Controlled clinical comparison of bioMerieux VITAL and BACTEC NR-660 bloodculture systems for detection of bacteremia and fungemia in adults

A total of 9,446 blood cultures were collected from adult patients at three university-affiliated hospitals. Of these, 8,943 cultures were received wi th both aerobic bottles filled adequately; 885 yielded 1,016 microorganisms , including 622 isolates (61%) that were the cause of sepsis, 337 isolates (33%) that were contaminants, and 57 isolates (6%) that were indeterminate as the cause of sepsis, With the exception of Staphylococcus aureus, which was recovered more often from VITAL aerobic bottles, more pathogenic microo rganisms were recovered from BACTEC NR6 (aerobic) bottles than from VITAL a erobic bottles. Growth of pathogenic microorganisms was detected earlier in VITAL aerobic bottles. A total of 8,647 blood cultures were received with both anaerobic bottles filled adequately; 655 yielded 740 microorganisms, i ncluding 486 isolates (66%) that were the cause of sepsis, 215 isolates (29 %) that were contaminants, and 39 isolates (6%) that were indeterminate as the cause of sepsis, More pathogenic microorganisms were recovered from VIT AL anaerobic bottles than from BACTEC NR7 (anaerobic) bottles. Growth of pa thogenic microorganisms was detected earlier in VITAL anaerobic bottles. In 8,500 sets all four bottles were received adequately filled. When paired a erobic and anaerobic bottle sets (systems) were compared, more pathogenic m icroorganisms (again with the exception of S. aureus) were recovered from t he BACTEC system. For the 304 septic episodes (253 unimicrobial and 51 poly microbial), significantly more were detected by the BACTEC system. We concl ude that VITAL requires modification to improve recovery of pathogenic micr oorganisms to make it competitive with other commercially available blood c ulture systems.