Blood culture is the most sensitive method in the detection of bacteremia. For pediatric patients a weight-based blood collection is recommended. BACTEC Plus Aerobic and BACTEC Peds Plus Blood Culture bottles are marketed for use in adults and pediatrics respectively. Comparison of blood cultures systems and bottle types is well described in the literature. However, to our knowledge there is no data available that compares paired pediatric and adult blood culture bottles in a set in terms of recovery and time to detection (TTD).
Since 2007, a weight-based blood volume collection for blood cultures was implemented in our institution. In the microbiology laboratory, the actual blood volume inoculated to each bottle was determined by subtracting the initial bottle weight (adjusted for the weight of the cap) from the bottle weight after inoculation of blood. Only the paired, weight-matched (less than 50% difference in volume of blood inoculated) blood culture sets for all patients with a positive blood culture from March 2007 to August 2009 were included in the study.
A total of 559 paired, weight-matched blood culture sets that signaled positive were analyzed. Of these 363 (65.0%) pathogens were recovered from both bottles, and 98 (17.5%) from the Peds Plus and Plus Aerobic, respectively (Figure). Staphylococcus aureus (24.0%), Staphylococcus epidermidis (13.8%), Streptococcus pneumoniae (7.5%) and Escherichia. coli (7.0%) were the five most common organisms recovered. For these organisms, the recovery and TTD in the Peds Plus and Plus Aerobic blood culture bottles were compared. However, the two isolates of Kingella kingae were recovered both in the pediatric bottle only. For the blood culture sets with recovery of a microorganism from both bottles type, the median TTD in the BACTEC Peds Plus and the Plus Aerobic was 13.5 h (p=0.05) in each bottle.
This study indicates that there is no significant difference in the detection of bacteremia and TTD between the BACTED Peds Plus and BACTEC Plus Aerobic blood culture bottles in a pediatric population. Except for Kingella spp which preferentially grew in pediatric bottle, all other pathogens showed no preference for a specific blood culture bottle.