Controlled clinical evaluation of Isolator and ESP aerobic blood culture systems for detection of bloodstream infections.

A controlled clinical evaluation comparing the Isolator system (Wampole Laboratories, Cranbury, N.J.) and the ESP 80A blood culture bottle in the automated ESP system (Difco Laboratories, Detroit, Mich.) was performed with 10,535 blood culture sets from patients with suspected septicemia. Of 1,150 positive cultures, 844 positive cultures from 285 patients with 394 septic episodes fulfilled the study criteria for minimum blood sample requirements in each system and clinical significance of isolates. The Isolator system detected statistically significantly more positive cultures of Staphylococcus aureus (P < 0.001), Enterococcus spp. (P = 0.007), Escherichia coli (P = 0.001), Alcaligenes xylosoxidans (P = 0.02), Xanthomonas maltophilia (P = 0.01), Candida albicans (P < 0.001), and Candida glabrata (P = 0.05). The Isolator system detected significantly more septic episodes due to S. aureus (P < 0.001), X. maltophilia (P = 0.02), and C. albicans (P = 0.004) than did the ESP 80A bottle; however, the two systems did not otherwise significantly differ in their abilities to detect septic episodes due to other organisms.