Comparison of recovery of anaerobic bacteria using the Anoxomat, anaerobic chamber, and GasPak jar systems.

The Anoxomat system provides an automated evacuation-replacement technique to create an anaerobic or microaerophilic environment in a jar. We evaluated the Anoxomat system for the growth of obligate anaerobes and for the recovery of anaerobic organisms from clinical specimens, and compared its performance to that of an anaerobic chamber and the GasPak System. Of the 54 stock strains tested, the Anoxomat, the chamber, and the GasPak recovered 95%, 95% and 93% at 24 h, respectively. On 29 occasions (51%), the colonies on the Anoxomat plates were slightly larger than those in the chamber and on 17 (30%) occasions larger than the colonies on the GasPak jar plates. At 48 h, the Anoxomat, the chamber, and the GasPak recovered 93.5%, 94.4% and 88.9%, respectively; of 108 anaerobes isolated from 31 clinical specimens. Methylene blue indicators became decolorized (average of 10 tests) within 2 h inside the Anoxomat jars, 2 h 10 min inside the anaerobic chamber, and 2 h 30 min inside the GasPak jars.