RESISTANCE TO ANTIMICROBIAL AGENTS USED FOR ANIMAL THERAPY IN PATHOGENIC-BACTERIA, ZOONOTIC-BACTERIA AND INDICATOR BACTERIA ISOLATED FROM DIFFERENT FOOD ANIMALS IN DENMARK - A BASE-LINE STUDY FOR THE DANISH INTEGRATED ANTIMICROBIAL RESISTANCE MONITORING PROGRAM (DANMAP)

This study describes the establishment and first results of a continuo us surveillance system of antimicrobial resistance among bacteria isol ated from pigs, cattle and broilers in Denmark. The three categories o f bacteria tested were: 1) indicator bacteria (Escherichia coli, Enter ococcus faecalis, Enterococcus faecium), 2) zoonotic bacteria (Campylo bacter coli/jejuni, Salmonella enterica, Yelsinia enterocolitica), and 3) animal pathogens (E. coli, Staphylococcus aureus, coagulase-negati ve staphylococci (CNS), Staphylococcus hyicus, Actinobacillus pleuropn eumoniae). A total of 3304 bacterial isolates collected from October 1 995 through December 1996 were tested for susceptibility to all major classes of antimicrobial agents used for therapy in Denmark. Bacterial species intrinsically resistant to an antimicrobial were not tested t owards that antimicrobial. Acquired resistance to all antimicrobials w as found. The occurrence of resistance varied by animal origin and bac terial species. In general, resistance was observed more frequently am ong isolates from pigs than from cattle and broilers. The association between the occurrence of resistance and the consumption of the antimi crobial is discussed, as is the occurrence of resistance in other coun tries. The results of this study show the present level of resistance to antimicrobial agents among a number of bacterial species isolated f rom food animals in Denmark. Thus, the baseline for comparison with fu ture prospective studies has been established, enabling the determinat ion of trends over time.