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Roger Stephan - One of the best experts on this subject based on the ideXlab platform.
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comparison of virulence and antibiotic resistance genes of food poisoning outbreak isolates of staphylococcus aureus with isolates obtained from bovine mastitis milk and Pig Carcasses
Journal of Food Protection, 2011Co-Authors: Sophia Johler, Franziska Layer, Roger StephanAbstract:Staphylococcus aureus is the etiological agent in a variety of infections in humans and livestock and produces enterotoxins leading to staphylococcal food poisoning (SFP), one of the most prevalent foodborne intoxication diseases worldwide. Pork and bovine milk are considered possible sources of SFP because Pig skin is often colonized by S. aureus and bovine mastitis caused by S. aureus is common, but conclusive data are limited. The objective of the present study was to compare S. aureus isolates associated with cases of SFP with isolates obtained from bovine mastitis milk and Pig Carcasses. DNA microarray analysis and spa gene typing were performed with 100 S. aureus isolates: 20 isolates related to outbreaks of SFP in humans, 39 isolates obtained from Pig Carcasses, and 41 isolates collected from bovine mastitis milk. No overlap in spa types was observed for SFP isolates (t008, t015, t018, t024, t056, t084, t279, t377, t383, t648, t733, t912, t1239, t1270, t4802, and t6969) and isolates gathered from milk or pork. The porcine isolates were assigned to t034, t208, t337, t524, t899, t1939, t2922, t2971, t4475, and t7006, and the bovine isolates belonged to t267, t524, t529, t1403, t2953, t7007, t7008, and t7013. Comparison of microarray profiles revealed similar virulence gene patterns for isolates collected from the same host (Pigs or cattle) but few similarities between SFP isolate profiles and the profiles of isolates obtained from bovine mastitis milk and Pig Carcasses. Although only some bovine and porcine isolates possessed the β-lactamase gene blaZ (milk, 24%; pork, 28%), significantly higher numbers of SFP isolates contained blaZ (90%). Investigations of these isolates provided no evidence that pork or bovine mastitis milk represent common sources of SFP.
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antibacterial activity of decontamination treatments for Pig Carcasses
Food Control, 2011Co-Authors: Marianne Loretz, Roger Stephan, Claudio ZweifelAbstract:Prevention or reduction of carcass contamination with food-borne pathogens during slaughter is of particular importance. Antimicrobial intervention technologies are therefore gaining increasing interest in the slaughter process. In this review, we screened the available recent literature on the decontamination of Pig Carcasses and appraised the antibacterial activity of treatments. Compared to poultry and beef Carcasses, data on decontamination treatments for Pig Carcasses are so far limited and mainly physical and chemical interventions were investigated. Physical treatments were on the one hand part of the normal Pig slaughter process. Dependent on time and temperature conditions, the bactericidal effect of scalding was shown in several studies, whereas the effect of singeing or chilling differed widely. On the other hand, interventions as hot water spraying, steam treatment or ultraviolet light were additionally applied with the specific objective of carcass decontamination. Hot water spraying and steam treatment thereby yielded bacterial reductions ranging from 1.0 to 2.1 orders of magnitude. Chemical interventions primary included lactic and acetic acid. Under commercial conditions, lactic acid treatment yielded bacterial reductions ranging from 0.2 to 1.0 orders of magnitude.
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characteristics of staphylococcus hyicus strains isolated from Pig Carcasses in two different slaughterhouses
Meat Science, 2008Co-Authors: Ch Hassler, Claudio Zweifel, Sabine Nitzsche, Carol Iversen, Roger StephanAbstract:In a previous study, we showed that coagulase positive staphylococci, which are often used as indicators for Staphylococcus aureus, are frequently found on Pig Carcasses. Further characterization of the strains identified only a minor part as S. aureus. Selected non-S. aureus strains were all identified as Staphylococcus hyicus, However, two studies described in this species strains that produce staphylococcal enterotoxins. The aim of the present study was to further characterize such coagulase positive S. hyicus strains isolated from Pig Carcasses and to assess the results for their food safety relevance. A total of 189 strains from two abattoirs were characterized. Phenotypically, 98.9% showed non-Pigmented colonies, 99.5% no haemolysis and 67.7% were egg yolk-positive. DNase activity was found in all but one isolate. Only five of the 189 strains were resistant to the antimicrobials tested. One strain harboured the mecA gene. Exfoliative toxin genes were detected in 31 (16.4%), S. aureus enterotoxin genes in none of the strains. The PFGE genotyping results show only a limited number of clusters. Cluster I included more than 50% of the strains. The fact that similar or closely related PFGE patterns of S. hyicus can be found on Carcasses after bleeding in both abattoirs indicates the occurrence of widespread strains in the Swiss Pig population. Moreover, the genotyping results revealed a remarkable homogeneity in S. hyicus strains isolated from different process stages in abattoir B, which could indicate a recontamination problem with persisting strains.
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microbiological contamination of Pig and cattle Carcasses in different small scale swiss abattoirs
Meat Science, 2008Co-Authors: Claudio Zweifel, Roland Fischer, Roger StephanAbstract:Abstract A total of 750 Pig Carcasses and 535 cattle Carcasses from 17 small-scale abattoirs were sampled by excision at four sites (Pig: neck, belly, back, ham; cattle: neck, brisket, flank, rump). Samples were examined for total viable counts (TVC) and Enterobacteriaceae . Mean TVCs ranged from 2.4 to 4.2 log 10 CFU cm −2 on Pig Carcasses and from 2.7 to 3.8 log 10 CFU cm −2 on cattle Carcasses. With regard to EU Regulation (EC) No 2073/2005, TVCs were mainly considered satisfactory (Pig: 81.3%; cattle: 71.4%). Amongst sites, the back (Pigs) and neck (cattle) tended to yield higher TVCs. Enterobacteriaceae were detected in low counts on 23.9% of Pig Carcasses and 21.7% of cattle Carcasses. Amongst abattoirs, Enterobacteriaceae prevalence on Pig and cattle Carcasses ranged from 2.0% to 56.0% and from 0.0% to 55.0%, respectively. Consequently, criteria of the EU Regulation proved to be a suitable tool for the appraisal of microbiological results (TVCs) from Pig and cattle Carcasses from small-scale abattoirs. Because the occurrence of Enterobacteriaceae on Carcasses was too infrequent to ensure log normality, frequencies should be compared for these organisms.
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phenotypic and genotypic traits of staphylococcus aureus strains isolated from Pig Carcasses
Veterinary Microbiology, 2007Co-Authors: Sabine Nitzsche, Claudio Zweifel, Roger StephanAbstract:A total of 142 S. aureus strains isolated from Pig Carcasses from abattoirs A (n = 98) and B (n = 44) were characterized by phenotypic and genotypic traits. Phenotypically, 96% showed yellow-Pigmented colonies, 63% b/d hemolysis, 85% were egg yolk-positive and 99% were positive for clumping factor/protein A. Only 25% of the strains were resistant to the antimicrobials tested (abattoir A: 19%; abattoir B: 39%), especially to penicillin and ampicillin. None of the strains harbored the mecA gene, which is conserved in methicillin-resistant S. aureus. The biofilm associated genes icaA, icaD and bap were present in 100%, 100% and 0% of the strains. Genes for staphylococcal enterotoxin (SE) were detected in 51% (abattoir A) and 14% of the strains (abattoir B). Among strains harboring SE genes (n = 56), 63%, 31%, 4% and 2% tested positive for seg/sei, seg, sei and sec, respectively. The amplification of the 3 0 end of the coagulase gene (coa) yielded amplicons of 400, 436, 602, 682 or 776 bp. Coa restriction profile (CRP) analysis using HaeIII resulted in seven patterns (a‐d, e1‐e3). CRP (c) was detected most frequently at both abattoirs, whereas CRP (a) was restricted to abattoir A and CRP (e3) to abattoir B. In the slaughter process (abattoir B), (i) two CRPs (b and d) were only found before dehairing/singeing, and (ii) four CRPs (c, e1‐e3) were identified throughout the process. The genotyping revealed a remarkable homogeneity in S. aureus strains from the two different abattoirs and the slaughter process stages. These results may be explainedbythe distributionof a limited number ofS. aureusgenotypes in the Pig population. Moreover, as the predominant CRPs (c, e1‐e3) persisted throughout the slaughter process in abattoir B, it may be hypothesized that these types are characterized by colonization advantages. # 2006 Elsevier B.V. All rights reserved.
I Van Damme - One of the best experts on this subject based on the ideXlab platform.
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occurrence distribution and diversity of listeria monocytogenes contamination on beef and Pig Carcasses after slaughter
Meat Science, 2020Co-Authors: Niels Demaitre, L De Zutter, I Van Damme, Annemie Geeraerd, G Rasschaert, K De ReuAbstract:Abstract In this study we investigated the prevalence and location of Listeria monocytogenes and hygiene indicator bacteria on beef and Pig Carcasses. Carcasses were sampled after slaughter and before cooling at eight and nine sites on the carcass, respectively. For each sample, detection and enumeration of Listeria was performed, as well as the enumeration of Total Aerobic Counts (TAC) and Enterobacteriaceae. The L. monocytogenes isolates were also typed to determine pulsotypes and clonal complexes (CC). L. monocytogenes was detected on 46% [95% CI: 35–56%] of beef and 22% [95% CI: 11–32%] of Pig Carcasses. Contamination levels at the different carcass sites differed considerably between beef and Pigs. Genetic typing of strains suggests that carcass contamination originates from both incoming animals with transmission during slaughter practices as well as persistent (CC9) contamination from the slaughterhouse environment. These findings can be used to understand the complexity of introduction and persistence of this pathogen in slaughter facilities. Accurate correlation of L. monocytogenes presence proved unfeasible with any of the tested hygiene indicator bacteria.
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reduced contamination of Pig Carcasses using an alternative pluck set removal procedure during slaughter
Meat Science, 2018Co-Authors: W Biasino, L De Zutter, J Woollard, Wesley Mattheus, Sophie Bertrand, Mieke Uyttendaele, I Van DammeAbstract:This study compared the current Pig slaughter procedure where the pluck set is completely removed with a procedure where the pluck set is partially removed, leaving the highly contaminated oral cavity, tonsils and tongue untouched. The effect on carcass contamination was investigated by enumerating hygiene indicator bacteria (total aerobic count, Enterobacteriaceae and E. coli) and cefotaxime-resistant E. coli (CREC) as well as assessing Salmonella and Yersinia enterocolitica presence on the sternum, elbow and throat of Pig Carcasses. Using the alternative pluck set removal, significantly lower mean numbers of hygiene indicator bacteria on throat samples and E. coli on elbow samples were found. Less Pig Carcasses were highly contaminated and a lower presence and level of CREC was observed. No difference in Salmonella or Yersinia enterocolitica presence was seen. The data in this study can help to assess the effect of this alternative procedure on the safety of pork and subsequently public health.
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quantification distribution and diversity of esbl ampc producing escherichia coli on freshly slaughtered Pig Carcasses
International Journal of Food Microbiology, 2018Co-Authors: W Biasino, L De Zutter, Mieke Uyttendaele, C Garciagraells, N Botteldoorn, T Gowda, I Van DammeAbstract:This study quantified cefotaxime-resistant E. coli (CREC) on nine different carcass areas of 104 freshly slaughtered Pig Carcasses. In 49% [95% confidence interval (95% CI): 29-69%] of the Carcasses CREC could be isolated and enumerated (using Tryptone Bile Agar with X-Glucuronide supplemented with 1 mg/L cefotaxime). Proportions of positive samples varied between carcass areas from 1% [95% CI: 0-10%] (loin) to 23% [95% CI: 10-44%] (head). Maximum concentrations on positive samples ranged between -0.6 log10 CFU/cm2 (loin, elbow before evisceration) and 1.7 log10 CFU/cm2 (head). The head was significantly more frequently contaminated than the loin (p = 0.027) and ham (3% [95% CI: 1-15%]). The foreleg was significantly more frequently contaminated (20% [95% CI: 13-30%]) than the ham. Combination disk diffusion assays revealed that 81% of the CREC isolates were extended-spectrum beta-lactamases (ESBL) producers, 13% were AmpC cephalosporinases (AmpC) producers and 2% ESBL and AmpC co-producers. Genotyping denoted blaCTX-M-gr1 (63%) and blaTEM (40%) as most present antibiotic resistance genes. Multiple gene combinations in one isolate and multiple combinations of genotypes and phenotypes among isolates of one sample were observed. These quantitative data can be used for intervention strategies to lower human exposure to CREC.
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correlation between slaughter practices and the distribution of salmonella and hygiene indicator bacteria on Pig Carcasses during slaughter
Food Microbiology, 2018Co-Authors: W Biasino, L De Zutter, Wesley Mattheus, Sophie Bertrand, Mieke Uyttendaele, I Van DammeAbstract:This study investigated the distribution of hygiene indicator bacteria and Salmonella on Pig Carcasses. Moreover, the relation between hygiene indicator counts and Salmonella presence as well as associations between specific slaughter practices and carcass contamination were determined for each carcass area. Seven Belgian Pig slaughterhouses were visited three times to swab five randomly selected Carcasses at nine different areas, after evisceration and trimming. Information about slaughter practices was collected using a questionaire. In all samples, the E. coli and Salmonella presence was analyzed and Enterobacteriaceae and total aerobic bacteria were quantified. Average total aerobic counts ranged from 3.1 (loin, pelvic duct, ham) to 4.4 log10 CFU/cm2 (foreleg). Median Enterobacteriaceae numbers varied between 0.4 (ham) an 1.8 log10 CFU/cm2 (foreleg). E. coli and Salmonella presence ranged from 15% (elbow) to 89% (foreleg) and 5% (elbow) to 38% (foreleg), respectively. Positive relations were found between hygiene indicator counts and Salmonella presence at the head, sternum, loin and throat. Several slaughter practices, such as splitting the head and incising tonsils, were associated with higher levels of hygiene indicator bacteria and Salmonella. These findings can be used to educate slaughterhouse personnel and estimate the public health risk involved in consumption of different pork cuts.
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contamination of freshly slaughtered Pig Carcasses with enteropathogenic yersinia spp distribution quantification and identification of risk factors
International Journal of Food Microbiology, 2015Co-Authors: I Van Damme, Gerty Vanantwerpen, Kurt Houf, D Berkvens, Julie Bare, Georges Wauters, L De ZutterAbstract:Abstract A cross-sectional survey was undertaken to determine the overall prevalence of enteropathogenic Yersinia spp. in the tonsils, feces and on Carcasses of Pigs at slaughter. Moreover, factors associated with Yersinia contamination of freshly eviscerated Pig Carcasses were studied. Yersinia enterocolitica serotype O:3 was isolated from the tonsils and feces of 55.3% and 25.6% of Pigs, and Y. pseudotuberculosis from 1.4% and 0.6%, respectively. The pathogens were also recovered from 39.7% of carcass surfaces post-evisceration. The highest prevalence was found at the mandibular region (28.9%), followed by the sternal region (16.4%), pelvic duct (7.8%), and split surface near the sacral vertebrae (6.9%). Regarding the quantification of the pathogen, the median concentration of pathogenic Y. enterocolitica was 4.14 log10 CFU/g in tonsils with countable numbers (n = 143) and 2.80 log10 CFU/g for fecal samples with countable numbers (n = 26). The quantitative load on the carcass surface was generally low as the majority of the carcass samples (97.0%) had Yersinia concentrations below the detection limit of enumeration (
Armel Davenel - One of the best experts on this subject based on the ideXlab platform.
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quantification of muscle subcutaneous fat and intermuscular fat in Pig Carcasses and cuts by magnetic resonance imaging
Meat Science, 2006Co-Authors: M Monziols, Guylaine Collewet, Armel Davenel, Michel Bonneau, Francois Mariette, Maryline KoubaAbstract:Abstract The aim of this study was to determine the suitability of magnetic resonance imaging (MRI) to predict tissue composition of Pig Carcasses and cuts. Twenty-four Pig Carcasses were cut into the four primary cuts that were analyzed with a low field MRI imager before a total dissection. Images were then processed to identify and quantify pixels representing muscle, subcutaneous fat and intermuscular fat fractions. MRI provided a good prediction of muscle content in cuts and Carcasses, with R 2 ranging from 0.970 to 0.997. The prediction was slightly less accurate for total fat (0.951 ⩽ R 2 ⩽ 0.986) or subcutaneous fat (0.918 ⩽ R 2 ⩽ 0.994). Finally, the prediction of intermuscular fat content in considering intermuscular fat classified pixels was acceptable only for the belly ( R 2 = 0.837).
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Determination of the lean meat percentage of Pig Carcasses using magnetic resonance imaging.
Meat science, 2005Co-Authors: Guylaine Collewet, P. Bogner, Paul Allen, H. Busk, A. Dobrowolski, E. Olsen, Armel DavenelAbstract:Abstract The purpose of Workpackage 3 of the European EuPigclass project was to test indirect methods of measuring the lean meat percentage of a carcass that would be less costly, at least as accurate and more consistent than dissection. Magnetic resonance imaging was one of the three indirect methods tested to measure the lean meat weight and the lean meat percentage of Pig Carcasses, the other methods being X-ray CT and vision techniques. One hundred and twenty Carcasses from three different genotypes and from both sexes were slaughtered. The left parts of the Carcasses were fully dissected and the right parts were investigated with an indirect method using a 1.5T MRI system. The acquisition protocol was chosen to give an optimized contrast between fat and muscle tissues. Two different approaches, image segmentation and PLS regression, were used to extract information from the images. Automatic image segmentation was performed to quantify the volume of muscle in the images and gave a standard error of prediction using a linear regression with the dissection of the left half Carcasses of 586 g and 1.10% for lean meat weight and lean meat percentage, respectively. PLS regression using the signal intensities histograms gave an estimation error of 465 g for lean meat weight. These results showed that MRI could be used in place of full dissection for authorizing and monitoring classification equipment of Pig Carcasses.
L De Zutter - One of the best experts on this subject based on the ideXlab platform.
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occurrence distribution and diversity of listeria monocytogenes contamination on beef and Pig Carcasses after slaughter
Meat Science, 2020Co-Authors: Niels Demaitre, L De Zutter, I Van Damme, Annemie Geeraerd, G Rasschaert, K De ReuAbstract:Abstract In this study we investigated the prevalence and location of Listeria monocytogenes and hygiene indicator bacteria on beef and Pig Carcasses. Carcasses were sampled after slaughter and before cooling at eight and nine sites on the carcass, respectively. For each sample, detection and enumeration of Listeria was performed, as well as the enumeration of Total Aerobic Counts (TAC) and Enterobacteriaceae. The L. monocytogenes isolates were also typed to determine pulsotypes and clonal complexes (CC). L. monocytogenes was detected on 46% [95% CI: 35–56%] of beef and 22% [95% CI: 11–32%] of Pig Carcasses. Contamination levels at the different carcass sites differed considerably between beef and Pigs. Genetic typing of strains suggests that carcass contamination originates from both incoming animals with transmission during slaughter practices as well as persistent (CC9) contamination from the slaughterhouse environment. These findings can be used to understand the complexity of introduction and persistence of this pathogen in slaughter facilities. Accurate correlation of L. monocytogenes presence proved unfeasible with any of the tested hygiene indicator bacteria.
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reduced contamination of Pig Carcasses using an alternative pluck set removal procedure during slaughter
Meat Science, 2018Co-Authors: W Biasino, L De Zutter, J Woollard, Wesley Mattheus, Sophie Bertrand, Mieke Uyttendaele, I Van DammeAbstract:This study compared the current Pig slaughter procedure where the pluck set is completely removed with a procedure where the pluck set is partially removed, leaving the highly contaminated oral cavity, tonsils and tongue untouched. The effect on carcass contamination was investigated by enumerating hygiene indicator bacteria (total aerobic count, Enterobacteriaceae and E. coli) and cefotaxime-resistant E. coli (CREC) as well as assessing Salmonella and Yersinia enterocolitica presence on the sternum, elbow and throat of Pig Carcasses. Using the alternative pluck set removal, significantly lower mean numbers of hygiene indicator bacteria on throat samples and E. coli on elbow samples were found. Less Pig Carcasses were highly contaminated and a lower presence and level of CREC was observed. No difference in Salmonella or Yersinia enterocolitica presence was seen. The data in this study can help to assess the effect of this alternative procedure on the safety of pork and subsequently public health.
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quantification distribution and diversity of esbl ampc producing escherichia coli on freshly slaughtered Pig Carcasses
International Journal of Food Microbiology, 2018Co-Authors: W Biasino, L De Zutter, Mieke Uyttendaele, C Garciagraells, N Botteldoorn, T Gowda, I Van DammeAbstract:This study quantified cefotaxime-resistant E. coli (CREC) on nine different carcass areas of 104 freshly slaughtered Pig Carcasses. In 49% [95% confidence interval (95% CI): 29-69%] of the Carcasses CREC could be isolated and enumerated (using Tryptone Bile Agar with X-Glucuronide supplemented with 1 mg/L cefotaxime). Proportions of positive samples varied between carcass areas from 1% [95% CI: 0-10%] (loin) to 23% [95% CI: 10-44%] (head). Maximum concentrations on positive samples ranged between -0.6 log10 CFU/cm2 (loin, elbow before evisceration) and 1.7 log10 CFU/cm2 (head). The head was significantly more frequently contaminated than the loin (p = 0.027) and ham (3% [95% CI: 1-15%]). The foreleg was significantly more frequently contaminated (20% [95% CI: 13-30%]) than the ham. Combination disk diffusion assays revealed that 81% of the CREC isolates were extended-spectrum beta-lactamases (ESBL) producers, 13% were AmpC cephalosporinases (AmpC) producers and 2% ESBL and AmpC co-producers. Genotyping denoted blaCTX-M-gr1 (63%) and blaTEM (40%) as most present antibiotic resistance genes. Multiple gene combinations in one isolate and multiple combinations of genotypes and phenotypes among isolates of one sample were observed. These quantitative data can be used for intervention strategies to lower human exposure to CREC.
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correlation between slaughter practices and the distribution of salmonella and hygiene indicator bacteria on Pig Carcasses during slaughter
Food Microbiology, 2018Co-Authors: W Biasino, L De Zutter, Wesley Mattheus, Sophie Bertrand, Mieke Uyttendaele, I Van DammeAbstract:This study investigated the distribution of hygiene indicator bacteria and Salmonella on Pig Carcasses. Moreover, the relation between hygiene indicator counts and Salmonella presence as well as associations between specific slaughter practices and carcass contamination were determined for each carcass area. Seven Belgian Pig slaughterhouses were visited three times to swab five randomly selected Carcasses at nine different areas, after evisceration and trimming. Information about slaughter practices was collected using a questionaire. In all samples, the E. coli and Salmonella presence was analyzed and Enterobacteriaceae and total aerobic bacteria were quantified. Average total aerobic counts ranged from 3.1 (loin, pelvic duct, ham) to 4.4 log10 CFU/cm2 (foreleg). Median Enterobacteriaceae numbers varied between 0.4 (ham) an 1.8 log10 CFU/cm2 (foreleg). E. coli and Salmonella presence ranged from 15% (elbow) to 89% (foreleg) and 5% (elbow) to 38% (foreleg), respectively. Positive relations were found between hygiene indicator counts and Salmonella presence at the head, sternum, loin and throat. Several slaughter practices, such as splitting the head and incising tonsils, were associated with higher levels of hygiene indicator bacteria and Salmonella. These findings can be used to educate slaughterhouse personnel and estimate the public health risk involved in consumption of different pork cuts.
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contamination of freshly slaughtered Pig Carcasses with enteropathogenic yersinia spp distribution quantification and identification of risk factors
International Journal of Food Microbiology, 2015Co-Authors: I Van Damme, Gerty Vanantwerpen, Kurt Houf, D Berkvens, Julie Bare, Georges Wauters, L De ZutterAbstract:Abstract A cross-sectional survey was undertaken to determine the overall prevalence of enteropathogenic Yersinia spp. in the tonsils, feces and on Carcasses of Pigs at slaughter. Moreover, factors associated with Yersinia contamination of freshly eviscerated Pig Carcasses were studied. Yersinia enterocolitica serotype O:3 was isolated from the tonsils and feces of 55.3% and 25.6% of Pigs, and Y. pseudotuberculosis from 1.4% and 0.6%, respectively. The pathogens were also recovered from 39.7% of carcass surfaces post-evisceration. The highest prevalence was found at the mandibular region (28.9%), followed by the sternal region (16.4%), pelvic duct (7.8%), and split surface near the sacral vertebrae (6.9%). Regarding the quantification of the pathogen, the median concentration of pathogenic Y. enterocolitica was 4.14 log10 CFU/g in tonsils with countable numbers (n = 143) and 2.80 log10 CFU/g for fecal samples with countable numbers (n = 26). The quantitative load on the carcass surface was generally low as the majority of the carcass samples (97.0%) had Yersinia concentrations below the detection limit of enumeration (
Francis Butler - One of the best experts on this subject based on the ideXlab platform.
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modelling the effect of chilling on the occurrence of salmonella on Pig Carcasses at study abattoir and batch levels by meta analysis
International Journal of Food Microbiology, 2013Co-Authors: Ursula Gonzalesbarron, Vasco Cadavez, James J Sheridan, Francis ButlerAbstract:Abstract The effect of chilling on the occurrence of Salmonella on Pig Carcasses was investigated at study, abattoir and batch level by meta-analysis. Both the fixed-effects and random-effects model confirmed (p Salmonella occurrence on Pig Carcasses; although the random-effects solution was preferred to account for the significant variability in effect size (p Salmonella incidence on Pig Carcasses by a mean ratio of ~ 1.6 (95% CI: 1.0–2.6). Multilevel meta-analysis models investigating study characteristics that could explain the heterogeneity ( τ 2 ) in the true effect size among primary studies ( τ 2 = 0.578), among surveyed abattoirs ( τ 2 = 0.431), and among sampled batches ( τ 2 = 0.373), revealed that study size (represented by the moderating variables of ‘total sample size’ and ‘number of batches sampled in an abattoir’) and ‘carcass swabbed area’ have a significant impact (p Salmonella occurrence. This inconsistency to elucidate the effect of chilling arises because of the many factors influencing both the performance of the chilling operation and the measurement itself. Meta-analysis was not only instrumental to show that small-size studies (i.e., only one batch sampled per abattoir, total number of sampled Carcasses per batch 2 ) lead to imprecise and even conflicting conclusions, but most importantly, enabled definition of the characteristics of a well-designed study having a minimum statistical power to produce precise results. A sound experimental design derived by multilevel meta-analysis consists of swabbing carcass areas of at least 500 cm 2 from 25 pre-chill and 25 post-chill Carcasses from a single production batch, with a minimum of two batches sampled per surveyed abattoir. If the survey were to be conducted in more than one abattoir, the total sample size should not be less than 400. Two methods to test for publication bias, a common problem in meta-analysis, suggested that whilst the presence of unpublished small-size studies is probable, it is not likely that this would significantly bias the overall chilling effect estimated in this study.
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estimation of prevalence of salmonella on Pig Carcasses and pork joints using a quantitative risk assessment model aided by meta analysis
Journal of Food Protection, 2009Co-Authors: U G Barron, Ilias Soumpasis, Francis Butler, D M Prendergast, S J Duggan, Geraldine DuffyAbstract:This risk assessment study aimed to estimate the prevalence of Salmonella on Pig Carcasses and pork joints produced in slaughterhouses, on the basis that within groups of slaughter there is a strong association between the proportion of Salmonella-positive animals entering the slaughter lines (x) and the resulting proportion of contaminated eviscerated Pig Carcasses (y). To this effect, the results of a number of published studies reporting estimates of x and y were assembled in order to model a stochastic weighted regression considering the sensitivities of the diverse Salmonella culture methods. Meta-analysis was used to assign weights to the regression and to estimate the overall effect of chilling on Salmonella incidence on Pig Carcasses. The model's ability to produce accurate estimates and the intrinsic effectiveness of the modeling capabilities of meta-analysis were appraised using Irish data for the input parameter of prevalence of Salmonella carrier slaughter Pigs. The model approximated a Salmon...
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estimation of prevalence of salmonella on Pig Carcasses and pork joints using a quantitative risk assessment model aided by meta analysis
Journal of Food Protection, 2009Co-Authors: U G Barron, Ilias Soumpasis, Francis Butler, D M Prendergast, S J Duggan, Geraldine DuffyAbstract:This risk assessment study aimed to estimate the prevalence of Salmonella on Pig Carcasses and pork joints produced in slaughterhouses, on the basis that within groups of slaughter there is a strong association between the proportion of Salmonella-positive animals entering the slaughter lines (x) and the resulting proportion of contaminated eviscerated Pig Carcasses (y). To this effect, the results of a number of published studies reporting estimates of x and y were assembled in order to model a stochastic weighted regression considering the sensitivities of the diverse Salmonella culture methods. Meta-analysis was used to assign weights to the regression and to estimate the overall effect of chilling on Salmonella incidence on Pig Carcasses. The model's ability to produce accurate estimates and the intrinsic effectiveness of the modeling capabilities of meta-analysis were appraised using Irish data for the input parameter of prevalence of Salmonella carrier slaughter Pigs. The model approximated a Salmonella prevalence in pork joints from Irish boning halls of 4.0% (95% confidence interval, 0.3 to 12.0%) and was validated by the results of a large survey (n = 720) of Salmonella in pork joints (mean, 3.3%; 95% confidence interval, 2.0 to 4.6%) carried out in four commercial pork abattoirs as part of this research project. Sensitivity analysis reinforced the importance of final rinsing (r = -0.382) and chilling (r = -0.221) as stages that contribute to reducing considerably the occurrence of Salmonella on the final product, while hygiene practices during jointing seemed to moderate only marginally the amount of contaminated pork joints. Finally, the adequacy of meta-analysis for integrating different findings and producing distributions for use in stochastic modeling was demonstrated.
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a meta analysis study of the effect of chilling on prevalence of salmonella on Pig Carcasses
Journal of Food Protection, 2008Co-Authors: Gonzales U Barron, D Bergin, Francis ButlerAbstract:In the field of food safety, meta-analysis can be used to combine results of prevalence studies of pathogens at critical stages within the food processing chain so that policy makers can access reliable and concise information on the effectiveness of interventions for controlling and preventing foodborne illnesses in humans. The objective of this work was to demonstrate the applicability of a parametric approach of meta-analysis to the specific case of determining the overall effect of chilling on Salmonella prevalence on Pig Carcasses. A meta-analysis was performed on each of two parameters measuring effect size for binary outcomes (relative risk and risk difference). Both meta-analyses confirmed that the chilling operation has a significant beneficial effect (P < 0.001) on the reduction of Salmonella prevalence on Pig Carcasses. Because risk difference is a parameter sensitive to the differences across studies in carcass swab areas and Salmonella detection methods, its meta-analysis highly reflected this heterogeneity (P < 0.001). However, parameterization of relative risk, not being biased by the above sources of variability, did not give rise to heterogeneity among studies and produced a fixed-effects meta-analysis solution, which is deemed more suitable for compilations based on a small number of individual studies (n = 9). Because of the systematic approach of meta-analysis (i.e., individual studies are weighed according to precision) and its reliance for actual data, the output distribution of the relative risk effect size (approximately eN(-0.868,0.166)) merits consideration for inclusion in the chilling stage of quantitative risk assessments modeling the prevalence of this pathogen along the pork production chain.