Comparison of susceptibility results of anaerobic organisms determined by agar dilution method and sceptor anaerobe MIC/ID micro broth dilution panels

A commercial broth microdilution system (Sceptor Anaerobe MIC/ID, BBL) for susceptibility testing of anaerobic bacteria was compared to a reference agar dilution system. Of the 172 organisms tested, only 7% failed to grow sufficiently for testing in the Sceptor system. In 1,590 antibiotic/organism combinations, 86.7% of the Sceptor results were identical or within one doubling dilution of the reference system. In 91.9% of the cases, interpretation of the results was same in both systems. Two hundred and twelve MIC values, however, differ by greater than or equal to 2 log2 dilution from the reference system. Due to this reduced correlation in the actual MIC values with the reference results, further studies are warranted before the Sceptor system can be recommended for routine use.