Abstract: Objective To analyze the distribution and genotyping of aminoglycoside modifying enzyme genes in gram-negative bacilli from some hospitals in Changchun area and to provide a reasonable basis for the application of antibiotics. Methods Amikacin-resistant and gentamicin-resistant strains were screened using agar dilution tests,and the aminoglycoside modifying enzyme genes were amplified by PCR and analyzed by sequencing.
Results The resistant rates of 69 strains of gram-negative bacilli to  amikacin and gentamicin were 44.9% and 87.0%,respectively.63 strains of gram-negative bacilli (91.3%) were aminoglycoside modifying enzyme-positive,the genotypes of aminoglycoside modifying enzymes included aac(3)-Ⅰ,aac(3)-Ⅱ,aac(6′)-Ⅰb,ant(3")-Ⅰ,and ant(2")-Ⅰ,with positive rates of 4.3%,81.2%,43.5%,33.3%,and 13.0%,respectively.But the aac(6′)-Ⅱ　was not found.
Conclusion The genotypes of aminoglycoside modifying enzymes of gram-negative bacilli in local area are aac(3)-Ⅰ,aac(3)-Ⅱ,aac(6′)-Ⅰb,ant(3")-Ⅰ,and ant(2")-Ⅰ,and the most common of aminoglycoside modifying enzyme genes is aac(3)-Ⅱ.Reasonable application of aminoglycosid
e antibiotics to reduce bacterial resistance has great significance.

Key words: gram-negative bacilli, aminoglycoside modifying enzymes, antibiotic-resistance