INTRODUCTION

A diabetic foot infection is defined as any inframalleolar infection in a person with diabetes mellitus, and most arise from diabetic foot ulcers. Diabetic foot ulcers are portals of entry for infection in hosts with impaired immunity as well as physiologic limitations to wound healing. Therefore, all diabetic foot ulcers should be treated as chronic wounds that will not heal on their own – intervention is mandatory. Moreover, it is critical that infected diabetic foot ulcers be recognized and treated promptly because they represent the biggest risk factor for nontraumatic amputations in the diabetic population.

EPIDEMIOLOGY

Diabetic foot infections account for the largest number of diabetes–related hospital bed days. In the United States alone, about 82,000 limb amputations are performed annually in those with diabetes, and an amputation in a diabetic patient is associated with a 5-year mortality rate between 39% and 68%.

CLINICAL FEATURES

Purulent secretions, necrotic tissue, and signs of inflammation including pain, redness, warmth, tenderness and induration indicate infection of a diabetic foot ulcer (Figure 27.1, Table 27.1). All patients seen in the acute care setting with diabetic foot ulcers should undergo a basic peripheral vascular exam including palpation of the peripheral pulses and measurement of the ankle brachial index in each leg. An ankle brachial index is calculated by dividing the blood pressure in the calf of the affected foot by the blood pressure in the upper extremity.