2 Case Report
A 75-year-old man was admitted to the emergency department with a 2-day history of constant leg pain and difficulty walking. The patient had a past medical history of acute myocardial infarction and cerebral infarction, and he was receiving treatment for hypertension, diabetes, chronic kidney disease and alcoholic liver cirrhosis (Child-Pugh C).
On emergency admission, the patient appeared unwell and was in pain, with clear consciousness. His temperature was 36.0°C, blood pressure 82/66 mmHg, pulse 103 beats/min and respiratory rate of 30 breaths/min. His oxygen saturation was 100% (on 10 L/min oxygen), and he showed signs of acute respiratory distress.
Physical examination revealed purpura, snowball crepitation and cutaneous sensory deficit on the left lower left leg. No injuries were evident on the skin surface (Fig 1 ). The patient was unable to flex or extend his left knee and ankle because of pain; however, the dorsalis pedis pulses were intact. Enhanced computed tomography scans showed inflammation of fat tissue and air inside the extensor digitorum longus muscle, the fibularis brevis and the fibularis longus. The Laboratory Risk Indicator for Necrotising Fasciitis (LRINEC) score was 10, based on these values: C-reactive protein 531 mg/L, white blood cells 5.0 × 103 cells/mm3, haemoglobin 10.5 g/dL, sodium 126 mmol/L, creatinine 7.09 mg/dL and glucose 37 mg/dL. These findings suggested that this case had a very high possibility of necrotising fasciitis. Given the clinic, biologic and radiologic factors of this case, a diagnosis of NSTI was made.
After the diagnosis was made—2 h after the patient was presented to the emergency department—surgical fasciotomy was performed (Fig. 2 ) to determine the extent of the infection, to assess the need for debridement or amputation and to obtain specimens for Gram staining and culture. First, a 30-cm incision over the most indurated and erythematous area of the left lateral aspect of the calf. On incision, a large amount of fluid and purulence with a foul odour was released. However, macroscopic examination showed no necrosis for the fascia and the muscle tissue of the extensor hallucis longus muscle and extensor digitorum longus muscle. The incision wound was irrigated with large volumes of normal saline but the leg was not amputated.
Tracheal intubation for airway maintenance and mechanical ventilation were performed. The patient was administered meropenem (1 g every 12 h), vancomycin hydrochloride (1 g every 24 h) and clindamycin (600 mg every 8 h). Continuous renal replacement therapy was initiated for metabolic acidosis. His blood pressure was unable to be maintained without administration of a vasopressor agent, so noradrenalin 0.5 μg/kg/min and vasopressin 2 units/h were initiated.
Subsequently, 8 h after presentation, blood cultures revealed the presence of a gram-negative bacillus, and polymyxin B immobilised fibre column direct hemoperfusion was performed. In addition, thrombomodulin and antithrombin III were administered for disseminated intravascular coagulation based on these values: platelets 5.7 × 1010/L, d-dimer 4.2 µg/mL and prothrombin ratio 76%.
On evaluation 18 h after presentation, the purpura of his skin was spreading rapidly. Continuously increasing concentrations were noted for lactic acid (maximum 17 mmol/L), blood creatine kinase (maximum 5657 U/L) and potassium (maximum 7.7 mEq/L). Based on the assumption that his infection was now uncontrollable, the decision was made to amputate the leg. However, 24 h after presentation, before amputation could begin, the patient died.
The following day, the only pathogen detected in culture samples from the blood, fascia and fluid obtained from the wound was E. coli . Histologic examination showed degenerated fascia and fatty tissue with a bacterial colony present. The susceptibility of the E. colistrain to antibiotics was pansensitive. Based on all of these findings, necrotising fasciitis caused by E. coli was diagnosed. Further culture sample analysis revealed that the E. coli strains belonged to sequence type (ST) 127 in multi-locus sequence typing (MLST) and phylogenetic group B2 with various virulence genes, as shown inTable 1 .