Impact of added copper, alone or in combination with chlortetracycline, on growth performance and antimicrobial resistance of fecal enterococci of weaned piglets

• Published in: Journal of animal science 2020-03, Vol.98 (3), p.1-11
• Main Authors: Capps, Kaylen M, Amachawadi, Raghavendra G, Menegat, Mariana B, Woodworth, Jason C, Perryman, Kurt, Tokach, Mike D, Dritz, Steve S, DeRouchey, Joel M, Goodband, Robert D, Bai, Jianfa, Apley, Mike D, Lubbers, Brian V, Nagaraja, Tiruvoor G
• Format: Article
• Language: English
• Subjects: Abundance; Acclimation; Acclimatization; Animal Feed - analysis; Animals; Anti-Bacterial Agents - pharmacology; Antibiotics; Antimicrobial resistance; Bacteria; Bacterial Proteins - pharmacology; Chloramphenicol; Chloromycetin; Chlortetracycline; Chlortetracycline - administration & dosage; Chlortetracycline - pharmacology; Copper; Copper - administration & dosage; Copper - pharmacology; Daptomycin; Deoxyribonucleic acid; Diet; Diet - veterinary; DNA; Drug resistance; Drug Resistance, Bacterial - drug effects; Enterococcus; Enterococcus - drug effects; Erythromycin; Factorial design; Feces - microbiology; Genetics; Gentamicin; Hogs; Kanamycin; Lincomycin; Linezolid; Male; Microbial Sensitivity Tests - veterinary; Microbiology and Microbiome; Minimum inhibitory concentration; Sampling; Streptomycin; Sulfate; Swine - growth & development; TCRB gene; Tigecycline; Tylosin
• ISSN: 0021-8812; 1525-3163; 1525-3163
• DOI: 10.1093/jas/skaa003

Abstract Studies suggest a link between added copper (Cu) and co-selection of antimicrobial resistance (AMR) in Enterococcus spp., but data are inconsistent. This study aimed to assess the impact of added Cu, alone or with a feed-grade antimicrobial, on growth performance, transferable Cu resistance gene (tcrB) prevalence, abundance of tcrB in fecal community DNA, and AMR in fecal enterococci in weaned piglets. A total of 320 barrows (DNA 200 × 400, DNA Genetics) weaned at approximately 21 d of age with 7.4 kg (7.4 ± 0.06 kg) BW were used in a 28-d study. Piglets were fed a common non-medicated diet for 7 d of acclimation. Treatments were arranged in a 2 × 2 factorial design with main effects of added Cu (0 vs. 200 mg/kg Cu from Cu sulfate) and chlortetracycline (0 vs. 440 mg/kg CTC). Growth performance and fecal samples were obtained on days 0, 14, and 28. There was no evidence (P > 0.05) for Cu and CTC interaction in growth performance. Pigs fed diets with added Cu had increased (P  0.05) from days 15 to 28 and 0 to 28. Pigs fed diets with CTC had improved (P  0.05). Prevalence of tcrB-positive enterococci was higher on day 14 than other sampling days (P = 0.002). Prevalence of tetracycline resistance gene [tet(M)]-positive enterococci was not affected by treatments or day (P > 0.05). Prevalence of macrolide resistance gene [erm(B)]-positive enterococci had a significant treatment and sampling day interaction (P = 0.021). The abundance of the tcrB gene in feces, quantified by PCR, was not affected by Cu treatment. The median Cu minimum inhibitory concentrations (MIC) of tcrB-negative and -positive isolates were 3 and 20 mM, respectively (P