When the skin of the foot is broken, the patient is at great risk of infection as there is a clear portal of entry for invading bacteria. At every patient visit, the foot should be examined for local signs of infection, cellulitis or osteomyelitis. If these are found, antibiotic therapy is indicated However, in the presence of neuropathy and ischemia, the inflammatory response is impaired. Furthermore, there may be a failure of vasodilation due to an impaired axon reflex (56). Also, the patient lacks protective pain sensation, which would otherwise automatically force him to rest.
Topical anti-microbials may be used (57). Iodine is effective against a wide spectrum of organisms. At high concentrations it can be toxic to human cells, but bacteria are more sensitive to these effects than human cells such as the fibreblast. Povidone-iodine is effective in anti-bacterial prophylaxis in burn patients. Cadexomer-iodine consists of microspheres, formed from a three dimension lattice of cross linked starch chains and has been used with success in diabetic foot ulcers. Silver compounds are also widely used in anti-bacterial prophylaxis (58). Mupirocin is active against gram positive bacteria, including methicillin resistant staphylococcus aureus (MRSA).
It is important to maintain close surveillance of the ulcer to detect signs of infection that would be an indication for antibiotic therapy. A controlled trial was conducted in patients with neuropathic ulcers who were randomized to oral amoxicillin plus clavulinic acid or matched placebo. At 20 days follow-up, there was no significant difference in outcome (59). In a small RCT, antibiotic therapy of uninfected ulcers reduced the incidence of clinical infection and hospital admission and amputation and increased the prospects of healing (64). In this study, 32 patients with new foot ulcers were treated with oral antibiotics and 32 patients without antibiotics. In the group with no antibiotics, 15 patients developed clinical infection compared with none in the antibiotic group (P < 0.001). Seven patients in the nonantibiotic group needed hospital admission and three patients came to amputation (one major and 2 minor). Seventeen patients healed in the nonantibiotic group compared with 27 in the antibiotic group (p < 0.02). When the 15 patients who developed clinical infection were compared to 17 patients who did not, there were significantly more ischemic patients in the infected group. Furthermore, out of the 15 patients who became clinically infected, eleven had positive ulcer swabs at the start of the study compared with only one patient out of 17 in the noninfected group (p < 0.01). From this study, it was concluded that diabetic patients with dean ulcers associated with peripheral vascular disease and positive ulcer swabs should be considered for early antibiotic treatment.
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