NCBI Bookshelf. A service of the National Library of Medicine, National Institutes of Health.

Holzheimer RG, Mannick JA, editors. Surgical Treatment: Evidence-Based and Problem-Oriented. Munich: Zuckschwerdt; 2001.

Cover of Surgical Treatment

Surgical Treatment: Evidence-Based and Problem-Oriented.

Show details

Diabetic foot infections

, M.D. and , M.D.

Author Information

People with diabetes mellitus comprise only 3% of the U.S. population, however they account for more than half of all non-traumatic lower extremity amputations and have only a 40% 5-year survival after amputation. Diabetic foot ulcers cause 20% of all diabetic hospital admissions, carry a 15- to 30-fold increased risk of lower extremity amputation, cost more than $4500 to treat per episode, and proceed 85% of all lower extremity amputations in people with diabetes. Clearly, diabetic foot problems result in high individual costs and a large national economic burden, yet there is a paucity of level I (grade A) medical literature focusing on this problem.

Definition, pathogenesis, and epidemiology

Diabetic foot infections range from local fungal infections of the nails to necrotizing limb- or life-threatening infections.

The term diabetic foot infection comprises many different entities that span a continuum of infectious processes. Poor nail hygiene and fungal nail infections frequently serve as portals of entry for bacterial infection, however diabetics are no more prone to fungal nail infections than non-diabetics (grade C). Cellulitis and minor web-space infections may progress more rapidly in diabetics due to the combination of immune dysfunction and delayed detection secondary to diabetic neuropathy and retinopathy. Clinical signs of infection (elevated WBC and ESR, fever, etc.) may not manifest until the infection is advanced (grade C). The typical bacterial pathogens encountered vary with the Wagner grade (table I) and severity of infection. Early infections are generally monomicrobial, whereas advanced infections tend to be polymicrobial (grade C).

Table I. Wagner classification and associated pathogens.

Table I

Wagner classification and associated pathogens.

The infected neuropathic ulcer is one of the most common presentations of diabetic foot infection.

Autonomic neuropathy leads to arteriovenous shunting and anhidrosis resulting in decreased capillary-bed perfusion, dry and thickened skin, which is prone to cracking thereby permitting bacteria to breach the skin's protective barrier. Motor neuropathy results in claw-toe deformity, intrinsic muscle wasting and distortion of the foot's normal weight-bearing surface, predisposing the foot to focal pressure necrosis and ulceration. Sensory neuropathy and impaired proprioception decrease the foot's ability to adapt to repetitive local stresses and resultant ulcers tend to progress unnoticed in the insensate foot. Neuropathy sets the stage for ulcer recurrences, treatment failures and the Charcot foot, which is irreversible. Neuropathic ulcers typically develop at areas of increased plantar pressure, most frequently under the first, second and fifth metatarsal heads (grade C). These ulcers are colonized with bacteria that may invade into deeper structures, including bone, ultimately leading to gangrene and all-too-frequently amputation. Fortunately, yearly screening with the 5.07 Semmes-Weinstein monofilament facilitates the rapid identification of diabetic neuropathy and allows preventative measures to be intensified before ulcers develop (grade C).

The Wagner classification grades diabetic foot ulcers based on depth of tissue penetration and necrosis. Low grades are generally infected with gram-positive organisms and higher grades with polymicrobial flora.

Table I defines each Wagner grade and the pathogens likely to be encountered for each grade.

Diabetics are faced with a 15% to 20% lifetime incidence of developing a foot ulcer, which is the leading cause of hospital admission in diabetic patients, and often signifies the start of a downward spiral that may lead to amputation. One prospective study found a 70% 5-year recurrence rate among diabetics who primarily healed a foot ulcer (grade C). Hospitalized diabetics are 2.8 times more likely to die in the hospital and their length-of-stay is twice that of non-diabetic patients. Mortality data for each Wagner grade are not available, however lower extremity amputation carries a 5-year survival of only 40%.


Osteomyelitis frequently accompanies neuropathic ulcers and presents a difficult diagnostic challenge.

Bone detected bluntly by probing a diabetic pedal ulcer may help make the diagnosis of osteomyelitis. “Probing to bone” was 66% sensitive and 85% specific for osteomyelitis in one prospective study (grade B). Plain radiographs are of limited value in diagnosing acute osteomyelitis, since radiographic changes usually lag behind the clinical infection. Although plain radiographs are not sensitive for osteomyelitis, bony destruction on plain films is diagnostic for osteomyelitis. Technetium bone scans are very sensitive for osteomyelitis but their lack of specificity limits their clinical usefulness. Similarly, leukocyte scans are sensitive, but lack specificity since they cannot distinguish overlying cellulitis from deeper bone infections. The combination of technetium bone scanning followed by leukocyte-scintigraphy was 92.9% accurate in diagnosing osteomyelitis in one prospective study (grade C). Gallium scanning was ineffectual in diagnosing pedal osteomyelitis (grade C). Recently, magnetic resonance imaging has been advanced as a sensitive test for osteomyelitis though it is hindered by the fact that it is unable to differentiate acute osteoarthopathy from osteomyelitis. A recent cost-analysis of diabetic foot infection treatments concluded that noninvasive testing for osteomyelitis adds significant expense to treatment costs while having little impact on outcomes (grade C).

Antibiotic therapy

Of the three widely accepted methods of obtaining microbiologic culture specimens, none stands out superior to the others and the preferred method remains a controversial issue. Swabbing the surface of an infected ulcer with a cotton-applicator will recover mostly colonizing bacteria and rarely yields anaerobic bacteria if they are present. Culture specificity is increased if swabbing is proceeded by deep curettage to reveal a clean ulcer base, although this technique is also suboptimal for anaerobic isolation. Needle aspiration of deep tissues approached though adjacent, prepped skin is more likely to recover anaerobes, however needle aspiration is a blind technique which may miss the infectious focus altogether. Even under the best of circumstances, anaerobes are recovered only 74% to 95% of the time (grade C).

Antibiotics are one of the mainstays of treating diabetic foot infections, however to date surprisingly few randomized controlled studies have been published regarding their use in diabetic foot infections.

The polymicrobial nature of diabetic foot infections has been documented in the past, however an increasing body of literature supports the concept that not all bacterial isolates need to be eradicated for clinical improvement (grade C). In fact, some investigators have noted that a good clinical response occurs in some patients infected with one or more organisms resistant to the antibiotics that they were receiving (grade C). Following sharp debridement and culturing, antibiotic therapy should be initiated after considering factors influencing the microbial population such as recent antibiotic use, institutionalization, Wagner grade and vascular status. Early infections are frequently managed on an outpatient basis but clinical judgment should be exercised in assessing which infection warrants hospitalization and parenteral antibiotics. Soft tissue infections usually require 2–3 weeks of antibiotic therapy, while osteomyelitis often needs months of therapy and frequent debridements. Parenteral antibiotics are usually indicated at the start of therapy since gastroparesis and acute illness may adversely effect the absorption of oral agents. Table II reviews potential antibiotic regimens that have been described in the literature (grade A and C).

Table II. Literature derived antimicrobial regimens.

Table II

Literature derived antimicrobial regimens.

Non-surgical treatments

Since a non-healing ulcer precedes 85% of lower extremity amputations in diabetics, it is obvious that preventing and healing these ulcers is desirable. Multiple studies have documented the link between diabetic neuropathy and foot ulcers (grade B and C) as well as the benefit of total-contact casting in healing neuropathic ulcers (grade C). Total-contact casts are thinly padded, molded plaster casts applied to the lower extremity of diabetics with non-infected neuropathic ulcers that unload pressure off the ulcer and promote healing while maintaining ambulation. Therapeutic foot ware, rocker-bottom shoes, the Carville splint, and Scotch™ cast appliances have all been described as adjuncts in healing ulcers and preventing amputations (grade A and C). Recently, interest has focused on growth factors as a means of promoting ulcer healing. Human recombinant platelet-derived-growth-factor (Becaplermin) has become commercially available and has been shown to increase the incidence of ulcer healing in chronic non-healing ulcers when compared to placebo (grade A and B). Conversely, fibroblast-growth-factor has been shown to be no more effective than placebo in fostering ulcer healing (grade B). A prospective placebo controlled study of granulocyte colony-stimulating-factor has found that it promotes earlier resolution of cellulitis, shorter hospital lengths-of-stay and decreased parenteral antibiotic usage in patients admitted with acute diabetic foot infections (grade A). Unfortunately, once healed, neuropathic ulcer recurrence rates may be as high as 70% over the next 5-years. Hyperbaric oxygen therapy has been shown to reduce the major amputation rate in a small study of patients with severe diabetic foot infections, especially in those with evidence of ischemic vascular disease (grade C). Other anecdotal modalities have been advanced as potential treatments of diabetic foot infection but their lack of supporting literature limits their use.

Surgical treatment

The removal of devitalized tissue to control infection and creation of an environment favorable for healing, while maximizing the structural and physical integrity of the foot, is the central goal of surgical intervention in treating diabetic foot infections.

Surgical procedures span a range from simple outpatient debridements to guillotine amputations in diabetics with life-threatening infections.

Abscesses of the foot or toes are best approached through lateral incisions that avoid weight-bearing surfaces. Diamond shaped incisions in the plantar or dorsal surfaces are used to drain the web space. Sadly, infections arising in this area frequently extended into the central compartment of the foot and mandate more extensive debridement. Neuropathic ulcers and their associated calluses should be sharply debrided to facilitate healing, since debridement alone has been shown to positively affect healing (grade C). Osteomyelitis frequently results from direct extension to bone from a neuropathic ulcer and is more effectively treated by surgical resection than antibiotics alone (grade C). The surgical treatment of neuropathic ulcers has been shown to reduce healing time and decrease infectious complications when compared to non-operative management (grade A and C). Elective foot surgery in diabetics carries only a modest increased risk of infection (grade C) and may prevent the development of more serious infectious sequelae such as amputations. Amputations for diabetic foot infections should not follow the classic textbook descriptions, rather they should be limited to removing all necrotic, devitalized tissue and bone while sparing as much skin and tissue as possible. Arterial reconstructive surgery is an important adjunct to therapy and may be required to heal an amputation or non-healing ulcer, in patients with documented vascular disease. Arterial bypass surgery to the pedal vessels has reduced the incidence of lower extremity amputations for diabetic foot infections (grade C), nonetheless the percentage of amputees who are diabetic remains disproportionately high. Attempts to reduce the incidence of lower extremity amputations has shown that multi-disciplinary team management, with emphasis on preventative measures, is one of the more effective means of accomplishing this goal (grade C).


Despite the magnitude of the problem presented by diabetic foot ulcers and infections, too few randomized controlled studies have been performed. While reducing the incidence of lower extremity amputations and limiting diabetic foot problems is a widely embraced goal, the optimal strategy to realize this remains in doubt.

Careful monitoring, preventative measures, altering the weight-bearing surface of the foot, liberal debridements to control local infections, antibiotics and creation of an environment conducive to healing will remain the foundation of good foot care in diabetic patients.


Apelqvist J, Larsson J, Agardh C D. Long-term Prognosis for Diabetic Patients with Foot Ulcers. J Intern Med. (1993);233:485–491. [PubMed: 8501419]
Bridges R M, Deitch E A. Diabetic Foot Infections: Pathophysiology and Treatment. Surg Clin North Am. (1994);74:537–555. [PubMed: 8197529]
Caputo G M, Cavanagh P R, Ulbrecht J S, Gibbons G W, Karchmer A W. Assessment and management of foot disease in patients with diabetes. NEJM. (1994);331:854–860. [PubMed: 7848417]
Eckman M H, Greenfield S, Mackey W C, Wong J B, Kaplan S, Sullivan L, Dukes K, Pauker S G. Foot infections in diabetic patients: decision and cost-effectiveness analyses. JAMA. (1995);273:712–720. [PubMed: 7853629]
Faglia E. et al. Adjunctive systemic hyperbaric oxygen therapy in treatment of severe prevalently ischemic diabetic foot ulcers. Diabetes Care. (1996);19:1338–1343. [PubMed: 8941460]
Gerding D N. Foot infections in diabetic patients: the role of anaerobes. Clin Inf Dis. (1995);20 (suppl 2):S283–288. [PubMed: 7548576]
Gough A. et al. Randomised placebo-controlled trial of granulocyte-colony stimulating factor in diabetic foot infection. Lancet. (1997);350:855–859. [PubMed: 9310604]
Grayson M L. et al. Probing to bone in infected pedal ulcers. JAMA. (1995);273:721–723. [PubMed: 7853630]
Johnson J E. et al. Prospective study of bone, indium-111-labeled white blood cell, and gallium-67 scanning for the evaluation of osteomyelitis in the diabetic foot. Foot Ankle Int. (1996);17:10–15. [PubMed: 8821280]
Mayfield J A. et al. Preventative foot care in people with diabetes. Diabetes Care. (1998);21:2161–2177. [PubMed: 9839111]
Piaggesi A. et al. Conservative surgical approach versus non-surgical management for diabetic neuropathic foot ulcers: a randomized trial. Diabetic Med. (1998);15:412–417. [PubMed: 9609364]
West N J. Systemic antimicrobial treatment of foot infections in diabetic patients. Amer J Health-Sys Pharm. (1995);52:1199–1207. [PubMed: 7656109]
Wieman T J, Smiell J M, Su Y. Efficacy and safety of a topical gel formulation of recombinant human platelet-derived growth factor-bb (becaplermin) in patients with chronic neuropathic diabetic ulcers. Diabetes Care. (1998);21:822–827. [PubMed: 9589248]
Copyright © 2001, W. Zuckschwerdt Verlag GmbH.
Bookshelf ID: NBK6985


  • PubReader
  • Print View
  • Cite this Page

Related information

Recent Activity

Your browsing activity is empty.

Activity recording is turned off.

Turn recording back on

See more...