Rapid Test Diagnoses Severe Sepsis

The discovery of the test could cut back on the lengthy diagnostic time, which can take 24 to 48 hours usually required to confirm if a patient is suffering from sepsis and increase the odds that they will respond to treatment.

Scientists at the University of British Columbia (Vancouver, BC, Canada) recruited 72 total patients which proved subsequently to include 37 sepsis patients. The majority of patients, 83%, were enrolled from the emergency room. Blood was collected in EDTA tubes at the time of initial blood culture, and immediately placed on ice. Plasma and buffy coat were separated and two aliquots transferred into bar-coded cryovials at -20 °C until they were transferred to a -80 °C freezer.

Transcriptomic analysis was performed by the high throughput sequencing of complementary DNA (cDNAs) (ribonucleic acid sequencing, RNA-Seq) and cDNA libraries were prepared from total RNA using the TruSeq Stranded Total RNA Sample Prep Kit with Ribo-Zero sample preparation guide (Illumina; San Diego, CA, USA). RNA-Seq was performed on Illumina’s GAIIx instrument using a single read run of 63 bp-long sequence reads.

All patients who were suspected to have infection upon first clinical presentation were confirmed in 19 of the 37 individuals who were eventually diagnosed with sepsis. Nevertheless, similar levels of significance of association of the endotoxin tolerance signature with sepsis were observed for this group as a whole, and for that subset of the group with confirmed infections. Amongst those with sepsis, the Endotoxin Tolerance Signature was significantly enriched in the culture positive group, although there was a trend towards enrichment in the culture negative group.

The full 99 gene Endotoxin Tolerance Signature was useful for characterizing the immune dysfunction in sepsis, but a smaller number of genes would be of more use in a diagnostic test. The team selected genes that showed greater than 1.5-fold differential expression between sepsis patients and controls, and identified a core-set of 31 genes from the original 99 gene Endotoxin Tolerance Signature. The new test for the genetic signature takes as little as one hour and identified 96% of patients who were at the very early stages of sepsis.

Robert E.W. Hancock, PhD, a professor of microbiology and senior author of the study, said, “We identified a gene signature that is associated with the eventual diagnosis of sepsis and subsequent organ failure. We can test for this genetic signature as soon as the patient arrives in the emergency ward. With sepsis, every hour counts, the treatment involves aggressive antibiotics but the most potent drugs can't be administered until a diagnosis is confirmed because of the risk of antibiotic resistant bacteria.” The study was published on October 7, 2014, in the journal EbioMedicine.

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University of British Columbia
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