Foot infections are a common, complex, and serious problem in diabetic patients. Infections usually begin in foot ulcers, which are associated with neuropathy, vasculopathy, and various metabolic disturbances. These infections are potentially limb and sometimes life threatening. Etiologic agents are usually aerobic gram-positive cocci, but chronic or serious infections often contain gram-negative rods and anaerobes. Chronic infections can lead to contiguous bone infection. Diagnosing osteomyelitis may require imaging studies (especially magnetic resonance imaging) and occasionally bone biopsy. In addition to proper cleansing, debridement, and local wound care, diabetic foot infections require carefully selected antibiotic therapy. Serious infections necessitate hospitalization for initial parenteral broad-spectrum antibiotic therapy, but appropriately selected patients with mild infections can be treated as outpatients with oral (or even topical) agents. Initial antibiotic selection is usually empiric; modifications may be needed based on the results of properly obtained cultures and the clinical response. Therapy should be active against staphylococci and streptococci, with broader-spectrum agents indicated if polymicrobial infection is likely. Levels of most antibiotics, except fluoroquinolones, are often subtherapeutic in infected foot tissues. The duration of therapy ranges from a week (for mild soft tissue infections) to over 6 weeks (for osteomyelitis). No single antibiotic agent or combination has proven to be optimal. With appropriate local, surgical, and antimicrobial therapy, most diabetic foot infections can now be successfully treated.
