Infections in wounds concern about 2% of the population in developed countries at least once in their lifetime. These kinds of infections can lead to serious complications such as sepsis and need to be diagnosed as fast as possible. But how to find out in a fast way, if a wound is infected?

So far, wound diagnostics comprise time-consuming (minimum 24 hours) and also painful procedures, such as biopsy. The decision about potential antibiotics has to be made in an early stage and lacks a tailor-made therapy for the patient at the moment. Thus, the demand for a faster alternative for the detection of infectious wounds is existing and several working groups all over the world are working on efficient solutions.

The fastest way might be the detection of enzymes that are produced by the human immune response and the wound bacteria. Researchers from the George Washington University in Washington D.C. have published an electrochemical detection method, which is based on the identification of specific molecules produced by Pseudomonas aeruginosa (causing purulence).

In Europe, acib researchers around Doris Schiffer and Georg Gübitz together with their partners at Qualizyme currently are focussing on key enzymes in context with immune response. The particular activities of these enzymes (also called biomarkers) can easily be detected by colour change approaches. The vision is to facilitate the monitoring of the wound status for nurses and doctors by detection of wound infections within 1 minute (recently published).

The choice of the right “wound detectives”

The key enzymes for the published acib/Qualizyme method were derived from the immune response side and are all detectable by colorimetric assays:

• Myeloperoxidase (MPO), an enzyme that is mainly expressed in white blood cells and has an anti-microbial function by producing a weak acid. Since MPO has a heme pigment, a MPO rich wound secretion is characterized by its green colour.
• Human neutrophil elastase/Cathepsin G, which are typical serine proteases produced during inflammation and cause the damage of bacteria.
• Lysozyme, which has the ability to destroy the bacterial cell wall and occurs in almost every human secretion, such as tears, saliva and human milk.

During diagnosis of wound secretions, the combination of at least two enzymes turned out to be important in order to avoid overlooking an infection, because not all wounds were tested positively for the activity of all three enzymes. Also different diseases (diabetes, cardiac, pulmonary, arterial, renal and others), antibiotic treatment, age and gender had to be considered. 85% of the wounds were correctly diagnosed.

The application field of these research activities is obvious: chronical wounds can be easily monitored and also postoperative complications because of infections can be minimized. With this perspective only a German proverb is left: let the time heal all wounds.