Study of antimicrobial susceptibility of Enterococcus spp isolated from wild mammals from the Autonomous Community of Aragón (Spain)

Enterococcus spp are present in the gastrointestinal tract of animals, humans and in the environment. The most important are E. faecalis and E. faecium, but other enterococci can produce nosocomial infections. Enterococci have intrinsic and acquire mechanisms of antimicrobial resistance easily. Vancomycin is the last line of defense against these infections. The resistance acquired through the VanA and VanB2 genes is easily transmitted

The aim of this study is to determine if enterococci isolated from wild mammals of the Aragón Community (Spain), exhibit resistance to important antibiotics and carry genes of vancomycin resistance.

Between 2022 and 2024, 99 rectal samples were collected from recently dead mammals at the Wildlife Recovery Center-La Alfranca. After isolation on Slanetz-Barley agar, they were identified in MALDI-TOF-MS. The Kirby-Bauer test was applied to detect susceptibility to antimicrobials. The vanA and vanB genes were searched by PCR, with specific primers.

The mammal species were 33 badger, 23 beech marten, 11 American mink, 9 hedgehog, 6 common otter, 4 wild cat, 4 red fox, 3 common genet, 3 bat, 1 wolf, 1 guinea pig and 1 ferret.

It was isolated 126 enterococci: 63 E. faecalis, 31 E. faecium, 14 E. hirae, 11 E. mundtii, 2 E. avium, 2 E. gllinarum, 1 E. durans, 1 E. villorum 1 E. casseliflavus

The intermediate halo for the erythromycin, ciprofloxacin, and vancomycin was observed in 82, 56, and 29 enterococci, respectively. Thirty-three enterococci were resistant to tetracycline. None enterococci was resistant to clhoramphenicol, linezolid and teicoplanin. One E. faecalis was vancomicyn resistant. Ninenty strains were selecte to search for VanA and VanB2 genes, and were negative.

Conclusion: Enterococci isolated from 99 wild mammals in Aragón (Spain) showed high susceptibility to the antibiotics tested and did not carry vanA or vanB2 genes.