Evaluation of the VITAL (bioMérieux) automated blood culture system using blind subculture

Objective. This study was performed to determine the ability of the VITAL system to detect and allow recovery of microorganisms that are difficult to grow, such as Brucella spp., yeasts, or anaerobes, as well as to determine the need for blind subcultures after the incubation period. Methods. A prospective evaluation of the system was performed, and 8247 blood culture bottles were processed. The standard was blind subculture from all the bottles after 5 days of incubation. Results. There were 3.2% false-positive and 0.6% false-negative results (72% of clinical importance). The system sensitivity for yeasts was 41%. The mean time for detection of Neisseria meningitidis was 31.9 ± 2.8h, for Brucella spp. 119.7 ± 2h, and for yeast 51.5 ± 27.8 h. Conclusions. The VITAL system poses has serious difficulties in the detection of N. meningitidis, Brucella spp., yeast and methicillin- and aminoglycoside-resistant Staphylococcus aureus (MARSA). The low system sensitivity for yeast detection makes the blind subculture necessary after the incubation period.