TRANSFERABLE AMIKACIN RESISTANCE IN GRAM-NEGATIVE BACTERIAL ISOLATES

Seven amikacin-resistant strains of Enterobacteriaceae isolated in Slo vakia and Germany were included in this study. The strains were also r esistant in vitro to high levels of gentamicin, tobramycin, netilmicin and isepamicin. Phosphocellulose paper binding assays indicated that resistance to aminoglycosides was due to synthesis of aminoglycoside a cetyltransferase AAC(6)-I in combination with aminoglycoside phosphotr ansferase APH(2''), a mechanism until now only identified in staphyloc occi and streptococci. This mechanism of aminoglycoside resistance has also been found in two isolates of klebsiella pneumoniae from Germany . The substrate profile suggested that in addition to AAC(6)-I and APH (2''), several strains also produced AAC(3)-II. Aminoglycoside resista nce was found to be transferable to Escherichia coli 3110 riF(r) in al l isolates, and R plasmids of 36-45 MD were detected in donor and tran sconjugant strains. All isolated plasmids from transconjugants encoded resistance to aminoglycosides by genes encoding the enzymes AAC(6')-I and APH(2'').