Comparison of the Quantum II Bacterial Identification System and the AutoMicrobic System for the identification of gram-negative bacilli.

The Quantum II Bacterial Identification System (BID; Abbott Laboratories) is a microprocessor-based spectrophotometric system for identification within 4 to 5 h of both enteric and nonenteric gram-negative bacilli. We compared the BID with the AutoMicrobic System (AMS; Vitek Systems, Inc.), using the most recent gram-negative identification card and software (AMS-GNI), for the identification of 501 clinical isolates of gram-negative bacilli, including 382 belonging to the Enterobacteriaceae and 119 nonenteric organisms. The API 20E (Analytab Products) was used as the reference system. The BID correctly identified 375 (98.2%) of the Enterobacteriaceae isolates and 111 (93.2%) of the nonenteric isolates; the AMS-GNI correctly identified 374 (97.9%) and 115 (96.6%) isolates, respectively. The BID identified all isolates within 5 h, whereas the AMS-GNI identified only 35% within this time period. The BID performed comparably to the AMS-GNI for the identification of most gram-negative bacilli. Simplicity, speed, and relatively low reagent cost make the BID a competitive system for many clinical laboratories.