Assessment of Analytical Sensitivity and Detection Time of Microbial Growth Using Automated Blood Culture Systems — Results of the Comparative Study

The aim of the study was to compare the analytical sensitivity and microbial growth detection time using the BACT/ALERT 3D 120 (bioMérieux, France), YUNONА LABSTAR 100 (SCENKER, China), and Autobio BC 120 (Autobio, China) blood culture analyzers. Material and methods. The study was conducted in two stages. 1) In vitro: suspensions of 10 clinical strains at concentrations simulating bacteremia (30 CFU/ml, final dilution 1–2 CFU/vial). 2) Clinical phase: 197 blood cultures from 89 cardiothoracic surgery patients, tested in parallel using only the BACT/ALERT 3D 120 and YUNONA LABSTAR 100 systems. At both stages, samples were inoculated into pairs of aerobic and anaerobic vials, and the presence of growth and its detection time were assessed. Results. In the in vitro phase, the total sensitivity was 80.5%, 77.5%, and 74.5% for the YUNONA LABSTAR 100, BACT/ALERT 3D 120, and Autobio BC 120 systems, respectively. During aerobic cultivation of gram-negative bacteria, detection rates were high in all systems (90–100%). Under anaerobic conditions, the YUNONA LABSTAR 100 system showed the maximum sensitivity for this group (72.5%), while the Autobio BC 120 system showed the minimum sensitivity (45%). The efficacy profiles differed: the advantage of the Autobio BC 120 system in the detection speed of enterobacteria under aerobic conditions (median 11.5 h vs. 13–13.9 h for others) was combined with its lower sensitivity of anaerobic vials for gram-positive bacteria (77.5% vs. 100% for the BACT/ALERT 3D 120 and YUNONA LABSTAR 100 systems). A notable finding was the growth of P. aeruginosa in all anaerobic vials of the YUNONA LABSTAR 100 system. For Candida spp., all systems showed lower sensitivity and longer detection times compared to bacteria. In the clinical phase, growth was confirmed in 19 cases (9.6%). Under aerobic conditions, both systems detected growth in 73.7% of vials. In anaerobic vials (excluding obligate aerobes), growth was detected by the BACT/ALERT 3D 120 system in 75% of cases, which was more frequent than with the YUNONA LABSTAR 100 system (56.3%). The overall sensitivity for detecting a bacteremia episode was 89.5% (17/19) for the BACT/ALERT 3D 120 system versus 73.7% (14/19) for the YUNONA LABSTAR 100 system, meaning the BACT/ALERT 3D 120 system detected 3 more bacteremia cases. The analysis by pathogen groups showed that for enterobacteria and gram-positive cocci, the sensitivity of the BACT/ALERT 3D 120 system was higher. Complete agreement in identification between both systems was observed in only 47.4% of samples, with the overall discrepancy rate reaching 52.6%. Conclusion. The diagnostic efficacy of the compared systems is variable and depends on the type of microorganism and cultivation conditions. Superiority in individual in vitro parameters (e.g., speed) does not guarantee a similar result in clinical practice, where stable sensitivity in detecting a bacteremia episode is key. The high percentage of discrepancies between modern systems confirms the validity of recommendations for collecting multiple samples to improve bacteremia detection.

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