Gut E. coli–Collinsella signature associated with Wagner 4 gangrenous diabetic foot ulcers
A three-MAG gut metagenomic signature — enriched E. coli and depleted Collinsella — distinguishes gangrenous diabetic foot (Wagner 4) from less severe grades, with an out-of-bag AUC of 0.703.
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Context
Diabetic foot ulcers are a leading cause of non-traumatic amputation. Whether the gut microbiome reflects systemic features linked to advanced ulcer severity was previously unclear.
What the study showed
Global community diversity did not separate Wagner 4 from Wagner 1-3, arguing against broad ecological restructuring with disease severity. Genome-resolved analysis using random forest stability selection and covariate-adjusted MaAsLin2 converged on three MAGs: one E. coli MAG enriched in Wagner 4 and two Collinsella MAGs depleted in Wagner 4. The three-MAG classifier achieved an out-of-bag AUC of 0.703.
How it was done
Cross-sectional shotgun metagenomic sequencing of stool from 43 type 2 diabetes patients with active DFU (Wagner 1-3, n=30; Wagner 4, n=13); de novo assembly and binning yielded 440 dereplicated medium-to-high-quality MAGs.
Risk of bias
Small, imbalanced sample (n=43; only 13 in the Wagner 4 group) limits statistical power and external validity; cross-sectional design precludes causal inference; assessment is based on the abstract alone.
What this study does NOT prove
The study does not prove that gut microbiota causes or drives diabetic gangrene, nor that the three-MAG signature has validated predictive value in independent cohorts.
In clinical practice
Findings are hypothesis-generating. Current evidence does not support clinical use of gut microbiome profiling for diabetic foot severity stratification.
Limitations
Small, imbalanced sample (n=43; only 13 in the Wagner 4 group) limits statistical power and external validity; cross-sectional design precludes causal inference; assessment is based on the abstract alone.
Technical appendix
Version history
- 1.0 · 2026-10-27 — Auto-generated under Evidence Standard v1.0