Occurrence of Vancomycin-Resistant Enterococci in Foods of Animal Origin Purchased in Tuscany

Abstract

Enterococci are ubiquitous microorganisms, commonly found in plants, insects and wild animals, and are normal residents of the gastrointestinal tract of both animals and humans. They frequently occur in large numbers in certain foods, especially those of animal origin. Over the last 10 years, enterococci have emerged as major nosocomial pathogens, thus representing an increasingly important problem for public health, in relation to their ability to acquire resistance to some antimicrobial agents of relevance to human therapy, such as glycopeptides, particularly vancomycin. In this regard, the food chain represents a possible source of vancomycin-resistant enterococci for humans, mainly as a result of the use of avoparcin, a vancomycin-like glycopeptide, as a feed additive for growth promotion of farm animals, as undoubtedly established by previous studies (Bates, 1997; Mc Donald et al., 1997). Although the utilization of avoparcin in animal husbandry has been banned since 1997, VRE have recently been isolated from foods of different typology (Giraffa et al., 2000; Knijff et al., 2002), therefore investigation into the frequency of recovery of VRE at this level is still recommendable. Thus, the present survey was carried out with the aim of evaluating the occurrence of VRE in foods of animal origin purchased in Tuscany, considering that these microorganisms could play a relevant role both directly as potential pathogens for humans, as well as in relation to their capability to spread antibiotic resistance genes to other pathogenic bacteria, such as Staphylococcus aureus.