Enumeration and identification of microorganisms present in bioaerosols in a swine harvesting facility

Abstract

The objectives of this study were to isolate and enumerate airborne bacteria, and yeast and mold before and during pork harvesting in a USDA-inspected processing facility, and determine the impact of bioaerosols on the harvesting and chill room environments. Air samples were collected before and during three separate pork harvesting processes at the bleeding, dehairing, and back splitting areas and in the holding cooler (0^oC), using an Andersen N6 single stage impactor. Carcass surface bacteria swabs were collected from the chilled carcasses after being held in the cooler for 24 h. Total airborne bacteria, Staphylococcus spp., and Enterobacteriaceae counts increased (P < 0.05) during harvesting when compared to counts prior to harvest. Predominant Gram negative airborne bacteria isolated during harvesting included Enterobacteriaceae and Pseudomonadaceae families, and predominant Gram positives were Staphylococcus, Microbacterium, Bacillus and Micrococcus species.  Potentially pathogenic Staphylococcus aureus and Salmonella spp. were isolated from bioaerosols generated during harvesting and from the pork carcasses.  Neither Listeria spp. nor Escherichia coli O157:H7 were isolated from the bioaerosol samples or carcasses. The isolation of Staphylococcus and Salmonella from air samples and carcass swabs revealed that bioaerosols during harvesting may transport bacteria and contribute significantly to contamination of pork carcasses, and the resulting finished products.