Diabetic foot infections are responsible for more days in the hospital than any other aspect of diabetes. Of the 120,000 lower extremity amputations performed in America each year, about 83% are directly attributed to diabetes.  Often the podiatrist is the first physician to see and diagnose these foot infections.

Infections in a diabetic foot are challenging  because of immune compromise, decreased sensation to the feet, and poor circulation.  The usual source of infection is as a callus that becomes an open wound (ulcer) from excessive pressure to the area.  Once the ulcer is open, bacteria can enter and begin to invade the soft tissue and eventually the bone.  Ingrown toe nails are another common source of infection.

How is an infection diagnosed?  The diagnosis is made from clinical exam findings like redness, heat, swelling, pain, difficulty moving the foot, foul wound odor, or draining pus.  Pain is often absent in patients with diabetes.  If an infection is suspected a gram stain and culture of the wound can be used to identify the infecting organism.  Sometimes a blood culture is performed for more serious infections.

Interestingly, growth on a culture does not mean there is infection. For example, a culture of your mouth would grow lots of bacteria.  However, that does not mean your mouth is infected.

A thorough physical exam and history are essential for working up diabetic foot infection.  Is there an open wound, where is it, and what does it look like?  Is the wound full thickness or is there exposed bone?  Has the patient been compliant with staying off their foot or checking their blood sugar levels daily? Red streaking on the skin, fever, flue like symptoms, low blood pressure, confusion, and lymph node tenderness can indicate a severe infection.

Diagnostic testing is also helpful for working up a diabetic foot infection.  Blood sugar levels should be tested because elevated levels decrease healing potential. An elevated white count or sedimentation rate can be used to monitor inflammation. X-rays are useful to screen for bone infection, but may take 10-14 days to show changes.  Therefore, more alternative tests like bone scans and MRIs should also be considered. Sometimes circulation tests are also ordered (in some circles this has been nicknamed to toe-and-flow).

Mild infections are treated with antibiotics pills, wound care, offloading the foot (contact casting, crutches, walkers), and control of blood sugar levels.  Severe infections require intravenous antibiotics, hospitalization, incision and drainage, and even amputations (toe, foot, leg).  An amputation is a very disheartening experience for a patient, but is usually done to save their life or prevent further limb loss.

A team approach is important when treating diabetic foot infections. The team may include a podiatrist, infectious disease specialist, primary care provider, vascular surgeon, a teaching nurse, endocrinologist, orthopedic surgeon, pedorthist, and a physical therapist.

A recent study by Dr. Jeffrey Robbins describes five-year mortality rates after new-onset of diabetic foot sores between 43% and 55% and up to 74% for patients with lower-extremity amputation. These rates are higher than those for cancer of the prostate, breast, colon, and Hodgkin's disease.  Therefore, a diabetic foot sore with infection should be taken very seriously.

Prevention is preferable to amputation. Diabetic patients should be educated about daily foot inspections at home by their nurse and physician.  Diabetic patients should learn how to recognize signs of infection and take steps to prevent them.  Special shoes, inserts, braces, and surgery to correct deformity may all help prevent infection and amputation.