Quantification of airborne dust, endotoxins, human pathogens and antibiotic and metal resistance genes in Eastern Canadian swine confinement buildings

Pig farming practices in Eastern Canada changed drastically into intensified and specialized operations. In large confined finishing facilities, workers are now exposed to concentrated biological particles (bioaerosols) for prolonged periods of time. Occupational exposure to airborne dust, endotoxins, bacteria, human pathogenic agents (Staphylococcus aureus, methicillin-resistant S. aureus, Salmonella spp., Mycobacterium avium, Clostridium difficile and Listeria monocytogenes), and antibiotic and metal resistance genes (cephalosporin, colistin, zinc) were investigated in 10 swine confinement buildings (SCBs). Average concentration in SCBs for airborne total dust and endotoxins was 3.62mg/m(3) and 9.03x10(3)EU/m(3), respectively. All the human pathogenic agents and resistance genes investigated in this study were detected in bioaerosols of at least one SCB, with S. aureus and czrC gene (zinc resistance) being recovered from all buildings. A colistin resistance gene (mcr-1) was found in 6 out of 10 SCBs despite restricted use of the antimicrobial agent in Eastern Canadian swine herds. The present study reinforces the fact that SCBs contain bioaerosols that may contribute to the development of adverse health effects among workers.