Abstract
Fast identification of pathogens directly from positive blood cultures is of highest importance to supply an adequate therapy of bloodstream infections (BSI). There are several platforms providing molecular-based identification, detection of antimicrobial resistance genes, or even a full antimicrobial susceptibility testing (AST). Two of such test systems allowing rapid diagnostics were assessed in this study: The Biofire FilmArray® and the Genmark ePlex®, both fully automated test system with a minimum of hands-on time. Overall 137 BSI episodes were included in our study and compared to conventional culture–based reference methods. The FilmArray® is using one catridge including a panel for the most common bacterial and fungal BSI pathogens as well as selected resistance markers. The ePlex® offers three different cartridges for detection of Gram-positives, Gram-negatives, and fungi resulting in a broader panel including also rare pathogens, putative contaminants, and more genetic resistance markers. The FilmArray® and ePlex® were evaluated for all 137 BSI episodes with FilmArray® detecting 119 and ePlex® detecting 128 of these. For targets on the respective panel of the system, the FilmArray® generated a sensitivity of 98.9% with 100% specificity on Gram-positive isolates. The ePlex® system generated a sensitivity of 94.7% and a specificity of 90.7% on Gram-positive isolates. In each case, the two systems performed with 100% sensitivity and specificity for the detection of Gram-negative specimens covered by each panel. In summary, both evaluated test systems showed a satisfying overall performance for fast pathogen identification and are beneficial tools for accelerating blood culture diagnostics of sepsis patients.
Highlights
As bacteremia and sepsis are still leading causes of morbidity and mortality [1, 2], fast diagnosis of the causative organism and appropriate antimicrobial therapy are essential for rapid treatment decisions [3]
To speed up the identification and antimicrobial susceptibility testing (AST) of Gram-negative bacteria in positive blood cultures, the Accelerate Pheno® system (Accelerate® Diagnostics, USA) was evaluated for fast ID and AST compared to culture-based diagnostics [12]
Gram-positive organisms, 33 were monomicrobial with Gram-negative organisms and 6 episodes were caused by yeast strains (Tab.1)
Summary
As bacteremia and sepsis are still leading causes of morbidity and mortality [1, 2], fast diagnosis of the causative organism and appropriate antimicrobial therapy are essential for rapid treatment decisions [3]. The BioFire FilmArray® Blood Culture Identification Panel (Biomerieux, Nürtingen, Germany) is a CE-marked multiplex PCR system, which allows identification of 24 targets at once including Gram-positives, Gram-negatives, and fungi, as well as three antibiotic resistance genes. The ePlex® system (Genmark Diagnostics, Carlsbad, USA) is endowed with three variable cartridges for pathogen identification Deploying this test allows the detection of Gram-positives, Gram-negatives, and fungi. The aim of the present prospective study was the comparative analysis of two molecular based Blood Culture Identification panels in comparison to conventional culturedependent ID methods in terms of (i) correct detection and identification of the pathogen, (ii) correct prediction of resistance genes and genotypes, and (iii) suitability for implementation in a diagnostic routine workflow
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