The VITEK 2 (bioMérieux, Marcy LÈtoile, France) and the Phoenix systems (BD Diagnostic Systems, Sparks, Md.) are automated instruments for rapid organism identification and susceptibility testing. We evaluated the workflow, the time to result, and the performance of identification and susceptibility testing of both instruments. A total of 307 fresh clinical isolates were tested: 141 Enterobacteriaceae, 22 nonfermenters, 93 Staphylococcus spp., and 51 Enterococcus spp. Manipulation time was measured in batches, each with seven isolates, for a total of 39 batches. The mean (؎ standard deviation [SD]) manipulation time per batch was 20.9 ؎ 1.8 min for Phoenix and 10.6 ؎ 1.0 min for VITEK 2 (P < 0.001). Mean (؎SD) time to result for all bacterial groups was 727 ؎ 162 min for Phoenix and 506 ؎ 120 min for VITEK 2 (P < 0.001). Concerning identification, Phoenix and VITEK 2 yielded the same results for nonfermenters (100%), staphylococci (97%), and enterococci (100%). For 140 Enterobacteriaceae strains evaluated, 135 (96%) were correctly identified by Phoenix and 137 (98%) by VITEK 2 (P ؍ 0.72). The overall category agreement for all isolates was 97.0% for both instruments. The minor error rate, major error rate, and very major error rate for all bacterial isolates tested were 3.0, 0.3, and 0.6 and 2.8, 0.2, and 1.7 for Phoenix and VITEK 2, respectively (P values of 0.76, 0.75, and 0.09). The VITEK 2 system required less manual manipulation time and less time than the Phoenix system to yield results.Automated identification and susceptibility test systems significantly advanced clinical microbiology. Fast and reliable results which improve clinical outcomes and the reduction of costs have been noted by several authors (2, 3, 5). Various systems have been presented during the last years, such as the Vitek Classic (bioMérieux, Marcy LЈÈtoile, France), the more automated VITEK 2 (bioMérieux) and Microscan Walkaway (Dade-Behring MicroScan, Sacramento, CA), and the recently developed Phoenix system (BD Diagnostic Systems, Sparks, Md.).Fast results provided by these instruments are not only due to short incubation times for identification (ID) and antimicrobial susceptibility testing (AST) of bacterial isolates but also to hands-on time for setting up the different devices. We compared the different manipulation steps required by the VITEK 2 and Phoenix systems for setting up bacterial isolates for ID and AST. Additionally, the time to result was recorded for each system. The workflow analysis was the main focus of this evaluation; however, efficient workflow must generate accurate results. Therefore, performance characteristics with regard to ID and AST were also investigated. ID results were compared to API systems (bioMérieux), and AST results were compared to standard broth microdilution as recommended by the National Committee for Clinical Laboratory Standards (NCCLS) (14).(The findings of this study were partly presented at the 103rd Gen. Meet. Am. Soc. Microbiol., abstr. C-250, 2003.) MATERIALS AND METHODS Bacterial...
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