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To determine the prevalence, levels, genetic fingerprints and antibiotic susceptibility of L. monocytogenes isolated from the beef-processing environment.
The NCBA will collect 500 environmental and carcass samples from each of two beef slaughtering plants over the course of five months between May and October 2002 for a total of approximately 5000 samples. Two commercial laboratories will perform the necessary approved microbiological analyses on each of the 5000 collected samples to isolate, detect and confirm the presence of the pathogen, Listeria monocytogenes. The labs will then provide ARS with a confirmed L. monocytogenes isolate from each positive sample and 2-3 isolates of other Listeria species. Upon receipt of the isolates, ARS will catalog and maintain stock cultures of the confirmed L. monocytogenes isolates and the unconfirmed Listeria isolates. The unconfirmed isolates will be analyzed to confirm whether or not they are L. monocytogenes. All confirmed L. monocytogenes isolates will be characterized by pulsed field gel electrophoresis (PFGE), ribotyping and antibiotic susceptibility testing.