Molecular characterization of extended-spectrum-beta-lactamase-producing Escherichia coli isolates from red foxes in Portugal

The presence of broad-spectrum-cephalosporin-resistant Escherichia coli isolates and the implicated mechanisms of resistance and virulence factor genes were investigated in red fox ( Vulpes vulpes ) in Portugal. Cefotaxime-resistant E. coli isolates were isolated from two of 52 fecal samples (4 %), being both ESBL producers. The β-lactamase genes found in the two isolates were bla SHV-12 + bla TEM-1b . The tet (A) and sul 2 genes were also detected in these isolates, together with the non-classical class 1 integron ( intI1 - dfr A12- orf F- aad A2- cml A1- aad A1- qacH -IS 440 - sul 3) with the PcH1 promoter. The two isolates belonged to the phylogroup A. Amino acid changes in GyrA (S83L + D87G) and ParC (S80I) proteins were identified in our study. Concerning MLST typing, both isolates were assigned to ST1086, never found before in wild animals, and they presented closely related PFGE patterns. This study reveals the presence of ESBL-producing E. coli isolates, in a wild ecosystem, which could be disseminated through the environment to other niches.