Differences in antibiotic resistance patterns of Enterococcus faecalis andEnterococcus faecium strains isolated from farm and pet animals

The prevalence of acquired resistance in 146 Enterococcus faecium and 166 E nterococcus faecalis strains from farm and pet animals, isolated in 1998 an d 1999 in Belgium, against antibiotics used for growth promotion and for th erapy was determined, Acquired resistance against flavomycin and monensin, two antibiotics used solely for growth promotion, was not detected. Avoparc in (glycopeptide) resistance was found sporadically in E, faecium only. Avi lamycin resistance was almost exclusively seen in strains from farm animals . Resistance rates were higher in E. faecium strains from broiler chickens than in strains from other animal groups with tylosin and virginiamycin and in E, faecalis as well as in E, faecium strains with narasin and bacitraci n, Resistance against ampicillin was mainly found among E. faecium strains from pets and was absent in E. faecalis, Tetracycline resistance occurred m ost often in strains from farm animals, while enrofloxacin resistance, only found in E, faecalis, occurred equally among strains from all origins. Res istance against gentamicin was very rare in broiler strains, whereas resist ance rates were high in strains from other origins, It can be concluded tha t resistance against antibiotics used solely for growth promotion was more prevalent in E, faecium strains than in E, faecalis strains. With few excep tions, resistance against the different categories of antibiotics was more prevalent in strains from farm animals than in those from pets,