Matrix-assisted laser desorption ionization-time of flight mass spectrometry has emerged as a rapid, cost-effective alternative for bacterial species identification. Identifying 60 blind-coded nonfermenting bacteria samples, this international study (using eight laboratories) achieved 98.75% interlaboratory reproducibility. Only 6 of the 480 samples were misidentified due to interchanges (4 samples) or contamination (1 sample) or not identified because of insufficient signal intensity (1 sample).Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) has emerged as a fast and costeffective alternative for bacterial species identification in microbiology. On the basis of mass analysis of the protein composition of a bacterial cell, which is assumed to be characteristic for each bacterial species, it is possible to determine the species within few minutes, starting from whole cells, cell lysates, or crude bacterial extracts (2, 3, 5, 6). The proof of principle of MALDI-TOF MS for bacterial species identification was shown a decade ago (2, 5, 6); however, due to low reproducibility, it has not been widely adopted in clinical microbiology. We have recently shown that use of a larger mass range for detection (2,000 to 20,000 Da), dedicated analysis software for spectral pattern matching, and a highquality reference database of spectra generated from qualitycontrolled culture collection strains resulted in accurate species identifications, with high intralaboratory reproducibility (7). For interlaboratory reproducibility, there are only very limited data available (8, 10). We therefore evaluated the interlaboratory reproducibility for MALDI-TOF MS-based species identification in a multicenter study, applying the above-described MALDI-TOF MS improvements.(

The incidence of vancomycin-resistant Enterococcus faecium isolation was low (

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...

The performance of the BD Phoenix Automated Microbiology System (BD Diagnostic Systems, Sparks, Md.) was assessed for identification (ID) and antimicrobial susceptibility testing (AST) for the majority of clinically encountered bacterial isolates in a European collaborative two-center trial. A total of 469 bacterial isolates of the genera Staphylococcus (275 isolates), Enterococcus (179 isolates), and Streptococcus (15 isolates, for ID only) were investigated; of these, 367 were single patient isolates, and 102 were challenge strains tested at one center. Sixty-four antimicrobial drugs were tested, including the following drug classes: aminoglycosides, beta-lactam antibiotics, beta-lactam-beta-lactamase inhibitors, carbapenems, cephems, folate antagonists, quinolones, glycopeptides, macrolides-lincosamides-streptogramin B (MLS), and others. Phoenix ID results were compared to those of the laboratories' routine ID systems (API 32 Staph, API 32 Strep, and VITEK 2 [bioMérieux, Marcy l'Etoile, France]); Phoenix AST results were compared to those of frozen standard broth microdilution (SBM) panels according to NCCLS guidelines (NCCLS document M 100-S 9, approved standard M 7-A 4). Discrepant results were repeated in duplicate. Concordant IDs of 97.1, 98.9, and 100% were observed for staphylococci, enterococci, and streptococci, respectively. For AST results the overall essential agreement was 93.3%; the category agreement was 97.3%; and the very major error rate, major error rate, and minor error rate were 1.2, 1.9, and 1.3%, respectively. In conclusion, the Phoenix ID results showed high agreement with results of the systems to which they were being compared; the AST performance was highly equivalent to that of the SBM reference method.The clinical microbiology laboratory is confronted with an alarming increase of antimicrobial resistance on a global scale (7,8,9,13). Furthermore, the emergence of bacterial isolates with special resistance mechanisms such as oxacillin-resistant staphylococci or vancomycin-resistant enterococci constitutes a major problem, especially in intensive care units (1, 4). Both accurate and rapid diagnosis of oxacillin-resistant staphylococci and vancomycin-resistant enterococci has therefore become essential in the current health care environment.The BD Phoenix Automated Microbiology System (BD Diagnostic Systems, Sparks, Md.[BD]) is a newly developed instrument for the reliable and accurate identification and susceptibility testing for the majority of clinically encountered strains. The system is comprised of disposable panels, which combine both identification testing (ID) and antimicrobial susceptibility testing (AST), and an instrument which performs automatic reading at 20-min intervals during incubation. The system claims to provide accurate and rapid susceptibility results with easy workflow for the laboratory worker.We report on the ability of the Phoenix system to accurately perform ID and AST of clinical and challenge isolates in a large collaborative two-center trial involving th...

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