Reference | Gast1987 (20031) (Excluded)

The Single Comb White Leghorn chicks used in Experiment 1 were obtained from the poultry farm at The Ohio State University in Columbus, Ohio. Turkey poults for Experiments 2, 3, 4, and 5 were from a line maintained at the Ohio Agricultural Research and Development Center in Wooster, Ohio (Nestor, 1980). Each group of newly hatched chicks or poults was housed in a modified Horsfall-Bauer isolation unit and provided water and antibiotic-free starter feed ad libitum. In all experiments, an Escherichia coli culture (hereafter designated as EC) was used as a donor of drug resistance determinants. This culture, obtained from Colorado Animal Research Enterprises in Fort Collins, Colorado, was resistant to kanamycin (kan), tetracycline (tet), and ampicillin (amp). In Experiment 1, a strain of Salmonella arizonae (hereafter referred to as SA) obtained from the National Veteri n a r y Services Laboratories in Ames, Iowa, was utilized as a plasmid recipient. This culture demonstrated resistance to nalidixic acid (nal) and streptomycin (str). In Experiments 2-5, a strain of Salmonella typhimurium (hereafter designated as ST) obtained from Colorado Animal Research Enterprises was used as the plasmid recipient. The three determinants were always transferred together, indicating a close degree of genetic linkage. All testing for antibiotic susceptibility was by the standardized single disc method of Bauer et_ a_l. (1966), using BBL Sensi-Discs

After the chicks or poults were sacrificed by cervical dislocation, tissues were aseptically removed and tested for the presence of the coliform and Salmonella strains. Intestinal samples consisted of approximately 2.5 cm segments, removed from the proximal ends of the ceca and adjacent regions of the large and small intestines. Liver samples of approximately 2 g each were also removed. From each bird sacrificed in these studies, three intestinal samples and three liver samples were removed. One sample of each type was evaluated for the presence of EC, one for the presence of ST (or SA in Experiment 1), and the final sample was tested for the presence of ST (or BA) which had received kan, tet, and amp resistance determinants from EC. After removal, each sample was transferred directly to a tube of broth media.

AST Method: None

Reference explicitly reports AST breakpoints: True

Reference reports using a MIC table: True