Study on the Microbiological Characteristics of Infection in Diabetic Foot Ulcers (Wagner Grades 2-4) and Their Impact on Outcomes.

ObjectiveTo evaluate the influence of microbiological characteristics on Wagner grade and 12-month outcomes in hospitalized patients with Wagner grade 2-4 diabetic foot ulcers (DFUs).MethodsThis single-center retrospective cohort included 205 culture-positive infected DFUs with complete 12-month follow-up. Grade 4 was the severity outcome; nonhealing/readmission was adverse. Associations between each major organism and Wagner grade 4 were assessed using hierarchical logistic regression with sequential adjustment for host characteristics, HbA1c and WBC, and CRP, PCT, and ESR. Results were interpreted jointly across models, with Benjamini-Hochberg correction applied to the 11 organism-specific tests within each model.ResultsGrades 2/3/4 comprised 49/59/97 patients; 162 healed, 22 were unhealed, and 21 readmitted. Staphylococcus aureus was most frequent but not robustly associated. Of 19 Enterococcus-positive patients, 16 had grade 4. Enterococcus detection showed a positive association with grade 4 after adjustment for host characteristics, HbA1c, and WBC count (OR, 8.02; 95% CI, 2.11-30.46; q = 0.024). After additional adjustment for CRP, PCT, and ESR, the estimate remained positive but was attenuated (OR, 5.27; 95% CI, 1.16-23.89; raw P = 0.031) and did not meet the prespecified false-discovery-rate criterion (q = 0.172). No individual organism was robustly associated with the composite adverse outcome. Compared with one organism, two and ≥3 organisms yielded ORs 2.50 (95% CI, 1.09-5.72) and 4.89 (95% CI, 1.40-17.11); ≥3 organisms remained associated in sensitivity analysis (OR, 5.02; 95% CI, 1.42-17.76).ConclusionsAmong hospitalized patients with culture-positive Wagner grade 2-4 DFUs, Staphylococcus aureus was most common but showed limited independent associations with severity or 12-month outcomes. Enterococcus spp. clustered in grade 4 wounds, although its independent association was inconsistent across adjusted models. Detection may mark severe wound complexity but should not independently guide grading or treatment. Detection of ≥3 organisms was associated with increased risk of the 12-month composite adverse outcome, but the imprecise estimate requires prospective multicenter validation.