Antibiotikaeinsatz in der Bayerischen Schweinehaltungspraxis ABYS: Antibiotikaeinsatz und Antibiotikaresistenz in ökologischen Betrieben

Between 2012 and 2014, ABYS study recorded antibiotic use, detection and resistance data for 23 organic and 35 conventional pig farms. Antibiotic contents of farm-made fertilizers were assessed by LC/MS-MS. Phenotypic antimicrobial resistance was investigated in Escherichia (E.) coli (indicator bacteria); antimicrobial resistance genes of the total bacterial microbiota (sul(II), tet(A), tet(B), tet(M); marker Measured in nUDD (number of animals treated multiplied by treatment days), colistin was the most frequently used antibiotic, in organic farms followed by tylosin, doxycycline and amoxicillin. Antibiotic residues were rarely detected; however, manure contained up to 10^8 antimicrobial resistance genes per gram; concentrations were higher when the antibiotic had been used on farm. In six farms, antimicrobial resistant E. coli were tracked from the moment when pigs were placed on farm. Some isolates carried a broad variety of resistances from the very beginning that were maintained until slaughter, despite the fact that partly no antibiotics were applied during fattening. Approaches for reducing carry-over of antimicrobial resistant bacteria will be discusse