Researchers Find New Way to Identify Pathogens

Issue Date: 
September 28, 2015

There are plenty of ways in the lab to determine which bug is bugging you when you’re sick. The University of Pittsburgh’s Xinyu Liu, Sanford Asher, and colleagues may have found a faster method.

Xinyu Liu“You can do a swab and culture the bacterium or fungi, but that takes days,” Liu says. “You can examine the DNA, but that takes another day or two. It’s a pretty tedious process. So, before the identity of the pathogen can be determined, doctors give infected people a broad-spectrum antibiotic that kills everything.”

It would be better for the patient, then, to correctly identify the pathogen in question as soon as possible and treat it with a specific antibiotic aimed directly at the offending bug.

Liu, assistant professor of chemistry in Pitt’s Kenneth P. Dietrich School of Arts and Sciences, along with Asher, Distinguished Professor of Chemistry, and others, have developed a method of identifying pathogens that uses spectroscopy, which determines an object’s identity through the type of light it emits. Their work was published in the German Chemical Society’s journal, Angewandte Chemie International Edition.

Sanford AsherThe Liu-Asher team developed a specifically engineered protein hydrogel that interacts with carbohydrates on the surface of a fungus named Candida albicans, which is responsible for oral thrush and skin yeast infections and can be life threatening for immune-compromised patients. 

When the protein hydrogel interacts with the carbohydrates on the surface of C. albicans, it shrinks the 2-D photonic crystals where the hydrogel resides, emitting a specific light signature that can be recognized by the naked eye or a spectroscope. This happens almost immediately, much faster than the days other methods require. 

The broader implications are large, the researchers say. Different antibodies could be used, for example, to make hydrogels tailored for specific pathogens such as staph and E. coli. Or people living in rural areas or underdeveloped countries might be able to use such a method to determine if their food or water is contaminated or their children are infected with deadly pathogens.