EN
The definition of antibiotics and disinfectants (biocides) has been presented. Pre-existence of antimicrobial resistance in bacteria was mentioned. The ability of bacteria to develop antibiotic resistance was characterized. Different mechanisms by which a bacterial population can develop resistance to one antibiotic and simultaneously to several antibiotics have been defined. It was stressed that the most frequent mechanism responsible for the acquisition of antibiotic resistance by a bacterial cell is the occurrence of horizontal gene transfer (HGT) between a resistant bacterial strain and a susceptible one. Remarks concerning the selection of resistant bacteria against one or more antibiotics simultaneously were given. It was concluded that prudent use of antibiotics in veterinary medicine should be obligatory, because reducing the use of these drugs is very important in controlling antibiotic resistance in bacteria, including pathogens. In the second part of the paper the resistance of bacteria to disinfectants was described. It was demonstrated that the mechanisms of bacterial resistance between antibiotics and disinfectants differ: however, similarities also exist. As in case of disinfectants, prudent use was also advised.