Comparative evaluation of the RAPID ID 32A kit system, miniaturized standard procedure and a rapid fermentation procedure for the identification of anaerobic bacteria

The RAPID ID 32A and a rapid fermentation procedure were compared with a miniaturized standard procedure for the identification of 102 isolates of anaerobic bacteria belonging to 11 genera. The miniaturized standard procedure identified all 102 isolates at the genus level and 90 at the species level. The rapid fermentation procedure failed to identify 12 and 24 isolates at the genus and species levels respectively and is unsatisfactory.

The RAPID ID 32A system misidentified 4 isolates (4%) at the genus level, 3 of which could have been avoided if the results of the Gram stain, the fundamental procedure in medical microbiology, had been taken into account. The system correctly identified 89 isolates at the species level. Since it does not produce species identifications within the genera Mobiluncus and Veillonella of which 7 and 2 isolates respectively were included in the study, the percentage of correct identifications at the species level is 96.7% (90/93). The RAPID ID 32A system is about 25 times more expensive than the miniaturized standard procedure if the investment for a gas chromatograph is not taken into account.