Reference | Heider2009 (10207)

Objective—To estimate the relationship between therapeutic use of ceftiofur and recovery of Escherichia coli and Salmonella spp with reduced susceptibility to ceftriaxone from feces of dairy cattle. A cross-sectional study of a convenience sample of 50 Ohio dairy herds was conducted. Nine veterinarians in private practice were con-tacted from across the state of Ohio for help in the recruitment of prospective dairy herd study participants. Herds were voluntarily enrolled in the study if dairy herd owners permitted the investigators to collect fecal samples from their cows and if the dairy herd owners or managers would agree to answer survey questions regarding demographic and antimicrobial usage on their farm. Samples were collected from each herd a single time between the summer of 2004 and the spring of 2006. In the laboratory, selective media were used in an attempt to recover E coli with reduced susceptibility to ceftriaxone and Salmonella spp from each fecal sample. At the time of sample collection, dairy herd owners or managers were given a short survey that assessed basic herd demographic information and antimicrobial use on the farm, including ceftiofur. Information was collected on cattle in all stages of production and also on antimicrobials used to treat various types of diseases on each farm. Owners of the study herds were contacted by telephone and asked to report the proportion of cows that were treated with ceftiofur in a 3-month period (January 1 through March 31, 2006) according to farm records. This variable was used as the primary risk factor of interest. Of the 50 herds initially enrolled in the study, only 43 herds provided this additional information, and the remaining 7 herds were not included in the final analysis.

Sampled 3,840 mature dairy cows on 50 dairy herds in Ohio. Fresh fecal samples were collected from all lactating cows in study herds that were milking < 100 cows. In herds that were milking > 100 cows, a maximum of 100 fecal samples were collected from lactating cows. Approximately 25g of feces was obtained from the rectum of each cow by use of individual palpation sleeves. Samples were placed in individual containers to prevent cross-contamination, transported to the laboratory, and processed on the day of collection.

AST Method: Agar Dilution

Reference explicitly reports AST breakpoints: True

Reference reports using a MIC table: False