Catarina Geraldes ^1,2* Catarina Araújo ^1,2 Ana Catarina Pinheiro ^1,2 Mónica Afonso ^3,4 Sandra Carapeto ^5,6 Cláudia Verdial ⁵ Eva Cunha ^1,2 Raquel Abreu ^1,2 Luís Tavares ^1,2 Lélia Chambel ⁷ Solange Gil ^1,2,8 Manuela Oliveira ^1,2,9

• ¹ Centre for Interdisciplinary Research in Animal Health, Faculty of Veterinary Medicine, University of Lisbon, Lisboa, Portugal
• ² Veterinary and Animal Research Center, University of Trás-os-Montes and Alto Douro, Vila Real, Portugal
• ³ CIISA - Centre for Interdisciplinary Research in Animal Health, Faculty of Veterinary Medicine, University of Lisbon, Lisbon, Portugal
• ⁴ AL4AnimalS - Associate Laboratory for Animal and Veterinary Science, Faculty of Veterinary Medicine, University of Lisbon, Lisbon, Portugal
• ⁵ Faculty of Veterinary Medicine, University of Lisbon, Lisbon, Portugal
• ⁶ University of Copenhagen, Copenhagen, Capital Region of Denmark, Denmark
• ⁷ Institute of Biosystems and Integrative Sciences (BioISI), Lisbon, Portugal
• ⁸ Veterinary Teaching Hospital, Faculty of Veterinary Medicine, University of Lisbon, Lisbon, Portugal
• ⁹ Centre for Ecology, Evolution and Environmental Changes, Faculty of Sciences, University of Lisbon, Lisbon, Portugal

Enterococcus are considered an important genus in terms of Hospital-Acquired Infections (HAIs), which means that their characterization regarding resistance and virulence profiles in the hospital environment is of extreme importance. This article addresses this issue through the characterization of enterococci collected from a Veterinary Biological Isolation and Containment Unit (BICU). A total of 73 isolates, collected from different surfaces of a Veterinary BICU, were identified as Enterococcus through PCR at species level, after which 34 isolates were selected as representatives using (GTG)5 fingerprinting. These isolates were further characterized phenotypically in terms of antimicrobial resistance through disk diffusion and of virulence factors' expression. The majority of the enterococci isolated presented resistance to erythromycin (79.4%), ampicillin (73.5%), amoxicillin-clavulanic acid (70.6%), tetracycline (67.6%), ciprofloxacin (58.8%) and levofloxacin (50.0%), and were able to produce hemolysin (88.2%) and biofilm (82.3%). Furthermore, in terms of pathogenicity, three isolates (8.8%) were classified as high threats and two (5.9%) as moderate threats. The degree of resistance, production of virulence factors and the percentage of isolates classified as moderate or high threat means that a constant vigilance of such strains in veterinary units, but also of clinics and hospitals in general, is an important tool in terms of infection prevention and consequent reduction of HAIs.