Contamination of beef lean and fat tissue surfaces by Salmonella typhimurium and Listeria monocytogenes was evaluated using phosphate buffer or sterilized manure as an inoculation menstruum. Immersion in inoculated phosphate buffer resulted in an increase in numbers of attached cells during the 120 min inoculation for both bacterial species. Tissue immersed in inoculated manure generally showed an increase in cell numbers up to 10 min of immersion with only slight increases in cell numbers from 10 to 120 min. Fewer cells attached to either tissue type from the manure inoculum (P<0.05), although actual numerical differences were small.
1Present address: Ft. Keogh Livestock & Range Research Station, Rt. 1, Box 2021, Miles City, MT 59301.
2Mention of trade names, proprietary products, or specific equipment does not constitute a guarantee or warranty of the product by the USDA and does not imply its approval to the exclusion of other products that may also be suitable.