Reference | Beach_2002_JoofFoPr (10359)

Two types of cattle were sampled in this study: feedlot cattle and nonfeedlot (adult) beef cattle. Feedlot cattle were sampled from July to September, and nonfeedlot cattle were sampled from October to December. The feedlot and the farms were located in the central part of Texas. One hundred feedlot cattle were sampled (25 cattle on each of four different sampling days). All of the feedlot cattle were transported from the same feedlot and slaughtered at the same plant, located 15 miles away. Ninety-six nonfeedlot cattle were sampled (25 cattle on each of two sampling days, 26 cattle on one sampling day, and 20 cattle on one sampling day). The nonfeedlot cattle were transported from one of two different farms and slaughtered at the same plant, which was not the same plant used for the feedlot cattle. The farms were located 29 miles from the plant. The cattle were identified by unique ear tag numbers at the feedlot or farm, and these specific identification numbers were used throughout the process for each sample to identify the cow from which that sample was derived.

Eight swab samples were collected:(A) pretransit rectal swabs, (B) pretransit hide swabs, (C) pretransit environmental swabs from the transport vehicle, (D) posttransit rectal swabs, (E) posttransit hide swabs, (F) posttransit environmental swabs from the transport vehicle, (G) environmental swabs from the holding pen and knock box, and (H) postslaughter carcass swabs. At the feedlot or farm, cattle were restrained in a squeeze chute for the collection of rectal and hide swabs. At the slaughter facility, rectal and hide swabs were obtained from the cattle either while the animal was in the chute leading to the knock box or after the animal had been hung on the rail. Carcass swabs were acquired following hide and viscus removal and prior to any carcass decontamination procedure. Rectal swabs (samples A and D) were collected with the BBL Cultureswab (with Cary-Blair medium and a single plastic applicator; Becton Dickinson, Sparks, Md.). The swab was inserted approximately 10 cm into the rectum until appropriate fecal material covered the swab. Hide (samples B and E) and carcass(sample H) swabs were collected with the Biopro Sampling System (International Bioproducts, Seattle, Wash.). Sterile sponges were hydrated with 25 ml of sterile Butterfield’s buffer (International Bioproducts) approximately 12 h before they were used. Sponge swabs were collected from the hide with sterile disposable gloves. Approximately 100 cm^2 was swabbed in the area immediately ventral to the tuber ischii (commonly called the pin bone) in the hindquarter region. Sterile disposable gloves were also used to collect sponge swabs from the carcass. Approximately 100 cm^2 was swabbed in the brisket region anterior to the navel on the ventral midline. Following collection of the hide and carcass sponge swabs, each sponge was placed into a unique square 60-ml Nalgene wide-mouth bottle containing 10 ml of Cary-Blair transport medium. Drag swabs of the floor and sponge swabs of the walls were collected from the transport vehicle before the cattle were loaded (sample C) as well as from the slaughter facility after the cattle were unloaded (sample F). Furthermore, whenever possible, drag swabs were obtained from the holding pen at the slaughter facility before the cattle entered the pen and after they vacated the pen (sample G). Sponge swabs were also obtained from the knock box whenever possible (sample G). After collection, drag swabs were placed in unique round 250-ml Nalgene wide-mouth polyethylene bottles (Nalge) containing 30 ml of 23 skim milk (Difco). After collection, sponge swabs were placed in unique square 60-ml Nalgene widemouth bottles (Nalge) containing 10 ml of Cary-Blair transport medium (Difco).

AST Method: Disk Diffusion

Reference explicitly reports AST breakpoints: False

Reference reports using a MIC table: False