Objective:To investigate the role of autophagy-related molecules Beclin1 and LC3 in diabetic foot infection with multidrug resistant (MDR) Staphylococcus aureus.Methods:From June 2016 to October 2017, 62 patients with diabetic foot infected by Staphylococcus aureus were selected as the diabetic foot infection group, and 38 patients with foot burns were selected as the control group. Staphylococcus aureus isolation, identification and drug sensitivity test were carried out. According to drug resistance, the patients with diabetic foot infection were further divided into multidrug resistance group and non-multidrug resistance group. The granulation tissue of foot wound was collected and the expression of Beclin1 and LC3 was detected by immunohistochemistry. The expression of LC3 in macrophages was detected by immunofluorescence double staining.Results:The levels of glycosylated hemoglobin, white blood cell count and erythrocyte sedimentation rate in diabetic foot infection group were significantly higher than those in control group ( P<0.05). Multidrug-resistant Staphylococcus aureus was detected in 30 cases (48.39%) of 62 patients with diabetic foot infection, 2 cases (5.26%) of 38 patients in the control group, and the detection rate of multidrug-resistant Staphylococcus aureus in the diabetic foot infection group was significantly higher than that in the control group ( P<0.05). The white blood cell count, neutrophil ratio and C-reactive protein levels in MDR group were significantly higher than those in non-MDR group ( P<0.05). Immunohistochemical examination showed that the expression levels of Beclin1 and LC3 in wound granulatin tissue of diabetic foot infection group were significantly lower than those in control group ( P<0.01); the expression levels of Beclin1 and LC3 in wound granulation tissue of multidrug resistance group were significantly lower than those in non-multidrug resistance group ( P<0.05). Immunofluorescence double staining showed that the co-expression intensity of LC3 and CD14 in wound granulation tissue of diabetic foot infection group was significantly lower than that of control group, suggesting that LC3 expression in macrophages was significantly reduced. Conclusions:The expression of Beclin1 and LC3 in the wound granulation tissue of diabetic foot patients infected with Staphylococcus aureus decreased significantly, especially in those infected with multidrug resistant Staphylococcus aureus. The occurrence and development of multidrug resistance of Staphylococcus aureus in diabetic foot patients may be related to the decrease of autophagy level.