Analysis of the species distribution and drug resistance of pathogenic microorganisms causing diabetic foot infections in Southwest China from 2020 to 2024: a retrospective cross-sectional analysis

Abstract

Diabetic foot infections (DFIs) are severe and costly complications of diabetes, often resulting in disability and significant health challenges. These infections place a substantial burden on both individuals and society. The increasing incidence of infections, coupled with the rising resistance to antibacterial drugs, has further complicated treatment strategies. A cross-sectional study was conducted involving 484 hospitalized DFI patients at the Affiliated Hospital of Southwest Medical University from 2020 to 2024. Pathogens and their resistance profiles were identified through wound cultures and drug sensitivity tests. Multivariate logistic regression was employed to examine the risk factors associated with DFIs and the infection rates of multidrug-resistant organisms (MDROs). Among 445 detected pathogens, Gram-positive bacteria predominated (49.66%), with Staphylococcus aureus being the most common (28.53%), followed by Gram-negative bacteria (46.29%), with Escherichia coli as the most prevalent (9.88%). Fungi accounted for 4.04%. Antibacterial drug resistance analysis revealed that Gram-positive isolates showed high resistance to penicillin (88.89%) and erythromycin (50.00%) but remained highly susceptible to linezolid (0.79% resistance). Gram-negative bacteria demonstrated significant resistance to third-generation cephalosporins, particularly ceftriaxone (46.51%), but maintained excellent sensitivity to carbapenems, with imipenem resistance at only 2.33%. Multivariate analysis identified peripheral neuropathy as a significant risk factor for DFIs, while prior ulcer history (OR = 2.497, P = 0.001) and lower hs-CRP levels (OR = 0.989, P = 0.013) were independently associated with MDROs infection. In this region, Gram-positive bacteria remained predominant overall, but Gram-negative bacteria increased significantly in severe or chronic ulcers, exhibiting severe resistance. A dynamic pathogen shift was observed, with decreased Staphylococcus aureus and increased Escherichia coli, the latter showing high resistance to common antibacterial drugs and challenging empirical treatment. Carbapenems, glycopeptides, and oxazolidinones retained effectiveness against corresponding pathogens for severe and multidrug-resistant DFI but require cautious use. Decreased hs-CRP and ulcer history were independent risk factors for multidrug-resistant organism (MDRO) infection, warranting vigilance in immunosuppressed patients.

Keywords: Antibacterial drug resistance; Diabetic foot; Microbial infection; Pathogenic bacteria distribution; Risk factors.