title: Comparison of Crystal Enteric/Nonfermenter system, API 20E system, and Vitek AutoMicrobic system for identification of gram-negative bacilli.
abstract: A comparative evaluation of the Crystal Enteric/Nonfermenter system (Crystal; Becton Dickinson, Cockeysville, Md.), API 20E (API; bioMérieux Vitek, Inc., Hazelwood, Mo.), and the Vitek GNI card (Vitek; bioMérieux Vitek) was performed with 512 clinical isolates of gram-negative bacilli, including 381 members of the family Enterobacteriaceae and 131 nonenteric bacilli. With supplemental testing, API, Crystal, and Vitek correctly identified to the genus and species level 505 (98.6%), 489 (95.5%), and 494 (96.5%) of the 512 isolates, respectively. Supplemental testing, as specified by the manufacturer, was required to identify 119 (23.2%), 18 (3.5%), and 5 (1.0%) of the isolates with the three systems, respectively. Of the 381 isolates from the family Enterobacteriaceae, API and Crystal correctly identified 90.3 and 91.6% by 18 to 24 h without supplemental testing, respectively, and Vitek identified 92.4 and 96.1% following 10 and 18 h of incubation, respectively. Of the 131 nonenteric organisms, API and Crystal correctly identified 28.2 and 93.9% by 18 to 24 h without supplemental testing, respectively, and Vitek identified 84.0% by 10 h and 93.9% by 18 h. Errors in identification with each system were infrequent and appeared to be randomly distributed among the genera evaluated. The three systems were comparable in accuracy when either a weighted clinical laboratory profile of organisms or a group of selected isolates in a stress test sample was evaluated (P > 0.05). There were no significant differences between the three systems in their ability to identify either the isolates in the weighted group or those in the stress test (P > 0.05). Crystal compared favorably with API and Vitek, which have established track records in clinical laboratories, and is acceptable for the identification of members of the Enterobacteriaceae and nonenteric bacilli in a clinical microbiology laboratory.
authors.affiliation: Department of Pathology and Laboratory Medicine, Hartford Hospital, Connecticut 06102-5037.
authors.forename: A
authors.initials: A
authors.lastname: Robinson
authors.forename: Y S
authors.initials: YS
authors.lastname: McCarter
authors.forename: J
authors.initials: J
authors.lastname: Tetreault
mesh_terms: D001431:Bacteriological Techniques / Q000592:standards / Q000706:statistics & numerical data; D003951:Diagnostic Errors; D004755:Enterobacteriaceae / Q000145:classification / Q000302:isolation & purification; D004756:Enterobacteriaceae Infections / Q000175:diagnosis; D005069:Evaluation Studies as Topic; D006090:Gram-Negative Bacteria / Q000145:classification / Q000302:isolation & purification*; D016905:Gram-Negative Bacterial Infections / Q000175:diagnosis; D006801:Humans; D011786:Quality Control; D013045:Species Specificity; D013997:Time Factors