A MAJOR PROBLEM: Two-thirds of all amputations involve infection. Infection is favored by dysfunction of the antibacterial defense systems due to high blood glucose and vascular disorders.
Diagnosis: General signs of infection are usually not found. A careful exploration is required to rule out or confirm osteitis in order to guide surgery and plan the antibiotic regimen. A history of chronic and/or recurrent ulceration or direct signs at inspection may be suggestive of osteitis. Radiographic signs are late and nonspecific. Scintigraphy scans are difficult to interpret. Magnetic resonance imaging can be quite helpful in difficult cases.
Bacteriological proof: Staphylococcus aureus and to a lesser extent streptococci account for almost all of the superficial infections in the diabetic foot. In case of deep ulceration, it is important to obtain deep specimens at surgical cleansing as more superficial samples are easily contaminated. Nevertheless, if Staphylococcus aureus is isolated from pus coming from a deep zone fistulizing to the skin, it is likely the causal agent since 80% of all bone infections involve S. aureus. Other germs besides staphylococci and streptococci include enterobacteria (40%), enterococci (26%) and pseudomonas (7%). Several germs are involved in about 70% of cases with a probable synergetic effect between the different bacterial colonies within the infected tissues.