Evaluation of the RapID CB plus system for identification of coryneform bacteria and Listeria spp

In a stress test, the recently introduced RapID CB Plus system (Remel Inc. [formerly Innovative Diagnostic Systems], Norcross, Ga.) was challenged with a diverse set of gram-positive rods comprising 345 strains of coryneform bacteria and 33 strains of Listeria spp. representing a total of 49 different taxa. Overall, within 4 h, the system correctly identified 80.9% of the strains on the species level and 12.2% of the strains on the genus level. Only 3.7% strains were misidentified, and for 3.2% of the strains no identification was provided. Difficulties with the system were mainly due to occasional uncertainties in reading reactions for acid production from carbohydrates and, to a lesser extent, aminopeptidase reactions. It is concluded that the system may also perform well under the conditions of a routine clinical laboratory.