A longitudinal field trial assesing the impact of feeding waste milk containing antibiotic residues on the prevalence of ESBL-producing Escherichia coli in calves.

摘要: A longitudinal field trial was carried out on a farm known to harbour cefotaximase (CTX-M)-positive Escherichia coli, in order assess the impact of feeding waste milk containing antibiotic residues (WM+AR) prevalence these bacteria faeces calves. Fifty calves were alternately assigned one two groups at birth and fed either replacer (control group) or WM+AR (treatment group). Faecal samples collected from all daily for first week after enrolment, twice weekly until weaning, then further six weeks. Environmental calf housing weekly. powdered examined CTX-M-positive E. coli. Total coli faecal enumerated using selective media. Regression analyses performed bacterial count data population-averaged approach based generalised estimating equations (GEE) account repeated measurements individual over time. Cefquinome, fourth generation cephalosporin, detected 87% mean concentration 0.746 mg/l. All environmental sampling locations yielded Significantly more pen floor positive treatment group. Calves group shed greater numbers than control throughout study, shedding decreased slower rate persisted larger number compared with where declined significantly There no difference between proportion isolates that CTX-M-positive. These findings indicate increased amount resistant faeces. Shedding longer WM+AR, weaning.