Antibacterial substances are used in considerable amounts as growth promoters in animal husbandry. There are, however, incalculable risks for human health resulting from the use of particular feed additives. Even 30 years ago the detection of transferable antibiotic resistance in Enterobacteriaceae led to the demand that antibiotics used in human chemotherapy, or for which cross-resistance against human therapeutics has been demonstrated, should be prohibited as growth promoters. The application of molecular methods to typing and characterization of bacteria and their resistance genes has provided more concise evidence for the transfer of antibiotic resistance among animal husbandry and humans as to resistance to glycopeptides (vanA gene cluster) and to streptogramins (satA).