A novel method of sampling and processing wound fluid for subsequent immunoassay analysis in diabetic foot ulcerations

OBJECTIVEdIndiabeticfootulcers,wound fluidinflammatorymediatorshavepreviouslybeen proposed as surrogate markers for nonhealing. However, currently available wound fluid sampling techniquesarenotsuitableforclinicalpracticeduetolowlevelsofexudateandahighlogisticaleffort. The aim of this investigation was to assess 1) the technique of superficial wound swabbing for harvesting wound fluid; and 2) the quality of the collected fluid for immunoassay analysis of inflammatory mediators. RESEARCH DESIGN AND METHODSdBoth nylon-flocked swabs and film dressings wereusedtocollectwound fluidfromfootulcersofdiabeticpatients.Inrandomlyselectedpatients, levels of wound fluid inflammatory mediators and matrix metalloproteases were determined using multiplexed bead-based sandwich immunoassays with respect to both sampling methods. Wound fluid spike-in experiments were performed to evaluate the impact of different sample processing protocols on subsequent immunoassay analysis. RESULTSdUsing the swabbing technique, a median amount of 40 m L( 2–120 mL) wound exudatewascollected,whichallowedthemeasurementofseveralmultiplexpanels.Comparingboth sampling methods, a similar qualitative protein recovery was observed with a trend to analyte enrichment by swabbing. Sample processing using swabs did not affect analyte recovery, with the exception of interleukin (IL)-8, thymus and activation-regulated chemokine, IL-17A, interferong–induced protein 10, and IL-4. CONCLUSIONSdThequalityof wound fluid collectedby superficialswabbing isnotinferior to the current standard technique. Combined with subsequent bead-based sandwich immunoassayanalysis,thisnewmethodoffersanoninvasivetechnique,suitablefordailyclinicalroutines,for assessment of inflammatory activity in diabetic foot ulcers. Diabetes Care 35:2113–2120, 2012