Abstract: Objective To evaluate the performance of VITEK^ 2 COMPACT automatic bacterial identification system(VITEK 2C) plus AST GN-13 for the susceptibility of Acinetobacter baumannii to amikacin. Methods Three methods [broth microdilution(BMD), Kirby-Bauer(KB), and VITEK 2C] were used to determine the susceptibility of amikacin to 38 clinical isolates of Acinetobacter baumannii, and then the performances of VITEK 2C and KB were evaluated by using BMD as a reference method. Genes encoding aminoglycoside-modifying enzymes were amplified by multiple polymerase chain reaction(PCR). Results Comparing BMD as the reference method, VITEK 2C plus AST-GN13 yielded major errors in 19 isolates (50.0%) and minor errors in 2 isolates (5.3%). Multiple PCR results of aminoglycoside-modifying enzyme gene were consistent with the results of BMD. Conclusions The VITEK 2C has limitations, which requires that KB should be used for the susceptibility of Acinetobacter baumannii to amikacin.

Key words: Acinetobacter baumannii, Broth microdilution, Aminoglycoside-modifying enzyme