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ARS Home » Plains Area » Clay Center, Nebraska » U.S. Meat Animal Research Center » Meat Safety and Quality » Research » Research Project #437742

Research Project: Evaluation of Sampling Methods for Detecting, Salmonella and Characterizing Antimicrobial Susceptibility of Salmonella and E. coli in Swine

Location: Meat Safety and Quality

Project Number: 3040-42000-020-01-I
Project Type: Interagency Reimbursable Agreement

Start Date: Mar 1, 2020
End Date: Feb 28, 2022

Objective:
Determine the equivalence of the following aggregate sampling methods: 2 pooled pen-floor fecal samples, 2 boot-socks, and 2 sets of pen-rope-samples for: 1) Detecting prevalence of Salmonella enterica 2) Characterizing the predominant AMR phenotypes of Salmonella and E. coli 3) Characterizing the effects of E.coli isolate sample size (1 to 5) for each of these aggregate sample collection methods on the E. coli AMR phenotypes that are detected.

Approach:
A total of 576 samples will be obtained from 6 swine production facilities. Six samples will be obtained from each pen of grower and finisher pigs. Sixteen pens (8 grower, 8 finisher) will be sampled for Salmonella and 12 of these pens (6 grower, 6 finisher) will also be sampled for E. coli. The 6 samples that will be obtained from each pen will consist of a complete set of aggregate samples: 2 pools of individual pen-floor fecal pats, 2 boot-socks, and 2 sets of ropes. Prior surveillance predicts that 7% and 94% of the samples will be positive for Salmonella and E. coli respectively, this will yield approximately 41 Salmonella and 407 E. coli positive samples. For each Salmonella positive sample, 4 isolates will be obtained for an estimated total of 164 Salmonella isolates. For each E. coli positive sample, 5 isolates will be obtained for an estimated total of 2,035 E. coli isolates. Antimicrobial susceptibilities (Minimum Inhibitory Concentrations) for each of 14 antimicrobials included in CMV3AGNF plate (azithromycin, chloramphenicol, tetracycline, cefoxitin, ceftriaxone, ceftiofur, ampicillin, amoxicillin-clavulanic acid, ciprofloxacin, gentamicin, nalidixic acid, sulfisoxazole, trimethoprim-sulfamethoxazole, and streptomycin) will be obtained for the expected 164 Salmonella and 2,035 E. coli isolates.