Antimicrobial Resistance of Enterococcus Species Isolated from Wild Mammals in Aragón, Spain

Antimicrobial resistance is currently one of the major public health threats. In order to prevent its spread, the WHO, OIE and FAO have formed an alliance to promote the study of antibiotic resistance evolution in human, animal and environmental bacteria posing a public health threat; however, the studies performed in wild animals are scarce so far. The main objective of this study was to assess the antibiotic resistance of Enterococcus spp. isolated from wild mammals in Aragón, Spain.

Rectal samples were collected from 103 wild mammals - 70 hunt prey and 33 rescued animals. Isolates were identified by matrix-assisted laser desorption/ionisation-time of flight mass spectrometry and susceptibility tests to 10 antibiotics were also carried out. Statistical analysis was performed (P ≤ 0.05).

A total of 126 isolates of seven different Enterococcus species were recovered. Among them, E faecalis (37.60%), E. casseliflavus (20.63%) and E. faecium (17.46%) were the most prevalent. The antibiotics quinupristin-dalfopristin and ciprofloxacin most frequently lost efficacy against the isolates. Multi-drug resistance was more prevalent in enterococci isolated from the rescued mammals.

This study found resistance widely distributed among enterococci isolated from the studied mammals. This points to the need for additional study of its genetic determinants and investigation of the sources and measures to avoid contributory environmental contamination.