Chlortetracycline-Resistant Intestinal Bacteria in Organically Raised and Feral Swine

Abstract

Organically raised swine had high fecal populations of chlortetracycline (CTC)-resistant (growing at 64 μg CTC/ml) Escherichia coli, Megasphaera elsdenii, and anaerobic bacteria. By comparison, CTC-resistant bacteria in feral swine feces were over 1,000-fold fewer and exhibited lower taxonomic diversity.