Disposable, Electrochemical Sensor IDs Wound Infections in Seconds

An inexpensive, disposable electrochemical sensor may be able to detect Pseudomonas aeruginosa (P. aeruginosa) infections in wounds in real-time at the point of care, according to a pilot study published in Wound Repair and Regeneration. The new method cuts time to infection detection and characterization from 24 hours to a mere minute, allowing improved antibiotic selection that holds benefits both for patient care and the health system.

“For the field of wound care, there is a compelling need to develop rapid alternatives for bacterial identification in the clinical setting, where it generally takes over 24 hours to receive a positive identification,” writes senior author Victoria Shanmugam, M.D., from George Washington University in Washington, D.C. The authors say that even new molecular identification methods require an initial incubation period before analysis is possible. To date, the standard for clinical identification of bacterial infections requires overnight plated cultures.

The new method identifies a metabolite molecule (pyocyanin) produced by the Pseudomonas bacteria, which commonly infects chronic wounds. To test the sensor, researchers used wound fluid (7.5 μL) from 12 patients with chronic wounds enrolled in the WE-HEAL Study. The electrochemical results were compared against 16S rRNA profiling using 454 pyrosequencing.

The researchers found that the sensor technology correctly identified nine sample matches, but had two false negatives and 3 false positives. Overall, the detection method had a sensitivity of 71 percent and specificity of 57 percent for detection of Pseudomonas. The authors say this demonstrates potential for the technology as a rapid, point-of-care diagnostic with “ongoing enhancement.” Since the electrochemical detection strategy eliminates sample preparation, results are available in less than a minute.

“Despite the polymicrobial nature of human wound specimens, there do not appear to be other redox-active molecules that would impede the probe performance in a clinical setting,” writes Shanmugam and colleagues. “Although still unclear if it is necessary, the detection limit of electrochemical sensors can be improved by switching to micro and nanofabricated electrodes, albeit with increased sensor cost. Nevertheless, future technological advances will lead to reduced costs and more sensitive electrochemical sensors, making this approach a practical option.”

Takeaway: With further refinement, a rapid, point-of-care diagnostic that could instantly identify Pseudomonas, a common cause of wound infection, would enable better patient care and stewardship of antibiotics.