Salmonella in Feed and the Relationship to Strains Found in Swine Fecal and Envrionmental Samples
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Publisher:The Ohio State University
Series/Report no.:The Ohio State University. Department of Microbiology Honors Theses; 2011
Abstract: Salmonella is a zoonotic foodborne pathogen with several common serotypes which can be ingested through contaminated meat. Feed, environmental, and fecal samples were all found to contain Salmonella in a previous study conducted by the IDMEL. The purpose of this new study was to identify and characterize the possible role of Salmonella in the feed, and its phenotypic and genotypic relationship with fecal and environmental samples. A total of 280 isolates were tested and categorized based on serogrouping, genotyping, antimicrobial susceptibility testing, and PFGE DNA fingerprinting. The results demonstrated five genotypic clusters of highly similar isolates. Four of these clusters showed a genotypic relationship between the isolates of feed origin and those of fecal origin. The four clusters identified with feed and fecal isolate relationships were serogroup B with AmStTeKm resistance, serogroup C with SuTe resistance, serogroup B with Te resistance, and serogroup E with Te resistance. The study also identified a high proportion of multi-drug resistant isolates. The most common multi-drug resistant patterns were SuTe (20.4%), Te (28.2%), and AmStTeKm (12.9%). Serogroups C (26.8%), E (13.6%), and B (42.5%) were found to be the most common. These patterns were found in the feed and fecal samples from the same barn at the same collection time. The significance of finding multidrug resistant, epidemiological connections between the isolates indicates feed as an important source of contamination. Therefore targeted intervention measures may be designed to reduce transmission and contamination of Salmonella, particularly multi-drug resistant strains, into the food supply.