Beta-lactam resistance in enterobacteria isolated from animal and water

The susceptibility to β-lactam antibiotics was analysed in thirty seven strains of enterobacteria from both animals and non-chlorinated water of rural areas from Corrientes, North-eastern Argentina. Twenty nine were isolated from animals: Klebsiella pneumoniae (n=9), Klebsiella oxytoca (n=1), Proteus mirabilis (n=7), Escherichia coli (n=12), and 8 from non-chlorinated water: E. coli (n=5), K. pneumoniae (n=2), K. oxytoca (n=1). The antibiograms were performed by the Kirby-Bauer technique using antibiotic discs of ampicillin, cefotaxime, cefepime, piperacillin and with β-lactamases inhibitors: clavulanic acid-amoxicillin, sulbactam- cefoperazone and tazobactam-piperacillin. Carbapenems with an EDTA disc as metallo β-lactamases inhibitor were also used. Neither phenotypically ESBL (extended-spectrum beta-lactamases) nor carbapenemase were detected. It can be inferred that the resistance observed in this assay may be attributed to a different source.