Performance of the new FilmArray Blood Culture Identification 2 panel and its potential impact on clinical use in patients with Gram-negative bacteremia

Introduction: Rapid diagnostic tests have been developed recently for rapid species or resistance genes identification, offering the potential to improve the selection of appropriate antibiotics. The newly developed FilmArray Blood Culture Identification 2 (BCID2) panel, which can identify more species and resistance genes, such as extended-spectrum beta-lactamase, is expected to make an impact on antimicrobial practice.

Methods: The consecutive 50 inpatients with Gram-negative bacilli bacteremia were enrolled to this retrospective single-center study. In addition to the existing FilmArray Blood Culture Identification (BCID) panel, we have implemented BCID2 panel for positive blood culture. The sensitivity and specificity of BCID and BCID2 panel were respectively calculated, and a simulation study of time to effective, optimal and de-escalation therapy was performed based on BCID or BCID2 result.

Results: A total of 52 Gram-negative organisms in 50 patients were identified from blood cultures. Of these, 45 (87%) organisms were detected by BCID2 panel, which was more than BCID panel (41 organisms, 79%). BCID2 panel detected 5 CTX-M genes, which were concordant with conventional method. The time to effective therapy did not differ between BCID arm and BCID2 arm; however, the median time to optimal therapy (34 h in BCID arm and 26 h in BCID2 arm, P = 0.0007) and the median time to de-escalation therapy (42 h in BCID arm and 22 h in BCID2 arm, P = 0.0005) were significantly shortened.

Conclusions: This simulation study of BCID2 panel showed high sensitivity and specificity, and the potential impact on shortening the time to optimal and de-escalation therapy.