Characterization of Enterococcus spp isolates from pets and their owners in Tunisia: emergence of optrA and vanA genes.

BACKGROUND: In Tunisia, data on pet-associated enterococci are limited. This study aimed to characterize enterococci isolates from companion animals, focusing on species distribution, antimicrobial resistance, and virulence determinants. MATERIALS AND METHODS: A total of 250 samples of varied types were collected from healthy companion animals (n = 66; 38 cats and 28 dogs), from whom nasal, buccal, and rectal swabs were obtained (3 s; owners who consented to sampling (n = 27), from whom nasal swabs were collected; sick pets (n = 18; 13 cats and 5 dogs), from whom urine (n = 11) and abscess (n = 7) specimens were obtained; and pet drinking water sources (n = 7). Enterococci isolates were identified using the Vitek2 (bioMérieux). Antimicrobial susceptibility testing was assessed using the disk diffusion method and the MIC determination for linezolid (according with the Clinical and Laboratory Standards Institute guidelines (CLSI M100 33rd, 2023). The antimicrobial resistances genes were detected by simplex or multiplex PCR. Four virulence genes (gelE, esp, ccf, and hyl) were detected by PCR. RESULTS: Ninety-one enterococci isolates were recovered, predominantly E. faecalis (53.8%), followed by E. faecium (20.9%), E. casseliflavus (13.2%), E. gallinarum (11%), and E. durans (1%). High resistance rates were observed to tetracycline (65.9%), erythromycin (60.4%), streptomycin (43.9%), and ampicillin (35.1%), with 58.2% (n = 53) of isolates exhibiting multidrug resistance (MDR). Vancomycin and linezolid resistance were detected in 16.48% (n = 15) and 27.47% (n = 25) of isolates, respectively, with optrA and vanA identified in three and one E. faecalis isolates, respectively. Virulence genes gelE (46%), ccf (53%), and esp (22%) were most frequent found in E. faecalis, highlighting its higher pathogenic potential. Notably, identical E. faecalis isolates with overlapping resistance profiles were found in pets and owners, suggesting possible interspecies transmission. CONCLUSION: These findings emphasize the role of companion animals as reservoirs of MDR and virulent enterococci and underscore the importance of One Health-oriented surveillance and prudent antimicrobial use to mitigate AMR dissemination within household and community settings.