Probe detects staph infection faster, more cheaply

Currently, to test if patients are infected with Staphylococcus bacteria, commonly known as staph, doctors have to take a biopsy and send it for analysis. Now, researchers from the University of Iowa have developed an ingenious noninvasive chemical probe that can detect the presence of a common species of staph in less than an hour.

The probe specifically targets Staphylococcus aureus, a species of staph that is common both inside hospitals and out in the general community. This species causes skin infections, and it can spread to the joints and bones and is potentially fatal, particularly in patients whose immune systems are already weak.

To design the probe, the team made use of the fact S. aureus shreds DNA. They exploited this feature to make the probe emit a light, which signals to doctors that the bacterium is present.

Speaking about their study, published in the journal Nature Medicine, first author and post-doctoral researcher Frank Hernandez says:

"Every year in the US half a million people become infected by S. aureus bacteria, and 20,000 of those who become infected die. We believe that we are significantly improving the actual methods for detecting bacteria with a simple approach, which we expect to be cheap, fast and reliable."

Corresponding author James McNamara, assistant professor in internal medicine, adds:

"We've come up with a new way to detect staph bacteria that takes less time than current diagnostic approaches. It builds on technology that's been around a long time, but with an important twist that allows our probe to be more specific and to last longer."

Currently, it can take days for doctors to find out if a patient is infected with staph, as they have to wait for lab results of biopsies. Prof. McNamara says they are "flying blind," and that it is "the state of medicine at this time."

Probe made of two molecules

The ingenious design of the probe hinges on a unique feature. It is a particle made of two molecules. One molecule gives off light under certain conditions, and the other molecule blocks that light.