Comparison of detection speed and yield in BACTEC NR-860 and Roche BCB blood culture systems

Detection speed and yield were compared between BACTEC NR-860 and Roche BCB blood culture systems. From a total of 1,550 paired blood cultures inoculated with the same volume of blood, 161 (10.4%) grew 180 organisms from 140 adult patients. Sixty-six percent of the isolates were clinically significant. The BACTEC system detected more clinically significant isolates than the BCB system, 91% vs 76% (p < 0.01), especially Enterobacteriaceae. In 39 paired blood cultures, 42 significant organisms were detected at different times in the two systems. The vast majority (93%) were detected first (on average 1 day faster) by the BACTEC system (p < 0.05), especially Escherichia coli and streptococci. Generally, detection times were shorter in the BACTEC system. Three fourths (76%) of all significant organisms were detected within the first incubation day as compared to less than half (42%) in the BCB system (p < 0.001). Generally, the agitated aerobic resin medium BACTEC 26 Plus had the fastest detection and highest yield in our study. The contamination rate, below 2% in both systems, was acceptable. The BACTEC NR-860 system with resin-containing media proved to be a reliable, sensitive and fast blood culture system, which deserves further investigation.