[Show abstract][Hide abstract] ABSTRACT: The VITEK 2 gram-positive (GP) identification card (bioMérieux, Marcy l'Etoile, France) has been redesigned to achieve greater
accuracy in the identification of gram-positive cocci. A total of 43 biochemical tests, including 17 enzymatic tests, are
present in the card and interpreted in a kinetic mode, for up to 8 h. The VITEK 2 database, used in conjunction with the GP
identification card, allows the identification of 115 different taxa. A total of 364 strains of GP cocci (217 Streptococcaceae strains and 147 Micrococcaceae strains) belonging to 31 taxa were tested with the new VITEK 2 GP identification card. Of the 364 strains, 105 were taken
from routine primary plating media. A total of 344 strains (94.5%) were correctly identified to the species level and 17 strains
(4.7%) were identified with low discrimination, requiring additional tests, whereas 1 strain (0.3%) was incorrectly identified
and 2 strains (0.5%) remained unidentified. Within 7 h of the start of incubation, more than 90% of all strains were identified.
Of the 105 primary cultures, 97% were correctly identified to the species level, 2% were identified with low discrimination,
and 1% remained unidentified. Identification performance data were independent of each of the three plating media used. It
is concluded that the new VITEK 2 GP identification card provides reliable results for the identification of GP cocci under
routine laboratory conditions.
[Show abstract][Hide abstract] ABSTRACT: The VITEK 2 card for gram-negative bacteria (bioMérieux,Marcy-l'Etoile, France) has been redesigned to improve the identification of fermenting and nonfermenting bacilli. Forty-seven biochemical tests, including 19 enzymatic tests, are present in the new card and interpreted in a kinetic mode. Final identification results are available within 10 h. The database allows the identification of 159 different taxa. Six hundred fifty-five gram-negative rods (GNR; 511 fermenters and 144 nonfermenters), representing 54 taxa, were tested. Strains were taken from fresh routine primary isolation plates (n = 157), from stored routine plates (n = 301), and from stock cultures (n = 197). Six hundred thirty-seven strains (97.3%) were correctly identified to the species level, 14 strains (2.1%) gave low discrimination results requiring additional tests, and 4 strains (0.6%) gave discordant results; not a single strain remained unidentified. Nearly 92% of all isolates were correctly identified within 7 h of incubation. The robustness of the system was demonstrated by the fact that strains were grown on four different agar media before testing. The system may also have the potential to be applied directly to primary isolation plates, since in this instance 96.2% of 157 GNR were correctly identified and 3.8% gave low discrimination results. The new VITEK 2 card for gram-negative bacteria seems to be a promising new tool for routine, rapid identification of GNR.
[Show abstract][Hide abstract] ABSTRACT: The present study describes the use of the automated BACTEC 9240 blood culture system, the Serum Separator Tube (SST), and the BD PHOENIX Automated Microbiology System in combination for the direct identification and antimicrobial susceptibility testing (AST) of gram-negative rods (GNRs) from positive blood cultures (BCs) without subculture. The study was conducted in three phases: (i) the recovery yield of Escherichia coli ATCC 25922 was determined with the SST between 0 and 8 h after spiked BC bottles turned positive; (ii) the identifications and susceptibility testing results obtained with the PHOENIX system for nine American Type Culture Collection strains of GNRs processed by the SST procedure and for colonies from agar medium were compared; and (iii) the procedure with the BACTEC system, SSTs, and the PHOENIX system was applied to positive cultures of blood from 309 patients during a 3-month period. The SST procedure with E. coli yielded sufficient numbers of cells to perform direct inoculation at any time between 0 and 8 h after a BC bottle turned positive. By using the identities obtained from pure cultures with the PHOENIX system and other biochemical identification systems as reference methods, the agreement between the reference methods and the PHOENIX system tested directly by using cultures of blood from patients was 92.9%. The 7.1% discrepant results were due to 6.5% incorrect identifications with the PHOENIX system with BC samples and 0.6% incorrect identifications with the PHOENIX system with samples from agar cultures. By AST the overall categorical accuracy was 99.0%, with 0.1% very major errors, 0.1% major errors, and 0.8% minor errors. In conclusion, use of the combination of the BACTEC system, SSTs, and the PHOENIX system has the potential to allow the agar isolation step to be skipped and the procedures for rapid direct identification and susceptibility testing of GNRs from positive BCs to be improved both in hospital-based and in central non-hospital-based laboratories.