Detection of a second mechanism of resistance to gentamicin in animal strains of Escherichia coli.

One mechanism of plasmid-mediated resistance to gentamicin in Escherichia coli strains isolated from animals is due to the synthesis of the aminoglycoside 3-N-acetyltransferase type IV. A second mechanism of plasmid-mediated resistance to gentamicin was detected in animal strains of E. coli in France and is due to the production of the aminoglycoside 3-N-acetyltransferase type II. The molecular relationships among plasmids encoding this enzyme were studied.