The IRIDICA BAC BSI Assay: Rapid, Sensitive and Culture-Independent Identification of Bacteria and Candida in Blood

Bloodstream infection (BSI) and sepsis are rising in incidence throughout the developed world. The spread of multi-drug resistant organisms presents increasing challenges to treatment. Surviving BSI is dependent on rapid and accurate identification of causal organisms, and timely application of appr...

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Published in:	PloS one Vol. 11; no. 7; p. e0158186
Main Authors:	Metzgar, David, Frinder, Mark W, Rothman, Richard E, Peterson, Stephen, Carroll, Karen C, Zhang, Sean X, Avornu, Gideon D, Rounds, Megan A, Carolan, Heather E, Toleno, Donna M, Moore, David, Hall, Thomas A, Massire, Christian, Richmond, Gregory S, Gutierrez, Jose R, Sampath, Rangarajan, Ecker, David J, Blyn, Lawrence B
Format:	Journal Article
Language:	English
Published:	United States Public Library of Science 06-07-2016 Public Library of Science (PLoS)
Subjects:	Algorithms Anti-Bacterial Agents - therapeutic use Antibiotics Assaying Bacteria Bacteria - isolation & purification Bacterial artificial chromosomes Bacterial Infections - blood Biological Assay - methods Biology and Life Sciences Blood Candida Candida - isolation & purification Candidiasis - blood Care and treatment Causes of Contaminants Culture Deoxyribonucleic acid Diagnosis DNA DNA Primers DNA probes Drug resistance Drug Resistance, Bacterial Drug Resistance, Fungal Emergency medical care Genetic testing Hospitals Humans Identification Identification methods Infections Ionization Laboratories Limit of Detection Mass spectrometry Mass spectroscopy Medicine Medicine and Health Sciences Microorganisms Mortality Multidrug resistance Mycobacterium Organisms Physical Sciences Polymerase Chain Reaction Primers Public health Reproducibility of Results Research and Analysis Methods Scientific imaging Sensitivity and Specificity Sepsis Sepsis - blood Sepsis - microbiology Spectrometry, Mass, Electrospray Ionization Yeast United States California United States > US Maryland Baltimore Maryland Germany
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Summary:	Bloodstream infection (BSI) and sepsis are rising in incidence throughout the developed world. The spread of multi-drug resistant organisms presents increasing challenges to treatment. Surviving BSI is dependent on rapid and accurate identification of causal organisms, and timely application of appropriate antibiotics. Current culture-based methods used to detect and identify agents of BSI are often too slow to impact early therapy and may fail to detect relevant organisms in many positive cases. Existing methods for direct molecular detection of microbial DNA in blood are limited in either sensitivity (likely the result of small sample volumes) or in breadth of coverage, often because the PCR primers and probes used target only a few specific pathogens. There is a clear unmet need for a sensitive molecular assay capable of identifying the diverse bacteria and yeast associated with BSI directly from uncultured whole blood samples. We have developed a method of extracting DNA from larger volumes of whole blood (5 ml per sample), amplifying multiple widely conserved bacterial and fungal genes using a mismatch- and background-tolerant PCR chemistry, and identifying hundreds of diverse organisms from the amplified fragments on the basis of species-specific genetic signatures using electrospray ionization mass spectrometry (PCR/ESI-MS). We describe the analytical characteristics of the IRIDICA BAC BSI Assay and compare its pre-clinical performance to current standard-of-care methods in a collection of prospectively collected blood specimens from patients with symptoms of sepsis. The assay generated matching results in 80% of culture-positive cases (86% when common contaminants were excluded from the analysis), and twice the total number of positive detections. The described method is capable of providing organism identifications directly from uncultured blood in less than 8 hours. The IRIDICA BAC BSI Assay is not available in the United States.
Bibliography:	ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 Competing Interests: This work was supported by Ibis Biosciences, an Abbott company, which manufactures and markets the IRIDICA System and the IRIDICA BAC BSI Assay. Abbott employees (including, but not limited to, the authors DM, MWF, MAR, HEC, DMT, DM, TAH, CM, GSR, JRG, RS, DJE, and LBB) were partly or entirely responsible for study design, data collection and analysis, the decision to publish, and preparation of the manuscript. The aforementioned authors’ salaries were paid by Abbott, many are Abbott stockholders, and some are named on patents related to the IRIDICA BAC BSI Assay and the IRIDICA System. The IRIDICA System and the BAC BSI Assay are currently on market in Europe under CE Mark. Abbott also provided financial and material support to the Johns Hopkins Department of Emergency Medicine and Clinical Microbiology Laboratory (including, but not limited to, the authors RER, SP, KCC, SXZ, and GDA) for sample collection efforts and provision of microbiological analyses, clinical data, and organism stocks used in analytical studies. This does not alter our adherence to PLOS ONE policies on sharing data and materials. Conceived and designed the experiments: D. Metzgar MWF RER SP KCC SXZ MAR HEC DMT D. Moore TAH CM GSR JRG RS DJE LBB. Performed the experiments: D. Metzgar MWF KCC SXZ GDA MAR GSR JRG LBB. Analyzed the data: D. Metzgar MWF SP GDA MAR HEC DMT D. Moore TAH CM JRG RS DJE LBB. Contributed reagents/materials/analysis tools: RER SP KCC SXZ GDA HEC DMT D. Moore TAH CM GSR JRG. Wrote the paper: D. Metzgar MWF RER SP KCC HEC DMT D. Moore TAH CM GSR JRG RS DJE LBB. Current address: Illumina, San Diego, California, United States of America
ISSN:	1932-6203 1932-6203
DOI:	10.1371/journal.pone.0158186