Detection and Characterization of Vancomycin-Resistant Enterococci in Farm Animals and Raw Meat Products in Italy

Abstract

The emergence of vancomycin-resistant enterococci (VRE) in Europe has been ascribed to the long-time use of the glycopeptide antibiotic avoparcin as feed additive in food animals, until its ban in 1997 in EU. The pres- ence 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 eval- uated the impact of avoparcin withdrawal on the presence of VRE in raw meat products. Broilers and pigs were both found to be frequently colonized by VRE, as 36% and 24.6% of the flocks or the herds, respec- tively, were positive. Molecular typing of VRE strains by PFGE showed that animals housed in different pens within the same farm were colonized by clonally related strains. After the avoparcin ban, a decrease in the rate of VRE contamination in meat products was 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 of VRE from all sources carried the vanA resistance gene and included Enterococcus faecium, E. faecalis, E. hirae, E. durans, and E. gallinarum. None of the strains carried the vanB gene, whereas constitutively resistant vanC-positive strains were frequently found. Our results show that avoparcin withdrawal has been successful in reducing VRE contamination in meat products. However, this measure needs to be complemented by a prudent use of glycopeptide antibiotics in human medicine.

Clonal Spread of a Vancomycin-Resistant Enterococcus faecium Strain among Bloodstream-Infecting Isolates in Italy

“…The species identification and the genotypes of glycopeptide resistance were obtained by a previously described multiplex PCR assay (7).…”

“…To analyze clonal relatedness among the isolates, total genomic DNAs were digested with SmaI and separated by pulsed-field gel electrophoresis (PFGE) by previously described methods (7). Isolates whose profiles differed by one to six bands were assigned to different subtypes of the same type.…”

“…In European countries, including Italy, VRE have been demonstrated in the feces of farm animals and in animalderived foods, such as raw meat products (7). After discontinuation of the use of avoparcin, the frequency of VRE in these reservoirs decreased significantly (1; A. Pantosti, M. Del Grosso, S. Tagliabue, A. Macrì, and A. Caprioli, Letter, Lancet 354:741-742, 1999).…”

Antimicrobial resistance profile of Staphylococcus aureus isolated from raw meat: A research for methicillin resistant Staphylococcus aureus (MRSA)

“…In Europe, prevalence of MRSA is increasing: from 0.1-1.5% for Denmark, Sweden and The Netherlands, to 30.3-34.4% for Spain, France and Italy (Voss, Milatovic, Wallrauch-Schwarz, Rosdahl, & Braveny, 1994). In the United States, the prevalence of methicillin resistance among nosocomial S. aureus extracts increased from 2.1% in 1975 to 35% in 1991 (Grosso et al, 2000) and it is greater than in community S. aureus isolates (Panlilio, Culver, & Gaynes, 1992).…”

“…of Epid. Immuniz., 2001): the use of antimicrobial avoparcin in pork and poultry meat manufacturing factories as a feed additive is correlated to the increase of VRE prevalence in food of animal origin, and consequently in community and in nosocomial isolates (Børgen, Sorum, Wasteson, & Kruse, 2001;Grosso et al, 2000;Mü ller, Ulrich, Ott, & Mü ller, 2001). The possibility of transmission of MRSA through food was unknown until 1994 (Kluytmans et al, 1995); however, today we know that when a few cells of S. aureus enter an immunocompetent organism, they are destroyed by the gastric juices, but when an immunocompromised patientÕs food contains cells of S. aureus, these can reach the circulatory system and cause infections that may evolve to septicaemia.…”