Rapid identification of nonfermentative gram-negative rods by the Corning N/F system.

A total of 1,298 nonfermentative gram-negative rods were used to evaluate the performance of the individual biochemical tests in the N/F System and to determine whether the observed results included sufficient key reactions for rapid identification. The system included an oxidase test, two screening tubes providing 5 test reactions designed primarily to identify pigment-producing strains of Pseudomonas aeruginosa, and a plate providing 12 test reactions designed to identify other nonfermenters. With both the tubes and plates, most results were consistent with expected conventional test reactions. Use of the tubes permitted the identification of 90% of the strains of P. aeruginosa in 24 h and 97% in 48 h. Use of the plates permitted the identification of 95% of the other oxidative nonfermenters within 24 h and 96% within 48 h. Only 26% of weak and nonoxidative nonfermenters were identified because of the nonreactivity of these organisms in this system. There were no misidentifications based on misleading test results.