A 32 year old male who was a known IVDU, presented with a 12 hour history of increasing swelling in his left leg. He had a purulent discharge from a chronic sinus in his left groin.
On examination, he had warm erythematous sinuses in both groins. The left sinus was discharging foul smelling pus. He had a tachycardia 120 bpm and pyrexia 38.2 degrees C, blood pressure (BP) 136/86. He was alert and orientated to time, place and person. Blood tests revealed a white cell count (WCC) of 15.9 x 109/l, a C-Reactive Protein (CRP) of 21 mg/dl and blood cultures were taken. He was treated with broad spectrum antibiotics Vancomycin, Clindamycin, Ciprofloxacin, Gentamicin and Metronidazole in line with the latest advice from microbiology because of a recent outbreak of anthrax in the local IVDU population. Within 24 hours of collection, all 6 blood culture bottles grew gram positive organisms suggestive of Bacillus anthracis and he was referred for consideration of surgery. The cultured Bacillus anthracis organism was susceptible to all the above antibiotics. Clinically there was no abscess to drain so he had a computed tomography (CT) scan of his abdomen, pelvis and thighs performed. This showed loculated fluid and inflammatory change anterior to the left psoas muscle extending down to the iliacus [Figure 1]. In the pelvis, the left pectineus and adductor magnus were oedematous possibly reflecting muscle necrosis [Figure 2].
Given that he was clinically well his conservative management and monitoring continued. Over the next five days there were signs of improvement with a reduction in the inflammatory markers and no evidence of organ dysfunction. In consultation with colleagues in microbiology, infectious diseases and public health a further CT scan was performed to ensure that there was no collection to drain as the limited local experience suggested that drainage and debridement of collections and necrotic tissues resulted in optimal management. This scan showed that the retroperitoneal and thigh changes had improved slightly. Within a further 24 hours he had developed an area of cellulitis over the left thigh and lower abdomen and a Magnetic Resonance Imaging (MRI) was carried out. This showed diffuse oedematous change in the muscles and subcutaneous fat of the left leg from the level of the inguinal region to below the knee. After contrast, there were areas which did not show evidence of contrast enhancement with an irregular enhancing margin. The absence of discrete high signal on the STIR images was thought to represent areas of non-perfused musculature, possible undergoing necrotic change [Figure 3].
He underwent an exploration of his left thigh. This revealed chronically indurated subcutaneous tissues in keeping with his long history of injecting into the area. There was some oedematous fluid but no evidence of a collection or necrotic muscle. Post-operatively he made a steady recovery.
Treatment with Vancomycin, Ciprofloxacin and Clindamycin continued for 14 days. Negative Pressure Wound Therapy (NPWT) device was applied utilising the Venturi  wound sealing kit. This followed the therapy application technique first described by Chariker et al using saline-moistened gauze, a silicone drain and clear, semi-permeable adhesive film, together with lower pressures, usually between 60-80 mmHg.15
The dressings were changed three times per week and wound exudate collection canisters changed as required when full. He was discharged on a 4 week course of oral Ciprofloxacin 400 mg twice a day and continued with NPWT. Following 4 weeks of treatment, the wound dimensions had reduced from 300 cm3 [Figure 4] to 68 cm3 [Figure 5], a reduction in size of 77%. He remains well and attends regular review at outpatient clinic.