EVALUATION OF THE RAPID CB PLUS SYSTEM FOR IDENTIFICATION OF CORYNEBACTERIUM SPECIES AND OTHER GRAM-POSITIVE RODS

Due to the difficulty of identifying Corynebacterium spp. with standar d methods, we compared them with the RapID CB Plus system (Remel, Lene xa, Kans. [formerly Innovative Diagnostic Systems, Norcross, Ga.]), wh ich consists of 4 carbohydrate and 14 preformed enzyme tests, for the identification of 98 clinical isolates of Corynebacterium sp., other c oryneforms, Listeria monocytogenes, and 17 ATCC strains. Forty (95%) o f 42 strains of Corynebacterium spp. were accurately identified to the species level by the RapID CB Plus system, and two additional strains of C. striatum were identified with one additional conventional test for lipid requirement. Twenty-seven (75%) of the 36 coryneform strains tested were identified correctly to the species level. However, three of four strains of Brevibacterium sp. and all seven of the L. monocyt ogenes strains were identified to the genus level only. Actinomyces st rains had variable results, and the one strain of Arcanobacterium haem olyticum tested was not identified. Overall, the RapID CB Plus system compared favorably with the conventional methods, was easy to inoculat e and interpret, and is promising as a new method for identification o f gram-positive bacilli.