Efficacy of the FilmArray blood culture identification panel for direct molecular diagnosis of infectious diseases from samples other than blood.

Molecular-based techniques reduce the delay in diagnosing infectious diseases and therefore contribute to better patient outcomes. We assessed the FilmArray blood culture identification (BCID) panel (Biofire Diagnostics/bioMérieux) directly on clinical specimens other than blood: cerebrospinal, joint, pleural and ascitic fluids, bronchoscopy samples and abscesses. We compared the results from 88 samples obtained by culture-based techniques. The percentage of agreement between the two methods was 75 % with a Cohen κ value of 0.51. Global sensitivity and specificity using the FilmArray BCID panel were 71 and 97 %, respectively. Sensitivity was poorer in samples with a low bacterial load, such as ascitic and pleural fluids (25 %), whereas the sensitivity for abscess samples was high (89 %). These findings suggest that the FilmArray BCID panel could be useful to perform microbiological diagnosis directly from samples other than positive blood cultures, as it offers acceptable sensitivity and moderate agreement with conventional microbiological methods. Nevertheless, cost-benefit studies should be performed before introducing this method into algorithms for microbiological diagnostics.

Molecular diagnosis of bloodstream infections with a new dual-priming oligonucleotide-based multiplex PCR assay.

Mortality from bloodstream infections (BSIs) correlates with diagnostic delay and the use of inappropriate empirical treatment. Early PCR-based diagnosis could decrease inappropriate treatment, improving patient outcome. The aim of the present study was to assess the clinical utility of this molecular technology to diagnose BSIs. We assessed a new dual-priming oligonucleotide-based multiplex PCR assay, the Magicplex Sepsis Test (MST) (Seegene), along with blood culture (BC). A total of 267 patients from the intensive care unit and haematology and emergency departments were enrolled. Clinical data were also used by physicians to determine the likelihood of infection. Ninety-eight (37 %) specimens were positive: 29 (11 %) by both the MST and BC, 29 (11 %) by the MST only, and 40 (15 %) by BC only. The proportion of agreement between the two methods was 73 % (Cohen's κ: 0.45; 0.28-0.6; indicating fair to moderate agreement). According to clinical assessment, 63 (64 %) positive specimens were considered BSIs: 23 (36 %) were positive by both the MST and BC, 22 (35 %) were positive only by BC, and 18 (29 %) were positive only by the MST. Thirty-eight (14 %) positive specimens by the MST and/or BC were considered as contaminants. Of 101 specimens collected from patients receiving antibiotics, 20 (20 %) were positive by the MST and 32 (32 %) by BC. Sensitivity and specificity were 65 % and 92 %, respectively, for the MST and 71 % and 88 %, respectively for BC. We concluded that the MST shows a high specificity but changes in design are needed to increase bacteraemia detection. For viability in clinical laboratories, technical improvements are also required to further automate the process.