Heterogeneity of 6'-N-acetyltransferases of type 4 conferring resistance to amikacin and related aminoglycosides in members of the family Enterobacteriaceae.

DNA-DNA hybridization and immunoblotting were used to assess the relatedness between the 6'-N-acetyltransferases of type 4 encoded by plasmid pAZ007 from a clinical isolate of Serratia marcescens and those encoded by NR79 and R5. The absence of detectable DNA-DNA homology and of immunological cross-reactivity suggests the existence of at least two distinct 6'-N-acetyltransferase type 4 genes that mediate amikacin resistance in gram-negative bacilli.