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

Abstract

Aims: To analyse the occurrence of faecal carriage of vancomycin-resistant enterococci (VRE) in Buteo buteo and to study the associated resistance and virulence genes.

Methods and results: 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.

Conclusions: The intestinal tract of B. buteo could be a reservoir of vanA-positive enterococci.

Significance and impact of the study: First study focused to define the occurrence of vanA-containing Enterococcus strains in B. buteo.