Performance of enterobacteriaceae identification systems. An analysis of College of American Pathologists Survey data

Commercial systems designed and marketed for evaluation of Enterobacteriaceae are used in many clinical microbiology laboratories. Evaluations of these systems have been reported from several large laboratories. Identifications with one or more of these systems were compared with those obtained by conventional methods with many strains of organisms. The Microbiology Resource Committee of the College of American Pathologists designed two surveys to evaluate the performances of commercial systems with identical strains of organisms submitted to a large number of participants. The surveys used were the Special Bacteriology Survey D-D and the Comprehensive Microbiology Survey B-D submitted during 1975--1976. Single strains of Klebsiella pneumoniae and Serratia marcescens in pure culture were submitted in the Comprehensive Survey and the same strains of these organisms plus one strain each of Pseudomonas stuartii and Citrobacter freundii in the Special Survey. The data obtained from participants permitted comparisons to be made between the API-20E, Enterotube, and r/b systems. These comparisons included individual biochemical test results shared by at least two systems as well as the ability of each to identify the unknown organisms to genus alone and to both genus and species. The results are presented and subjected to statistical analysis.