A collaborative evaluation of a rapid automated bacterial identification system: the Autobac IDX

A collaborative evaluation of the Autobac IDX, a rapid, semi-automated bacterial identification system, was performed in three independent laboratories in three European countries. The system utilises growth inhibition by a series of chemical compounds. Subsequent analysis of the resultant data by quadratic discriminant function automatically results in a bacterial identification. Three sets of 30 strains were examined repeatedly in each of the participating laboratories. The reproducibilities obtained ranged from 85.6% to 96.6%, with an overall average of 91.8%. The accuracy of the system was also determined by examining 1076 isolates from the three participating laboratories. An overall accuracy of 90.3% was calculated by comparing the Autobac result with a reference method. When the results were weighted to represent clinical frequency, the accuracy was 93.6%.