Effect of in-feed administration of tylosin phosphate on antibiotic resistance in enterococci isolated from feedlot steers
Effect of in-feed administration of tylosin phosphate on antibiotic resistance in enterococci isolated from feedlot steers
Blog Article
Tylosin phosphate is a macrolide commonly administered to cattle in North America for the control of liver abscesses.This study investigated the effect of in-feed administration of tylosin phosphate to cattle at subtherapeutic levels and its subsequent withdrawal on macrolide resistance using enterococci as an Panasonic NN-CS89LB 4-in-1 Combination Steam Oven with Microwave indicator bacterium.Faecal samples were collected from steers that received no antibiotics and steers administered tylosin phosphate (11 ppm) in-feed for 197 d and withdrawn 28 d before slaughter.
Enterococcus species isolated from faecal samples were identified through sequencing the groES-EL intergenic spacer region and subject to antimicrobial susceptibility testing, identification of resistance determinants and pulsed-field gel electrophoresis profiling.Tylosin increased (P 0.05) between treatments on d 225.
This suggests that antibiotic withdrawal prior to slaughter contributes to a reduction in the proportion of macrolide resistant enterococci entering the food chain.Among the 504 enterococci isolates characterised, E.hirae was found to predominate (n=431), Outdoor Loveseat with Cushion followed by E.
villorum (n=32), E.faecium (n=21), E.durans (n=7), E.
casseliflavus (n=4), E.mundtii (n=4), E.gallinarum (n=3), E.
faecalis (n=1), and E.thailandicus (n=1).The diversity of enterococci was greater in steers at arrival than at exit from the feedlot.
Erythromycin resistant isolates harboured the erm(B) and/or msrC gene.Similar PFGE profiles of eryR E.hirae n pre- and post-antibiotic treatment suggests the increased abundance of eryR enterococci after administration of tylosin phosphate reflects selection for strains that were within the bovine gastrointestinal tract of cattle at arrival.