A previously healthy 13-year-old boy developed extensive subcutaneous emphysema of the lower limb after a penetrating injury to the knee. Clostridium perfringens was isolated from the wound. Despite surgical debridement and appropriate antibiotics, the emphysema recurred, and prolonged antibiotic treatment was required. This case highlights the distinction between gas gangrene and the lesser known entity of clostridial crepitant cellulitis.
Within hours of hitting his left knee on a wooden bench, a previously healthy 13-year-old boy heard a hollow sound when he tapped the knee. The knee became red and slightly swollen, but he was afebrile and otherwise well. He was treated with oral flucloxacillin. Three days later the knee became painful and immobile, and a radiograph showed extensive subcutaneous emphysema around the knee and distal thigh (Fig. 1). This and the hollow sound resolved after 5 days of treatment with intravenous penicillin and flucloxacillin and a further week of oral amoxicillin/clavulanate therapy. A few days later the patient pulled a 1-cm splinter from his knee.
The hollow sound recurred twice during the ensuing 2 weeks, each time with no pain or other symptoms, and on each occasion it was treated with intravenous penicillin and oral cephalexin. With each course of therapy the subcutaneous emphysema resolved clinically and radiologically.
The patient presented to us 4 weeks after the initial injury with the return of the hollow sound. He was afebrile and systemically well. There were no skin changes and no muscle tenderness. He had marked crepitus from ankle to groin with a hollow sound on tapping his upper leg (video at http://www.rch.unimelb.edu.au/mscl/crepitus). Inflammatory markers were mildly elevated (C-reactive protein 16 mg/l, erythrocyte sedimentation rate 35 mm/h), but peripheral white blood cell count was normal (5.8 × 109/l) and blood cultures were sterile. A Gram stain and culture of pus drained from a small pustule at the splinter exit wound site revealed no organisms. Computed tomography scan of the leg showed extensive gas in the subcutaneous tissues and fascial planes but no nidus of infection. Surgical exploration was deferred because he was improving, and he was treated with intravenous penicillin for 10 days.
Crepitus returned 1 day after stopping antibiotics. An ultrasound scan of his knee showed a linear object within the subcutaneous tissues. The prepatellar bursa was surgically explored and a 9-mm splinter of wood was removed. Tissue from the knee wound grew Clostridium perfringens. He was treated with intravenous penicillin for an additional 10 days, but the subcutaneous emphysema recurred 1 day after stopping antibiotics. The knee wound was reexplored, and the thigh was debrided. There were bubbles of gas within the subcutaneous tissues of the knee and around the fascia in the thigh. The muscles looked normal, and no further foreign body was discovered. Specimens from the wound revealed no organisms on microscopy or culture.
The wound was left open, and he was treated with hyperbaric oxygen and 21 days of therapy with intravenous high dose (60 mg/kg/dose every 4 h) penicillin. One day after stopping penicillin, subcutaneous emphysema recurred from his ankle to his abdominal wall. A radionuclide leukocyte scan and a magnetic resonance image failed to identify a focus for surgical intervention. It was thought that tiny splinters in the prepatellar bursa might be acting as the continuing nidus of infection. He was therefore treated with oral amoxicillin and clindamycin for 6 months. He has had no further recurrence during 6 months of follow-up.
Clostridial infections usually develop in the context of trauma, surgery or foreign body introduction, although they can occur spontaneously, especially in ischemic tissues. 1C. perfringens is an anaerobic gas-producing organism that classically causes severe myonecrosis (gas gangrene). However, C. perfringens can cause a spectrum of disease that includes the lesser known entity of crepitant cellulitis. 1 In contrast to the severe symptoms and signs of gas gangrene, there is minimal pain and little skin change in crepitant cellulitis. Systemic toxicity is mild despite the often extensive subcutaneous emphysema. There may be mild tissue necrosis in superficial tissues, but this never involves muscle. As with gas gangrene, surgical debridement is the cornerstone of treatment because antibiotics have diminished activity in necrotic areas. Surgery also may identify a foreign body, as in our patient, and can prevent compartment syndromes caused by pressure from gas production. Penicillin is the antibiotic of choice for crepitant cellulitis caused by C. perfringens. However, infections are often polymicrobial, and broader antibiotic cover may be necessary. Hyperbaric oxygen should also be considered. 2
Other causes of gas within tissues include infection with other anaerobic or facultative bacteria 1, 3, 4 (e.g. Clostridium septicum, peptostreptococci, Bacteroides spp. and Enterobacteriaceae such as Klebsiella) or fungi, 1 bowel perforation, 5 mechanical inflation 6 and factitious air injection. 7 In the latter case needle marks are invariably present as a clue to the diagnosis.
Our case highlights that gas in subcutaneous tissues is not always life-threatening. However, subcutaneous emphysema should alert clinicians to the possibility of gas gangrene and the need for early surgical intervention.
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