Microbiome of limb-threatening diabetic foot ulcers indicates the association of fastidious Stenotrophomonas and major amputation

Background: Proper identification of the polymicrobial microorganisms in patients with limb -threatening diabetic foot ulcers (LTDFUs) using conventional culture is insufficient. This prospective study evaluates the potential value of adjuvant molecular testing assisting in identify fastidious micro-organisms in LTDFUs compared to standard treatment alone. Methods: Ninety patients with LTDFUs received interdisciplinary and standard antibiotic treatment in a referral diabetic foot center. A simultaneous 16S amplicon sequencing (16S AS) specimen along with conventional culture collected at admission was used to retrospectively evaluate the microbiological findings and its association with amputation outcomes. Results: The microorganism count revealed by 16S AS overwhelmed that of conventional culturing (17 vs. 3 bacteria/ulcer respectively). The Stenotrophomonas spp. revealed in 29 patients were highly correlated with major (above ankle) amputation (OR: 4.76, 95% CI 1.01 -22.56), while only one had been concomitantly identified by conventional culturing. Thus, there were 27 cases without proper antibiotics coverage during treatment.