Clostridium septicum sepsis and its implications

Abstract

An elderly gentleman, who had 12 years earlier been successfully treated for colon cancer, presented with fever, rigours, right upper quadrant abdominal pain and tenderness. A CT of the abdomen revealed a colonic mass distal to the hepatic flexure with multiple gas locules and a walled off perforation. He underwent a right hemicolectomy. Histology confirmed multifocal colonic adenocarcinoma. His admission blood cultures grew Clostridium septicum. A week postoperatively he developed intermittent fevers and abdominal pain. Repeat CT revealed an abdominal collection adjacent to the new anastomosis, but more importantly, a sharply shouldered aneurysmal dilation of the infra-renal abdominal aorta. These findings prompted immediate surgical drainage of the collection, repair of the anastomostic leak, resection of the infected aortic aneurysm and replacement with a tube graft. This case highlights the clinical significance of C septicum bacteraemia: its association with occult colonic malignancy and with mycotic aneurysm formation. Clostridia isolated from blood cultures should not be dismissed as contaminants but fully identified to ensure appropriate patient management.

Background

The case report highlights the association of Clostridium septicum bacteraemia with colonic malignancy and its propensity to cause fulminant mycotic aneurysms, which if left untreated have a very high mortality. It also illustrates the need for laboratories to fully identify Clostridia found in blood cultures, so their predictive value for disease can be understood and the patient managed accordingly.

Case presentation

A 77-year-old gentleman with a history (12 years ago) of colon cancer, with complete resection, presented to the surgical unit with abdominal pain, fever and rigours. On admission he was febrile, tachycardic, with tenderness in the right upper quadrant and epigastrium on deep palpation. There was no rebound tenderness and bowel sounds were audible. Examination of other systems was unremarkable. The peripheral white blood cell count was 17×10⁹/L, C reactive protein>160 mg/L, chest x-ray was unremarkable and a normal urine dipstick. CT of the abdomen revealed a colonic mass distal to the hepatic flexure with multiple gas locules and a walled off perforation. He underwent right hemi-colectomy. Histology confirmed multifocal colonic adenocarcinoma. His admission blood cultures grew C septicum (figure 1). A week postoperatively he was noticed to have a low-grade pyrexia, lower abdominal pain and rising inflammatory markers. Repeat CT (figure 2) scanning revealed a 7 cm×3 cm central abdominal collection adjacent to the new anastomosis. More importantly, it also showed a sharply shouldered aneurysmal dilation of the infra-renal abdominal aorta with peri-aortic gas. In the light of this, review of the admission CT scan revealed small locules of gas within the aortic wall. These findings prompted immediate surgical drainage of the collection, repair of the anastamotic leak, resection of the infected aortic aneurysm and replacement with a tube graft. Culture of the aortic wall grew C septicum. He made an excellent recovery.

Figure 1.

Gram stain of blood culture—Clostridium septicum.

Figure 2.

CT scan of the abdomen—the arrow indicates gas within the wall of the abdominal aorta.

Differential diagnosis

• ■ Biliary sepsis

• ■ Bowel perforation

• ■ Recurrence of malignancy

Outcome and follow-up

He made a full recovery and was discharged 4 weeks after admission. He is currently receiving lifelong oral antibiotic therapy to prevent recurrence of sepsis in the newly inserted aortic graft.

Discussion

This case highlights the clinical significance of C septicum bacteraemia—its association with occult colonic malignancy^1–9 and secondary infective complications such as aortitis and mycotic aneurysm,^9–12 arthritis,¹³ endocarditis¹⁴ and endophthalmitis.¹⁵ Thirty-one cases of mycotic aortic aneurysm infected by C septicum have been previously reported. Progression to aneurysm formation occurs within 1–3 weeks of infection with a 6-month mortality of 100% if left untreated.⁸ The pathophysiology of the association is not understood.

Learning points.

• Clinicians caring for patients with Clostridium septicum bacteraemia should have a high index of suspicion for colonic cancer and infective arteritis, especially of the aorta.

• Laboratories should fully identify Clostridia in blood cultures, and not dismiss them as contaminants. Full identification can improve patient care because some members of the Clostridia family have specific disease associations.