Principles and practice of antibiotic therapy of diabetic foot infections.

Foot infections are a common and serious problem in diabetic patients. They usually occur as a consequence of a skin ulceration, which initially is colonized with normal flora, and later infected with pathogens. Infection is defined clinically by evidence of inflammation, and appropriate cultures can determine the microbial etiology. Aerobic gram-positive cocci are the most important pathogens; in chronic, complex or previously treated wounds, gram-negative bacilli and anaerobes may join in a polymicrobial infection. In all diabetic foot infections a primary consideration is whether or not surgical intervention is required, e.g. for undrained pus, wound debridement or revascularization. Antibiotic regimens are usually selected empirically initially, then modified if needed based on results of culture and sensitivity tests and the patient's clinical response. Initial therapy, especially in serious infections, may need to be broad-spectrum, but definitive therapy can often be more targeted. Severe infections usually require intravenous therapy initially, but milder cases can be treated with oral agents. Treatment duration ranges from 1-2 weeks (for mild soft tissue infection) to more than 6 weeks (for osteomyelitis). The choice of a specific agent should be based on the usual microbiology of these infections, data from published clinical trials, the severity of the patient's infection, and the culture results. Extension of infection into underlying bone can be difficult to diagnose and may require imaging tests, e.g. magnetic resonance scans. Cure of osteomyelitis usually requires resection of infected bone, but can be accomplished with prolonged antibiotic therapy. Various non-antimicrobial adjunct therapies may sometimes be helpful. Published in 2000 by John Wiley & Sons, Ltd.