High prevalence of TCRB, a copper resistance gene, in antibiotic-resistant enterococci from swines and piggeries environment

Copper is largely used as an animal growth-promoter in intensive animal production. Different Portuguese piggeries are reservoir of tcrB gene (coding for copper resistance) which is disseminated in different enterococcal species, samples and piggeries. Resistance to erythromycin seems to be more common among enterococci harbouring tcrB. This gene is frequently transferred using tetracycline or erythromycin as selective agents. The selection of antibiotic resistance bacteria in the animal setting might be associated with the use of antibiotics and/or biocides.