Evaluation of the discriminatory powers of the dienes test and ribotyping as typing methods for Proteus mirabilis

A total of 63 clinical isolates of Proteus mirabilis collected over a 19-mo nth period were typed by the Dienes test and ribotyping, Ribotyping was per formed using the fully automated RiboPrinter Microbial Characterization Sys tem (Qualicon, Wilmington, Del.). Isolates that were indistinguishable by t he Dienes test and/or ribotyping were characterized further by pulsed-field gel electrophoresis (PFGE). Most of the isolates represented unique strain s as judged by the Dienes test and ribotyping. Forty isolates represented 4 0 different ribotypes and Dienes types. The remaining 23 isolates were grou ped into 13 Dienes types, 12 ribotypes, and 14 PFGE types. The index of dis crimination was 0.980 for the Dienes test, 0.979 for ribotyping, and 0.992 for PFGE. Both the Dienes test and ribotyping are useful methods for identi fying individual strains of P. mirabilis, The Dienes test is simple, inexpe nsive, and easy to perform, It can be performed in virtually any laboratory and should be used in the initial epidemiologic characterization of P. mir abilis isolates.