Lessons from a case of gas gangrene.
A 55-year-old man with type 2 diabetes mellitus was seen in the emergency department on a Friday evening because he was systemically unwell and noted problems with his right foot. He was afebrile but hypotensive and tachycardic. His right foot was not painful but it was swollen, warm and erythematous with deep ulcers under the great toe and first metatarsal head and subcutaneous crepitus up to the tarsus. Pedal pulses could not be palpated on the right foot because of edema, but were normal on the left. He had leukocytosis, azotemia and hyperglycemia. Plain x-rays of the foot (Figure 1) confirmed the presence of subcutaneous gas, but revealed no evidence of osteomyelitis. A CT-scan (Figure 2) also showed intramedullary clusters of gas within the first metatarsal bone and between the tarsal bones.
Intravenous therapy with broad-spectrum antibiotics (clindamycin and ciprofloxacin) and fluids was started and the patient was hospitalized on the general surgery service. He was urgently taken to the operating theatre for an exploration of the plantar ulcer through a large incision, and tissue biopsies were taken for microbiological analysis. Pus was evacuated from the flexor tendon sheets, the wound was thoroughly irrigated with iodine solution and a drain was inserted (Figure 3, a).
On Monday (2 days after surgery) a team of diabetic foot specialists saw the patient. Although he had improved there was persistent subcutaneous gas. He was immediately taken to surgery where all infected soft tissue was resected, the hallux and first metatarsal were amputated and he had an exploration and debridement up to the tarsus. The navicular and cuneiform bones remained exposed through the wound (see Figure 3 b, with inlay that shows the initial incision).
Over the next few days local and systemic signs of infection subsided. Cultures of the wound tissue grew six bacterial organisms, including aerobes (Staphylococcus aureus, Enterococcus faecalis, Morganella morganii, Klebsiella oxytoca, Corynebacterium amycolatum) and anaerobes (gram-positives and Porphyromonas, but no Clostridium species). Because the blood cultures grew only S. aureus and E. faecalis, the antibiotic regimen was narrowed to just amoxicillin/clavulanic acid. Negative pressure wound therapy with intermittent iodine solution instillation was applied to the wound. A wound specimen obtained 3 days after surgery grew E. faecalis, K. oxytoca and M. morganii (resistant to amoxicillin/clavulanate). A vascular examination was interpreted as showing no evidence of peripheral arterial disease (ABI >1 and normal pedal Doppler signals).
The wound bed improved with proliferation of granulation tissue (Figure 3, c-e; day 2, 14, 22 post debridement) but the exposed bones required coverage with a free muscle flap, which required intra-arterial angiography to assess the donor tibial posterior artery. Surprisingly, this revealed a short in-stent occlusion of the superficial femoral artery, but with good collateral flow and infrageniculate arteries. Vascular surgeons thus performed a superficial femoral endovascular recanalization (Figure 4). The plastic surgeons then performed a musculocutaneous latissimus dorsi flap (Figure 3, e), anastomosing its pedicle to the posterior tibial artery (Figure 3, f), with concurrent split thickness skin grafting. The patient’s wounds improved (Figure 3, g) and he was discharged after 44 days of hospitalization. At outpatient follow-up two months later the wound was healing with a good functional result (Figure 3, h).
Although limb salvage was ultimately accomplished in this patient, in retrospect several management decisions were suboptimal. Examining what we did right and wrong afforded us an opportunity to learn valuable lessons in dealing with a difficult clinical problem. We should have started with broader spectrum antibiotic therapy and more aggressive initial surgery in this severe infection. More effort should have been made earlier to evaluate the vascular status. We learned that better access to multidisciplinary input must be available over the weekend (and at other minimally staffed times). Ultimately, good specimens for culture allowed for optimized antibiotic therapy and multidisciplinary surgical and medical care provided a good outcome.
Dimitri Aerden, MD
Diabetic Foot Clinic, Universitair Ziekenhuis, Brussels, Belgium
Benjamin A. Lipsky, MD
University of Washington, Seattle, USA; University of Oxford, Oxford UK; University of Geneva, Geneva, Switzerland