A survey of clinical isolates of Enterobacteriaceae using a series of DNA probes for aminoglycoside resistance genes.

DNA probes specific for the aminoglycoside adenylyltransferase ANT(2"), the aminoglycoside phosphotransferases APH(3')-I and APH(3')-II, and the aminoglycoside acetyltransferases AAC(3)-I, AAC(3)-V and AAC(6')-I were used to screen 151 clinical isolates for the presence of these resistance determinants. The two most common resistance genes in the study isolates were those encoding ANT(2") and APH(3')-I. The phenotypic pattern of aminoglycoside resistance, as determined by a modified disk diffusion test correlated well with the genotypes of the organisms as established using DNA probes, although strains carrying the ANT(2") gene could express one of several phenotypes.