Impact of the bacteriology of diabetic foot ulcers in limb loss.

Infections in feet of patients with diabetes mellitus is common, complex and costly. The aim of this study to investigate the isolated microorganisms in infected diabetic foot ulcers, and the impact of these infectious agents in limb loss in a tertiary medical center in Mexico City. We conducted a retrospective review in diabetic patients with infected foot ulcers from 1997 to 2014. Diabetic foot was defined according to the World Health Organization (WHO), the bacteriology of wound cultures and the impact of microorganisms in limb loss (major amputation) was studied. Patient's demographics, comorbidities, wound characteristics, and other factors associated in clinical outcomes were determined. A total of 165 subjects with soft tissue infections and/or osteomyelitis and positive cultures were included. One hundred and five (64%) were male, with a mean age of 60 year old +/- 15. One hundred fifty-nine (96%) had Type 2 diabetes mellitus, 68 (41%) history of peripheral arterial disease (PAD) and 97 (59%) patients had osteomyelitis. In 89 patients (54%), cultures were polymicrobial and one single organism was isolated in 76 cultures (46%). During the follow up, 96 (58%) patients preserved their limbs and 69 (42%) required major amputation (above or below knee). Sixty percent of patients that suffered from limb loss had polymicrobial culture (p = 0.13). Growth of Escherichia coli and Enterococcus faecium (p = 0.03) and E. coli and Morganella morgagnii (p = 0.03) was associated to limb loss. Among monomicrobial cultures, infections associated with Proteous mirabilis had higher rate of progression to limb loss (p = 0.03). PAD was associated to limb loss (p = 0.001). Management of diabetic foot requires a multimodality approach. In this study, in patients that received appropriate antibiotic therapy and optimal surgical management, we observed that history of PAD, polymicrobial and isolated P. mirabilis infections were variables associated with higher rate of limb loss.