Laboratory evaluation of the AutoMicrobic system for identification of Enterobacteriaceae

The Enterobacteriaceae Biochemical Card used with the AutoMicrobic system (Vitek Systems, Inc., Hazelwood, Mo.) was compared with the API 20E system (Analytab Products, Plainview, N.Y.) for identifying members of the family Enterobacteriaceae. A total of 1,401 clinical isolates representing 18 species were identified by the AutoMicrobic and API 20E systems over a 5-month period. Discrepancies between these systems were resolved by conventional methods. Overall, 98.3% of the isolates were identified correctly by the AutoMicrobic system in 8 h, with 94.2% having an AutoMicrobic system confidence level greater than or equal to 90%; 92.9% of the isolates were identified correctly by the 20E system after 24 h of incubation. Discrepancies between the two systems occurred in 3.1% of the isolates. Of these, 40.9 and 59.1% proved to be correct by the AutoMicrobic and API 20E systems, respectively.