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

The BacT/Alert (BTA) (Organon Teknika, Durham, NC) and Isolator 10 (IS O) (Wampole Laboratories, Cranbury, NJ) blood culture systems were eva luated for their ability to detect aerobic and facultatively anaerobic microorganisms in blood of adult patients. For each culture 8 mt of b lood was inoculated into both the aerobic standard BTA bottle and the ISO tube. Of 7,259 paired culture sets, 1,168 organisms were recovered , and 667 (57.1%) of these were considered clinically significant. Thi s represented 540 clinically significant positive cultures from 266 pa tients. Of the significant isolates, 410 were recovered by both system s, 108 by BTA only and 149 by ISO only (P < .025). Overall, the BTA de tected 77.7% of the significant isolates, whereas ISO detected 83.8%. The ISO recovered significantly more isolates of Staphylococcus aureus (P = .0001), coagulase-negative Staphylococcus spp (P < .01), and non -Enterobacteriaceae gram-negative rod species (P < .0025), whereas the BTA detected significantly more isolates of Streptococcus spp (P < .0 025). Growth of S aureus (P < .0025), Enterococcus spp (P < .0025), an d Streptococcus spp (P < .0075) was detected earlier by the BTA when l aboratory coverage was available during the first shift only (7:30 AM to 4:00 PM), and additionally of Enterobacteriaceae (P < .0005) and ot her gram-negative rod species (P < .0001) if coverage was extended to 12:00 AM. Yeasts were detected more rapidly by the ISO (P < .0025). Th e ISO contamination rate (5.9%)was sis times that of the BTA. Taking i nto account its ability to rapidly detect most organisms, its automate d and thus labor-saving features, and the minimal contamination rate a ssociated with its use, the BTA appears to be a reliable alternative t o the ISO as a blood culturing system, although improvement in detecti on of staphylococci and non-Enterobacteriaceae gram-negative rods woul d be desirable.