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). Significantly more isolates required supplemental testing with API than with Crystal or Vitek (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.

Evaluation of Vitek GNI+ and Becton Dickinson Microbiology Systems Crystal E/NF identification systems for identification of members of the family Enterobacteriaceae and other gram-negative, glucose-fermenting and non-glucose-fermenting bacilli

“…Other evaluations of the Crystal E/NF have reported accuracies ranging from 47 to 97% after initial incubation and error rates as low as 0.8% (6,(8)(9)(10). The numbers and identifications of strains that were tested in those studies more closely represent the assortment of organisms found in clinical laboratories on a daily basis than do the organisms used in this study.…”

Identification of Yersinia pestis by BBL Crystal Enteric/Nonfermenter Identification System

“…1,1996), which now includes the variations in arabinose fermentation so often seen with isolates of Y. pestis, should increase the accuracy of this system. In previous studies, API correctly identified 88 to 99.4% of the enteric, nonfermentative bacteria tested (3,(5)(6)(7)(8)(9), and API 20NE correctly identified 75.3% of these bacteria (10). These older systems clearly misidentify the less reactive bacteria, which could lead to misdiagnosis.…”

Potential use of molecular-typing methods for the identification and characterization of salmonella enterica serotypes isolated in the poultry production chain

“…Salmonella infections may cause gastroenteritis, involving an abrupt onset of nausea, fever, vomiting, and diarrhea, with several virulence factors involved (Baumler et al, 1998;Schaechter et al, 2001). Some outbreaks affecting the population are caused by specific Salmonella serovars (serotypes), and the difficulty in detecting carriers makes these a potential source of contamination, particularly due to detection limitations of culture techniques, which are also time-consuming (Robinson et al, 1995;Aspinall et al, 1992).…”