Laboratory-based evaluation of the colorimetric VITEK-2 Compact system for species identification and of the Advanced Expert System for detection of antimicrobial resistances: VITEK-2 Compact system identification and antimicrobial susceptibility testing

Abstract

The newly redesigned colorimetric VITEK-2 Compact system with updated Advanced Expert System (AES) (bioMerieux, Marcy l'Etoile, France) was evaluated for its accuracy and rapidity to identify clinical isolates and to detect several antimicrobial resistances. Overall, the VITEK-2 gave 95.8% of compatibility with the reference API strips (bioMerieux) in the identifications (IDs) of Gram-positive cocci (GPC), Gram-negative rods (GNR), and yeasts. The accuracy was finally estimated to 98.3% through additional confirmatory tests. Also, >90% of IDs of GPC and GNR were obtained within 7 h of incubations. The VITEK AES correctly detected 97.7% of antimicrobial resistances, including extended-spectrum β-lactamases, oxacillin and inducible clindamycin resistances in staphylococci, vancomycin resistance in enterococci, and penicillin and erythromycin resistances in Streptococcus pneumoniae. The most resistant isolates were identified within 12 h of incubations. In conclusion, the new colorimetric VITEK-2 Compact system with AES greatly improved its accuracy in species ID and detection of antimicrobial resistances, and it will be highly acceptable to clinical microbiology laboratory function.