Extended-spectrum beta-lactamase-producing Escherichia coli through the poultry production chain in Argentina.

The presence of extended-spectrum β-lactamases-producing Escherichia coli (ESBL-EC) in food production systems is a public health problem, since they can be transmitted to humans. The aims of this study were to isolate and characterize ESBL-EC from poultry farms located in Argentina. Resistances to β-lactams (first-, third-, and fourth-generation cephalosporins, penicillin), tetracyclines, quinolones, sulfonamides, phosphonates and aminoglycosides were found among the 40 ESBL-EC isolates. In addition, a wide range of antimicrobial resistance profiles were identified. The most frequent accompanying resistance to non-β-lactam antibiotics was tetracycline (97.5 %), followed by ciprofloxacin (82.5 %). All ESBL-EC isolates were multidrug resistant, and were grouped into four blaCTX-M groups: blaCTX-M-2 (75 %), followed by blaCTX-M-1, blaCTX-M-1/blaCTX-M-2, and blaCTX-M-2/blaCTX-M-8. Of the 40 ESBL-EC isolates, 31 carried genes encoding integrase, 28 were positive for intI1- qacEΔ1- sul1, three for intI1, three were identified as Verocytotoxin-producing E. coli (VTEC) and most of the studied isolates belonged to the phylogroup E. This study reports the presence of CTX-M in E. coli obtained from poultry production in Argentina and that CTX-M-2 was the main mechanism responsible for third generation cephalosporins resistance. Also, showed that apparently healthy chickens in Argentina harbor commensal multidrug-resistant (MDR) ESBL-EC, with resistances to antibiotics of critical importance for human and veterinary medicine.