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 R
²
value of 0.97. The reader instrument's hardware architecture and software algorithm are described below in detail.