Rapid molecular detection of pathogenic microorganisms and antimicrobial resistance markers in blood cultures: evaluation and utility of the next-generation FilmArray Blood Culture Identification 2 panel.

Rapid detection of pathogens causing bloodstream infections (BSI) directly from positive blood cultures is of highest importance in order to enable an adequate and timely antimicrobial therapy. In this study, the utility and performance of a recently launched next-generation fully automated test system, the Biofire FilmArray® Blood Culture Identification 2 (BCID2) panel, was evaluated using a set of 103 well-characterized microbial isolates including 29 antimicrobial resistance genes and 80 signal-positive and 23 signal-negative clinical blood culture samples. The results were compared to culture-based reference methods, MALDI-TOF, and/or 16S rDNA sequencing. Of the clinical blood culture samples, 68 were monomicrobial (85.0%) and 12 polymicrobial (15.0%). Six samples contained ESBL (blaCTX-M), two MRSA (mecA), and three MRSE (mecA) isolates. In overall, the FilmArray BCID2 panel detected well on-panel targets and resistance markers from mono- and polymicrobial samples. However, one Klebsiella aerogenes and one Bacteroides ovatus were undetected, and the assay falsely reported one Shigella flexneri as Escherichia coli. Hence, the sensitivity and specificity for detecting microbial species were 98.8% (95%CI, 95.8-99.9%) and 99.9% (95%CI, 99.8-99.9%), respectively. The sensitivity and specificity for detecting of resistance gene markers were 100%. The results were available within 70 min from signal-positive blood cultures with minimal hands-on time. In conclusion, the BCID2 test allows reliable and simplified detection of a vast variety of clinically relevant microbes causing BSI and the most common antimicrobial resistance markers present among these isolates.

Rapid detection of antimicrobial resistance markers with Allplex™ Entero-DR assay directly from positive blood culture bottles.

A method for rapid detection of one extended-spectrum ß-lactamase (ESBL) and five carbapenemase-encoding genes as well as vancomycin resistance markers directly from blood cultures using the Allplex™ Entero-DR assay (Seegene, Seoul, South Korea) is presented. Altogether 28 previously well-characterized resistant Gram-negative bacilli and Enterococcus spp., and 142 clinical blood cultures containing Gram-negative bacilli or Gram-positive cocci were analyzed. The method had 100% sensitivity and specificity for detecting blaOXA-48-like, blaKPC, blaVIM, blaIMP, blaNDM, blaCTX-M, vanA, and vanB. The lowest detectable amount of viable cells in blood culture samples were 5.39·104 CFU/mL, 6.66·104 CFU/mL, 5.13·103 CFU/mL, 6.09·104 CFU/mL, 6.66·104 CFU/mL, 6.66·104 CFU/mL, 3.12·104 CFU/mL, and 5.34·104 CFU/mL for the blaKPC, blaOXA-48-like, blaVIM, blaIMP, blaNDM, blaCTX-M, vanA, and vanB, respectively. The results were available within 90 min from signal positive blood cultures, as no separate DNA extraction steps were needed, and the assay showed no interference from blood or culture media used allowing reliable and simplified detection of the resistance markers.