Laboratory evaluation of amikacin susceptibility testing by the AutoBac I system

A total of 319 clinical isolates were compared for amikacin susceptibility by AutoBac I and Bauer-Kirby disk diffusion methods. There was an overall agreement of 98.5% between AutoBac I and Bauer-Kirby. An additional 23 strains resistant to amikacin, obtained from Bristol Laboratories, registered a 65% overall agreement. The sensitivity readings differed between the two methods for 13 organisms: 11 were minor discrepancies, intermediate by one of the two methods, and 2 were very major discrepancies, resistant by disk diffusion and susceptible by AutoBac I.