L'antibiotico-resistenza in ceppi di E. coli isolati da specie aviari e cunicole commerciali e selvatiche

Antimicrobial-resistance is a public health problem world-wide and it is largely attributed to horizontal exchange of transferable genetic ele-ments such as plasmids carrying integrons (Sunde and Norstrom, 2006). The aim of this study was to define the antimicrobial-resistance phenotypes and to characterize class 1 and class 2 integrons in E. coli isolated both from commercial and wild birds and lagomorphs between 2006 and 2012 in Italy. The strains isolated form lagomorphs were also genotyped and screened for Plasmid-Mediated Quinolones Resistance (PMQR) genes and plasmids. Strains were examined for antimicrobial susceptibility by agar disk diffusion method. Class 1 and class 2 integrons were detected by real-time PCR and gene cassettes content identified by DNA sequencing. PMQR genes were screened by PCR and DNA sequencing. Clonal relatedness of the isolates from lagomorphs was assessed by Multilocus Sequence Typing (MLST). Plasmids were characterized by PCR-Based Replicon Typing (PBRT). Class 1 integrons were detected in multi-drug resistant E. coli both from commercial and wild birds and lagomorphs while class 2 integrons were found only in domestic avian species. Different gene cassettes were identified but the most common were combinations of aadA, sat and dfrA, codifying for aminoglycosides and trimethoprim resistance. Of the 172 E. coli isolates from lagomorphs, 12.2% (21/172) carried oqxAB, none other PMQR de-terminants. All but 3 oqxAB positive E. coli strains were recovered from farm rabbits and most of them were associated with the predominant CC17 and carried from 1 to 7 different plasmid types, such as IncF, IncHI1, IncI1, IncR, IncN, IncP, IncX1, IncY, and ColE. This study pro-vides new insights on the prevalence and dissemination of integrons and oqxAB in E. coli from farm and wild animals, suggesting that these species may be reservoir of these genetic determinants in Italy and thus a potential source of multi-drug resistant E. coli for human