Management and outcomes of people presenting with new diabetes-related foot infections: a prospective observational study from Australia and New Zealand

Introduction: Infections precede nearly all hospitalizations and amputations related to diabetes-related foot disease. Focusing on antibiotic management, we aimed to report the outcomes of people presenting with a new diabetes-related foot infection (DFI). Research design and methods: In this prospective study conducted in Australian and New Zealand hospitals between 2018 and 2020, patients with diabetes, a foot ulcer and a newly diagnosed DFI were eligible for enrollment. DFI was categorized as mild or moderate/severe DFI, with the latter further categorized according to the presence of osteomyelitis. The primary outcome was healing of the index ulcer or amputation site at 6 months. Multivariable logistic regression analyses adjusted for potential confounders were undertaken to investigate the relationship between ulcer healing and infection severity, intravenous antibiotic duration and total antibiotic duration. Results: Of 234 included patients presenting to 20 centers (mean age 61 years, 77% male), 15% had mild DFI, 31% moderate or severe DFI without osteomyelitis, and 54% moderate or severe DFI with osteomyelitis. Methicillin-resistant Staphylococcus aureus was identified in 7% (16/214) and Pseudomonas aeruginosa in 3% (7/214). Median (IQR) days of total antibiotic management were 18 (10, 22) for mild DFI, 20 (11, 40) for moderate or severe DFI without osteomyelitis and 34 (15, 51) for moderate or severe DFI with osteomyelitis. Healing at 6 months was 73% (22/30) in those with mild DFI, 68% (42/62) in moderate or severe infections without osteomyelitis and 62% (69/111) in moderate or severe DFI with osteomyelitis. After adjusting for confounders, none of infection severity, intravenous antibiotic duration or total antibiotic duration were associated with ulcer healing. Conclusions: Healing at 6 months following DFI does not appear to be associated with infection severity or antibiotic management. To plan clinical trials of antibiotic therapy for DFI, further work is required to define target subgroups and meaningful trial endpoints.