Evaluation of the automated Bact-Alert system for pediatric blood culturing

The Organon Teknika BacT/Alert (Organon Teknika, Durham, NC), using the Pedi-BacT 20 mL aerobic bottle (BPBCS) was compared to the Wampole Isolator (WI) 1.5 Microbial tube (Wampole Laboratories, Cranbury, NJ), for detection and recovery of pediatric pathogens. The BPBCS continuously monitors culture bottles for changes in CO2 concentrations, while WI cultures are examined twice daily for appearance of colonial growth on agar media. Of 5,175 paired blood cultures, 383 pathogens were recovered from 606 positive cultures. There were 272 pathogens recovered by both systems, 64 from BPBCS only, and 47 from WI only. Overall recovery rates were 88% for BPBCS and 83% for WI. There was no significant difference between the two systems in detection or times to positivity of staphylococci, Enterobacteriaceae, or pseudomonads. Trends toward better recovery of streptococci (20 vs. 10) and fastidious microaerophiles (3 vs. 0) were found with BPBCS, whereas more slowly growing pathogens (Rochalimaea henselae [1], Mycobacterium avium-intracellulare [1]) were recovered by WI only, but because of their lower frequency did not achieve statistical significance. Detection of Haemophilus influenzae (14.9 hours in WI vs. 45.4 hours in BPBCS) was faster with WI. False positive plus contaminant cultures were detected in 5.9% BPBCS versus 1.5% WI. BPBCS offers detection of bacteremia at a rate comparable to WI with advantages of automation.