Reference | Benazet_1980_Poulscie (10362)

In the first experiment two groups (A and C) of 10 chicks each were fed a diet without nosiheptide and two groups (B and D) of 10 each a diet supplemented with nosiheptide at 20 g/t. Groups A and B were inoculated orally with a strain of Salmonella typhimurium, var. Copenhagen. Groups C and D were not infected. At intervals after inoculation the following data were collected: the number of salmonella excreted per gram of feces, the proportion of salmonella resistant to antibacterial agents commonly used in human and veterinary medicine, and their degree and spectrum of resistance. In the second experiment two groups of 10 chicks each were fed as follows: group E (control group) a diet without nosiheptide (basal diet) and group F the basal diet for the first 15 days then the nosiheptide-supplemented diet (20 g/t) for the following 33 days. The day before the nosiheptide-supplemented feed was given for the first time and at the end of the experiment (33 days later) the proportion of fecal coliforms resistant to antibacterial agents commonly used in human and veterinary medicine as well as their degree and spectrum of resistance was determined in both groups of chicks. For both experiments, the feed to which nosiheptide had been added was given from the time the chicks were 16 days old (5 days before inoculation with salmonella in the first experiment) until the end of the experiments. For the first experiment, 40 unsexed Selaf 915 chicks, 1 day of age, were obtained from the Poultry Research Station of Magneraud, Institut National de la Recherche Agronomique (INRA). For the first 15 days, chicks were housed together in a heated battery. From the 16th day they were housed individually in 4 groups (batteries) of 10 chicks each. Groups A and C were placed in the same room and groups B and D in an adjoining room. A strain of Salmonella typhimurium, var. Copenhagen (variant resistant to nalidixic acid of the strain DVR 101) was used for the first experiment. The microorganism was sensitive to the following antibacterial agents: ampicillin, cephalothin, chloramphenicol, furazolidone, gentamicin, kanamycin, neomycin, streptomycin, and tetracycline. It was resistant to sulfadiazine and nalidixic acid. Chicks that were 21 days of age were inoculated orally using a syringe (groups A and B); 6.4 x 10^5 organisms were given to each chick of 1 mL. For the second experiment, 20 unsexed chicks, (DERCO 309 strain) 1 day of age, were obtained from the De Rycke Hatchery. The chicks were first housed together and then individually in two groups (E and F) of 10 each. The two batteries were placed in two adjoining rooms as in the first experiment.

In the first experiment, confirmation of the absence of Salmonella in chicks before inoculation was determined on the 7th and 6th days before inoculation by sampling 1 g of feces from each chick (aliquot from 6 to 7 g of fresh dropping). Bacteriological tests of feces were conducted for each chick on days 2, 4, 6, 8, 10, 12, 14, 21, and 28 postinoculation. Each sample was 1 g in size. In the second experiment, a sample was removed from the cloaca of each chick using a sterile swab. The swab was rinsed in 2 ml of sterile glucose peptone water. Samples were collected twice: immediately before treatment, and at the end of the treatment.

AST Method: Unclear

Reference explicitly reports AST breakpoints: Uncertain

Reference reports using a MIC table: False