Specificity of 4'''-acetylation by an aminoglycoside-modifying enzyme in arbekacin-resistant strains of methicillin-resistant Staphylococcus aureus.

Four arbekacin (ABK)-resistant clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA) were studied regarding their mechanism of aminoglycoside-resistance. Metabolites of amikacin (AMK) and gentamicin(GM) were obtained by reaction with excess amounts of crude enzyme preparation extracted from the ABK-resistant MRSA strains. Then the metabolites were then isolated and analyzed by means of 1H, 13C-nuclear magnetic resonance. The AMK-modification was 4'''-N-acetylation. However, the site of GM-acetylation may be 6'-N-position by these strains.