Novel approach to bacterial identification that uses the autobac system

A new system for the rapid identification of gram-negative bacilli on the Autobac system is described. This system utilizes growth inhibition profiles to a panel of differentially inhibitory chemical agents. These profiles are analyzed with a two-stage quadratic discriminant analysis to arrive at the organism identification. The system identifies 30 different groups of gram-negative bacilli, including the most clinically significant Enterobacteriaceae and glucose nonfermenters. A total of 3,726 strains, distributed among the 30 groups, was tested. The Autobac system agreed with the conventional biochemical identification 88.4% of the time. When the individual group results were weighted to reflect clinical frequency, the result was a 93.1% agreement.