MLST and a genetic study of antibiotic resistance and virulence factors in vanA-containing Enterococcus from buzzards (Buteo buteo)

To analyse the occurrence of faecal carriage of vancomycin-resistant enterococci (VRE) in Buteo buteo and to study the associated resistance and virulence genes. The presence of VRE was investigated in 33 faecal samples of B. buteo. Samples were seeded in Slanetz-Bartley agar plates supplemented with vancomycin for VRE recovery. Genes encoding antimicrobial resistance and virulence were studied by polymerase chain reaction. Vancomycin-resistant Enterococcus faecium isolates were characterized by multilocus sequence typing. VRE with an acquired mechanism of resistance (vanA genotype) were detected in 9% of samples analysed (Ent. faecium and Enterococcus durans). In addition, 27% of samples contained VRE with an intrinsic mechanism of resistance (Enterococcus gallinarum, vanC1). All vanA-containing isolates showed resistance to tetracycline and erythromycin and harboured the tet(M) and/or tet(L) genes, in addition to the ermB gene. The vat(E) and/or vat(D), cat(A) and aph(3′)-IIIa genes were identified in quinupristin-dalfopristin-, chloramphenicol-, and kanamycin-resistant vanA-containing strains, respectively. The sequence types ST273 and ST5 were identified in two vanA-positive Ent. faecium isolates, and the presence of hyl, gelE, cylA, cylL and cylM virulence genes and gelatinase activity were identified in Ent. faecium ST5 strain. The intestinal tract of B. buteo could be a reservoir of vanA-positive enterococci. First study focused to define the occurrence of vanA-containing Enterococcus strains in B. buteo.