Fast Diagnostic Tool Investigated for Wound Infections

A novel concept for a fast diagnostic tool for wound infection based on enzymes triggered release of dye from a polymeric matrix has been investigated.

For the development of a simple diagnostic tool, a liquid lysozyme assay was adapted to a solid system and the matrix consisted of alginate/agarose and peptidoglycan covalently labeled with Remazol brilliant blue.

Scientists from the Graz University of Technology (Austria) collected wound fluid from 10 postoperative wounds, 8 decubitus ulcer wounds, and 8 blisters and analyzed by biochemical techniques. The detection of wound infection was based on lysozyme and elastase triggered release of the dye from a peptidoglycan matrix. Incubation of 8% labeled agarose/peptidoglycan blend layers with infected wound fluid samples for two hours at 37 °C resulted in a four-fold higher amount of dye released than measured for noninfected wounds. Lysozyme activity in postoperative wounds and decubitus (bed sore) wound fluids was significantly elevated upon infection (4,830 ± 1,848 U/mL), compared to noninfected wounds (376 ± 240 U/mL).

A seven-fold higher amount of dye was released in case of infected wound fluid samples compared to noninfected ones using an alginate/peptidoglycan beads assay. By using Western blotting techniques, proteases including the gelatinase matrix metalloproteinases MMP-2 and MMP-9, and elastase were detected in wound fluids. A slight synergistic effect was measured by dye release for peptidoglycan hydrolysis, between lysozyme and these proteases. Incubation of a double-layer system consisting of stained and nonstained peptidoglycan with infected wound fluids resulted in a color change from yellow to blue, thus allowing simple visual detection of wound infection.

The authors concluded that such a diagnostic tool would allow early intervention with suitable treatment and could reduce clinical intervention and the use of antibiotics. The tool is based on human enzymes, which can be detected in wound fluid samples in a very fast way and which were shown to be elevated in case of infection. The study was published in September 2011, in the journal Diagnostic Microbiology and Infectious Disease.

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Graz University of Technology