Detection and characterization of vancomycin-resistant enterococci in farmanimal and raw meat products in Italy

The emergence of vancomycin-resistant enterococci (VRE) in Europe has been ascribed to the long-time use of the glycopeptide antibiotic avoparcin as f eed additive in food animals, until its ban in 1997 in EU, The presence of VRE in food of animal origin is believed to represent a potential risk For the consumer. We studied the fecal carriage of VRE in broiler chickens and slaughter pigs in Italy before the avoparcin ban and evaluated the impact o f avoparcin withdrawal on the presence of VRE in raw meat products. Broiler s and pigs were both found to be frequently colonized by VRE, as 36% and 24 .6% of the flocks or the herds, respectively, were positive. Molecular typi ng of VRE strains by PFGE showed that animals housed in different pens with in the same farm were colonized by clonally I elated strains. After the avo parcin ban, a decrease in the rate of VRE contamination in meat products wa s observed. Such a decrease was statistically significant in poultry (from 18.8% to 9.6%) but not in pork products (from 9.7% to 6.9%). The majority o f VRE from all sources carried the vanA resistance gene and included Entero coccus faecium, E. faecalis, E. hirae, E. durans, and E, gallinarum, None o f the strains carried the vanB gene, whereas constitutively resistant vanC- positive strains were frequently found. Our results show that avoparcin wit hdrawal has been successful in reducing VRE contamination in meat products. However, this measure needs to be complemented by a prudent use of glycope ptide antibiotics in human medicine.