TABLE 1.
BioFire FilmArray BCID2 and BCID panel results compared to reference method results for bacterial organism identification and antimicrobial resistance gene detection from 90 positive blood culturesa
| Reference method (no. of results) | FilmArray BCID2 panel (no. of results) | FilmArray BCID panel (no. of results) |
|---|---|---|
| Gram-negative organisms (77) | ||
| Acinetobacter baumannii (3) | Acinetobacter calcoaceticus-Acinetobacter baumannii complex (3) | Acinetobacter calcoaceticus-Acinetobacter baumannii complex (3) |
| Bacteroides fragilis (8) | Bacteroides fragilis (8) | – |
| Citrobacter freundii (1) | Enterobacterales (1) | Enterobacteriaceae (1) |
| Enterobacter cloacae complex (2) | Enterobacter cloacae complex (2) | Enterobacter cloacae complex (2) |
| Escherichia coli (11) | Escherichia coli (11) | Escherichia coli (11) |
| Klebsiella aerogenes (9) | Klebsiella aerogenes (9) | Enterobacteriaceae (9) |
| Klebsiella oxytoca (3) | Klebsiella oxytoca (3) | Klebsiella oxytoca (3) |
| Klebsiella pneumoniae (14) | Klebsiella pneumoniae group (14) | Klebsiella pneumoniae (14) |
| Klebsiella variicola (8) | Klebsiella pneumoniae group (8) | Klebsiella pneumoniae (8)b |
| Ochrobactrum anthropi (1) | – | – |
| Pseudomonas aeruginosa (1) | Pseudomonas aeruginosa (1) | Pseudomonas aeruginosa (1) |
| Salmonella spp. (8) | Salmonella (8) | Enterobacteriaceae (8) |
| Stenotrophomonas maltophilia (8) | Stenotrophomonas maltophilia (8) | – |
| Gram-positive organisms (54) | ||
| Brevibacterium casei (1) | – | – |
| Enterococcus faecalis (9) | Enterococcus faecalis (9) | Enterococcus (9) |
| Enterococcus faecium (8) | Enterococcus faecium (8) | Enterococcus (8) |
| Staphylococcus aureus (9) | Staphylococcus aureus (9) | Staphylococcus aureus (9) |
| Staphylococcus epidermidis (11) | Staphylococcus epidermidis (11) | Staphylococcus (11) |
| Staphylococcus haemolyticus (4) | Staphylococcus (4) | Staphylococcus (4) |
| Staphylococcus lugdunensis (9) | Staphylococcus lugdunensis (9) | Staphylococcus (9) |
| Staphylococcus pasteurii (1) | Staphylococcus (1) | Staphylococcus (1) |
| Staphylococcus pettenkoferi (1) | Staphylococcus (1) | Staphylococcus (1) |
| Streptococcus salivarius (1) | Streptococcus (1) | Streptococcus (1) |
| Total organisms (131) | Total organisms (129) | Total organisms (113) |
| Antimicrobial resistance genes (53) | ||
| blaCTX-M-15 (11) | CTX-M (11) | – |
| blaCTX-M-27 (5) | CTX-M (5) | – |
| blaKPC-3 (6) | KPC (6) | KPC (6) |
| blaKPC-31 (2) | KPC (2) | KPC (2) |
| blaNDM-1 (3) | NDM (3) | – |
| blaOXA-23 (2) | – | – |
| blaOXA-48 (4) | OXA-48-like (4) | – |
| blaVIM-1 (4) | VIM (4) | – |
| mecA (12) | mecA/C (6),c mecA/C, and MREJ (5) | mecA (10)d |
| vanA (4) | vanA/B (4) | vanA/B (4) |
| Total genes (53) | Total genes (50) | Total genes (22) |
Including results from 55 monomicrobial and 35 polymicrobial blood cultures (BCs) from patients with clinically relevant bloodstream infection (BSI) (Table S1). Boldface indicates all molecular targets identified at the species or genus level (i.e., organisms) or detected (i.e., genes) only in the BioFire FilmArray BCID2 panel. Dashes indicate the absence of detection(s) due to off-panel organisms/genes identified/detected by the reference method and not the BioFire FilmArray BCID2 or BCID panel.
These results were interpreted as correct identifications because the BCID panel’s K. pneumoniae assay had been designed to detect both K. pneumoniae and K. variicola, which is a closely related species to K. pneumoniae.
The BCID2 panel uses the detection of mecA/C alone to identify staphylococci other than Staphylococcus aureus (SOSA) such as S. epidermidis and S. lugdunensis (above listed) or that of mecA/C and MREJ together to identify MRSA. However, BCID2 also signals mecA/C alone in polymicrobial BCs that grow MRSA together with S. epidermidis or S. lugdunensis. Thus, we excluded mecA/C-positive results of two BCs that grew mecA-positive S. aureus (correctly detected as MRSA) and mecA-negative S. epidermidis (Table S1). This allowed inclusion of four mecA/C-positive results in total. Additionally, three mecA genes in samples that grew S. haemolyticus (identified as Staphylococcus) were undetected because the BCID2 does not perform mecA/C detection for an organism not identified at the species level. These results were considered to be from off-panel genes and, thus, were excluded from the analysis.
The BCID panel signals the presence of mecA gene alone also in the case of polymicrobial BCs growing two different mecA-positive organisms. Thus, we included two other mecA-positive results in the analysis, which regarded two polymicrobial BCs, one growing 1 mecA-positive S. aureus plus 1 mecA-positive S. epidermidis and the other one growing 1 mecA-positive S. aureus plus 1 mecA-positive S. haemolyticus (Table S1). This allowed inclusion of 12 mecA results in total.