Case Report

gas gangrene without wound: both lower extremities affected simultaneously

Abstract

Gas gangrene is a necrotizing soft tissue infection characterized by muscular necrosis and gas formation. It develops quickly and can cause septic shock and death. In adults, gas gangrene used to be a well-known complication of war wounds. Recently, cases of spontaneous or nontrau- matic gas gangrene have been reported in both adults and children. We report a case of nontraumatic gas gangrene involving both the lower extremities simultaneously. Patho- genesis of this fatal soft tissue infection is discussed. We also review the diagnosis and treatment aspects of this entity.

A 46-year-old woman presented to the ED with fever and a 3-day history of pain in both the lower extremities without a history of trauma. She was clouding of consciousness and had fecal incontinence at the time of admission. On initial examination, the vital signs of the patient were temperature of 39.4?C, pulse of 132 beats per minute, respiratory rate of 35 breaths per minute, and blood pressure of 129/63 mm Hg. Crepitus and ecchymotic areas were noted in both legs, especially on the left which progressed with marked swelling during the next 2 hours, along with blisters filled with thin dark exudates. Blood test showed the white blood cell count was 5.1 x 10⁹/L, the hemoglobin was 119 g/L, the platelet count was 183 x 109/L, and the serum creatinine was 101 umol/L (within the reference range). Doppler ultrasonogra- phy and computed tomography of both legs were taken immediately. Doppler analysis found deep venous and artery thrombus in the left leg beneath the level of the knee. Computed tomography scan showed gas formation in both legs and extensive myolysis in the left (Fig. 1). A diagnosis of gas gangrene was made and the patient was started on intravenous Penicillin G, clindamycin, metronidazole, and fluid resuscitation. At the same time, a Surgical consultation was obtained and the patient was taken to the operation room 5 hours after admission. Incisions were made in the left leg and a foul smelling thin exudate was obtained. The underlying muscles were necrotic and Gram-positive bacilli were found in the exudates with few leukocytes (Fig. 2). A disarticulation of the left leg at the knee and a decompression of the right leg were performed. The patient was sent to the

intensive care unit and all the wounds were kept open postoperatively. Despite the intensive care treatment and repeated surgical site debridement, the conscious and hemodynamic status of the patient deteriorated and she died 3 days after admission. Permission for an autopsy was refused. histologic examination of the amputated leg showed necrotizing fasciitis and focal myonecrosis.

Gas gangrene is a rare and often life-threatening infection resulting from rapid invasion and destruction of muscle tissue with the specific clinical sign of gas formation. The pathogens most frequently responsible are clostridia. Only 6 members of the clostridial species can invade muscle and cause myonecrosis in humans [1,2], and of those, Clostri- dium perfringens and C septicum are responsible for the majority of clinically relevant infections. Clostridium perfringens accounts for 80% to 95% of reported cases that always result from the contamination of an open wound [3]. Nontraumatic or spontaneous gas gangrene is a rare entity (b10% of reported cases) and almost exclusively caused by C septicum [2-4]. This form of infection is more deadly than wound-related myonecrosis because of its insidious onset with subsequent rapid clinical deterioration [5].

Clostridia are large, Gram-positive, anaerobic bacilli that are nonpathogenic in normal gut flora. Clostridium septicum is aerotolerant and capable of translocating by hematogenous spread [3] when gut barrier is impaired. It was reported that most patients with C septicum infection had abnormal Pathologic findings in the bowel, such as

Fig. 1 CT scan showing gas formation in both legs and extensive myolysis in the left leg.

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tion [2,3]. The recommended regimen includes high-dose intravenous penicillin, 18 to 24 MU/d in divided doses, and clindamycin [3]. A third- or fourth-generation cephalosporin usually is added to provide proper coverage against mixed infection. Aggressive surgical exploration is critical and should be instituted as soon as possible. At the infected site, decreased tissue perfusion will make it difficult for systemically administered antibiotics to have an effect. So it is urgent for surgeons to remove the bacterial-contaminated and necrotic tissue and eliminate the anaerobic environment.

The mortality rate for spontaneous gas gangrene remains high, ranging from 67% to 100%, and most patients die on the first day of illness [6]. In the case presented here, the patient did not survive the fatal infection in the end mainly

Fig. 2 Gram-positive bacilli found in exudates with few leukocytes.

carcinoma, diverticulitis, infarction, enterocolitis, and vol- vulus [3,6]. In the case presented here, no Pathologic changes in the gut had been discovered so the site of bacterial entry is unclear. However, the immune system of the patient could have been impaired as she was very easy to catch a cold and hard to recover which was reported by her family members. Because clostridia can reproduce readily in low-oxygen conditions, infections are usually seen in the setting of decreased Blood supply. In our case, thrombus was found in both artery and vein in the left leg that could have caused a decrease in local oxygen tension. So the left leg was probably the site of initial infection.

The period between clostridial contamination to myone- crosis ranges from 6 to 48 hours [2]. In anaerobic settings, the bacilli proliferate, producing exotoxins that overwhelm the host defenses and initiate a cycle of tissue destruction, local ischemia, bacterial proliferation, and toxin production [3]. Clinically, this process is characterized by pain that is out of proportion to the physical findings. Clostridial prolifera- tion generates carbon dioxide and hydrogen gases that will move along tissue plane and separate them. Further tissue necrosis and gas formation result in significant edema and the characteristic feature of palpable emphysema, and then blebs or bullae containing a thin, dark, foul-smelling fluid may appear secondary to the necrosis beneath the surface. Shock progresses very rapidly and death usually occurring in 24 to 48 hours [2].

Treatment for gas gangrene involves supportive mea- sures, antimicrobial therapy, and timely surgical interven-

because of her late admission.

Jun Lu MD Xiao-tao Wu MD Xiang-fei Kong MD Wen-hao Tang MD

Orthopaedics Department of ZhongDa Hospital Southeast University, Nanjing, Jiangsu, China

Jian-ming Cheng MD Hai-liang Wang MD

Clinical Biology Department of ZhongDa Hospital Southeast University, Nanjing, Jiangsu, China

doi:10.1016/j.ajem.2008.01.051

References

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