[Laboratory-based evaluation of a fully automated microbiology system, RAISUS for species-identification and...

A fully automated microbiology system, RAISUS newly developed (Nissui Pharmaceuticals Co., Ltd., Tokyo) was evaluated for gram-positive and gram-negative clinical isolates. In the species-identification, the RAISUS comparably identified 200 of 202 isolates (99.0%) consisting of 10 species of gram-positive cocci and of 16 species of gram-negative bacilli. When compared to the MicroScan Walk/Away, which resulted in six misidentifications, the RAISUS showed higher accuracy in species-identification. In the evaluation of antimicrobial susceptibility test, the RAISUS gave comparable minimum inhibitory concentrations (MICs) and category interpretations. Of 693 testings for gram-positive and of 721 testings for gram-negative isolates, 655 (94.5%) and 688 (95.4%) testings gave comparable interpretations to the reference microdilution test, respectively. Most identification results were reported within 5-hour incubation by RAISUS, and susceptibility test results were 4 to 7 hour-incubations. With these results obtained through laboratory-based evaluation, it became apparent that the RAISUS has enough accuracy and rapidity to determine species-identification and antimicrobial susceptibility, and is applicable to the routine testing in clinical laboratories.