I was searching the same issue and I found this in a reference
"A plasmid-mediated acetyltransferase, now known as AAC(6′)-Ib or AacA4 [26,27,34,161], was first reported in P. aeruginosa that conferred resistance to amikacin besides other aminoglycosides but not gentamicin C1 [160,162,163] "
This is the full article link
Article Amikacin: Uses, Resistance, and Prospects for Inhibition