The accuracy of a new 4-h Enterobacteriaceae identification kit, not previously tested with food isolates, was evaluated by using 265 known bacterial cultures. These clinical and food isolates represented 11 genera of Enterobacteriaceae; about 10% were atypical strains. Micro-ID test strips were inoculated from 24-h brain heart infusion agar slants and then incubated at 37 C for 4 h. With initial tests, 251 of the 265 cultures (95%) were correctly identified to species. When cultures initially misidentified were re-inoculated into Micro-ID, accuracy of identification increased to 98%. In tests to determine whether this multitest system would perform efficiently if incubated overnight at a lower temperature. 100 cultures of Enterobacteriaceae were inoculated into Micro-ID strips and incubated at 22 C for 16 h. Under these conditions, the system correctly identified 86 cultures to genus and 78 to species. Most of the misidentifications involved Enterobacter agglomerans. The degree of accuracy of Micro-ID at 22 C for 16 h was comparable to that at 37 C for 4 h, i.e., 95%, for identification to genus of the following: Arizona, Citrobacter, Edwardsiella, Escherichia, Klebsiella, Proteus, Salmonella, Serratia, Shigella and Yersinia.

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