Phenotypic and Genotypic Traits of Vancomycin-Resistant Enterococci from Healthy Food-Producing Animals

Abstract

Food-producing animals may be a reservoir of vancomycin-resistant enterococci (VRE), potentially posing a threat to animal and public health. The aims of this study were to estimate the faecal carriage of VRE among healthy cattle (n = 362), pigs (n = 350), sheep (n = 218), and poultry (n = 102 flocks) in Switzerland, and to characterise phenotypic and genotypic traits of the isolates. VRE were isolated from caecum content of six bovine, and 12 porcine samples respectively, and from pooled faecal matter collected from 16 poultry flock samples. All isolates harboured vanA. Three different types of Tn1546-like elements carrying the vanA operon were identified. Conjugal transfer of vanA to human Enterococcus faecalis strain JH2-2 was observed for porcine isolates only. Resistance to tetracycline and erythromycin was frequent among the isolates. Our data show that VRE harbouring vanA are present in healthy food-producing animals. The vanA gene from porcine isolates was transferable to other enterococci and these isolates might play a role in the dissemination of VRE in the food production chain.

Enterococci, from Harmless Bacteria to a Pathogen

“…Resistance to tetracyclines and erythromycin is also commonly detected among the indicator enterococci isolates from animals and food [ 24 ]. Further, in a few European studies, putative linkage of glycopeptide, macrolide, and tetracycline-resistant genes have been implicated in the occurrence of VRE in the feces of food-producing animals [ 26 , 27 ].…”

“…However, this potential hazard has been widely recognized. Identical Tn 1546 variants among VRE isolates have been recovered from food-producing animals and humans, indicating a common human and animal reservoir for van A elements [ 17 , 27 ]. Moreover, strains from human-adapted CCs causing most enterococcal infections may eventually be recovered from farm and pets (e.g., E. faecium CC17 and E. faecalis CC2), and strains from CCs commonly found among animals have also been isolated from humans (e.g., E. faecium CC5, E. faecalis ST16 or CC21) [ 21 ].…”

Prevalence of Vancomycin-Resistant Enterococci and Antimicrobial Residues in Wastewater and Surface Water

“…Unfortunately, vancomycin-resistant enterococci (VRE) are increasingly common and pose a serious therapeutic problem [4][5][6][7]. There may be numerous sources of VRE, including the human gastrointestinal tract, animals, the hospital environment and wastewater [8][9][10][11][12][13].…”

Enterococci, from Harmless Bacteria to a Pathogen

“…Resistance to tetracyclines and erythromycin is also commonly detected among the indicator enterococci isolates from animals and food [24]. Further, in a few European studies, putative linkage of glycopeptide, macrolide and tetracycline-resistant genes have been implicated in the occurrence of VRE in the faeces of food-producing animals [26,27].…”

“…However, this potential hazard has been widely recognized. Identical Tn1546 variants among VRE isolates have been recovered from food-producing animals and humans, indicating a common human and animal reservoir for vanA elements [17,27]. Moreover, strains from human-adapted CCs causing most enterococcal infections may eventually be recovered from farm and pets (e.g., E. faecium CC17 and E. faecalis CC2), and strains from CCs commonly found among animals have also been isolated from humans (e.g., E. faecium CC5, E. faecalis ST16 or CC21) [21].…”