Evaluation of the new RapID-ANA II system for the identification of clinical anaerobic isolates

Abstract

The RapID-ANA II System (Innovative Diagnostic Systems, Inc., Atlanta, Ga.) is a recently revised and marketed 4-h system for the identification of anaerobic bacteria. The system was compared with conventional identification methods for its ability to identify 566 clinical anaerobic isolates. Overall, the system identified correctly to genus and species 68% of the total isolates (62% of 204 gram-negative bacilli, 70% of 69 nonsporeforming gram-positive bacilli, 74% of 130 Clostridium isolates, and 72% of 163 anaerobic cocci), without the use of additional tests. With the additional tests suggested by the manufacturer, 78% of the total isolates were identified correctly to species. The routine use of a few simple and practical tests (e.g., egg yolk agar for Clostridium spp.), in addition to the RapID-ANA II, would improve significantly the accuracy of the system in the identification of anaerobic bacteria. This second-generation system offers a number of improvements over the original system, including an updated data base and the option of overnight refrigeration of the system before the addition of reagents.