BACKGROUND: Enterobacterales are a common cause of bloodstream infections (BSI), and the dissemination of extended-spectrum beta-lactamases (primarily CTX-M) and important carbapenemases (IMP, KPC, NDM, OXA-48, and VIM) among the Enterobacterales is associated with increased morbidity and mortality. The BIOFIRE® FILMARRAY® Blood Culture Identification 2 (BCID2) Panel builds upon the existing BIOFIRE® FILMARRAY® Blood Culture (BCID) Panel by addition/modification of assays for the rapid detection of bacteria, yeast, and select antimicrobial resistance (AMR) genes in positive blood culture (PBC). This study evaluated the expanded coverage of the updated assays for Enterobacterales (7 species-level and 2 pan-reactive) and 6 associated AMR genes.
METHODS: Reactivity and specificity of these assays were evaluated using in silico sequence data and pure-culture isolates. Concordance with reference methods was examined for 1,074 residual PBC samples collected from US and European clinical laboratories, with pathogen detections compared to routine culture and AMR gene detections compared to routine antimicrobial susceptibility testing (AST) in conjunction with molecular assays.
RESULTS: The in silico assessment indicated reactivity with 207 species, representing 46 genera from 7 families of Enterobacterales as well as nearly all known alleles of AMR genes. Analytical testing confirmed reactivity with 108/108 available species, representing 31 genera from 5 families, as well as the detection of CTX-M (16 types, 12 hosts), IMP (6 types, 3 hosts), KPC (7 types, 9 hosts), NDM (4 types, 4 hosts), OXA-48 (5 types, 4 hosts), and VIM (3 types, 3 hosts) genes. Prospective testing detected 27 species of Enterobacterales in 269/1,074 PBC, with associated detections of CTX-M (46, 3 hosts), KPC (4, 1 host), NDM (1,1 host), and VIM (4, 2 hosts) genes and demonstrated excellent concordance with reference methods. 2/2 false positive results were resolved with sequencing, and 1/1 false negative result is currently under investigation. No cross-reactivity was observed in analytical or prospective testing.
CONCLUSIONS: The BIOFIRE® BCID2 Panel will detect a wide variety of clinically relevant Enterobacterales, indicate the carriage of select AMR gene(s) when present, and is expected to aid timely and effective antimicrobial therapy.
Data presented are from assays that have not been cleared or approved for diagnostic use.