When using traditional culture methods, it takes labs 24 to 72 hours to detect the presence of an infection in a wound. Culture swabs collected from wounds are incubated, but the tests aren't always 100% accurate. A wound infection isn't always detected, and the patient has already waited up to 3 days for an answer for their pain.
The process is time consuming for wound care clinicians and can cause delays in treatment.
Constructing the Probe
Edgar Goluch, PhD, associate professor of chemical engineering in the College of Engineering at Northeastern University in Boston, Mass., saw the need to develop a quicker method for detecting infections.He created an electrochemical device to meet this goal.
"My group at Northeastern wanted to use our sensor technology to measure the rates at which bacteria produce the quorum sensing molecules (QSMs) and other metabolites, because that had not been done very accurately or systematically before," said Goluch. "Once we started doing the measurements, we noticed that the bacteria were making a lot of these QSMs and that they were incredibly unique to each bacterial species. That's when I got the idea that we could use our sensors to detect infections by simply detecting the QSMs."
The device consists of a small probe(less than 1 cm in length) designed to detect pyocyanin, a bacterial quorum-sensing molecule produced by the bacterium Pseudomonas. If the molecule is detected by the sensor, then clinicians know that Pseudomonas is present in the wound.
"The probe opens up a door for real-time detection in the clinical setting," said Victoria Shanmugam, MD, FACR, FACP, director of the division of rheumatology and an associate professor of medicine at The George Washington University (GWU) Medical Faculty Associates. Shanmugam was approached by Goluch, who wanted to determine if the device would have any clinical use.
"It was kind of a lucky coincidence," Shanmugam said. "He came to the wound clinic at GWU Hospital and as I was listening to the story, I knew I had the perfect experiment that would be very quickly able to test whether the probe would have a role in wound specimens."
Goluch interviewed nearly 100 people who worked with bacterial infections in order to determine if there was a need for the probe and its type of infection detection. "I figured the wound care center at GWU Hospital would treat a lot of wounds, so I started my interviews there," Goluch explained. "Vicki [Shanmugam] happened to be working there that day, and during my interview, we realized how my probe was a great fit with her WE-HEAL research. The rest is history." WE-HEAL stands for wound etiology and healing.
The research and data collection was funded by the National Center for Advancing Translational Science through its clinical and translational science awards program and by the National Institute of Nursing Research (NINR).
"A major NINR research focus area is improving the understanding of the symptoms and complications of chronic conditions using new advances in genetics and genomics," said Patricia A. Grady, PhD, RN, FAAN, director of NINR. After reviewing applications for chronic wound treatment, NINR representatives chose to award a grant to the WE-HEAL project.
Shanmugam and Goluch were also joined by Agnes Chan, PhD, assistant professor at the J. Craig Venter Institute in Rockville, Md., to begin testing the probe.
The WE-HEAL study was already in progress at Shanmugam Laboratory by the time Goluch approached Shanmugam. WE-HEAL examines the interplay of the host immune response, the wound-bed microbiome and pain pathways to investigate factors that play roles in wound healing.
Using the standard genetic testing method for infection, the researchers already knew which patients' wounds in the WE-HEAL program had Pseudomonas. These patients were retested using the probe. Fourteen wound fluid samples and biofilms were extracted from 12 patients for analysis.
The probe was able to correctly identify the presence of pyocyanin in samples containing Pseudomonas bacteria 73% of the time. It correctly identified the absence of the bacterium 53% of the time. From the 14 samples of wound fluid and biofilm tested, the probe successfully identified nine correct matches, had two false negatives and three false positives.
"This method is incredibly quick, taking about 30 seconds per sample," Shanmugam said. The device is small enough to fit in the palm of her hand and is simple to use. The next steps in modification include finding a software program to read the results in real time. "Our goal is to make it bedside accessible," Shanmugam said.
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The Next Steps
In addition to saving time in detecting and diagnosing a wound infection, the device saves the unmeasurable cost of time spent with patients, according to Shanmugam. With the probe, healthcare providers would be able to assist patients quicker than with the current wound infection detection method. Healthcare workers would be able to treat more patients each day and more rapidly start patients on the right treatment for infections.
The team will continue to work on improving the probe. Long-term goals include finding various mechanisms to improve design and accuracy of detection. The team wants to begin clinical trials as well.
"This research, if successfully translated into practice, can transform procedures used by wound care nurses," Grady said. NINR's mission includes improving clinical patient care through new studies and methods of learning. "We look forward to tracking the progress of the probe and the promise it shows for improved outcomes for chronic wound patients."
For now, the probe detects only the molecules for Pseudomonas. The researchers hope to harness other molecules in a similar fashion.
"We want to detect other bacterial species with this probe, not just Pseudomonas. So we have to slightly modify each sensor on the probe to detect more QSMs," said Goluch. "My group at Northeastern is in the process of doing this now."
Autumn Heisler is a staff writer. Contact her at email@example.com.