A comparison of four commercial systems for the identification of nonfermentative gram-negative bacilli

Four commercial systems for the identification of glucose nonfermentative, gram-negative bacilli and the conventional system used in our laboratory were compared. The API 20E, Roche Oxi/Ferm Tube, BBL Minitek, Flow N/F System, and our system were compared for accuracy, time needed for identification and number of isolates needing additional testing. A total of 241 different isolates were used. The API 20E identified 86.7% correctly; Oxi/FermTube, 83.0%; Minitek, 93.4%; N/F System, 90.5%; and our system, 90.0%. Within 24 hours after isolation, the API 20E identified 25.7%; Oxi/Ferm Tube and Minitek, 0%; N/F System 27.3%; and our system, 35.7%. After 48 hours, the API 20E identified 74.7%; Oxi/Ferm Tube, 35.7%; Minitek, 45.2%; N/F System, 83.0%; and our system, 94.6%. The number of isolates that required additional testing for identification by the API 20E was 119; Oxi/Ferm Tube, 161; Minitek, 88; N/F System, 43; and our system, 36. Ease of performance, technologist time, and level of identification required by individual laboratories are discussed.