Bayleyegn Molla from the College of Veterinary Medicine at the Ohio State University and colleagues there and at North Carolina State University published a paper in Applied and Environmental Microbiology into the occurrence of Salmonella enterica in pig feed.

The researchers explain that the purpose of this study was to determine the occurrence and genotypic relatedness of Salmonella enterica isolates recovered from feed and faecal samples in commercial swine production units.

Of 275 feed samples, Salmonella was detected in 10 feed samples that originated from eight of 36 (22.2 per cent) barns, with a prevalence of 3.6 per cent (10 out of 275 samples).

In faecal samples, a prevalence of 17.2 per cent was found at the early finishing stage (1,180 out of 6,880 samples), with a significant reduction in prevalence (7.4 per cent) when pigs reached market age (392 out of 5,321 samples).

Of the 280 Salmonella isolates systematically selected for further characterization, 50 per cent of the feed isolates and 55.3 per cent of the isolates of faecal origin showed similar phenotypes based on antimicrobial resistance patterns and serogrouping. About 44 per cent of the isolates were multi-drug resistant.

Pulsed-field gel electrophoresis (PFGE) genotyping grouped the 46 representative isolates into five genotypic clusters, of which four of the clusters consisted of genotypically related isolates recovered from feed and fecal samples.

Molla and co-authors conclude that the occurrence of genotypically related and, in some cases, clonal strains, including multidrug-resistant isolates in commercially processed feed and faecal samples, suggests the high significance of commercial feed as a potential vehicle of Salmonella transmission.

Reference

Molla B., A. Sterman, J. Mathews, V. Artuso-Ponte, M. Abley, W. Farmer, P. Rajala-Schultz, W.E.M. Morrow and W.A. Gebreyes. 2010. Salmonella enterica in commercial swine feed and subsequent isolation of phenotypically and genotypically related strains from faecal samples. Applied and Environmental Microbiology, 76 (21): 7188-7193. doi:10.1128/AEM.01169-10

Further Reading

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