Chapter 135. Gas Gangrene and Other Clostridial Infections (Part 3) docx

Chapter 135. Gas Gangrene and Other Clostridial Infections (Part 3) Spontaneous nontraumatic clostridial myonecrosis (gas gangrene). A man in his 50s presented with severe pain in the right upper extremity. Over several hours, he developed progressive swelling and discoloration in that extremity (A), with hemorrhagic ecchymoses and bullae (B). Gram's stain of aspirate from bullous lesions revealed gram-positive bacilli (C). The patient underwent amputation of the extremity. Tissue Gram's stain (D) also showed gram-positive bacilli, and surgical cultures grew C. septicum. Subsequent evaluation of the patient led to the diagnosis of invasive colonic carcinoma. (Images used with permission of Stephen Calderwood, MD, and www.idimages.org.) Clostridia have been isolated from suppurative infections of the female genital tract, particularly tuboovarian and pelvic abscesses. The major species involved has been C. perfringens. Most of these suppurative infections are mild, with no evidence of uterine gangrene. C. perfringens has been isolated from as many as 20% of diseased gallbladders at surgery. One clinical syndrome, emphysematous cholecystitis, is caused by clostridial species at least 50% of the time. In this syndrome, gas forms in the biliary radicles and the wall of the gallbladder. Emphysematous cholecystitis is seen most often in diabetic patients. Although the mortality rate in this entity is higher than in more common forms of cholecystitis, there is no evidence of myonecrosis. Clostridia are among the many organisms found in empyema fluid or isolated by transtracheal aspiration from patients with lung abscesses. There is no unique clinical clue to the presence of clostridia (as opposed to other organisms) in these infections. C. perfringens has been reported as a cause of empyema arising from aspiration pneumonia, pulmonary emboli, and infarction. However, the majority of cases of clostridial empyema are secondary to trauma. Skin and Soft Tissue Infections Various categories of traumatic wound infections due to clostridia have been described: simple contamination, anaerobic cellulitis, fasciitis with or without systemic manifestations, and anaerobic myonecrosis. Simple Contamination Clostridia are cultured most often from wounds in the absence of clinical signs of sepsis. As many as 30% of battle wounds are contaminated by clostridia without signs of suppuration, and 16% of penetrating abdominal wounds yield clostridia on culture despite treatment with cephalothin and kanamycin. In cases of trauma, clostridia are isolated with equal frequency from suppurative and well- healing wounds. Thus the diagnosis of clostridial infection should be based on clinical rather than bacteriologic criteria. Localized Infection of the Skin and Soft Tissue Without Systemic Signs This condition, originally referred to as anaerobic cellulitis, is a localized infection involving the skin and soft tissue and is due to clostridia alone or with other bacteria. There are no systemic signs of toxicity, although the infection may invade locally, producing necrosis. These infections tend to be relatively indolent, spreading slowly to contiguous areas. Localized infections are relatively free of pain and edema. Perhaps because of the lack of edema, gas that is limited to the wound and the immediately surrounding tissue may be more evident than in gas gangrene. In these localized infections, gas is never found intramuscularly. Cellulitis, perirectal abscesses, and diabetic foot ulcers are typical infections from which clostridial species can be isolated. If inadequately treated, these localized infections advance by extension through subcutaneous tissue and fascial planes into muscle and may produce severe systemic disease with signs of toxemia. A localized form of suppurative myositis has been described in heroin addicts. These patients develop local pain and tenderness in discrete areas (particularly the thigh and forearm), with the subsequent appearance of fluctuance and crepitance that require surgical drainage. The unusual aspect of these infections is that they remain localized without systemic signs of toxicity. Moreover, the affected local areas are not necessarily sites of trauma or heroin injection. Pathologic examination reveals subcutaneous abscesses, purulent myositis, and fasciitis from which clostridia are recovered in pure culture; on occasion, mixed infections involving aerobes and anaerobes are found. Wound botulism has been reported in association with the injection of black tar heroin. Spreading Cellulitis and Fasciitis with Systemic Toxicity This condition involves diffuse spreading cellulitis and fasciitis, without myonecrosis and with only mild inflammation in muscle. Patients present with the abrupt onset of a syndrome that progresses rapidly (within hours) through the fascial planes. In cases with suppuration and gas in soft tissues as well as overwhelming toxemia, the infection is rapidly fatal. On physical examination there is subcutaneous crepitation but little localized pain. Surgery is of no proven value because there are no discretely involved tissues amenable to resection, as may be the case in myonecrosis. However, in rapidly advancing fasciitis, incision of the affected area is still the cornerstone of therapy. The initial local lesion may be quite innocuous and arises from an area involved by tumor or other infection and not by injury. The systemic toxic effects include hemolysis and injury of capillary membranes. Usually, this infection is fatal within 48 h, despite intensive therapy involving antitoxin and exchange transfusion. This syndrome is seen most commonly in patients with carcinoma, especially of the sigmoid or the cecum. Presumably, the tumor invades the fascia, and colonic contents leak into the abdominal wall. Patients present with extreme toxicity and occasionally with total- body crepitation. The syndrome differs from necrotizing fasciitis caused by other organisms in three respects: (1) rapid mortality, (2) rapid tissue invasion, and (3) the systemic effects of the toxin, typified by massive hemolysis. . Chapter 135. Gas Gangrene and Other Clostridial Infections (Part 3) Spontaneous nontraumatic clostridial myonecrosis (gas gangrene) . A man in his 50s presented. than in gas gangrene. In these localized infections, gas is never found intramuscularly. Cellulitis, perirectal abscesses, and diabetic foot ulcers are typical infections from which clostridial. infections are relatively free of pain and edema. Perhaps because of the lack of edema, gas that is limited to the wound and the immediately surrounding tissue may be more evident than in gas