Evaluation of a semi-automated 24-hour commercial system for identification ofEnterobacteriaceae and other gram-negative bacteria

Monnet, Dominique; Lafay, D.; Desmonceaux, M.; Boeufgras, J. M.; Allard, F; Freney, J.

doi:10.1007/bf01972003

Cited by 8 publications

(5 citation statements)

References 13 publications

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“…Results from other investigators indicate that the Vitek ID-GNB cards correctly identified 85.3 to 100% of P. aeruginosa strains routinely isolated from no CF patients (8,11,16). Finally, Saiman et al examined 189 mucoid and nonmucoid strains of P. aeruginosa from CF patients by MicroScan Autoscan and received correct identification rates of only 83% and 86%, respectively (20).…”

Section: Discussionmentioning

confidence: 99%

Validation of Vitek 2 Nonfermenting Gram-Negative Cards and Vitek 2 Version 4.02 Software for Identification and Antimicrobial Susceptibility Testing of Nonfermenting Gram-Negative Rods from Patients with Cystic Fibrosis

et al. 2009

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Accurate identification and antimicrobial susceptibility testing (AST) of nonfermenters from cystic fibrosis patients are essential for appropriate antimicrobial treatment. This study examined the ability of the newly designed Vitek 2 nonfermenting gram-negative card (NGNC) (new gram-negative identification card; bioMérieux, Marcyl'Ètoile, France) to identify nonfermenting gram-negative rods from cystic fibrosis patients in comparison to reference methods and the accuracy of the new Vitek 2 version 4.02 software for AST compared to the broth microdilution method. Two hundred twenty-four strains for identification and 138 strains for AST were investigated. The Vitek 2 NGNC identified 211 (94.1%) of the nonfermenters correctly. Among morphologically atypical microorganisms, five strains were misidentified and eight strains were determined with low discrimination, requiring additional tests which raised the correct identification rate to 97.8%. Regarding AST, the overall essential agreement of Vitek 2 was 97.6%, and the overall categorical agreement was 92.9%. Minor errors were found in 5.1% of strains, and major and very major errors were found in 1.6% and 0.3% of strains, respectively. In conclusion, the Vitek NGNC appears to be a reliable method for identification of morphologically typical nonfermenters and is an improvement over the API NE system and the Vitek 2 GNC database version 4.01. However, classification in morphologically atypical nonfermenters must be interpreted with care to avoid misidentification. Moreover, the new Vitek 2 version 4.02 software showed good results for AST and is suitable for routine clinical use. More work is needed for the reliable testing of strains whose MICs are close to the breakpoints.Pseudomonas aeruginosa is the most important cause of lung infections in patients with cystic fibrosis (CF) (14). In our hospital, 50% of sputum-producing CF patients are colonized in their lower airways with P. aeruginosa or other nonfermenting bacteria. Accurate identification and antimicrobial susceptibility testing (AST) are essential for appropriate antimicrobial therapy.A variety of automated commercial systems for identification and susceptibility testing of nonfermenting bacteria are available (2,3,12,19,20). They are widely used because of the increasing volumes of clinical specimens processed by clinical laboratories and perceived cost effectiveness. The automated systems decrease the in-laboratory turnaround time and enable a faster targeted antimicrobial therapy. Unfortunately, errors in classification and AST by any test system can have serious implications for the clinical outcome of patients. The most frequently reported errors have involved the inaccurate identification of nonfermenters due to their phenotypic variations and slower growth rates and the inconsistencies between the tested broad-spectrum ␤-lactam antibiotics. Because of the perceived inaccuracies of AST from CF isolates, a consensus conference on CF microbiology recommended the use of the disk diffusion method for ...

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Section: Discussionmentioning

confidence: 99%

Validation of Vitek 2 Nonfermenting Gram-Negative Cards and Vitek 2 Version 4.02 Software for Identification and Antimicrobial Susceptibility Testing of Nonfermenting Gram-Negative Rods from Patients with Cystic Fibrosis

et al. 2009

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“…A new well-based identification system, ID 32E, was recently developed by bioMérieux Vitek for the identification of Enterobacteriaceae and other nonfastidious gram-negative bacteria, after an incubation period of 22 Ϯ 2 h at 37 Ϯ 1°C (17,23). This system is an upgrading of the API 20E gallery and consists of 32 individual conic test wells (13 enzymatic, 3 biochemical, and 16 sugar utilization tests) in polystyrene trays (Table 1).…”

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confidence: 99%

“…Although phenotypic variants (5,6,15,20,21,23) can cause identification problems for some E. coli strains, nu- merous commercial systems or previous study on ID 32E systems (17,23) have been shown to identify E. coli with a fairly high degree of accuracy (11, 13, 14, 16, 19-22, 25-29, 32, 33, 36, 37). One strain serotyped as O74:H52 was found to be indole negative without affecting its identification as E. coli.…”

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confidence: 99%

Particular Biochemical Profiles for Enterohemorrhagic Escherichia coli O157:H7 Isolates on the ID 32E System

et al. 2001

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The ability of the ID 32E system to identify and discriminate 74 Escherichia coli O157 isolates among 106 E. coli non-O157 isolates was evaluated. The results showed atypical biochemical reactions but accurate identification at the species level and no unique biochemical profile numbers for E. coli O157, although these numbers were distinct from those of other serotypes.Verocytotoxigenic Escherichia coli (VTEC), a new public health problem worldwide, is represented by more than 100 serotypes that produce verocytotoxins, with two main serotypes, O157:H7 and O157:H(Ϫ). These last two serotypes, classified as enterohemorrhagic E. coli (EHEC), are implicated in hemorrhagic colitis, hemolytic-uremic syndrome, and thrombotic thrombocytopenic purpura. EHEC strains have been described as important and emergent food-borne pathogens (4, 18, 31). Other non-O157 VTEC serotypes, not deprived of pathogenicity, have been increasingly implicated in sporadic enteric diseases and outbreaks (18,31).Detection of E. coli O157:H7 is based on its recovery from samples and the presence of its virulence-associated factors (verocytotoxins) or the detection of its O157 antigens (3,30,31). Selective media for isolating O157:H7 strains rely on the fact that most of these strains display characteristic biochemical reactions (31): no ␤-glucuronidase activity and no D-sorbitol fermentation within 24 h at 37°C, except for some German or U.S. strains (10, 12). However, these last two biochemical features are not commonly used in routine clinical and food laboratories because of the simplicity of well-established commercial identification systems. The use of these systems on presumptive E. coli strains offers not only the advantage of confirming strains at the genus and/or species level but also the possibility to detect the presence of O157 EHEC by identifying profiles that are unique to these strains. For the Microscan dried conventional gram-negative identification panel (DadeMicroScan International, West Sacramento, Calif.), 90% of the tested E. coli O157:H7 strains shared two common biochemical profiles (1), whereas in the case of the API 20E (bioMérieux Vitek, Inc., Hazelwood, Mo.), 92% of the tested strains displayed the same profile (8).A new well-based identification system, ID 32E, was recently developed by bioMérieux Vitek for the identification of Enterobacteriaceae and other nonfastidious gram-negative bacteria, after an incubation period of 22 Ϯ 2 h at 37 Ϯ 1°C (17, 23). This system is an upgrading of the API 20E gallery and consists of 32 individual conic test wells (13 enzymatic, 3 biochemical, and 16 sugar utilization tests) in polystyrene trays (Table 1).A total of 180 serotyped E. coli strains were tested with the ID 32E system. These included 55 O157:H7 strains, 19 O157: H(Ϫ) strains confirmed by PCR on the rfb O157 locus (3), and 106 reference strains and laboratory isolates of non-O157:H7 or O157H(Ϫ) E. coli harboring (76 strains) or not harboring (30 strains) verocytotoxin genes, originating from patients, animals, and food...

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“…In this study, each strain identification was compared with that obtained by using reference biochemical tests, as performed at the Centers for Disease Control and Prevention (CDC) [4–6]. Commercial media were used whenever possible.…”

Section: Methodsmentioning

confidence: 99%

Evaluation of the ID 32E for the identification of Gram-negative glucose-fermenting and glucose-non-fermenting bacilli

O'Hara

Miller

1999

Clinical Microbiology and Infection

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OBJECTIVE: To evaluate the ID 32E bacterial identification system for accuracy in the identification of members of the family Enterobacteriaceae, Pseudomonas aeruginosa, Stenotrophomonas maltophilia, and Acinetobacter baumannii/Iwoffii. METHODS: Stock cultures of 497 Enterobacteriaceae and 27 commonly encountered non-enteric Gram-negative rods were tested in the ID 32E system. For each isolate, the resulting 11-digit profile number was converted to an identification using the APILAB Plus software (version 3.2.2). This identification was then compared to the reference identification obtained using conventional biochemicals. RESULTS: Of the 524 isolates tested, 405 (77.3%) were identified correctly; 52 (9.9%) were identified incorrectly. Sixty-seven (12.8%) identifications were either doubtful or unacceptable, and were not limited to any particular genus or species, with the exception of Ewingella americana and Serratia plymuthica, which did not grow well enough in the strip at 35 degrees C to be correctly identified. All five isolates of Acinetobacter Iwoffii were misidentified as Alcaligenes spp. CONCLUSIONS: With this challenge set of organisms, the ID 32E correctly identified 77.3% of the isolates tested. For commonly encountered isolates, the accuracy approached 90%. We conclude that the ID 32E offers an alternative for the identification of common clinical isolates.

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Evaluation of a semi-automated 24-hour commercial system for identification ofEnterobacteriaceae and other gram-negative bacteria

Cited by 8 publications

References 13 publications

Validation of Vitek 2 Nonfermenting Gram-Negative Cards and Vitek 2 Version 4.02 Software for Identification and Antimicrobial Susceptibility Testing of Nonfermenting Gram-Negative Rods from Patients with Cystic Fibrosis

Validation of Vitek 2 Nonfermenting Gram-Negative Cards and Vitek 2 Version 4.02 Software for Identification and Antimicrobial Susceptibility Testing of Nonfermenting Gram-Negative Rods from Patients with Cystic Fibrosis

Particular Biochemical Profiles for Enterohemorrhagic Escherichia coli O157:H7 Isolates on the ID 32E System

Evaluation of the ID 32E for the identification of Gram-negative glucose-fermenting and glucose-non-fermenting bacilli

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