Enumeration and Identification of Microorganisms Present in Bioaerosols in a Bovine Harvesting Facility

Abstract

The objectives of this study were to isolate and enumerate airborne bacteria, yeast and mold, and pathogenic bacteria before and during bovine harvesting in a USDA-inspected processing facility, and determine impact of bioaerosols on chilled carcasses after 24 h cold storage. Air samples were collected before and during three separate bovine harvesting processes at bleeding, hide removal, back splitting, cooler before and after chilling carcasses (0^oC), using an Andersen N6 single stage impactor. Carcass surface bacteria swabs were collected from chilled carcasses after 24 h storage. Except for cooler, total airborne bacteria (TAB), and yeast and mold (YAM) were similar (P> 0.05) before and during harvesting for all areas tested. Counts for coolers were lower (P< 0.05) before harvesting for YAM, and during harvesting for TAB and YAM, when compared to all other counts. Staphylococcus spp. increased during harvesting at bleeding pit and hide removal areas when compared to counts prior to harvesting. Predominant Gram negative airborne bacteria isolated during harvesting and on the carcasses included Enterobacteriaceae, and predominant Gram positive bacteria were Staphylococcus, Microbacterium spp. and Bacillus spp.  Potential pathogens isolated included Staphylococcus aureus, Salmonella Typhimurium, Shigella flexneri, Shigella Sonnei, and Pseudomonas aeruginosa. The isolation of bacteria from air samples and carcass swabs revealed that bioaerosols created during harvesting may be a significant vehicle for transporting bacteria and contributing significantly to cross contamination of bovine carcasses and finished products.  Neither Listeria spp. nor Escherichia coli O157:H7 were isolated from the bioaerosol samples or carcasses.