A Portable Colorimetric Reader for Early and Rapid Diagnosis of Sepsis

Septicemia or in short sepsis affects nearly 30 million people worldwide. Current clinical identification of sepsis includes culture-based methods that have a long turnaround time or monitoring of patient response that adds delay to therapy. There is currently no point-of-care care (PoC) device that allows both rapid and early sepsis diagnosis by the bedside. We have developed a portable colorimetric kit called Septiflo that gives concentration-dependent qualitative estimate of the sepsis-associated bacterial infection load in blood under 10 min. However, the results of this naked eye assessment remain somewhat subjective. In this paper, we present a handheld optical reader that can quantify the signal output of the Septiflo device making it a substantially more robust and accurate way to diagnose sepsis. The repeatability coefficient of variation (CoV) of this device when tested on five reference cartridges was found to be < 9 % and the reproducibility CoV across two reader instruments was < 8.2 %. The prototype instrument was also tested with human plasma samples in the clinically valid endotoxin concentration range of 1 to 1000 pg/mL. The calibrated values from the instrument and the known endotoxin concentrations correlated significantly with an R2 value of 0.97. The reader instrument’s hardware architecture and software algorithm are described below in detail.