Etiology of Diabetic Foot Infection in Patients with Poorly Controlled Diabetes

The aim of the study was to define the spectrum and susceptibility of microorganisms, isolated from diabetic foot ulcers in patients with poorly controlled diabetes, treated at the clinic of surgery, and compare microbial findings of specimens collected superficially and from deep tissues. The study included 19 patients with type 1 and 2 diabetes with clinical signs of infection. All patients were with poorly controlled diabetes and staged from 3rd to 5th grade according to the Wagner diabetic foot scale. Swab samples from non-debrided wounds and biopsy samples from deep tissues were collected from each patient. Specimens were inoculated on media for isolation of aerobic and anaerobic bacteria. Identification and susceptibility testing of the isolated oiganisms were performed by conventional methods, and VITEK 2 and mini API Systems (bioMerieux, France). A total of 88 bacterial isolates were cultured, comprising 56 clinical strains. Gram positive bacteria were the most common isolated organisms (53.57%), followed by Gram negative bacteria (26.78%) and anaerobic bacteria (19.64%). Staphylococcus aureus was the most common organism detected (10 strains), followed by Enterococcus spp. (7 strains), Escherichia coli (7 strains), Bacteroides spp. (6 strains) and various other organisms of low incidence. Polymicrobial infection was detected in 17 (89.47%) of the patients. In most of the cases infections were caused by 3 bacterial species. Mixed aerobic/anaerobic infections were detected in 9 (47.3%) patients. In 15 (78.94%) patients, there was a coincidence of bacterial findings from superficial and deep tissue samples. The strains isolated were susceptible to commonly used antimicrobials for treatment of diabetic foot infection. The predominant part of the diabetic foot infections were polymicrobial, caused by association between two or three microbial species. In half of the cases the infection was mixed. There was a good correlation between microbial findings from superficial swabs and deep tissue specimens when they were delivered to the microbiology laboratory immediately after collection.