81-year-old Man with Subcutaneous Gas

Presented by:

Dr. A. Sarabia, MDS Laboratory Services

Clinical Case:

An 81 year old man was admitted to hospital because of pain and subcutaneous emphysema (gas) in the right upper extremity. His previous history was unremarkable except for microcytic anemia, which had been recently investigated with upper endoscopy, revealing nothing of significance.

Within 10 hours of admission, the patient had developed subcutaneous gas involving most of his right side and a visible bruise over the right arm, surrounded by large bullae. He was taken to the operating room, where debridement of the necrotic muscle tissues involving right upper arm, shoulder and chest took place. During the procedure, he developed significant hypotension, which responded to medication and intravenous saline and albumin infusion. Postoperatively, however, he remained unresponsive and hypotensive. Disseminated intravascular coagulation developed. Within 30 hours of presentation to hospital, the patient died.

Questions:

• What organisms are associated with rapidly progressive gas-forming infections?
• What term is used to describe the above infectious process?
• During the operative procedure, tissue is sent to the laboratory for stat gram stain. This reveals only few neutrophils, and gram positive as well as negative bacilli, with no spores. What is the likely etiologic agent of infection?
• Why is there a paucity of neutrophils?
• What underlying medical conditions are associated with an infection as described above?

Discussion:

The above described case is one of "spontaneous myonecrosis".

Organisms that cause gas-forming infections in general include clostridia, gram negative enteric bacilli, Staph aureus, beta-hemolytic streptococci and a variety of anaerobes.

The finding of gram-negative rods in the tissue stains is consistent with a pure clostridial infection, for the organisms may be gram-negative in clinical material and in late cultures. Clostridia do not generally form spores in tissue. A paucity of inflammatory cells is a hallmark of clostridial infection, probably because of the effects of clostridial toxins.

Clostridia grow with incredible rapidity in devitalized tissues. As bacteria grow, they produce toxins and proteolytic enzymes, which cause severe local and systemic injury and facilitate the spread of the infection. By and large, clostridial species that produce toxins and proteolytic enzymes ie C. perfringens, C. septicum are the most virulent, those that produce proteolytic enzymes only ie C histolyticum, C. bifermentans, are less injurious and those that produce neither substance tend not to cause invasive disease.

The specific organism recovered in this case was Clostridium septicum. This species of clostridium is of the proteolytic group (hydrolyses gelatin), and swarms in culture. It has subterminal spores in "citron" forms, is Dnase positive and is sucrose negative.

The distribution of clostridia in soil, the gastrointestinal tract and the vagina and the need for devitalized tissues for growth dictate the clinical circumstances in which clostridial infections are found. Most infections arise by direct inoculation of soil or feces into tissues or by contiguous spread from the gastrointestinal tract or vagina, usually after an injury. Thus, about 50% of cases are complications of compound fractures, gastrointestinal trauma, and injections, and 34% are complications of surgical operations. However, 16% of the infections lack such antecedents and are termed "spontaneous".

Cases of "spontaneous" or "distant myonecrosis" usually result from bacteremia arising from an occult focus, usually in the bowel. Almost all isolates from these infections have been C. perfringens or C. septicum. Underlying diseases associated with spontaneous clostridial myonecrosis include carcinoma of the bowel, a hematologic malignant tumour, and diabetes mellitus. C. septicum, in particular, is associated with bowel tumours, in which anaerobic glycolysis prevales. Here, the organism proliferates, gains access to the systemic circulation, and metastasizes to peripheral muscle.

References:

• Case Records of the Massachusetts General Hospital (Case 5-1993). NEJM 1993; 328; 340-6.
• Allen S., C. Emery, and J. Siders. 1999 Clostridium., p. 654-671, In Manual Of Clinical Microbiology, 7th ed. ASM Press, Washington, DC.