Reference | Berge_2005_VeteRese (10248) (Excluded)

The objective of this study was to examine the effect of a single therapeutic dose of florfenicol on antimicrobial susceptibility patterns in faecal E. coli of steers within one month post treatment. Angus and Angus crossbred steers (n = 370), weighing approximately 270 kg were purchased directly from source A (n = 196) and B (n = 174). Cattle were used in two nutrition experiments, apart from the study here. Cattle were housed in 42 open concrete floor pens (8–10 head/pen). The ionophore monensin was incorporated into the diet at a rate of 20 grams/ton of feed, and was the only antimicrobial in feed or water. Two cattle from each pen (n = 84) were randomly enrolled into the study. At study day 11, one study animal from half the pens (n = 21) was randomly selected to receive a single 39.6 mg/kg dose of florfenicol by subcutaneous injection. The use of this treatment regime was within label indications.

Serial rectal faecal samples were obtained using cotton tipped swabs from all study animals on days 1, 14, 28, and 42. A total of 48 steers in 24 pens from source A and 36 steers in 18 pens from source B were sampled.

AST Method: Disk Diffusion

Reference explicitly reports AST breakpoints: True

Reference reports using a MIC table: False