CONTINUOUS MONITORING OF OXYGEN CONCENTRATIONS IN SEVERAL SYSTEMS FORCULTIVATION OF ANAEROBIC-BACTERIA

Anaerobic chambers and jars are the two conventional methods used in c linical microbiology laboratories to produce an anaerobic atmosphere. The evacuation-replacement method, the Oxoid AnaeroGen, the Merck Anae rocult A, the BBL GasPak, the BBL GasPakPlus, the Adams Scientific Gas Gendicator, the Difco Anaerobic, and the bioMerieux Generbox anaer sys tems were compared for the timed decrease in the oxygen concentration in an anaerobic jar. The experiment was repeated 10 times for each sys tem. The oxygen concentration was measured with an oxygen analyzer ser ies 3600 instrument (Orbisphere Laboratories, Neuchatel-Geneva Switzer land). The BBL GasPak, the BBL GasPakPlus, the bioMerieux Generbox, th e Adams Scientific GasGendicator, and the Difco Anaerobic systems cont ain sodium borohydride, which liberates hydrogen. The Anaerocult A sys tem contains iron powder which binds the oxygen. The active ingredient of the AnaeroGen system is ascorbic acid. The times to reach an O-2 c oncentration of 0.5% were 8 to 15 min for the evacuation-replacement m ethod, 26 to 41 min for the AnaeroGen system, 60 to 93 min for the Ana erocult A system, and 22 to 419 min for the sodium borohydride systems . The AnaeroGen system, the Anaerocult A system, and the evacuation-re placement method never failed to produce an anaerobic atmosphere. The sodium borohydride systems failed in 10 of 70 runs. These results sugg est that the evacuation-replacement method or the Oxoid AnaeroGen syst em should be used to produce an anaerobic atmosphere. The Anaerocult A system showed a good reproducibility, but the length of time required to reach an appropriately low level of oxygen was too long. Because o f the high failure rate, the borohydride systems cannot be recommended .