Assessment of RAISUS, a novel system for identification and antimicrobial susceptibility testing for enterococci

Abstract

RAISUS, a system developed by Nissui Pharmaceutical (Tokyo, Japan), is a novel fully automated system for rapid identification and antimicrobial susceptibility testing. The aim of this study was to compare RAISUS with VITEK systems and microdilution tests based on the National Committee for Clinical Laboratory Standards, with regard to the identification and susceptibility of 64 enterococci. The agreement rate between RAISUS and VITEK was 98.4% (63/64) for bacterial identification. One strain was identified as E. faecalis by RAISUS, but as E. faecium by VITEK. Regarding susceptibility tests, the range of essential agreement and agreement in clinical categories for RAISUS and VITEK ranged from 70.3% to 95.3% and from 68.8% to 96.9%, respectively. Results of antimicrobial susceptibility testing for vancomycin (VAN) showed very major, major, and minor errors in 0%, 3.1% (2/64), and 0%, respectively. RAISUS could provide reports of detection of VAN-resistant enterococci (VRE) within 5 h by using fluorogenic substances and redox. In conclusion, RAISUS could be useful in a clinical setting because it allows rapid identification of enterococci and the potential ability to detect VRE more promptly than the VITEK system.