Objective      To investigate the characteristics of bacterial infection and its relationship with vascular lesions in lower limbs of patients with diabetic foot.       Methods      Totally 103 patients with diabetic foot admitted in our department from 2009 to 2014 were enrolled in this study. All patients received bilateral lower limbs CT angiography (CTA) or lower limb angiography during the period of hospitalization

and then were divided into 4 groups (grade A to D) according to the scale of Trans-Atlantic Inter-Society Consensus (TASC). Secretions of diabetic foot ulcers were collected for culturing and drug susceptibility test. Chi square test was used to analyze the possible differences in the pathogen features and drug resistance among the 4 different TASC groups. One-way analysis of variance (ANOVA) was employed to detect the relevant factors (such as age

diabetes duration and course of diabetic foot

etc) and laboratory indexes [including ankle-brachial index (ABI)

toe-brachial index (TBI)

white blood cell count

neutrophil percentage and blood lipids

etc] on the differences among the different 4 TASC groups.       Results      There were significant differences in age

diabetes duration

ABI

TBI

and neutrophil percentage among the 4 TASC groups (P=0.000

0.001

0.000

0.006 and 0.039 respectively). There were 38 patients suffering from mild infections (36.9%)

46 moderate infection (44.7%)

and 19 severe infection (18.4%). Secretion culturing and drug susceptibility test showed that gram-positive bacteria infections accounted for 29.6%

gram-negative bacterial infections for 27.1%

fungal infection for 4.8%

and mixed infections for 38.5%. Among the 139 strains of pathogenic bacteria derived from the secretion cultures

the top 3 bacteria were 24 strains of Staphylococcus aureus (17.3%)

17 strains of Pseudomonas aeruginosa (12.2%) and 10 strains of Enterocoecus faecalis (7.2%). With the severity of vascular lesions in lower limbs

there were more mixed infections

covering significant higher percentage than other infections (P=0.004). The mixed infection cases accounted for 66.7% in the patients at TASC grade D.       Conclusion      Mixed infections are significantly associated with the severity of lower limb vascular lesions in diabetic foot. With the deterioration of the vascular lesion

the percentage of mixed infection is gradually increased. Revascularization can reduce mixed infection

and is helpful in improving the anti-infection treatment in the patients with diabetic foot.