HIGH-LEVEL KANAMYCIN RESISTANCE-ASSOCIATED WITH THE HYPERPRODUCTION OF AAC(3)II AND A GENERALIZED REDUCTION IN THE ACCUMULATION OF AMINOGLYCOSIDES IN ACINETOBACTER SPP

The clinical isolate of Acinetobacter baumannii strain SAK contains an actively transcribed aacC2 gene and a latent aadB gene that encode the aminoglycoside-modifying enzymes, AAC(3)II and AAD(2''), respectively. In an attempt to activate the aadB gene, the strain was cultured in the presence of kanamycin which is a substrate for AAD(2''). Although it was possible to isolate kanamycin resistant derivatives these were not associated with detectable AAD(2'') activity. Instead, there was a marked increase in the level of AAC(3)II activity which was associated with amplification of the aacC2 gene.