Sensing Array Speeds Diagnosis of Sepsis

The odor released by some of the most pathogenic microbes has become the basis for a faster and simpler way to diagnose blood infections and identify the specific microorganism.

This latest test produces results in 24 hours, compared to as much as 72 hours required with the test hospitals now use, and is suitable for use in developing countries and other areas that lack expensive equipment in clinical laboratories.

Scientists at the University of Illinois (Champaign, IL, USA) developed an inexpensive disposable liquid culture bottle that detects and identifies opportunistic human pathogenic microorganisms at clinically relevant concentrations in liquid media during cell culture. The device combines amplification of bacteria with detection and identification in a single sealed bottle. This single step device is composed of a nonsterile chemical sensing array that is strategically interfaced with a culture bottle, without compromising the sterility of the device.

The device consists of a plastic bottle, small enough to fit in the palm of a hand, filled with nutrient solution for bacteria to grow. Attached to the inside is a chemical sensing array (CSA), with 36 pigment dots. The dots change color in response to signature odor chemicals released by bacteria. A blood sample from a patient is injected into the bottle, which goes onto a simple shaker device to agitate the nutrient solution and encourage bacterial growth. Any bacteria present in the blood sample will grow and release a signature odor that changes the colors of pigment dots on the sensor. The test is complete within a day, and the results can be read in a pattern of color changes unique to each strain of bacteria.

The device can identify eight of the most common disease-causing bacteria with almost 99% accuracy under clinically relevant conditions. Other microorganisms can cause sepsis, and the scientists are working to expand the test's capabilities as the device could make an impact now in reducing the toll of sepsis. The results from nine microorganisms, including two strains of Escherichia coli and two strains of Enterococcus faecalis, illustrated the high reproducibility and identification ability of this technology.

James Carey, PhD, from the National University of Kaohsiung (Taiwan) and senior author said, “Our CSA blood culture bottle can be used almost anywhere in the world for a very low cost and minimal training. All you need is someone to draw a blood sample, an ordinary shaker, incubator, a desktop scanner, and a computer.” The study was presented at the 246th National Meeting & Exposition of the American Chemical Society held September 8–12, 2013 in Indianapolis (IN, USA).

Related Links:
University of Illinois
National University of Kaohsiung