Potential impact of the VITEK 2 system and the advanced expert system on the clinical laboratory of a university-based hospital

A study was designed to assess the impact of the VITEK 2 automated system a nd the Advanced Expert System (AES) on the clinical laboratory of a typical university-based hospital. A total of 259 consecutive, nonduplicate isolat es of Enterobacteriaceae members, Pseudomonas aeruginosa, and Staphylococcu s aureus were collected and tested by the VITEK 2 system for identification and antimicrobial susceptibility testing, and the results were analyzed by the AES. The results were also analyzed by a human expert and compared to the AES analyses. Among the 259 isolates included in this study, 245 (94.6% ) were definitively identified by VITEK 2, requiring little input from labo ratory staff. For 194 (74.9%) isolates, no inconsistencies between the iden tification of the strain and the antimicrobial susceptibility determined by VITEK 2 were detected by the AES, Thus, no input from laboratory staff was required for these strains. The AES suggested one or more corrections to r esults obtained with 65 strains to remove inconsistencies. The human expert thought that most of these corrections were appropriate and that some resu lted from a failure of the VITEK 2 system to detect certain forms of resist ance. Antimicrobial phenotypes assigned to the strains by the AES for beta -lactams, aminoglycosides, quinolones, macrolides, tetracyclines, and glyco peptides were similar to those assigned by the human expert for 95.7 to 100 % of strains. These results indicate that the VITEK 2 system and AES can pr ovide accurate information in tests For most of the clinical isolates exami ned and remove the need for human analysis of results for many. Certain pro blems were identified in the study that should be remediable with further w ork on the software supporting the AES.