Diabetic Foot Infections糖尿病足感染

foot infections are the most common problems in persons with diabetes. these individuals are 使容易感染；使易接受(病)predisposed to foot infections because of a compromised vascular supply secondary to diabetes. local trauma外伤，损伤 and/or pressure (often in association with .感觉,知觉缺失lack of sensation because of neuropathy), in addition to microvascular disease, may result in various diabetic foot infections. for additional information, see medscape’s diabetic microvascular complications resource center.台州市中心医院中西医结合科张茂华

the spectrum of foot infections in diabetes ranges from simple superficial cellulitis 蜂窝织炎to chronic osteomyelitis骨髓炎. infections in patients with diabetes are difficult to treat because these patients have impaired microvascular circulation, which limits the access of phagocytic 吞噬细胞cells to the infected area and results in a poor concentration of antibiotics in the infected tissues. for this reason, cellulitis is the most easily treatable and 可逆的reversible form of foot infections in patients with diabetes. deep skin and soft tissue infections are also usually curable, but they can be life threatening and result in substantial 实在的long-term morbidity.

in terms of the infecting microorganisms and the likelihood of successful treatment with antimicrobial therapy, acute osteomyelitis in people with diabetes is essentially the same as in those without diabetes. chronic osteomyelitis in patients with diabetes mellitus is the most difficult infection to cure. adequate surgical debridement, in addition to antimicrobial therapy, is necessary to cure chronic osteomyelitis.

patients with diabetes also can have a combined infection involving bone and soft tissue called fetid foot. this extensive, chronic soft tissue and bone infection causes a foul exudate and usually requires extensive surgical debridement and/or amputation.

individuals with diabetes may also have peripheral vascular disease that involves the large vessels, in addition to microvascular and capillary disease that results in peripheral vascular disease with gangrene. dry gangrene is usually managed with expectant care, and gross infection is usually not present. wet gangrene usually has an infectious component and requires surgical debridement and/or antimicrobial therapy to control the infection.

except for chronic osteomyelitis, infections in patients with diabetes are caused by the same microorganisms that can infect the extremities of those without diabetes. gas gangrene is conspicuous because of its low incidence in patients with diabetes, but deep skin and soft tissue infections, which are due to gas-producing organisms, frequently occur in patients with diabetes. in general, people with diabetes have infections that are more severe and take longer to cure than equivalent infections in other people.

pathophysiology

diabetes mellitus is a disorder that primarily affects the microvascular circulation. in the extremities, microvascular disease due to "sugar-coated capillaries" limits the blood supply to the superficial and deep structures. pressure due to ill-fitting shoes or trauma further compromises the local blood supply at the microvascular level, predisposing the patient to infection. the infection may involve the skin, soft tissues, bone, or all of these tissues.

diabetes also accelerates macrovascular disease, which is evident clinically as accelerating atherosclerosis and/or peripheral vascular disease. most diabetic foot infections occur in the setting of good dorsalis pedis pulses; this finding indicates that the primary problem in diabetic foot infections is microvascular compromise. impaired microvascular circulation hinders white cell migration into the area of infection and limits the ability of antibiotics to reach the site of infection in an effective concentration. diabetic neuropathy may be encountered in conjunction with vasculopathy. this may allow for incidental trauma that goes unrecognized (eg, blistering, penetrating foreign body).

in chronic osteomyelitis, a sequestrum and involucrum form; these represent islands of infected bone. bone fragments that are isolated have no blood supply. administered antibiotics do not penetrate the devascularized infected bone fragments; they can enter the area of osteomyelitis only via the remaining blood supply. therefore, antibiotic therapy alone cannot cure patients with chronic osteomyelitis without surgical debridement to remove these isolated infected elements. surgical debridement is essential to remove the infected bony fragments that the antibiotics cannot reach so that affected areas can be treated with antimicrobial therapy.

frequency

international

diabetic foot infections range from cellulitis to chronic osteomyelitis, and, globally, they are the most common skeletal and soft tissue infections in patients with diabetes.

mortality/morbidity

mortality is not common, except in unusual circumstances. the mortality risk is highest in patients with chronic osteomyelitis and in those with acute necrotizing soft tissue infections.