Caroline M. O Hara* Division of Healthcare Quality Promotion, Centers for Disease Control and Prevention, Atlanta, Georgia 30333

JOURNAL OF CLINICAL MICROBIOLOGY, Mar. 2006, p. 928 933 Vol. 44, No. 3 0095-1137/06/$08.00 0 doi:10.1128/jcm.44.3.928 933.2006 Evaluation of the Phoenix 100 ID/AST System and NID Panel for Identification of Enterobacteriaceae, Vibrionaceae, and Commonly Isolated Nonenteric Gram-Negative Bacilli Caroline M. O Hara* Division of Healthcare Quality Promotion, Centers for Disease Control and Prevention, Atlanta, Georgia 30333 Received 20 April 2005/Returned for modification 25 May 2005/Accepted 3 January 2006 The Phoenix 100 ID/AST system (Becton Dickinson Co., Sparks, Md.) is an automated system for the and antimicrobial susceptibility testing of bacterial isolates. This system with its negative (NID) panel was evaluated for its accuracy in the of 507 isolates of the family Enterobacteriaceae, 57 other nonenteric gram-negative isolates that are commonly isolated in clinical microbiology laboratories, and 138 isolates of the family Vibrionaceae. All of the isolates had been characterized by using approximately 48 conventional tube biochemicals. Of the 507 isolates of the Enterobacteriaceae, 456 (89.9%) were correctly the genus and species levels. The five isolates of Proteus penneri required an off-line indole test, as suggested by the system to differentiate them from Proteus vulgaris. The s of 20 (3.9%) isolates were correct to the but incorrect at the species level. Two (0.4%) isolates were reported as no. Miss to the genus and species levels occurred for 29 (5.7%) isolates of the Enterobacteriaceae. These incorrect s were spread over 14 different genera. The most common error was the mis of Salmonella species. The shortest time for a correct was 2 h 8 min. The longest time was 12 h 27 min, for the of a Serratia marcescens isolate. Of the 57 isolates of nonenteric gram-negative bacilli (Acinetobacter, Aeromonas, Burkholderia, Plesiomonas, Pseudomonas, and Stenotrophomonas spp.), 48 (84.2%) were correctly the genus and species levels and 7 (12.3%) were correctly the but not to the species level. The average time for a correct was 5 h 11 min. Of the Vibrionaceae spp., 123 (89.1%) were correctly identified at the end of the initial incubation period, which averaged 4 h. Based on the findings of this study, the Phoenix 100 ID/AST system NID panel falls short of being an acceptable new method for the of the Enterobacteriaceae, Vibrionaceae, and gram-negative nonenteric isolates that are commonly encountered in many hospital microbiology laboratories. Downloaded from http://jcm.asm.org/ The introduction of the Phoenix 100 ID/AST system (Becton Dickinson Co. [BD], Sparks, Md.) within the United States brings to four the number of automated systems on the market worldwide. The use of automated systems in clinical microbiology laboratories is widespread, and technologists rely heavily on their accuracy. Since bacterial s are linked to the algorithms for antimicrobial susceptibility testing in several of the machines, the accuracy of the affects the interpretation of the accompanying antimicrobial susceptibility tests. I evaluated the accuracy of the Phoenix 100 ID/AST system and the negative (NID) panel when they were used to identify members of the families Enterobacteriaceae and Vibrionaceae, members of the genera Aeromonas and Plesiomonas, and commonly isolated gram-negative nonenteric organisms. MATERIALS AND METHODS Identification system and software version. The NID panels were processed in a Phoenix 100 ID/AST system. All panels were processed according to the manufacturer s directions. Each NID panel contained 45 substrates plus two fluorescent positive control wells. The substrates used one of the following principles: enzymatic hydrolysis * Corresponding author. Mailing address: Division of Healthcare Quality Promotion, Centers for Disease Control and Prevention, Mailstop C16, Atlanta, GA 30333. Phone: (404) 639-2316. Fax: (404) 639-3822. E-mail: cmo1@cdc.gov. of the amide or glycosidic bond, which results in the release of a fluorescent coumarin or 4-methylumbelliferone derivative (13 substrates); resistance to an antimicrobial agent or utilization of a carbon source, which results in a reduction of the resazurin-based indicator (2 and 7 substrates, respectively); enzymatic hydrolysis of a colorless substrate, which releases a yellow end product (4 substrates); utilization of carbohydrates, which results in lower phs and changes in the phenol red indicator (16 substrates); hydrolysis of ornithine or urea, which results in a change in the fluorescent indicator; or hydrolysis of esculin, which results in a black precipitate in the presence of the ferric ion. Each panel must be inoculated within 2 h after its foil pouch is opened, and the panels must be loaded into the instrument within 30 min of inoculation. Only cotton-tipped swabs or wooden applicators are acceptable for preparation of the suspensions. A suspension of each 24-h-old isolate was made in the Phoenix 100 ID/AST broth to match the turbidity of a 0.5 McFarland standard by using a CrystalSpec nephelometer (Becton Dickinson). The panel was inoculated, the inoculation port was sealed with a panel closure, and the panel was loaded into the instrument. The current database is version 3.34, which contains 60 genera, 155 species, and 5 CDC enteric groups. Culture collection. The 702 isolates of biochemically typical and atypical members of the families Enterobacteriaceae, Vibrionaceae, and Aeromonadaceae and commonly isolated gram-negative nonenteric organisms were taken from the stock culture collection of the Centers for Disease Control and Prevention (CDC) and had previously been characterized with 48 conventional biochemicals by standard methods (4, 6, 8). All isolates of Vibrio cholerae and Vibrio parahaemolyticus were serotyped for confirmation. Isolates were maintained in defibrinated sheep blood at 70 C. Upon removal from the freezer, the isolates were passed three times on tryptic soy agar with 5% sheep blood (TSA II; BD Biosciences Inc., Sparks, Md.) before inoculation into the NID panels. All incubations were at 35 1 C, unless otherwise noted. Eighteen isolates of biochemically typical and atypical Salmonella spp. were obtained from either clinical microbiology laboratories in the United States or on July 22, 2018 by guest 928

VOL. 44, 2006 TESTING WITH THE PHOENIX SYSTEM 929 TABLE 1. Enteric isolates tested with NID card tested with correct Avg time (h:min) to correct Unidentified Cedecea davisae 6 6 3:16 Cedecea lapagei 4 4 3:30 Citrobacter amalonaticus 10 10 2:40 Citrobacter braakii 6 4 5:46 1 1 Citrobacter farmeri 5 5 6:17 Citrobacter freundii 2 2 3:12 Citrobacter koseri 10 9 2:30 1 Citrobacter sedlakii 1 1 Citrobacter werkmanii 4 3 4:59 1 Citrobacter youngae 5 5 4:42 Edwardsiella tarda 10 9 2:30 1 Enterobacter aerogenes 10 10 2:28 Enterobacter asburiae 10 9 4:17 1 Enterobacter cancerogenus 10 10 4:33 Enterobacter cloacae 10 6 2:49 2 2 Enterobacter gergoviae 10 8 4:29 2 Enterobacter hormaechei 6 4 4:14 2 Enterobacter sakazakii 10 10 4:13 (12 atypical isolates) 30 29 2:59 1 Escherichia fergusonii 10 10 2:24 Escherichia hermannii 10 10 3:33 Escherichia vulneris 10 10 2:31 Ewingella americana 10 10 2:35 Hafnia alvei 9 9 2:20 Klebsiella oxytoca 10 10 3:31 Klebsiella pneumoniae subsp. ozaenae 10 9 2:37 1 Klebsiella pneumoniae subsp. pneumoniae 10 9 2:45 1 Klebsiella pneumoniae subsp. rhinoscleromatis 10 10 2:16 Kluyvera ascorbata 5 5 2:33 Kluyvera cryocrescens 5 5 2:53 Leclercia adecarboxylata 10 10 2:40 Moellerella wisconsensis 8 8 2:16 Morganella morganii 10 10 4:52 Pantoea agglomerans 9 8 6:59 1 Proteus mirabilis 10 10 3:15 Proteus penneri 10 10 3:30 Proteus vulgaris 10 9 3:30 1 Providencia alcalifaciens 7 7 2:42 Providencia rettgeri 8 7 2:59 1 Providencia rustigianii 2 2 3:58 Providencia stuartii 14 13 3:16 1 Rahnella aquatilis 2 2 2:49 Raoultella ornithinolytica 10 9 4:13 1 Salmonella enterica subsp. arizonae 10 5 6:16 1 4 Salmonella enterica serovar Choleraesuis 2 1 2:12 1 Salmonella enterica serovar Gallinarum 1 1 4:14 Salmonella species 16 13 3:23 1 2 Salmonella species, lactose positive 1 1 3:19 Salmonella enterica serovar Paratyphi A 2 2 6:19 Salmonella enterica serovar Pullorum 1 1 6:18 Salmonella enterica serovar Typhi 2 2 4:19 Serratia fonticola 10 8 2:34 2 Serratia liquefaciens group 10 7 3:13 2 1 Serratia marcescens 10 10 3:51 Serratia odorifera (both biogroups) 10 10 2:20 Serratia plymuthica 10 10 3:22 Serratia rubidaea 10 8 4:02 1 1 Shigella boydii 3 2 12:10 1 Shigella dysenteriae 1 1 6:11 Shigella flexneri 2 1 4:19 1 Shigella sonnei 4 2 4:15 2 Yersinia enterocolitica 11 9 3:23 2 Yersinia frederiksenii 3 2 6:15 1 Yersinia intermedia 2 1 3:18 1 Yersinia kristensenii 2 0 2 Yersinia pseudotuberculosis 6 6 2:21 Yokenella regensburgei 10 8 7:00 2 Total 507 456 (89.9%) 3:53 20 (3.9%) 2 (0.4%) 29 (5.7%)

930 O HARA J. CLIN. MICROBIOL. TABLE 2. Problems in Correct to Phoenix system Citrobacter braakii Citrobacter koseri Citrobacter sedlakii Citrobacter werkmanii Edwardsiella tarda Enterobacter asburiae Enterobacter cloacae (2 strains) Enterobacter cloacae (2 strains) Enterobacter gergoviae (2 strains) Enterobacter hormaechei (typical) Klebsiella pneumoniae subsp. ozaenae Klebsiella pneumoniae subsp. pneumoniae Pantoea agglomerans Proteus vulgaris Providencia rettgeri Providencia stuartii, urea positive Raoultella ornithinolytica Salmonella enterica subsp. arizonae Salmonella enterica subsp. arizonae (four isolates) Salmonella enterica serovar Choleraesuis Salmonella species Salmonella species (H 2 S negative, lysine negative) Serratia fonticola (two isolates) Serratia liquefaciens group (two isolates) Serratia liquefaciens group Serratia rubidaea Serratia rubidaea Shigella boydii Shigella flexneri Shigella sonnei (two strains) Yersinia enterocolitica (two isolates) Yersinia frederiksenii Yersinia intermedia Yersinia kristensenii (2 isolates) Yokenella regensburgei (2 isolates) a ID,. Citrobacter freundii Citrobacter farmeri Citrobacter braakii the Salmonella reference laboratory at the CDC. These isolates had never been frozen and had been passed a minimal number of times since they were isolated from their respective patient source and before they were tested in the Phoenix system. Additional tests. The only additional biochemical test required by the Phoenix system for was the spot indole test to differentiate between Proteus penneri and P. vulgaris. Definitions. Correct means that the Phoenix system agreed with the reference biochemical at the genus and the species levels at the end of the incubation period. In this study, the incubation period ranged from2h8minto12h20min. Correct to genus means that the Phoenix system identified the organism to the correct genus but not to the species level, when that genus and species were included in the database. No means that the instrument could not identify the organism within the maximum allowable time of 12 h. means that the instrument misidentified the organism at a confidence value of 90% when that organism was contained within the database. A confidence level of 90% is the lower limit of acceptability for the Phoenix system. Any with a confidence value of 90% at 12 h is categorized as no. If an initial was in error, an additional passage on blood agar was made and the test was repeated in duplicate to eliminate the possibility of technical error. The best two of three answers were used for categorization of that isolate. Edwardsiella ictalura Enterobacter cloacae Enterobacter asburiae; Enterobacter amnigenus biogroup 1 Klebsiella pneumoniae subsp. ozaenae Proteus penneri Providencia stuartii Salmonella spp. Serratia marcescens Serratia marcescens Yersinia frederiksenii Yersinia intermedia Yersinia frederiksenii Yersinia enterocolitica No ID a ; Escherchia coli; Citrobacter youngae Citrobacter farmeri; Kluyvera ascorbata Pantoea agglomerans; three different answers for second isolate Citrobacter youngae Citrobacter freundii Pasteurella pneumotropica Shigella flexneri Proteus mirabilis Klebsiella oxytoca Shigella sonnei Klebsiella pneumoniae subsp. ozaenae Burkholderia cepacia Pantoea agglomerans Salmonella typhi (one isolate); three different answers (one isolate) ; Escherichia hermannii RESULTS Table 1 shows the results of testing of 507 isolates of the Enterobacteriaceae. At the end of the incubation period, 456 (89.9%) of the isolates were correctly identified, 20 isolates (3.9%) were correctly the only, and 29 isolates (5.7%) were incorrectly identified. Table 2 expands on the errors in to the species level or totally incorrect s (error). These 29 errors were scattered over 14 genera and were not concentrated in any one particular genus, with the exception of the genus Salmonella. The s for 317 (62.5%) isolates that were correct were completed in 4 h or less. The database of the Phoenix NID groups together as Salmonella species isolates that are neither of the serovar Choleraesuis, Gallinarum, Paratyphi, Pullorum, nor of S. enterica Typhi, subsp. arizonae. Of the 16 stock Salmonella species cultures that have been frozen at 70 C for many years, 13 were correctly identified (81.3%) and 2 were misidentified

VOL. 44, 2006 TESTING WITH THE PHOENIX SYSTEM 931 TABLE 3. Nonenteric isolates tested with NID card tested with correct Avg time (h:min) to correct Unidentified Acinetobacter baumannii complex 7 5 9:51 2 Acinetobacter lwoffi 5 3 12:19 1 1 Aeromonas (mixed species) 10 6 2:51 4 Burkholderia cepacia 7 6 3:03 1 Plesiomonas shigelloides 10 10 2:50 Pseudomonas aeruginosa 10 10 2:48 Stenotrophomonas maltophilia 8 8 2:30 Total 57 48 (84.2%) 5:11 7 (12.3%) 0 2 (3.5%) (12.5%). In an effort to learn if the Salmonella miss were the result of the isolates being frozen for many years, 18 fresh isolates were obtained from patients in community hospitals in 10 different states. These strains were passed only one time for a purity check before they were tested. Of the 18 fresh Salmonella isolates, 13 were correctly identified (72.2%) and 5 were misidentified (27.8%). What is particularly troublesome is that the seven misidentified isolates (stock or fresh) were called with a confidence level exceeding 90%. In an effort to learn why these errors occurred, I worked with the manufacturer to test certain isolates in conventional biochemicals, with those results being compared to the results from Phoenix system testing. Raw data were given to BD, which selected five of the isolates for testing in 1% Andrade s galacturonate. Of those five isolates, four (80%) gave the same result with the conventional substrate that was seen with the Phoenix panel; however, they were still misidentified as E. coli. Another disturbing set of results concerns the Shigella spp. The 10 isolates were not atypical in their biochemical results and should not have been difficult to identify, yet the instrument failed to identify 4 of them. Table 3 shows the results obtained from the testing of 57 isolates of seven nonenteric genera, of which 84.2% were correctly identified. The average time for a correct was5h11min, although the time was much shorter if the times for the Acinetobacter isolates are removed from the calculation. Table 4 shows the results of testing of 138 isolates of eight different species of Vibrio and Photobacterium damselae. Of those isolates, 89.1% were correctly identified, although only 44.9% of the correct s were obtained in 4 h or less. Less than 3.6% of these isolates not in the family Enterobacteriaceae were misidentified. Table 5 lists the errors for all the nonenteric isolates. While the 702 isolates tested presented a true challenge to the instrument, they do not reflect what is more likely seen in the daily workload of the clinical laboratory. On the basis of input from local area hospitals, an assortment of strains that approximate the relative numbers and types of strains likely to be routinely isolated in a clinical microbiology laboratory was randomly extracted from the challenge set. This weighted set of 118 strains gave the results shown in Table 6. Even with the weighted set of strains, it is recognized that some of the strains, if they were isolated in a clinical laboratory, would be subject to by using spot tests and would not be inoculated into a panel on an automated instrument. DISCUSSION Many clinical microbiology laboratories require that their systems perform at an accuracy of 90% or better, and many require a 95% accuracy. The Phoenix system accurately identifies isolates of the family Enterobacteriaceae only tested TABLE 4. Vibrio spp. isolates tested with NID card with correct Avg time (h:min) to correct Unidentified Vibrio alginolyticus 12 9 7:26 2 1 Vibrio cholerae 33 28 3:44 5 Vibrio fluvialis 11 11 2:21 Vibrio hollisae 10 10 3:07 Vibrio metschnikovii 9 8 2:09 1 Vibrio mimicus 10 10 2:51 Vibrio parahaemolyticus 34 29 8:48 3 2 Vibrio vulnificus 10 10 3:16 Photobacterium damselae 9 8 2:28 1 Total 138 123 (89.1%) 4:01 7 (5.1%) 3 (2.2%) 5 (3.6%)

932 O HARA J. CLIN. MICROBIOL. TABLE 5. Problems with s of nonenteric bacteria Correct to Phoenix Acinetobacter baumannii (two isolates) Acinetobacter lwoffi Acinetobacter lwoffi Aeromonas sobria Aeromonas caviae Aeromonas hydrophila (two isolates) Burkholderia cepacia Vibrio alginolyticus (two isolates) Vibrio alginolyticus Vibrio cholerae (five isolates) Vibrio metschnikovii Vibrio parahaemolyticus Photobacterium damselae Acinetobacter species Three different species Aeromonas caviae Three different species Aeromonas caviae; Aeromonas veronii Vibrio fluvialis; Vibrio parahaemolyticus (one isolate each) Vibrio mimicus (five isolates) 89% of the time. Even with a weighted set of organisms, the accuracy is 89%. In the only other published study of the Phoenix system that used conventional biochemicals for a reference method, Colodner et al. reported 90.2% accuracy when identifying 51 isolates of Vibrio vulnificus biotype 3 as Vibrio vulnificus (2). Because the present study did not include any biogroup 3 isolates, it is not known how the present results compare to those of Colodner and coworkers (2). Several evaluations that used other commercial products as the reference method have been performed. Endimiani et al. tested 136 nonfermenting gram-negative bacilli and reported 95.6% agreement between the Phoenix 100 ID/AST system and the ATB/ID32GN system (biomérieux, Marcy l Etoile, France) (5). All isolates of Pseudomonas aeruginosa and Stenotrophomonas maltophilia, perhaps the most commonly isolated nonfermenters in a hospital laboratory, TABLE 6. Results of testing of a weighted set of strains Total identified 30 29 1 Enterobacter cloacae 10 6 2 2 Klebsiella pneumoniae 10 9 1 Pseudomonas aeruginosa 10 10 Acinetobacter baumannii 7 5 2 Enterobacter aerogenes 6 6 Klebsiella oxytoca 6 6 Proteus vulgaris 6 5 1 Proteus mirabilis 5 5 Salmonella spp. 5 4 1 Serratia marcescens 5 5 Citrobacter freundii 4 4 Citrobacter koseri 4 3 1 Morganella morganii 3 3 Stenotrophomonas maltophilia 3 3 Providencia stuartii 2 2 Shigella spp. 2 1 1 Total 118 106 (89.8%) 7 (5.9%) 5 (4.2%) Pseudomonas [sic] oryzihabitans Burkholderia/Ralstonia (no additional tests given) Aeromonas caviae Yersinia ruckerii Aeromonas salmonicida; one isolate gave three different s Vibrio hollisae were correctly identified. Stefaniuk et al. reported an accuracy rate of 92.5% compared to the results of testing with the API 20E system when they tested 120 isolates that represented only eight of the most commonly encountered species of Enterobacteriaceae (11). The same study showed an agreement of 96.3% compared to the results obtained with the API 20NE system for the of 54 isolates of P. aeruginosa, Acinetobacter baumannii, and S. maltophilia. When Donay et al. used the same two reference systems for comparison of the results to those obtained with the Phoenix system, the s of 130 isolates of the Enterobacteriaceae and 57 isolates of nonenteric organisms showed accuracy rates of 94.6% and 89.4%, respectively (3). Brisse et al. tested 134 isolates of the Burkholderia cepacia complex from cystic fibrosis patients; they had been identified by five different molecular biology-based methods, and an accuracy rate of only 50% was reported (1). The rate of 85.7% in the present study is higher probably because none of the B. cepacia isolates in this study were from cystic fibrosis patients. These isolates are known to be more difficult to identify. Schreckenberger et al. compared the Phoenix NID to both the Vitek Legacy and the Vitek 2 colorimetric systems (P. C. Schreckenberger, K. L. Ristow, and A. M. Krilcich, Abstr. 105th Gen. Meet. Am. Soc. Microbiol., abstr. C-193, 2005). Testing 288 isolates of Enterobacteriaceae and 129 isolates of nonfermenters, they reported NID accuracy rates of 93.8% and 83.7%, respectively. In a related study by Funke and Funke-Kissling, in which 309 isolates were inoculated directly from positive blood culture bottles into the Phoenix NID panels, 92.9% of the isolates were correctly the genus and species (7). At this time, that is the only study that has addressed the concept of without prior isolation of the organism in pure culture. The Phoenix 100 ID/AST NID panels were easy to use. Once the suspension was made, the panel was inoculated, and the panel closure was snapped into place, the panel was completely sealed, thereby preventing possible contamination to the technologist. If, however, the panel was jostled unnecessarily or dropped, the liquid in the esculin well was disturbed

VOL. 44, 2006 TESTING WITH THE PHOENIX SYSTEM 933 enough that the baseline reading was not valid and the test with the panel was aborted. This study encountered three instances of panel closures that were mismolded during production. Because there were no obvious flaws in the closures, they were used, only to be ripped from the panel during the first rotation of the carousel. This action did not damage or jam the machine, but the test with the panel had to be aborted and set up again. BD is currently preparing to release an alternate inoculum procedure that uses an inoculum density equal to a 0.25 McFarland standard. This workflow has been validated for use with the current NID panels and allows the instrument to read panels inoculated either way simultaneously. The Phoenix instrument requires a bench that is able to support 500 pounds and that has at least 6 linear feet of space. The machine accommodates 99 panels, with one slot allocated for the permanently installed thermometer. No internal cleaning or maintenance of the machine is required. The Phoenix system validates itself on every cycle. All of the consumables that are required can be stored at room temperature. Panels are available in either -only formats or as combination panels with and antimicrobial susceptibility testing capabilities. The panels are read every 20 min; and calculations are made after the readings are taken at 2, 3, 4, 6, and 12 h. Panel testing ceases after 12 h 20 min. The Institute of Medicine report To Err is Human: Building a Safer Health System proposed a comprehensive approach to reducing medical errors and improving patient safety (9). While laboratory errors were not addressed directly, one of the recommendations was that heath care organizations implement proven medication safety practices. Because of issues related to increased resistance to antimicrobial agents in certain genera, it is imperative that the of causative agents of infection be as accurate as possible, preferably in the shortest time possible, thus allowing appropriate antimicrobial therapy to be initiated. In the 8th edition of the Manual of Clinical Microbiology (10), it is recommended that the accuracy of a system exceed 90% in its overall ability to identify common and uncommon bacteria normally seen in the hospital laboratory and that the system be able to identify commonly isolated organisms with at least 95% accuracy compared with the accuracies of conventional methods. With an overall accuracy of 88.9% for the of a challenge set of enteric and nonfermenter organisms and an accuracy of 89.8% for the of the weighted set of isolates, the Phoenix NID panel falls short of providing accurate s to satisfy these criteria. REFERENCES 1. Brisse, S., S. Stefani, J. Verhoef, A. Van Belkum, P. Vandamme, and W. Goessens. 2002. Comparative evaluation of the BD Phoenix and Vitek 2 automated instruments for of isolates of the Burkholderia cepacia complex. J. Clin. Microbiol. 40:1743 1748. 2. Colodner, R., R. Raz, I. Meir, T. Lazarovich, L. Lerner, J. Kopelowitz, Y. Keness, W. Sakran, S. Ken-Dror, and N. Bisharat. 2004. Identification of the emerging pathogen Vibrio vulnificus biotype 3 by commercially available phenotypic methods. J. Clin. Microbiol. 42:4137 4140. 3. Donay, J.-L., D. Mathieu, P. Fernandes, C. Prégermain, P. Bruel, A. Wargnier, I. Casin, F. X. Weill, P. H. Lagrange, and J. L. Hermann. 2004. Evaluation of the automated Phoenix system for potential routine use in the clinical microbiology laboratory. J. Clin. Microbiol. 42:1542 1546. 4. Edwards, P. R., and W. H. Ewing. 1972. Identification of Enterobacteriaceae, 3rd ed. Burgess Publishing Co., Minneapolis, Minn. 5. Endimiani, A., F. Luzzaro, A. Tamborini, G. Lombardi, V. Elia, R. Belloni, and A. Toniolo. 2002. Identification and antimicrobial susceptibility testing of clinical isolates of nonfermenting gram-negative bacteria by the Phoenix automated microbiology system. Microbiologica 25:323 329. 6. Farmer, J. J., III, M. A. Asbury, F. W. Hickman, D. J. Brenner, and the Enterobacteriaceae Study Group. 1980. Enterobacter sakazakii: a new species of Enterobacteriaceae isolated from clinical specimens. Int. J. Syst. Bacteriol. 30:569 584. 7. Funke, G., and P. Funke-Kissling. 2004. Use of the BD Phoenix automated microbiology system for direct and susceptibility testing of gram-negative rods from positive blood cultures in a three-phase trial. J. Clin. Microbiol. 42:1466 1470. 8. Hickman, F. W., and J. J. Farmer III. 1978. Salmonella typhi:, antibiograms, serology, and bacteriophage typing. Am. J. Med. Technol. 44:1149 1150. 9. Kohn, L. T., J. M. Corrigan, and M. S. Donaldson. 2000. To err is human: building a safer health system. National Academy Press, Washington, D.C. 10. O Hara, C. M., M. P. Weinstein, and J. M. Miller. 2003. Manual and automated systems for detection and of microorganisms, p. 185 207. In P. R. Murray, E. J. Baron, M. A. Pfaller, J. H. Jorgensen, and R. H. Yolken (ed.), Manual of clinical microbiology, 8th ed. American Society for Microbiology, Washington, D.C. 11. Stefaniuk, E., A. Baraniak, M. Gniadkowski, and W. Hryniewicz. 2003. Evaluation of the BD Phoenix automated and susceptibility testing system in clinical microbiology laboratory practice. Eur. J. Clin. Microbiol. Infect. Dis. 22:479 485.