Modeling Preharvest and Harvest Interventions for Escherichia coli O157 Contamination of Beef Cattle Carcasses

Department of Diagnostic Medicine and Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, Kansas 66506-5006, USA.
Journal of food protection (Impact Factor: 1.85). 09/2011; 74(9):1422-33. DOI: 10.4315/0362-028X.JFP-10-516
Source: PubMed


Field studies evaluating the effects of multiple concurrent preharvest interventions for Escherichia coli O157 are logistically and economically challenging; however, modeling techniques may provide useful information on these effects while also identifying crucial information
gaps that can guide future research. We constructed a risk assessment model with data obtained from a systematic search of scientific literature. Parameter distributions were incorporated into a stochastic Monte Carlo modeling framework to examine the impacts of different combinations of preharvest
and harvest interventions for E. coli O157 on the risk of beef carcass contamination. We estimated the risk of E. coli O157 carcass contamination conditional on preharvest fecal prevalence estimates, inclusion of feed additive(s) in the diet, vaccination for E. coli O157,
transport and lairage effects, hide intervention(s), and carcass intervention(s). Prevalence parameters for E. coli O157 were assumed to encompass potential effects of concentration; therefore, concentration effects were not specifically evaluated in this study. Sensitivity analyses
revealed that fecal prevalence, fecal-to-hide transfer, hide-to-carcass transfer, and carcass intervention efficacy significantly affected the risk of carcass contamination (correlation coefficients of 0.37, 0.56, 0.58, and −0.29, respectively). The results indicated that combinations
of preharvest interventions may be particularly important for supplementing harvest interventions during periods of higher variability in fecal shedding prevalence (i.e., summer). Further assessments of the relationships among fecal prevalence and concentration, hide contamination, and subsequent
carcass contamination are needed to further define risks and intervention impacts for E. coli O157 contamination of beef.

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    • "oneragan and Brashears , 2005 ) . Although interventions to reduce carcass contamination during processing are crit - ical to reducing human exposure to E . coli O157 , pre - har - vest interventions to reduce faecal prevalence and faecal to hide transfer were also important when multiple interven - tions were assessed in a risk assessment model ( Dodd et al . , 2011 ) . Risk assessment and prediction models suggest that a reduction in cattle shedding of E . coli O157 during the pre - harvest stage will reduce the burden of human E . coli O157 illnesses ( Rotariu et al . , 2012 ; Matthews et al . , 2013 ; Smith et al . , 2013 ) . Direct - fed microbials are defined by the US Food and Drug administra"
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    ABSTRACT: Human illness due to infections with Escherichia coli O157 is a serious health concern. Infection occurs through direct contact with infected animals or their faeces, through contaminated food or water and/or through person-to-person transmission. A reduction in faecal E. coli O157 shedding in cattle might reduce the burden of human infections. We used systematic review and meta-analysis to assess the efficacy of direct-fed microbials (DFM), compared with placebo or no treatment, fed during the pre-harvest stage of production in reducing faecal E. coli O157 shedding in beef cattle during field trials. Four electronic databases, Nebraska Beef Reports and review article reference lists were searched. A total of 16 publications assessing faecal shedding at the end of the trial and/or throughout the trial period were included. The majority of publicly disseminated trials evaluated the prevalence of E. coli O157 faecal shedding; only two evaluated the concentration of organisms in faeces. The prevalence of faecal E. coli O157 shedding in cattle is significantly reduced by DFM treatments (summary effect size for all DFM – OR = 0.46; CI = 0.36–0.60). The DFM combination Lactobacillus acidophilus (NP51) and Propionibacterium freudenreichii (NP24) was more efficacious in reducing the prevalence of faecal E. coli O157 shedding at the time of harvest and throughout the trial period compared with the group of other DFM, although this difference was not statistically significant. Furthermore, we found that the combination [NP51 and NP24] treatment was more efficacious in reducing the prevalence of faecal E. coli O157 shedding at the time of harvest and throughout the trial period when fed at the dose of 109 CFU/animal/day than any lesser amount, although this difference was not statistically significant. Feeding beef cattle DFM during the pre-harvest stage of production reduces the prevalence of E. coli O157 faecal shedding and might effectively reduce human infections.
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