“…The transfer of antibiotic resistance determinants from human and livestock sources to the environment has gained attention in the scientific community in the past decade (Silbergeld et al, 2008;Storteboom et al, 2010;Wright, 2010), with antibiotic resistance genes (ARGs) considered as emerging environmental contaminants (Pruden et al, 2006). Human wastes are nowadays better treated by centralized wastewater treatment plants than animal wastes with simple treatment systems such as lagoon and digester or even without any treatment before their discharge into the environment (McKinney et al, 2010;Liu et al, 2012;Zhou et al, 2013;He et al, 2014;Su et al, 2014b;Chen et al, 2015). In comparison with other livestock animals (broiler and cattle), antibiotics are commonly used as growth promoter in swine farming (Zhou et al, 2013;Durso and Cook, 2014), thus swine feedlots are of particular concern as potential hot spots for promoting the dissemination of antibiotic resistance (Gotz and Smalla, 1997;Cole et al, 2000;Binh et al, 2008).…”