CLINICAL COMPARISON OF THE ISOLATOR AND BACT/ALERT AEROBIC BLOOD CULTURE SYSTEMS

The performance characteristics of the Isolator (Wampole Laboratories, Cranbury, N,J.) and the BacT/Alert (Organon Teknika Corporation, Durham, N.C.) aerobic blood culture systems were compared for 6,009 blood culture sets obtained from patients with suspected bloodstream infections. The BacT/Alert aerobic bottle [BTA(O-2)] was continuously agitated while it was incubated in 5% CO2 at 36 degrees C; culture plates prepared from the Isolator tube [I(O-2)] were incubated in 5% CO2 at 37 degrees C. From 394 blood cultures, 416 clinically significant isolates of bacteria and yeasts were recovered. The overall yields for BTA(O-2) and I(O-2) were not significantly different (319 versus 336; P = 0.20). I(O-2) recovered significantly more staphylococcus (P < 0.05) and yeast isolates (P < 0.01). BTA(O-2) recovered significantly more aerobic and facultatively anaerobic gram-negative bacilli (P < 0.05), In blood culture sets which produced growth of the same organisms in both the BTA(O-2) and I(O-2) systems, the BTA(O-2) system detected growth sooner, but more rapid identification was possible with the I(O-2) system by virtue of earlier isolation of colonies on solid media.