Pathogen profile and inflammatory biomarkers in diabetic foot infections: correlation with disease severity

To characterize the profile of pathogenic bacteria and to investigate the association between key serum inflammatory biomarkers (IL-17, IL-12p70, HMGB1, IL-8, CRP) and disease severity in patients with diabetic foot infections (DFI). We conducted a retrospective analysis of 80 DFI patients (infected group) and 80 diabetic foot patients without concurrent infection (non-infected DF group). Pathogens were cultured from the infected group. Serum levels of the five biomarkers were measured and compared between groups, and their correlation with infection severity was analyzed. Changes in biomarker levels were also monitored before and after standardized treatment in the infected group. A total of 131 pathogenic bacterial strains were isolated from the DF-infected patients. Among these, Gram-negative bacteria accounted for 47.3% (62 strains), Gram-positive bacteria for 48.9% (64 strains), and fungi for 3.8% (5 strains). The serum levels of IL-17, IL-12p70, HMGB1, IL-8, and CRP in the infected group were significantly higher than those in the non-infected group (P < 0.05). Spearman’s correlation analysis revealed a positive correlation between DF infection severity and the levels of these serum markers (r = 0.618, 0.592, 0.722, 0.635, and 0.726, respectively; all P < 0.001). Furthermore, during the infection control period, the levels of these markers significantly decreased compared to those during the active infection period (P < 0.05). In this cohort, Gram-positive and Gram-negative bacteria were identified with nearly equal frequency as the predominant pathogens in DF infections, followed by a small proportion of fungal infections.The serum levels of IL-17, IL-12p70, HMGB1, IL-8, and CRP are significantly correlated with disease severity, suggesting their potential role in both reflecting inflammatory progression and assessing therapeutic response in DF. Not applicable.