Infection of the Foot

People with diabetes, especially those with very high blood glucose levels, have poorer defence against infection. Minor cuts and abrasions to the foot that we all get from time to time can turn into infection. So protect the feet with appropriate footwear. If there is a foot ulcer, the break in skin would also make infection much more likely to occur.
It is essential to distinguish between localized versus generalized foot infection because they require different intensity of treatment.

Localized foot infection is recognized by redness, heat and swelling confined to an area. Note the foot as a whole is not swollen. Oral antibiotics for a few days can usually eliminate the infection.



Localized foot infection associated with a neuropathic ulcer. Due to the neuropathy, the patient may not feel any pain or discomfort. Oral antibiotics are usually satisfactory but may need to be continued until the ulcer has healed.



Generalized foot infection. Note the whole foot is red and swollen. Oral antibiotics in higher dosage can be tried but if there is no rapid response (eg. within 24 hours), intravenous antibiotics and sometimes surgical intervention are urgently required because there is likely to be infected tissue deep inside the foot.



Foot infection complicated by osteomyelitis. In the presence of a foot ulcer there is a risk of the underlying bones being involved. X-ray may show bone destruction. Once there is osteomyelitis, a much higher dose of antibiotics and for a longer period (eg. several months) is often required to eradicate the infection. Quite often, intravenous antibiotic therapy is required. Sometimes the infected bones need to be surgically removed to help the foot heal.

Osteomyelitis in the early phase does not show up on X-ray but can be detected as a hot spot on a technetium bone scan, confirmed by a similar uptake in a white cell bone scan. MRI scan has emerged as the most sensitive and specific test for osteomyelitis and should be performed if the diagnosis is in doubt. If an ulcer is big (> 2cm) or so deep that bone can be probed at the bottom of the ulcer, one should suspect that osteomyelitis is present.




  Many patients are hesitant to take antibiotics and many doctors are hesitant to prescribe antibiotics. However, when infection is present in the foot of a person with diabetes, antibiotic treatment is required. Many feet are lost unnecessarily due to failure to treat the infection.