R G Amachawadi1, H M Scott1,2, C Aperce3, J Vinasco2, J S Drouillard3, T G Nagaraja1. 1. Department of Diagnostic Medicine and Pathobiology, Kansas State University, Manhattan, KS, USA. 2. Department of Veterinary Pathobiology, Texas A&M University, College Station, TX, USA. 3. Department of Animal Sciences and Industry, Kansas State University, Manhattan, KS, USA.
Abstract
AIMS: The objective was to investigate whether in-feed supplementation of copper, at elevated level, co-selects for macrolide resistance in faecal enterococci. METHODS AND RESULTS: The study was conducted in cattle (n = 80) with a 2 × 2 factorial design of copper (10 or 100 mg kg(-1) of feed) and tylosin (0 or 10 mg kg(-1) of feed). Thirty-seven isolates (4·6%; 37/800) of faecal enterococci were positive for the tcrB and all were Enterococcus faecium. The prevalence was higher among cattle fed diets with copper and tylosin (8·5%) compared to control (2·0%), copper (4·5%) and tylosin (3·5%) alone. All tcrB-positive isolates were positive for erm(B) and tet(M) genes. Median copper minimum inhibitory concentrations (MICs) for tcrB-positive and tcrB-negative enterococci were 20 and 4 mmol l(-1) , respectively. CONCLUSIONS: Feeding of elevated dietary copper and tylosin alone or in combination resulted in an increased prevalence of tcrB and erm(B)-mediated copper and tylosin-resistant faecal enterococci in feedlot cattle. SIGNIFICANCE AND IMPACT OF THE STUDY: In-feed supplementation of elevated dietary copper has the potential to co-select for macrolide resistance. Further studies are warranted to investigate the factors involved in maintenance and dissemination of the resistance determinants and their co-selection mechanism in relation to feed-grade antimicrobials' usage in feedlot cattle.
AIMS: The objective was to investigate whether in-feed supplementation of copper, at elevated level, co-selects for macrolide resistance in faecal enterococci. METHODS AND RESULTS: The study was conducted in cattle (n = 80) with a 2 × 2 factorial design of copper (10 or 100 mg kg(-1) of feed) and tylosin (0 or 10 mg kg(-1) of feed). Thirty-seven isolates (4·6%; 37/800) of faecal enterococci were positive for the tcrB and all were Enterococcus faecium. The prevalence was higher among cattle fed diets with copper and tylosin (8·5%) compared to control (2·0%), copper (4·5%) and tylosin (3·5%) alone. All tcrB-positive isolates were positive for erm(B) and tet(M) genes. Median copper minimum inhibitory concentrations (MICs) for tcrB-positive and tcrB-negative enterococci were 20 and 4 mmol l(-1) , respectively. CONCLUSIONS: Feeding of elevated dietary copper and tylosin alone or in combination resulted in an increased prevalence of tcrB and erm(B)-mediated copper and tylosin-resistant faecal enterococci in feedlot cattle. SIGNIFICANCE AND IMPACT OF THE STUDY: In-feed supplementation of elevated dietary copper has the potential to co-select for macrolide resistance. Further studies are warranted to investigate the factors involved in maintenance and dissemination of the resistance determinants and their co-selection mechanism in relation to feed-grade antimicrobials' usage in feedlot cattle.
Authors: Casey L Cazer; Erin R B Eldermire; Guillaume Lhermie; Sarah A Murray; H Morgan Scott; Yrjö T Gröhn Journal: Prev Vet Med Date: 2020-02-18 Impact factor: 2.670
Authors: Katherine L Huebner; Jennifer N Martin; Carla J Weissend; Katlyn L Holzer; Jennifer K Parker; Steven M Lakin; Enrique Doster; Margaret D Weinroth; Zaid Abdo; Dale R Woerner; Jessica L Metcalf; Ifigenia Geornaras; Tony C Bryant; Paul S Morley; Keith E Belk Journal: Sci Rep Date: 2019-02-22 Impact factor: 4.379
Authors: Gabhan Chalmers; Kelly M Rozas; Raghavendra G Amachawadi; Harvey Morgan Scott; Keri N Norman; Tiruvoor G Nagaraja; Mike D Tokach; Patrick Boerlin Journal: Genes (Basel) Date: 2018-10-18 Impact factor: 4.096