Evolutionary trends in bacteria isolated from moderate and severe diabetic foot infections in a Portuguese tertiary center

Diabetic Foot infections (DFI) are a major cause of hospitalization in patients with diabetes. The microbiological study of diabetic ulcers is essential to adequate antibiotic therapy and to minimize the selection of resistant microorganisms. The aim of this study was to characterize and to compare the evolution of isolated microorganisms between the biennium 2010–2011 and 2016–2017, in hospitalized patients with DFI. Retrospective evaluation of the clinical and analytical data of patients who were admitted due to DFI in 2010–2011 (group 2010/11) and 2016–2017 (group 2016/17). Only the first hospitalization for each patient was included. An adequate descriptive and comparative statistical analysis was performed. There were 274 admissions due to DFI, 151 in 2010/11 and 123 in 2016/17. There was an increase in admissions due to neuroischemic DFI (51.0% in 2010/11 to 61.8% in 2016/17, p = 0.048). Staphylococcus aureus (SA) was the most common isolate in 2010/11 (26.7%). In 2016/17 most cultures were mixed polymicrobial and isolation of Enterobacteriaceae and Pseudomonas aeruginosa increased from 2010/11 to 2016/17 (15.9% to 30.6%, p = 0.001, and 9.1% to 13.7%, p = 0.048, respectively). There was an increase in the prevalence of neuroischemic DFU. The Enterobacteriaceae family replaced SA as the most prevalent pathogen in DFI, with an increase in the isolation of gram-negative microorganisms and mixed polymicrobial cultures. Chronic neuroischemic infected ulcers usually present distinct bacterial isolates; knowledge about the most common agents is warranted in order to better select empiric antibiotic therapy. •In our study, we found an increase in the isolation of gram-negative microorganisms in diabetic foot infections (DFI).•The Enterobacteriaceae family replaced Staphylococcus aureus as the most prevalent pathogen in DFI.•The incidence of neuroischemic diabetic foot ulcers (DFU) increased compared to purely neuropathic infected ulcers.•Chronic neuroischemic DFI usually present with distinct bacterial isolates.