A 71-year-old female patient with type 2 diabetes was admitted to the hospital
because of a severe infection of her right foot. She had a history of type 2 diabetes diagnosed at the age of 51 years, diabetic nephropathy, background diabetic retinopathy— treated with laser — hypertension and ischemic heart disease. She also had a history of stroke at the age of 69 years. A heel ulcer caused after the rupture of a
blister under her right heel, which developed after walking in tight new shoes, had persisted for about 1 year. The ulcer progressively became deeper and larger. The patient reported two septic episodes with infection at the same site, for which she was hospitalized for prolonged periods.
On examination, her body temperature was 39.2 °C, blood pressure 90/50 mmHg, heart rate 120 beats/min and weak, and she was anuric. Her right foot and the tibia were warm, red and swollen. A large, foul-smelling, neuro-ischemic ulcer with gross purulent discharge was seen on the posterior surface of her right heel (Figure 8.38). The calcaneus was exposed.
A plain radiograph showed a large skin defect on the posterioplantar aspect of her heel and bone resorption of the posterior calcaneus (Figure 8.39). Extensive calcinosis of the posterior tibial artery and medial plantar branch artery was also noted. After surgical debridement, bone and deep tissue cultures were obtained. Immediate support with i.v. fluids and antibiotic administration was commenced (ciprofloxacin 400 mg x 3 and clindamycin 600 mg x 3) and her situation improved within 12 h.
Tissue cultures revealed Enterococcus spp., Acinetobacter baumannii, and Proteus mirabilis. Based on an antibio-gram, treatment was changed to ampicil-lin-sulbactam and continued for 2 weeks. Disarticulation through the ankle joint (Syme ankle disarticulation) was not feasible; a healthy heel flap and the heel pad is a prerequisite for this procedure so that the end of the stump is capable of bearing the patient's weight. Two weeks after her admission the patient sustained a below-knee amputation.
Empirical treatment with antibiotics in severe foot infections should always include agents against staphylococci, enterobacte-riaceae and anaerobes. In this case, two agents with good bone bioavailability were used since osteomyelitis was present. Therapeutic options in patients with severe foot infections include:
• Fluoroquinolone plus metronidazole or clindamycin. This combination is effective against Staphylococcus aureus (only methicillin-susceptible strains), entero-bacteriaceae, and anaerobes.
• ¡3-lactam and ¡3-lactamase inhibitor combinations (ticarcilline-clavulanic acid, piperacillin - tazobactam). Ampicillin -sulbactam is particularly active against Enterococcus spp. For patients who have received extensive antibiotic therapy, ticarcilline-clavulanic acid or piperacillin-tazobactam may be preferred because of their increased activity against nosocomial gram-negative bacilli. Such regimens are also effective against
Staphylococcus aureus (only methicillin sodium-susceptible strains), Streptococcus spp. and most anaerobes.
• In patients who have severe penicillin allergy, combination therapy with aztre-onam and clindamycin, or a fluoroquinolone and clindamycin is effective.
• Imipenem-cilastin or meropenem as monotherapy.
Doctors should always consider that:
• Modification of the treatment may be necessary according to the results of cultures.
• Vancomycin or teicoplanin are indicated in cases of infection with methicillin-resistant staphylococcal strains.
• Third generation cephalosporins should be used only in combination with other agents, as they have moderate anti-staphylococcal activity and lack significant activity against anaerobes.
• Aminoglycosides are nephrotoxic and they are inactivated in the acidic environment of the soft tissue infection and have poor penetration into bone.
Keywords: Osteomyelitis; heel ulceration; calcaneus; severe foot infection treatment; below-knee amputation
Atlas of the Diabetic Foot. N. Katsilambros, E. Dounis, P. Tsapogas and N. Tentolouris Copyright © 2003 John Wiley & Sons, Ltd.
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