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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Longitudinal study on transmission of MRSA CC398 within pig herds
Broens, E.M. ; Espinosa-Gongora, C. ; Graat, E.A.M. ; Vendrig, N.J. ; Wolf, P.J. van der; Guardabassi, L. ; Butaye, P. ; Nielsen, J.P. ; Jong, M. de; Giessen, A.W. van de - \ 2012
BMC Veterinary Research 8 (2012). - ISSN 1746-6148
resistant staphylococcus-aureus - livestock-associated mrsa - netherlands - prevalence - swine - quantification - carriage - workers - design - virus
Background Since the detection of MRSA CC398 in pigs in 2004, it has emerged in livestock worldwide. MRSA CC398 has been found in people in contact with livestock and thus has become a public health issue. Data from a large-scale longitudinal study in two Danish and four Dutch pig herds were used to quantify MRSA CC398 transmission rates within pig herds and to identify factors affecting transmission between pigs. Results Sows and their offspring were sampled at varying intervals during a production cycle. Overall MRSA prevalence of sows increased from 33% before farrowing to 77% before weaning. Overall MRSA prevalence of piglets was > 60% during the entire study period. The recurrent finding of MRSA in the majority of individuals indicates true colonization or might be the result of contamination. Transmission rates were estimated using a Susceptible-Infectious-Susceptible (SIS-)model, which resulted in values of the reproduction ratio (R0) varying from 0.24 to 8.08. Transmission rates were higher in pigs treated with tetracyclins and ß-lactams compared to untreated pigs implying a selective advantage of MRSA CC398 when these antimicrobials are used. Furthermore, transmission rates were higher in pre-weaning pigs compared to post-weaning pigs which might be explained by an age-related susceptibility or the presence of the sow as a primary source of MRSA CC398. Finally, transmission rates increased with the relative increase of the infection pressure within the pen compared to the total infection pressure, implying that within-pen transmission is a more important route compared to between-pen transmission and transmission through environmental exposure. Conclusion Our results indicate that MRSA CC398 is able to spread and persist in pig herds, resulting in an endemic situation. Transmission rates are affected by the use of selective antimicrobials and by the age of pigs.
Typing results of Methicillin-resistant Staphylococcus aureus (MRSA) resulting from the SafeGuard workpackage 2.3 "MRSA vet-net"
Köck, R. ; Klees, S. ; Stührenberg, B. ; Beneke, B. ; Gerth, C. ; Gundlach, S. ; Harlizius, J. ; Lambrecht, D. ; Nienhoff, H. ; Schulte-Wülwer, J. ; Wolf, P.J. van der; Broens, E.M. ; Graat, E.A.M. ; Friedrich, A.W. - \ 2011
Among animals high MRSA colonization rates have been documented especially in livestock (swine, poultry, cattle), which can be the source of zoonotic transmissions. Within work package 2.3 (WP 2.3) of SafeGuard, the partners perform multiple investigations into the occurrence of MRSA among (livestock) animals. The molecular typing of MRSA isolates found in these studies is a central aim of this work package. Since 2009, all MRSA isolated in longitudinal studies and prevalence investigations within the framework of WP 2.3 have been characterized using sequence-based typing of the S. aureus protein A (spa) gene. Spa types were clustered into spa clonal complexes (spa-CC) by the Based Upon Repeat Pattern (BURP) algorithm of the Ridom StaphType software. Results of spa typing were compared to multilocus-sequence typing (MLST) results available on the central spa-server and in recent publications. In total, 2147 MRSA isolates were spa-typed. Among these strains, 83 samples were from humans, 1800 from pigs or pig holdings, 257 from chickens or chicken abattoirs and 7 from other animals (cats, dogs, guinea pigs, cattle and sheep). Overall, 95% of all MRSA isolates were characterized by spa-CC011 (t011, t034, t108, t1184, t1197, t1250, t1255, t1451, t1606, t2330, t2346, t2576, t3423, t4652, t571, t588, t6247, t6320, t7621), indicative for the clonal lineage CC398 as determined by MLST. Ten isolates were associated with spa- CC002/2164 indicative for MLST CC5. Four isolates were found to belong to spa- CC1236/3992 described to represent MLST CC97. Ten spa types (n=61 isolates) indicative for multiple MLST CCs were not clustered with other types (t003, t015, t020, t127, t1430, t151, t1535, t5838, t7496, t899). Six spa types were excluded from BURP analysis due to the spa repeat length (t1344, t1456, t2383, t2510, t3041, t991). MRSA of the CC398 lineage were predominant among the isolates characterized in WP2.3. However, rare MRSA spa types were determined.
Transmission of livestock associated MRSA in pigs
Broens, E.M. ; Graat, E.A.M. ; Giessen, A.W. van de; Vendrig, N.J. ; Wolf, P.J. van der; Jong, M.C.M. de - \ 2011
In: Proceedings of the Society for Veterinary Epidemiology and Preventive Medicine, 23-25 March 2011, Leipzig, Germany. - - p. 63 - 68.
A longitudinal study on the persistence of Livestock Associated-MRSA in swine herds
Wolf, P.J. van der; Broens, E.M. ; Köck, R. ; Graat, E.A.M. - \ 2011
In: Proceedings of the 9th International Conference on the Epidemiology and Control of biological, chemical and physical hazards in pigs and pork, 19-22 June 2011, Maastricht, The Netherlands. - - p. 325 - 328.
In recent years, a new type of MRSA, now called livestock-associated MRSA (LA-MRSA), belonging to the clonal complex (CC) 398, has globally emerged in swine world wide. Aim of this study was to gain more insight into the persistence of LA-MRSA in different types of pig farms over a period of two years. To investigate this, 15 MRSA-positive herds from a previous study were selected; an additional pig farm was selected because this one was found to be positive with a human MRSA-strain. Starting in September 2009, five dust samples were collected every two months. Samples were analysed for MRSA and spa-typing was done to confirm that MRSA isolates belonged to CC398 and to gain insight into persistence of strains within a farm. Three herds were positive on all sampling occasions and were consistently contaminated with LA-MRSA. In the remaining herds, occasionally no positive dust samples were found at some sampling moments. The predominating spa -types were t011 and t108. A maximum of 5 different spa-types were found in two herds, with 3 different spa-types present in one sampling, indicating multiple introductions. These results show that LA-MRSA remains present on a pig farm over a long period. Most likely, transmission within the herd occurs after initial introduction, and an endemic situation seems to be the endpoint. The relatively low sensitivity of dust sampling compared to sampling of animals, the small sample size and lack of strict standardization of dust sampling might explain occasional negative samplings in overall positive herds. However, a true change of a positive MRSA-status to a negative status, followed by re-introduction cannot be ruled out in our study design.
Prevalence and risk factor analysis of livestock associated MRSA-positive pig herds in The Netherlands
Broens, E.M. ; Graat, E.A.M. ; Wolf, P.J. van der; Giessen, A.W. van de; Jong, M.C.M. de - \ 2011
Preventive Veterinary Medicine 102 (2011)1. - ISSN 0167-5877 - p. 41 - 49.
resistant staphylococcus-aureus - methicillin-resistant - swine - st398 - transmission - farms - model
In 2005, methicillin-resistant Staphylococcus aureus was found in pig herds and in humans in contact with pigs. To determine the prevalence of, this now-called livestock-associated (LA) MRSA among pig herds in the Netherlands and to identify and quantify risk factors, an observational study of 202 pig herds was performed between 2007 and 2008. Five environmental wipes and 60 nasal swabs from each herd were collected, and microbiological analysis was performed on single environmental samples and pooled nasal samples. A herd was considered MRSA-positive if =1 sample tested positive. The prevalence of MRSA-positive herds was 67% in breeding herds and 71% in finishing herds. Multivariable logistic regression analysis was then performed on data from 171 breeding herds. The number of MRSA-positive herds increased from ~30% at the start to ~75% at the end of the study, most likely due to transmission between herds. The prevalence of MRSA increased with herd size, as ~40% of smaller herds (80% of larger herds (>500 sows). Other risk factors (e.g. antimicrobial use, purchase of gilts and hygiene measures) were not significantly associated with MRSA, though associated with herd size. Herd size appeared to be a compilation of several factors, which made larger herds more often MRSA positive.
MRSA CC398 in the pig production chain
Broens, E.M. ; Graat, E.A.M. ; Wolf, P.J. van der; Giessen, A.W. van de; Duijkeren, E. van; Wagenaar, J.A. ; Nes, A. van; Mevius, D.J. ; Jong, M.C.M. de - \ 2011
Preventive Veterinary Medicine 98 (2011)2-3. - ISSN 0167-5877 - p. 182 - 189.
resistant staphylococcus-aureus - prevalence - farms - netherlands
In 2005, a distinct clone of methicillin resistant Staphylococcus aureus (MRSA CC398) was found in pigs and people in contact with pigs. The structure of the pig production chain in high technology pig husbandry enables pathogens to spread during animal trading, with an increasing prevalence in herds further down the chain. The objective of this study was to quantify the effect of the MRSA status of the supplying herd on the MRSA status of the receiving herd in order to gain more insight into the role of animal trading as a transmission route for MRSA CC398. Nasal samples (60–80 pigs per herd) were collected from 38 herds; in 20 herds, environmental samples were collected as well. Ten MRSA-positive herds (based on the results of nasal swabs of 10 individual pigs per herd) from a prior study were included in the data analysis. Herds were classified as MRSA positive if at least one sample tested positive. The 48 herds were part of 14 complete (40 herds) and 4 incomplete (8 herds) pig production chains. Fifty-six percent of the herds were classified as MRSA positive. MRSA-positive herds were observed at the start (breeding herds), middle (farrowing herds) and the end (finishing herds) of the pig production chain. All of the herds in 8 chains tested MRSA positive;, all of the herds in 5 chains tested MRSA negative and in the remaining 5 chains, MRSA-positive and MRSA-negative herds were detected. Seven spa types were found, which were all previously confirmed to belong to CC398. All of the isolates were susceptible to mupirocin, linezolid, rifampicin, fusidic acid and cotrimoxazole. Resistance against tetracycline, erythromycin and clindamycin was found in 100, 74 and 76% of the isolates, respectively. Seventy-nine percent of herds with a MRSA-positive supplier of pigs were MRSA positive, whereas 23% of herds with a MRSA-negative supplier were MRSA positive (OR = 10.8; 95% CI: 1.5–110.1; P = 0.011). The presence of entirely MRSA-positive and MRSA-negative chains and the strong association between the MRSA status of herds and their suppliers illustrates a large risk associated with purchasing pigs from MRSA-positive herds; a top-down strategy for future control programs is, therefore, a basic requirement. However, 23% of herds with a MRSA-negative supplier were MRSA positive and furthermore, 46% of the herds at the top of the pig production chain without a supplier tested MRSA positive. This underlined the need for the identification of additional risk factors for MRSA.
Transmission of methicillin resistant Staphylococcus aureus among pigs during transportation from farm to abattoir
Broens, E.M. ; Graat, E.A.M. ; Wolf, P.J. van der; Giessen, A.W. van de; Jong, M.C.M. de - \ 2011
The Veterinary Journal 189 (2011)3. - ISSN 1090-0233 - p. 302 - 305.
salmonella-typhimurium - rapid infection - high prevalence - risk-factors - netherlands - mrsa - exposure - workers - swine
The prevalence of methicillin resistant Staphylococcus aureus (MRSA) in pigs at abattoirs is higher than in pigs sampled on farms. This study investigated whether MRSA negative pigs can become MRSA positive during transportation from the farm to the abattoir after exposure to other pigs and environmental sources of MRSA. Nasal swabs were collected from four batches of pigs during loading at the farm, on arrival at the abattoir and after stunning. Environmental wipes were taken from lorries after transporting pigs and from lairages after holding pigs. All pigs (n = 117) tested MRSA negative before transportation. On arrival at the abattoir, 12/117 (10.3%) pigs in two batches tested MRSA positive. In lorries that tested positive after transportation, the prevalence of MRSA positive pigs was 21.1%, whereas no MRSA was detected in pigs that had been transported in lorries that tested negative after transportation. At stunning, all batches and 70/117 (59.8%) pigs tested MRSA positive. Pigs can become MRSA positive in the short period of time during transportation from the farm to stunning at the abattoir
Comparison of sampling methods used for MRSA-classification of herds with breeding pigs
Broens, E.M. ; Graat, E.A.M. ; Engel, B. ; Oosterom, R.A.A. van; Giessen, A.W. van de; Wolf, P.J. van der - \ 2011
Veterinary Microbiology 147 (2011)3-4. - ISSN 0378-1135 - p. 440 - 444.
resistant staphylococcus-aureus
Since the first report on methicillin resistant Staphylococcus aureus (MRSA) CC398 in pigs, several countries have determined the prevalence of MRSA-positive pig herds using different sampling and laboratory techniques. The objective of the study was to compare three sampling methods for MRSA-classification of herds. Therefore, nasal swabs of pigs and environmental wipes were collected from 147 herds with breeding pigs. Per herd, laboratory examination was done on 10 pools of 6 nasal swabs (NASAL), 5 single environmental wipes (ENVSINGLE) and one pool of 5 environmental wipes (ENVPOOL). Large differences in apparent prevalence of MRSA-positive herds between methods were found: 19.1% for ENVPOOL, 53.1% for ENVSINGLE, and 70.8% for NASAL. Pairwise comparisons of methods resulted in relative sensitivities of 26.9% (ENVPOOL vs. NASAL), 34.6% (ENVPOOL vs. ENVSINGLE), and 72.1% (ENVSINGLE vs. NASAL) with relative specificities of respectively 100%, 98.6% and 93.0%. Cohen's kappa was respectively 0.18, 0.32 and 0.55, thus varying between very poor and moderate agreement. Examination of environmental wipes is an easy and non-invasive method to classify herds for MRSA. The number of environmental wipes needed depends on e.g. required detection limits and within-herd prevalence. In low prevalent herds (e.g. herds with
Diagnostic validity of pooling environmental samples to determine the status of sow-herds for presence of Methicillin Resistant Staphylococcus aureus (MRSA)
Broens, E.M. ; Graat, E.A.M. ; Wolf, P.J. van der; Giessen, A.W. van de - \ 2009
In: Methicillin-resistant Staphylococci in Animals: Veterinary and Public Health Implications, London, England, 22-25 September 2009. - - p. 38 - 38.
MRSA ST398 in the pig production chain
Broens, E.M. ; Graat, E.A.M. ; Wolf, P.J. van der; Duijkeren, E. van; Nes, A. van; Wagenaar, J.A. ; Giessen, A.W. van de; Jong, M.C.M. de - \ 2009
In: Methicillin-resistant Staphylococci in Animals: Veterinary and Public Health Implications, London, England, 22-25 September 2009. - - p. 37 - 37.
Transmission of MRSA ST398 during transport of pigs from farm to slaughterhouse and during time spent in lairags at the slaughterhouse
Broens, E.M. ; Graat, E.A.M. ; Wolf, P.J. van der; Giessen, A.W. van de; Jong, M.C.M. de - \ 2009
In: Methicillin-resistant Staphylococci in Animals: Veterinary and Public Health Implications, London, England, 22-25 September 2009. - - p. 16 - 16.
Methicillin-resistant Staphylococcus aureus in people living and working in pig farms
Broek, I.V.F. van den; Cleef, B.A.G.L. van; Haenen, A. ; Broens, E.M. ; Wolf, P.J. van der; Broek, M.J.M. van den; Huijsdens, X.W. ; Kluytmans, J.A.J.W. ; Giessen, A.W. van de; Tiemersma, E.W. - \ 2009
Epidemiology and Infection 137 (2009)5. - ISSN 0950-2688 - p. 700 - 708.
intensive-care-unit - netherlands - humans - colonization - prevalence - strains - st398 - mrsa
We compared the prevalence of human and animal methicillin-resistant Staphylococcus aureus (MRSA) at pig farms in The Netherlands, and related this to individual and farm-level characteristics. More than half of the farms investigated (28/50) had MRSA in pigs or stable dust and about one third (15/50) of person(s) were identified as MRSA carriers. Human carriage was found only on farms with MRSA-positive pigs or dust. MRSA strains in human samples were the same spa-type as found in pigs and all were not typable by pulsed-field gel electrophoresis (NT-MRSA). Multivariate analyses showed that risk factors for human MRSA carriage were: working in pig stables (OR 40, 95% CI 8¿209) and the presence of sows and finishing pigs (OR 9, 95% CI 3¿30). Veterinary sample collectors sampling the pigs showed transient MRSA carriage only during the day of the farm visit. Working in pig stables with MRSA-positive pigs poses a high risk for acquiring MRSA, increasingly so when contact with live pigs is more intensive or long lasting
MRSA in pigs: a new threat to human health !? How many and which pig farms are MRSA-positive?
Broens, E.M. ; Graat, E.A.M. ; Wolf, P.J. van der; Broek, I.V.F. van den; Tiemersma, E.W. ; Giessen, A.W. van de; Jong, M.C.M. de - \ 2008
Can MRSA be transmitted through the pig production chain?
Broens, E.M. ; Graat, E.A.M. ; Wolf, P.J. van der; Duijkeren, E. van; Nes, A. van; Wagenaar, J.A. ; Giessen, A.W. van de; Jong, M.C.M. de - \ 2008
Prevalence study and risk factor analysis of NT-MRSA in pigs in the Netherlands
Broens, E.M. ; Graat, E.A.M. ; Wolf, P.J. van der; Broek, I.V.F. van den; Tiemersma, E.W. ; Giessen, A.W. van de; Jong, M.C.M. de - \ 2008
In: Proceedings of the 20th International Pig Veterinary Science Congress Volume 2 Poster Papers, Durban, South Africa, 22 - 26 June, 2008. - Durban, South Africa : Hein Jonker Media Management - p. 311 - 311.
Transmission of NT-MRSA during transport from farm to slaughterhouse and during time spent in lairages in slaughterhouses
Broens, E.M. ; Graat, E.A.M. ; Wolf, P.J. van der; Giessen, A.W. van de; Jong, M.C.M. de - \ 2008
In: Proceedings of the 20th International Pig Veterinary Science Congress Volume 2 Poster Papers, Durban South Africa, 22 - 26 June, 2008. - Durban, South Africa : Hein Jonker Media Management - p. 309 - 309.
Staphylococci and MRSA isolated from pigs with clinical symptoms
Wolf, P.J. van der; Rothkamp, A. ; Broens, E.M. - \ 2008
In: Proceedings of the 20th International Pig Veterinary Science Congress Volume 1 Keynote and Oral Papers, Durban, South Africa, 22 - 26 June, 2008. - Durban, South Africa : Hein Jonker Media Management - ISBN 9780620413633 - p. 166 - 166.
Transmission of NT-MRSA in the pig production chain in the Netherlands
Broens, E.M. ; Graat, E.A.M. ; Wolf, P.J. van der; Duijkeren, E. van; Nes, A. van; Wagenaar, J.A. ; Giessen, A.W. van de; Jong, M.C.M. de - \ 2008
Prevalence study and risk factor analysis of NT-MRSA in pigs in the Netherlands
Broens, E.M. ; Graat, E.A.M. ; Wolf, P.J. van der; Broek, I.V.F. van den; Tiemersma, E.W. ; Giessen, A.W. van de; Jong, M.C.M. de - \ 2008
In: ASM Conference Antimicrobial Resistance in Zoonotic Bacteria and Foodborne Pathogens, Copenhagen, Denmark, 15 - 18 June, 2008. - - p. 37 - 37.
Resistance and virulence determinants in MRSA isolated in 2007 from pigs, veal calves and food products.
Mevius, D.J. ; Dierikx, C.M. ; Verheijen, D. ; Veldman, K.T. ; Wit, B. ; Wolf, P.J. van der; Graveland, H. ; Huijsdens, X. ; Giessen, A. van der - \ 2008
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