Reference | Burow_2019_PrevVeteMedi (10370) (Excluded)

A convenience sample of breeding farms was selected by veterinarians of the animal health services in Bavaria and North Rhine-Westphalia from their client pool. We intended to include 10 herds administering antibiotics to weaners via water, 10 herds administering antibiotics to weaners via feed and 5 herds not treating pigs with antibiotics at all. Veterinarians recruited herds until these sample sizes were reached. Additional herds were recruited at a later date. In each recruited breeding herd, two sows were selected prior to farrowing by the veterinarian in consultation with the owner (58 sows total). All selected sows had had a minimum of three litters, with more than ten weaned piglets per pregnancy. From the litters of each of the two sows, the strongest seven piglets were selected by the veterinarian. Seven piglets were chosen to ensure that a minimum of five piglets was available throughout the study period. The two additional piglets were included as replacements for potential losses among the selected focal pigs per sow. Overall, 406 focal piglets from 29 commercial breeding herds/production chains (13 in Bavaria, 16 in North Rhine-Westphalia) were followed from birth to the end of the relevant fattening periods. 19 of the 29 herds were farrow-to-finish herds, another 9 sold the weaners to fattening farms, and one sold the piglets to a weaning farm, which then sold the weaners on to a fattening farm. Two production chains ended in the same fattening herd. Overall, the 29 production chains linked 39 different herds. Antibiotic treatments of the focal pigs, and all other pigs in contact with these animals, were documented in each production chain during the study period. All 406 study pigs were treated with antibiotics in variable frequencies. Overall, 35% of the pigs, linked to 10 production chains, received no treatment at all. Among those treated (264), most received one treatment (67%). One third of the pigs received more than one treatment (31% twice, 2% three times). In total, 410 antibiotic treatments were administered to the 264 pigs. Most pigs were treated with beta-lactams. However, treatments with polymyxins, tetracyclines and macrolides were also frequent. Treatment documentation of the sows was not collected. The study period lasted from April 2015 (when the first sows gave birth in one breeding herd) until October 2016 (when the last focal pigs in another production chain were finally sampled before slaughter). The study period per individual production chain lasted approximately 6 months.

Rectal swabs were taken once from the sow around farrowing and five times from each focal pig: after birth/while suckling (1), after weaning (2), at the beginning of the fattening period (3), at the beginning of the finishing period (4) and at the end of the finishing period. Of the 406 piglets, 229 were sampled five times as foreseen in the study protocol. A further 79 were sampled four times, 56 three times, 29 twice, and 12 once. At least four E. coli per production chain and sampling point, and one E. coli per litter of each dam and sampling point, were isolated.

AST Method: Broth Microdilution

Reference explicitly reports AST breakpoints: False

Reference reports using a MIC table: False