioritized emerging zoonosis(Havelaar et al. 2010) and also second in disease burden among 14 foodborne diseases (Mangen et al.2017). Data suggest that ingesting improperly cooked meat containing T. gondii is one of the major sources of infection in Europe and North America (Crotta et al. 2017; Guo et al. 2015). The contribution of pork to meatborne T. gondii infections is estimated to be11 % in the Netherlands (Opsteegh 2011) and is seen as an important possible source of human T. gondii infections (Foroutan et al. 2019). The European Food Safety Authority (EFSA) advised to perform serological testing of pigs and on farm audits on risk factors (EFSA 2011). To that end, a serological monitoring program was developed in a slaughterhouse in the Netherlands. In this study, the objective is to determine the association between within herd seroprevalence, corrected for misclassification of samples through Bayesian analyses, and risk factors for T. gondii on fattening pig farms in TheNetherlands.
    Materials and MethodsFrom 2015 to 2018, HACCP based audits were performedon 75 fattening pig farms in The Netherlands to identify the presence of potential T. gondii risk factors. All farms were conventional pig farms, with 15 farms being farrow to finish. As overall seroprevalence of T. gondii in pigs in the Netherlands is low, estimated at 5 % (1-12 % 95 % CI) by Foroutanet al. 2019, approached farms were chosen with the knowledge of previous serology data. In this way there would be farms with positive serum samples and farms without them included in the study. The audits were based on an updated version of the questionnaire from Mul et al. (2015) and covered the following topics: outdoor access, farm biosecurity, rodent control, presence of cats, feed and watersupply. In addition, serum samples (n=6272) from fattening pigs were obtained at slaughter throughout the year before the audit on the farm was performed. These samples were used for antibody testing bya PrioCHECK™ Toxoplasma Antibody ELISA. Data were analysed using Bayesian statistics, with the within farm T. gondii prevalence as dependent variable and potential risk factors as independent variables. As always with serology, misclassification due to false-positive or false-negative results can occur. Statistical methods have been developed to account for such misclassification, based on frequentistic as well as Bayesian approaches (Hui & Walter 1980; Josephet al. 1995). First, all independent variables wereanalysed in a univariate logistic model, and variables with a probability ≤0.25 that zero is included in the 95 % interval were analysed in a multivariable model. The multivariate logistic model was fitted using backward elimination until all remaining variables showed a probability ≤0.05 that zero is included in the 95 % interval. Two-way interaction terms were evaluated similarly to the main variables regarding statistical significance.
    ResultsDescriptive results showed that 50 out of the 75 farms had 1 or more positive serum samplein the year before the audit was performed. In total 438 samples were positive out of the 6272 samples. Final Bayesian analyses are currently being conducted. However, preliminary results from data analysis using frequentistic logistic multivariate regression identified two significant risk factors: the accessibility of pig feed for cats and theprovision of well water as drinking water for the pigs (Table 1).
    Discussion and ConclusionsThe use of serological testing seems to be a valuable guide and monitoring tool for the control of T.gondii in pork production. In a preliminary analysis, a higher within-herd T. gondii seroprevalence on fattening pig farms in the Netherlands was associated with the accessibility of pig feed for cats and the provision of well water as drinking water for the pigs. Improvements in farm management on fattening pig farms will likely contribute to reduction of the human disease burden and is presently studied.
    Association between within-herd seroprevalence and risk factors for Toxoplasma gondii in fattening pigs in the Netherlands
    Eppink, D.M. ; Bouwknegt, M. ; Oorburg, D. ; Urlings, H.A.P. ; Asseldonk, Marcel van; Wagenberg, Coen van; Krijger, I.M. ; Giessen, J.W.P. Van der; Swanenburg, M. ; Wisselink, H.J. - \ 2018
    In: Annual General Meeting of the European College of Veterinary Public Health, "Fading of the HACCP after four decades: new trends in VPH for food safety ", Perugia, 17th-19th October 2018. - European College of Veterinary Public Health (ECVPH) - p. 40 - 40.
    Samenvatting ESBL-Attributieanalyse (ESBLAT) : Op zoek naar de bronnen van antibioticaresistentie bij de mens
    Mevius, Dik ; Heederik, Dick ; Duijkeren, Engeline ; Veldman, Kees ; Essen, Alieda van; Kant, Arie ; Liakopoulos, Apostolos ; Geurts, Yvon ; Pelt, Wilfrid van; Mughini Gras, Lapo ; Schmitt, Heike ; Dierikx, Cindy ; Hoek, Angela van; Evers, Eric ; Roda Husman, Annemaria de; Blaak, Hetty ; Dissel, Jaap van; Smid, Joost ; Dohmen, Wietske ; Dorado-Garcia, Alejandro ; Havelaar, Arie ; Hordijk, Joost ; Wagenaar, Jaap ; Fluit, Ad ; Bunt, Gerrita van den; Bonten, Marc ; Velthuis, Annet ; Heuvelink, Annet ; Buter, Rianne ; Gonggrijp, Maaike ; Santman-Berends, Inge ; Lam, Theo ; Urlings, Bert ; Heres, Lourens ; Bouwknecht, Martijn ; Groot, Jacques de - \ 2018
    Netherlands : De Stichting TKI Agri&Food (TKI) - 11 p.
    Rapport ESBL-Attributieanalyse (ESBLAT) : Op zoek naar de bronnen van antibioticaresistentie bij de mens
    Mevius, Dik ; Heederik, Dick ; Duijkeren, Engeline ; Veldman, Kees ; Essen, Alieda van; Kant, Arie ; Liakopoulos, Apostolos ; Geurts, Yvon ; Pelt, Wilfrid van; Mughini Gras, Lapo ; Schmitt, Heike ; Dierikx, Cindy ; Hoek, Angela van; Evers, Eric ; Roda Husman, Annemaria de; Blaak, Hetty ; Dissel, Jaap van; Smid, Joost ; Dohmen, Wietske ; Dorado-Garcia, Alejandro ; Havelaar, Arie ; Hordijk, Joost ; Wagenaar, Jaap ; Fluit, Ad ; Bunt, Gerrita van den; Bonten, Marc ; Velthuis, Annet ; Heuvelink, Annet ; Buter, Rianne ; Gonggrijp, Maaike ; Santman-Berends, Inge ; Lam, Theo ; Urlings, Bert ; Heres, Lourens ; Bouwknecht, Martijn ; Groot, Jacques de - \ 2018
    Netherlands : De Stichting TKI Agri&Food (TKI) - 73
    Using serological monitoring, internet-based feedback and on-farm auditing to improve Toxoplasma gondii control at Dutch pig farms
    Oorburg, D. ; Eppink, Dorien ; Heijltjes, Janneke ; Bouwknegt, Martijn ; Urlings, Bert ; Giessen, Joke van der; Krijger, Inge ; Mul, Monique ; Swanenburg, M. ; Wisselink, H.J. - \ 2017
    In: 12th International Symposium on the Epidemiology and Control of Biological,Chemical and Physical Hazards in Pigs and Pork - Proceedings Book, Foz doIguaçu, august 21-24, 2017. - Embrapa - p. 201 - 201.
    Toxoplasma gondii is a relevant foodborne pathogen due to its human disease burden. In the Netherlands, pork is estimated to contribute to 11% of the meatborne T. gondii infections. The European Food Safety Authority advised to perform serological testing of pigs and on farm audits on risk factors for T. gondii infection.
    ESBL carriage in pig slaughterhouse workers is associated with occupational exposure
    Dohmen, W. ; Gompel, L. Van; Schmitt, H. ; Liakopoulos, A. ; Heres, L. ; Urlings, B.A. ; Mevius, D. ; Bonten, M.J.M. ; Heederik, D.J.J. - \ 2017
    Epidemiology and Infection 145 (2017)10. - ISSN 0950-2688 - p. 2003 - 2010.
    Antimicrobial resistance - bla - occupational epidemiology - pig abattoir workers - zoonosis
    We investigated the prevalence of extended-spectrum β-lactamase (ESBL) carriage in slaughterhouse workers and the association with occupational exposure to slaughter animals and products. Stool samples from 334 employees in a Dutch pig slaughterhouse were obtained. Presence of ESBL was determined by selective plating, microarray analysis, and gene sequencing. Questionnaires were used to collect personal and occupational information. The overall prevalence of ESBL carriage was 4·8% (16/334). All ESBL-producing isolates were Escherichia coli. The ESBL genes detected were bla CTX-M-1 (n = 8), bla CTX-M-15 (n = 3), bla CTX-M-27 (n = 2), bla CTX-M-24 (n = 1), bla CTX-M-55 (n = 1), and bla SHV-12 (n = 1). A higher prevalence of ESBL was seen in workers in jobs with as tasks ‘removal of lungs, heart, liver, tongue’ (33%), and ‘removal of head and spinal cord’ (25%). For further analysis, participants were divided in two groups based on potential exposure to ESBL as related to their job title. One group with an assumed higher exposure to ESBL (e.g. stable work, stabbing, dehairing, removal of organs) and another group with an assumed lower exposure to ESBL (e.g. refrigeration, packaging and expedition). In the ‘higher exposure’ group, ten out of 95 (10·5%) were carrying ESBL vs. six out of 233 (2·6%) in the ‘lower exposure’ group. Human ESBL carriage was significantly associated with job exposure in the slaughterhouse (OR 4·5, CI 1·6–12·6). Results suggest that ESBL carriage in slaughterhouse workers overall is comparable with the Dutch population. Within the slaughterhouse population a difference in carriage exists depending on their position along the slaughter line and tasks involved.
    Design of a Risk based Control System for Toxoplasma gondii in a pork supply chain
    Heres, L. ; Swanenburg, M. ; Koeijer, A.A. de; Boender, G.J. ; Oorburg, D. ; Urlings, B. ; Wisselink, H.J. - \ 2015
    In: Safepork 2015 Proceedings Book: Epidemiology and control of hazards in pork production chain. - - p. 81 - 84.
    Toxoplasma gondii is recognized as one of the major foodborne pathogens. The European Food Safety Authority (EFSA) concluded that T. gondii is one of the public health hazards in pigs to be covered within a modern meat inspection and advised to include serological testing of pigs and audits of pig farms to control T. gondii. A project is presented that develops a framework where this idea is practically implemented in a pork supply chain. The aim of the program is to reduce the contribution from the pork chain to the human toxoplasmosis disease burden. In the pilot at least one blood sample per batch at delivery at the slaughterhouse is tested with a Toxoplasma Elisa. With this screening 20 (1%) high risk herds were identified. These high risk farms and their controls, 2 per high risk farm, were followed up. More samples of risk farms and their controls were collected to get a better estimate of the within herd prevalence and to follow the development of serology over time. Additional MC-PCR was performed on hearts of pigs from these herds to confirm presence of infection, tissue cysts. Also farm assessments were done to verify the presence of risk factors at the identified farms. In the first farm where hearts were tested by PCR the presence of toxoplasma tissue cysts was shown. The results give insight in how risk based approaches with food chain information (FCI) for animals sent to slaughter could work, by substantiating how risk herds can be practically identified and which interventions are feasible. The results are discussed in the perspective of human health risks.
    Risk-oriented animal health and food safety management : Risk-based innovations in food safety management
    Heres, L. ; Hiller, A. ; Schulze Althoff, G. ; Urlings, B. - \ 2014
    In: Quality and Risk Management in Agri-Food Chains / Petersen, B., Nüssel, M., Hamer, M., Wageningen Academic Publishers - ISBN 9789086862368 - p. 173 - 181.
    Farmer compliance - Health-status certification - Hygiene practices - Inspection strategies - Serological monitoring

    Secure animal health is of utmost importance for human health, animal welfare, resource efficiency and the effectiveness of livestock production. Food safety hazards, zoonotic diseases and the use of pharmaceuticals such as antibiotics have potential impacts on human health and wellbeing. Therefore, on-farm health and risk management is crucial to safeguard animal products as well as trade with livestock. Appropriate infrastructures for preventive health management to improve animal and human health and wellbeing are at the core of a 'one health' approach with provides a challenge at all levels of science and business. This chapter will inform you about: which structures have been established and which innovations have been made in riskoriented animal health and food safety management; how animal health management services and health status certification can be organised according to the AMOR principles; how and why on-farm biosecurity requirements have changed and how management support should be organised to foster a future one-health strategy.

    Nieuwsbrief voedselVeiligheid (Journal)
    Urlings, Bert - \ 2014
    Nieuwsbrief voedselVeiligheid (2014).
    Nieuwsbrief voedselVeiligheid (Journal)
    Urlings, Bert - \ 2013
    Nieuwsbrief voedselVeiligheid (2013).
    Prevalence of Mycobacterium avium in Slaughter Pigs Based on Serological Monitoring Results and Bacteriological Validation
    Hiller, A. ; Oorburg, D. ; Wisselink, H.J. ; Solt-Smits, C.B. van; Urlings, H.A.P. ; Klein, G. ; Schulze Althoff, G. ; Heres, L. - \ 2013
    International Journal of Environmental Research and Public Health 10 (2013)9. - ISSN 1660-4601 - p. 4027 - 4038.
    swine lymph-nodes - rhodococcus-equi - nontuberculous mycobacteria - granulomatous lesions - subsp avium - infection - cattle - risk - epidemiology - supplement
    Mycobacterium avium (MA) is a potential food safety hazard in pigs. Blood samples of slaughtered pigs in the Netherlands and Germany were tested for the presence of MA antibodies to estimate the serological prevalence in the tested population. In the Dutch and German population 1.0% and 1.7% samples were positive, and 0.5% and 17.4% of the herds were at risk for having a MA infection respectively. The validity of the applied MA-ELISA was evaluated under field conditions. The specificity of the MA-ELISA was high (>98.4%). The average herd sensitivity was 18%. In the affected herds on average 50% of the animals were tested bacteriological positive for MA. It can be concluded that serological screening for the presence of MA antibodies is capable of identifying pig populations that are at risk for a MA infection.
    Approaches to reduce antibiotic resistance in the pork supply chain
    Heres, L. ; Dusseldorf, S. ; Oorburg, D. ; Urlings, H.A.P. - \ 2013
    In: Book of Abstracts of the 64th Annual Meeting of the European Federation of Animal Science, 26-30 August 2013, Nantes, France. - Wageningen : Wageningen Academic Publishers - ISBN 9789086862283 - p. 218 - 218.
    Impact of test sensitivity and specificity on pig producer incentives to control Mycobacterium avium infections in finishing pigs
    Wagenberg, C.P.A. van; Backus, G.B.C. ; Wisselink, H.J. ; Vorst, J.G.A.J. van der; Urlings, H.A.P. - \ 2013
    Preventive Veterinary Medicine 111 (2013)3-4. - ISSN 0167-5877 - p. 286 - 296.
    lymph-nodes - tuberculous lesions - slaughter pigs - food safety - environment - supplement - disease - quality
    In this paper we analyze the impact of the sensitivity and specificity of a Mycobacterium avium (Ma) test on pig producer incentives to control Ma in finishing pigs. A possible Ma control system which includes a serodiagnostic test and a penalty on finishing pigs in herds detected with Ma infection was modelled. Using a dynamic optimization model and a grid search of deliveries of herds from pig producers to slaughterhouse, optimal control measures for pig producers and optimal penalty values for deliveries with increased Ma risk were identified for different sensitivity and specificity values. Results showed that higher sensitivity and lower specificity induced use of more intense control measures and resulted in higher pig producer costs and lower Ma seroprevalence. The minimal penalty value needed to comply with a threshold for Ma seroprevalence in finishing pigs at slaughter was lower at higher sensitivity and lower specificity. With imperfect specificity a larger sample size decreased pig producer incentives to control Ma seroprevalence, because the higher number of false positives resulted in an increased probability of rejecting a batch of finishing pigs irrespective of whether the pig producer applied control measures. We conclude that test sensitivity and specificity must be considered in incentive system design to induce pig producers to control Ma in finishing pigs with minimum negative effects
    Implementierung einer risikoorientierten Fleischuntersuchung ohne Anschnitte beim Mastschwein in einem nord-deutschen Schlachtunternehmen
    Hiller, A. ; Heres, L. ; Schulze Althoff, G. ; Urlings, H.A.P. ; Klein, G. - \ 2012
    Archiv für Lebensmittelhygiene 63 (2012)4. - ISSN 0003-925X - p. 107 - 114.
    pathogenic yersinia-enterocolitica - food-chain information - consequences - respect - safety - pork
    Regulation (EC) 854/2004 opens up the opportunity to implement risk based meat inspection of fattening pigs without incision. A concept for implementation of a food safety improving meat inspection without incision was approved in practice and evaluated. It includes a serological monitoring for categorising pig herds according to the risk related to food safety concerning Mycobacterium ovum, a specific test to detect residues of antimicrobial substances and to fulfill the criteria of Regulation (EC) 1244/2007. The concept is suitable for practical implementation. In comparison to the traditional meat inspection system the new system enables control of food safety hazards on farm level. Omitting of incision of the mandibular lymph nodes showed a significant reduction in the cross contamination of Salmonella.
    Prediction of pork quality with near infrared spectroscopy (NIRS): 1. Feasibility and robustness of NIRS measurements at laboratory scale
    Kapper, C. ; Klont, R.E. ; Verdonk, J.M.A.J. ; Urlings, H.A.P. - \ 2012
    Meat Science 91 (2012)3. - ISSN 0309-1740 - p. 294 - 299.
    water-holding capacity - early post-mortem - reflectance spectroscopy - intramuscular fat - drip loss - meat - spectra - beef - attributes - carcass
    The objective was to study prediction of pork quality by near infrared spectroscopy (NIRS) technology in the laboratory. A total of 131 commercial pork loin samples were measured with NIRS. Predictive equations were developed for drip loss %, colour L*, a*, b* and pH ultimate (pHu). Equations with R2 > 0.70 and residual prediction deviation (RPD) = 1.9 were considered as applicable to predict pork quality. For drip loss% the prediction equation was developed (R2 0.73, RPD 1.9) and 76% of those grouped superior and inferior samples were predicted within the groups. For colour L*, test-set samples were predicted with R2 0.75, RPD 2.0, colour a* R2 0.51, RPD 1.4, colour b* R2 0.55, RPD 1.5 and pHu R2 0.36, RPD 1.3. It is concluded that NIRS prediction equations could be developed to predict drip loss% and L*, of pork samples. NIRS equations for colour a*, b* and pHu were not applicable for the prediction of pork quality on commercially slaughtered pigs.
    Prediction of pork quality with near infrared spectroscopy (NIRS) 2. Feasibility and robustness of NIRS measurements under production plant conditions
    Kapper, C. ; Klont, R.E. ; Verdonk, J.M.A.J. ; Williams, P.C. ; Urlings, H.A.P. - \ 2012
    Meat Science 91 (2012)3. - ISSN 0309-1740 - p. 300 - 305.
    water-holding capacity - early post-mortem - reflectance spectroscopy - intramuscular fat - drip loss - meat - spectra - beef - attributes - carcass
    Longissimus dorsi samples (685) collected at four processing plants were used to develop prediction equations for meat quality with near infrared spectroscopy. Equations with R2 > 0.70 and residual prediction deviation (RPD) = 2.0 were considered as applicable for screening. One production plant showed R2 0.76 and RPD 2.05, other plants showed R2 <0.70 and RPD <2.0 for drip loss %. RPD values were = 2.05 for drip loss%, for colour L* = 1.82 and pH ultimate (pHu) = 1.57. Samples were grouped for drip loss%; superior (<2.0%), moderate (2–4%), inferior (> 4.0%). 64% from the superior group and 56% from the inferior group were predicted correctly. One equation could be used for screening drip loss %. Best prediction equation for L* did not meet the requirements (R2 0.70 and RPD 1.82). pHu equation could not be used. Results suggest that prediction equations can be used for screening drip loss %.
    Livestock-associated MRSA ST398 carriage in pig slaughterhouse workers related to quantitative environmental exposure
    Gilbert, M.J. ; Bos, M.E.H. ; Duim, B. ; Urlings, H.A.P. ; Heres, L. ; Wagenaar, J.A. ; Heederik, D.J.J. - \ 2012
    Occupational and Environmental Medicine 69 (2012)7. - ISSN 1351-0711 - p. 472 - 478.
    resistant staphylococcus-aureus - time pcr assay - methicillin-resistant - high prevalence - netherlands - endocarditis - infections - personnel - bacteria - contact
    Objectives To assess livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) carriage among workers in pig slaughterhouses and assess associated risk factors, including occupational exposure to LA-MRSA. Methods A cross-sectional study in three Dutch pig slaughterhouses was undertaken. Nasal swabs of participants were taken. Nasal swabs and surface wipes, air and glove samples were screened for presence of methicillin-resistant Staphylococcus aureus (MRSA). MRSA was quantitatively determined on gloves and in air samples by culturing and real-time PCR. Results 11 of 341 (3.2%) participants were identified as nasal MRSA carriers. MRSA-positive workers were predominantly found at the start of the slaughter process. Major risk factors for carriage were working in the lairage and working in the scalding and dehairing area. Most nasal isolates (73%) belonged to the LA-MRSA clone ST398. MRSA ST398-positive environmental samples were found throughout the slaughter process. A clear decrease was seen along the slaughterline in the number of MRSA-positive samples and in the MRSA amount per sample. Conclusions This study showed that working in the lairage area or scalding and dehairing area were the major risk factors for MRSA carriage in pig slaughterhouse workers, while the overall prevalence of MRSA carriage is low. Occupational exposure to MRSA decreased along the slaughterline, and the risk of carriage showed a parallel decrease.
    Rapid prediction of pork quality : correlation of fresh meat measurements to pork water holding capacity and its technological quality
    Kapper, C. - \ 2012
    Wageningen University. Promotor(en): Bert Urlings, co-promotor(en): R.E. Klont; J.M.A.J. Verdonk. - S.l. : s.n. - ISBN 9789461734280 - 135
    varkensvlees - vleeskwaliteit - waterbergend vermogen - voedselverwerking - kwaliteit voor voedselverwerking - pigmeat - meat quality - water holding capacity - food processing - food processing quality

    Water holding capacity (WHC) of pork defines the sensory appreciation and processing yields of meat. Pork varies in WHC and is mainly generated by differences in post mortem muscle metabolism of carcasses. Nowadays, the pork processing industry performs sorting of carcasses and primal cuts on the basis of weight and lean characteristics. Additional sorting by WHC can further optimize processing yields of pork products. The aim of this thesis was to validate rapid prediction of pork WHC. The first objective of this thesis was to investigate the possibilities of a rapid prediction of pork WHC by measuring parameters such as pH, colour L*, drip loss%, water absorption, and by NIRS at laboratory scale and at pig processing plant scale. Results revealed that NIRS prediction equations could be developed to predict drip loss% and colour L* of pork samples. Equations for colour a*, b*, and pHu were not applicable for prediction of WHC. The positive results of NIRS to predict WHC and colour L* at laboratory scale led to further research to study NIRS prediction of pork quality (pH, colour L*, and WHC) under pig processing plant conditions. It was concluded that NIRS prediction equations can be used for screening WHC at pig processing plants. Also, characterization of moisture loss from muscle early post mortem and whether these losses are useful in predicting WHC of fresh pork was investigated. Results revealed moisture losses from muscle tissue early post mortem which suggested that select time periods correspond to culmination of biochemical and physical events facilitating moisture release, which can be used for early drip prediction. Results suggested an approach for capturing moisture release early post mortem which may be used to predict WHC in pork. The second objective was to investigate if predictions of pork WHC could be used to optimize processing of pork. Technological yields could not be predicted (R2< 0.21 and RPD < 1.1) by NIRS. Pre-selection of back bacons by NIRS predicted WHC values, did result in significant different average pHu and colour L* between both groups. It was concluded that NIRS can be used to predict rapid fresh ham quality for sorting and optimization of the cooked ham process. The overall conclusion of this thesis is that NIRS prediction equations for WHC can be developed for pork loin samples measured at pig processing plants and that these prediction equations can be used to optimize processing of pork.

    Usefulness of food chain information provided by Dutch finishing pig producers to control antibiotic residues in pork
    Wagenberg, C.P.A. van; Backus, G.B.C. ; Vorst, J.G.A.J. van der; Urlings, H.A.P. - \ 2012
    Preventive Veterinary Medicine 107 (2012)1-2. - ISSN 0167-5877 - p. 142 - 145.
    milk
    The EU prescribes that food business operators must use food chain information to assist in food safety control. This study analyses usefulness of food chain information about antibiotic usage covering the 60-day period prior to delivery of pigs to slaughter in the control of antibiotic residues in pork. A dataset with 479 test results for antibiotic residues in tissue samples of finishing pigs delivered to a Dutch slaughter company was linked to information provided by pig producers about antibiotic usage in these finishing pigs. Results show that twice as many producers reported using antibiotics in the group of 82 producers with antibiotic residues (11.0%) compared to the group without antibiotic residues (5.5%) (p = 0.0686). For 89% of consignments with a finishing pig with antibiotic residues, the producer reported ‘did not use antibiotics’. Food chain information about antibiotic usage provided by Dutch pig producers was no guarantee for absence of antibiotic residues in delivered finishing pigs.
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