Molecular cloning of amikacin resistance determinants from a Klebsiella pneumoniae plasmid.

A multiresistant Klebsiella pneumoniae strain, JHCK1, harbored several plasmids. One of these, plasmid pJHCMW1, carried determinants for resistance to amikacin in addition to kanamycin, tobramycin, and ampicillin. The amikacin resistance determinant(s) was cloned and studied by restriction mapping, insertion, and deletion analysis. The amikacin resistance gene(s) was localized in a 1.5-kilobase DNA fragment. This pJHCMW1 DNA region was responsible for not only the resistance to amikacin but also the resistance to kanamycin and tobramycin. The cloned DNA fragment specified both an acetyltransferase activity and a low level of phosphotransferase activity. The two activities were absent from mutants that did not confer resistance to amikacin, kanamycin, and tobramycin.