First Report on van A- Enterococcus faecalis Recovered from Soils Subjected to Long-Term Livestock Agricultural Practices in Azores Archipelago

Antibiotic resistance represents a serious threat to human health. Some agricultural practices may lead to the acquisition of antibiotic resistance on soil bacteria. The aim of this study was to characterize the antibiotic-resistant profile of enterococci in soils exposed to livestock agricultural practices in Azores archipelago. Twenty-four soil samples were collected in 3 different pasture lands of Sao Miguel Island from Azores archipelago, with a different number of grazing animals, and from a control site. Eight Enterococcus spp. isolates were recovered: E. faecium (n = 5), E. hirae (n = 1), E.faecalis (n = 1) and E. gallinarum (n = 1). The isolates were tested for antibiotic resistance and virulence genes. The E. faecalis isolate was resistant to vancomycin (VRE) and harboured the van(A), the aph(3′) and aac(6′)-Ie-aph(2′)-Ia antibiotic resistance genes as well the esp virulence gene. Almost all non-VRE isolates were resistant to erythromycin and ampicillin and harboured the erm(B) gene. The antibiotics used in dairy and beef livestock cattle production are excreted through manure, which may exert a selective pressure on soil bacteria, leading to a higher bacterial resistome in the soil. This represents a public health problem due to the negative consequences and it might represent to human health.