Susceptibility to tulathromycin in Mannheimia haemolytica isolated from feedlot cattle over a three-year period

Frontiers in Microbiology

Cassidy L. Klima¹  Tim A. McAllister¹  Trevor W. Alexander¹  Ed eTopp¹  Shaun R. Cook¹ 

[1] Agriculture and Agri-Food Canada;

关键词: Cattle;    Mannheimia haemolytica;    antimicrobial resistance;    tulathromycin;    feedlot;   

DOI  :  10.3389/fmicb.2013.00297

来源: DOAJ

【 摘 要 】

Mannheimia haemolytica isolated from feedlot cattle were tested for tulathromycin resistance.Cattle were sampled over a three-year period, starting 12 months after approval of tulathromycin for prevention and treatment of bovine respiratory disease.Nasopharyngeal samples from approximately 5,814 cattle were collected when cattle entered feedlots (N = 4) and again from the same cattle after ≥ 60 d on feed.The antimicrobial use history for each animal was recorded. Mannheimia haemolytica was isolated from 796 (13.7%) entry samples and 1,038 (20.6%) ≥ 60 d samples.Of the cattle positive for M. haemolytica, 18.5%, 2.9%, and 2.4% were administered therapeutic concentrations of tulathromycin, tilmicosin, or tylosin tartrate, respectively.In addition, 13.2% were administered subtherapeutic concentrations of tylosin phosphate in feed.In years one and two, no tulathromycin-resistant M. haemolytica were detected, whereas 5 isolates (0.4%) were resistant in year three.These resistant isolates were collected from three cattle originating from a single pen, were all serotype 1, and were genetically related (≥ 89% similarity) according to pulsed-field gel electrophoreses patterns.The five tulathromycin-resistant isolates were multi-drug resistant also exhibiting resistance to oxytetracycline, tilmicosin, ampicillin, or penicillin. The macrolide resistance genes erm(42), erm(A), erm(B), erm(F), erm(X) and msr(E)-mph(E), were not detected in the tulathromycin-resistant M. haemolytica.This study showed that tulathromycin resistance in M. haemolytica from a general population of feedlot cattle in western Canada was low and did not change over a three-year period after tulathromycin was approved for use in cattle.

【 授权许可】

Unknown