In vitro susceptibility of Enterococcus faecium isolated from food to growth-promoting and therapeutic antibiotics

A total of 76 E, faecium strains, isolated at retail level from raw poultry meat? cheese, raw pork, and preparations of cheese and I aw Fork, were tes ted for their susceptibility and resistance to growth-promoting antibacteri als used in animals and antibiotics used therapeutically in humans. All str ains were uniformly susceptible to the growth promoters bambermycin and avi lamycin. Resistance against bacitracin, virginiamycin and narasin was high among strains from poultry meat. With tylosin, a macrolide antibiotic used therapeutically and for growth promotion, resistance was mainly detected in strains originating from poultry meat, though also in some strains from po rk and from pork and cheese preparations. The therapeutic antibiotic dalfop ristin/quinupristin did not show full cross-resistance with the growth-prom oting antibiotic virginiamycin. With dalfopristin/quinupristin two differen t levels of resistance were found. Only one E. faecium strain isolated from poultry was resistant to the glycopeptides avoparcin and vancomycin. Only one poultry meat strain was highly resistant to ampicillin. However, nearly all poultry meat strains showed decreased sensitivity. Only 3 out of 24 po ultry strains were susceptible to minocycline, while all strains from other origins were susceptible to this tetracycline antibiotic. High-level strep tomycin resistance was seen in attains of all origins, though infrequently. High-level gentamicin resistance was not found. (C) 2000 Elsevier Science B.V. All rights reserved.