Molecular device could identify pathogens earlier and more precisely

Precision medicine, deemed a national priority by President Obama earlier this year, promises to help to ease the burden of antibiotic resistance through diagnostics that will more accurately identify the specific pathogen underlying disease. Now, researchers have developed a new technique that could enable an earlier and more accurate identification of the presence of a particular bacteria, virus or fungus even when the infection remains only in the respiratory or gastrointestinal tract.

Scientists have developed a molecular device made of DNA that can indicate the presence of a disease indicator or DNA molecule that is amplified into a massive signal that can be easily spotted. Essentially, the presence of the target triggers rolling circle amplification that enables the detection of the smallest quantities of metabolites, proteins or fragments of DNA.

Yingfu Li, professor at McMaster University

"This invention will allow us to detect anything we might be interested in, bacterial contamination or perhaps a protein molecule that is a cancer marker," Yingfu Li, a professor in the departments of Biochemistry and Biomedical Sciences, Chemistry and Chemical Biology at McMaster University, said in a statement.

"Our method can sensitively detect all of them, and it can do so in a relatively short period of time," he added. "This will be the foundation for us to create future diagnostic tests."

The new technique enables specific pathogens to be identified very early postinfection and the test does not require major equipment, so it can be run at room temperature in a variety of environments.

In fact, the researchers are working on a paper version to create a point-of-care test that would eliminate the need for laboratory instruments and enable the test to be run in a physician's office. The Biointerfaces Institute at McMaster has already developed a series of paper-based technologies to enable infection and contamination detection.

"The method we have developed allows us to detect targets at levels that are unprecedented," said John Brennan, the director of McMaster's Biointerfaces Institute, in a statement

"The test has the best sensitivity ever reported for a detection system of this kind--it is as much as 10,000 times more sensitive than other detection systems," he concluded. Diagnostic test sensitivity refers to the ability of a diagnostic test to correctly identify those with a disease--a true positive rate--while test specificity is the ability to correctly identify those who don't have the disease--a true negative rate.

- here are the release and the study