The stench released by disease-causing bacteria is the basis for a faster and simpler new way to diagnose blood infections and pinpoint the specific microbe, scientists reported at the 246th National Meeting & Exposition of the American Chemical Society. The new 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 hospital labs.
“We have a solution to a major problem with the blood cultures that hospitals have used for more than 25 years to diagnose patients with blood-borne bacterial infections,” said James Carey, PhD, of the National University of Kaohsiung in Taiwan in the Republic of China, who presented the report. “The current technology involves incubating blood samples in containers for 24 to 48 hours just to see if bacteria are present. It takes another step and 24 hours or more to identify the kind of bacteria in order to select the right antibiotic to treat the patient. By then, the patient may be experiencing organ damage, or may be dead from sepsis.”
Sepsis, a toxic response to blood-borne infections, kills more than 250,000 people each year in the US alone. That’s why a research team at the University of Illinois at Urbana-Champaign, which included chemistry professor Ken Suslick, and Carey, set out to develop a faster, simpler test.
Carey described a completely new way to identify bacteria compared to an earlier version of such a test developed at Illinois. The new device consists of a small plastic bottle filled with nutrient solution for bacteria to grow. Attached to the inside is a chemical sensing array (CSA), an “artificial nose,” 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. They say the new device can identify eight of the most common disease-causing bacteria with almost 99 percent accuracy under clinically relevant conditions.
The earlier device could detect odors given off by bacteria only after the bacteria were first grown in laboratory culture dishes.
