EN
The mechanisms of antibiotic resistance of bacteria have been presented, including spontaneous mutation, gene transfer and selection. Examples of the contribution of antimicrobial growth promoters to the domination of antibiotic resistant bacteria, pathogenic for humans and animals in bacterial populations, have been cited. The results obtained were the basis for the introduction of a ban prohibiting the use of antimicrobial growth promoters in animal feeds in Sweden, Denmark and some other Western European countries. The bans have resulted in a significant decrease of the number of antibiotic resistant bacteria in the animal reservoir, being of importance for public health. Taking this into account, since January the 1st 2006 the European Union has introduced a ban on the use of antimicrobial growth promoters for food animals for all member countries. Besides the positive effects of the earlier bans, negative consequences have also been observed, such as an increase of bacterial diseases and mortality in young poultry and weaners, higher expenses for veterinary interventions, a decrease of daily body gain and feed effectivity. The negative effects were noticed particularly in farms with insufficient animal welfare and management. Opinions have been cited indicating that the risk to human health connected with the use of antibiotics in food animals, including growth promoters, was not as high as expressed by the public health representatives. Final conclusions on this topic, however, require further research.