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United States Department of Agriculture

Agricultural Research Service

Research Project: Narms Pilot Study – Impact of Lairage on Capturing Antimicrobial Resistance and Use Data in Swine Project Number: 0204-41510-001-50
Project Type: Grant

Start Date: Aug 01, 2013
End Date: Sep 30, 2014

Objective:
1) Examine the potential impact of normal lairage practices on Salmonella and Campylobacter species antimicrobial resistance patterns post evisceration using cecal populations as the determinant measures. 2) To determine differences in Salmonella and Campylobacter responses to lairage and their respective ability to rapidly uptake antimicrobial resistant organisms as measured by differences in arrival fecal and post-evisceration cecal populations. 3) Based on analysis of datasets acquired in objectives 1 and 2, formulate a sampling strategy to evaluate on-farm antimicrobial resistance patterns at a point of first concentration – the abattoir lairage environment.

Approach:
This project will generate a dataset of Salmonella and Campylobacter species isolates which can be compared within and between lots of pigs from different locations presented to harvest at a high capacity abattoir in Iowa. This dataset will be representative of sampling that could be obtained from the majority of such locations (Number= <35) in the USA which harvest over 90% of market swine production (but which represents >95% of USA production capacity). This factor speaks to the scalability of the data generated, and its future utility as a surveillance tool. With the help of the cooperating abattoir we will select and sample two lots of farm direct market swine per day at the rate of 10 fecal and 10 cecal samples each. Environmental contributions of lairage will be assessed with 10 fecal samples collected in disparate pens of the lairage on the day of sampling. This will be repeated 7 days to provide 14 groups of swine from different locations for analysis. A total of 350 samples will be collected during this pilot. All samples will be cultured for Salmonella and Campylobacter species based on established culture morphology and biochemical reactions. Three typical isolates of each will be picked from culture media for further processing. All isolates will be identified and confirmed as Salmonella or Campylobacter, then subjected to evaluation by the NARMS panel for antimicrobial resistance and, for Salmonella isolates, serotype confirmation. Once that dataset is constructed epidemiologic techniques will be used to determine the effects of lairage on antimicrobial resistance pattern distribution for each target organism. Second, this dataset will be used to evaluate whether sufficient differences between Salmonella and Campylobacter isolations exist to justify a more in-depth exploration of lairage effects on Campylobacter transfer of antimicrobial resistance. The goal of further experimentation would be to clarify Campylobacter characterization as an on-farm marker for antimicrobial resistance prevalence. Third, analyses of the dataset will be used to determine appropriate sampling levels at the abattoir to achieve statistical results based on variations determined from this pilot. Fourth, the isolates characterized in this project will be retained and made available to evaluate additional biochemical tools in search of more definitive and reproducible attributes that can be developed into a more accurate and credible surveillance tool. Similarly the results may demonstrate that the abattoir cecal sample is not the appropriate measure to determine swine production site antimicrobial resistance patterns given current tools and understanding of the relationships between farm and abattoir populations. Results of these analyses will be presented at scientific conferences and in scientific journals to help inform future studies on antimicrobial resistance prevalence at the production site level. By selection and validation of the appropriate organisms and their laboratory characterization methods algorithms to predict production site resistance presence without direct sampling of production sites may be developed.

Last Modified: 9/10/2014
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