Bacterial infection is a major pathogenetic aspects in the formation of diabetic foot complications. Joining infection is the cause of performing amputations of the lower limbs in 25-72 % of cases, especially when diabetic foot is complicated by sepsis. The aim of our study was to identify differences in the microbial background of purulent foci in patients with diabetic foot syndrome complicated by sepsis and for the further development of the algorithm of directed antibiotic therapy. Material and methods. A total of 3653 patients in the dynamics of a complicated diabetic foot syndrome were examined. There were two groups: the first - patients who were treated during 2010-2014 (a comparison group), the second – during 2015-2019 (main group), which according to the gender ratio (χ2=0.09; P=0.7698) and age (P=0.17141) did not differ. The complex bacteriological studies consisted of determining the sensitivity of microorganisms to antibiotics, the qualitative composition of microbial pathogens and the number of microbial cells per 1 g of tissues. To determine the sensitivity of purulent microorganisms to antibiotics a quick method of determination on automated systems «Vitek-2» and «BacT/ ALERT» (France) was applied. Results and discussion. All patients with complicated diabetic foot syndrome were operated under general anesthesia. As a rule, operations on the anterior foot and «high» amputations were performed. 190 people died, death rate was 5.2 %. The analyzed data indicate that in patients with diabetic foot syndrome complicated by the number of microbial cells in tissue 1g to the site of infection did not exceed 105 – 106, while in patients with sepsis, this number was more than 50% was 107 – 1012. Isolation of aerobic monoinfection of purulent foci in patients with complicated diabetic foot syndrome in the period from 2010 to 2019 decreased from 51,4 to 44,4% (P <0,05) determined by an increase in the allocation of gram-positive microorganisms from 55,2 to 60,2% (P<0,05). The dynamics of microbiological research indicates an increase in the proportion of MRSA- staphylococci from 23,4 to 43,3 %. Determined microbial pathogens are characterized by a high level of antibiotic resistance, particularly to antibiotic-I-II generation. Conclusions. These experiments enable to distinguish particularly microbial background of purulent foci of the two groups of patients and determine antibiotic algorithms.