CONTROLLED COMPARISON OF BIOMERIEUX VITAL AND BACTEC NR-660 SYSTEMS FOR DETECTION OF BACTEREMIA AND FUNGEMIA IN PEDIATRIC-PATIENTS

The bioMerieux VITAL automated blood culture system measures a decreas e in fluorescence to detect the presence of microorganisms in blood, T o assess the performance of VITAL with AER aerobic medium versus that of the nonradiometric BACTEC NR-660 PEDS PLUS medium for the detection of sepsis in children, a total of 12,146 blood specimens were collect ed at three university medical centers and inoculated into AER and PED S PLUS bottles that were weighed before and after filling, The sample volumes were considered adequate in 6,276 bottle pairs, The total yiel d of isolates was 629, of which 489 (78%) were judged to be the cause of true infections, Staphylococci (P < 0.001) and yeasts (P < 0.05) we re detected more often in PEDS PLUS bottles, as were all microorganism s combined (P < 0.001), The improved detection in the PEDS PLUS medium was most marked for patients on antimicrobial therapy (P < 0.001), bu t remained statistically Significant even for patients not on therapy (P < 0.025), There were 431 episodes of sepsis, including 407 consider ed adequate for analysis, Of the 363 unimicrobial episodes, 278 were d etected by both bottles, 64 were detected by PEDS PLUS bottles only, a nd 21 were detected by AER bottles only (P < 0.01), No false-negative cultures were detected by terminal subculture of the PEDS PLUS bottles when the companion AER bottle was positive, However, there were 14 fa lse-negative cultures (7 yeasts, 5 staphylococci, 1 Enterococcus faeca lis, and 1 Enterobacter sp,) on terminal subculture of the AER bottles when the companion PEDS PLUS bottle was positive, When both systems w ere positive, the VITAL system detected bacteria earlier than did the BACTEC system by a mean of 1.6 h, Also, false-positive signals were le ss common with the VITAL system, We conclude that the VITAL system wit h AER medium must be modified to improve the detection of clinically i mportant staphylococci and yeasts if it is to perform comparably to th e BACTEC NR-660 nonradiometric system with PEDS PLUS medium for a pedi atric population.