The Infected Diabetic Foot: Does Negative Pressure Wound Therapy with Irrigation Reduce Bioburden and Improve Wound Healing?

The aim of this study was to compare the microbial loads of patients with diabetic foot infections treated with negative pressure wound therapy (NPWT) with and without irrigation with polyhexamethylene biguanide (NPWTi-P). This is a post hoc analysis of combined data of two randomized clinical trials. We evaluated people with diabetes treated with moderate and severe diabetic foot infections that required surgery. Tissue specimens were obtained after the initial surgery and following a second planned return to the operating room after 48-72 h of NPWT or NPWTi-P, prior to the second surgery. We used quantitative polymerase chain reaction (qPCR) to determine the total microbial loads (Log10 16S copies per gram of tissue). There was no difference in mean quantitative bacterial cultures among patients that received NPWT and NPWTi-P (before first surgery Log10: NPWT = 6.4 +/- 1.8, NPWTi-P = 7.5 +/- 1.7 vs before second surgery Log10: NPWT = 6.7 +/- 1.8, NPWTi-P = 7.6 +/- 1.9 p = .12). There was no difference in wound healing (59.5% vs 50.0%, p = .51) or time to heal (127 +/- 109.3 vs 143 +/- 95.9), p = .71). There were fewer re-infections in people that received traditional NPWT (28.6% vs 56.3%, p = .05).Level of Clinical Evidence: Level 1.