Clinical comparison of the Isolator 1.5 microbial tube and the BACTEC radiometric system for detection of bacteremia in children

The Isolator 1.5 microbial tube was compared with the BACTEC radiometric detection system for the detection of bacteremia in children. The Isolator 1.5 is a blood culture system designed for small volumes of blood (0.5 to 1.5 ml). The method involves lysis of the cells of the patient and the direct plating of the entire blood lysate on agar media appropriate for the growth of fastidious microorganisms. Of 1,500 paired samples inoculated into the two systems, 68 were positive for 73 clinically significant organisms. The Isolator 1.5 recovered 81% of the positive cultures compared with 84% recovered by the BACTEC system. The contamination rates were 8.7 and 3.1% for the Isolator 1.5 and the BACTEC system, respectively. In cultures positive by both systems, the mean time to detection was 4.1 h faster with the Isolator 1.5. The mean time to obtain isolated colonies was 26.6 h faster with the Isolator 1.5. These data indicate the potential value of the Isolator 1.5 microbial tube as a simple, rapid, and sensitive method for the detection of bacteremia in children