show Abstracthide AbstractThe VASIB project included 30 piglet-producing German farms. Those were tested within a one-year period. Bronchoalveolar lavage fluid (BALFs) samples, of healthy or respiratory tract diseased piglets, served for cultivation of respiratory tract pathogens. Besides, BALFs of diseased piglets were collected, before and after antimicrobial treatment. Further, antimicrobial residues were measured in piglet environment as well as piglet plasma.The aim of the study was to determine phenotypic and genotypic antimicrobial resistances in respiratory tract pathogens, e.g. S. suis. Additional, possible gene transfer or special mutations that mediate antimicrobial resistances were examined. Resistances were observed under the aspect of antimicrobial selection pressure during therapy or environmental antimicrobial residues.