An Immunosuppression Hidden Malignancy: Case Report of An Unexpected Clostridium Septicum Infection and Its Fatal Consequence

Background: Clostridium septicum is a gram-positive, spore-forming bacteria belonging to the human intestinal flora. Infections are rare but lead to high mortality and are associated with immunosuppression, malignancy and multipathogenic infections. We present the case of an immunocompromised patient in which an inapparent Clostridium septicum infection and colorectal cancer are simultaneously detected. Case presentation: A 67-year-old man was admitted to our hospital with fatigue and inappetence. Past medical history included lupus erythematosus, treated with prednisolone, azathioprine, and hydroxychloroquine, and coronary heart disease managed through stenting. His CRP was raised at 321mg/l (norm.: <5mg/l) and procalcitonin elevated at 0.65ng/ml (norm.: <0.005ng/ml) with a haemoglobin concentration of 9.5g/dl (norm.: 14-18mg/dl). Clostridium septicum and Staphylococcus saccharolyticus were both isolated from anaerobic blood cultures and the decision was taken to commence antibiotic treatment with clindamycin and piperacillin/tazobactam. Inflammatory markers decreased as a result. Additional results obtained from colonoscopy revealed adenocarcinoma of the ascending colon. The patient later went on to receive a right-sided hemicolectomy during elective surgery after developing impaired hemodynamic response due to gastrointestinal bleeding. Following a complete course of antibiotic therapy, the patient recovered from his surgery and the infection. Conclusion: The detection of infection with Clostridium septicum has clinical relevance due to its association with colon cancer. Once the bacteria have been identified, colonoscopy and antibiotic therapy are of vital importance. Immunocompromised patients may have a worsened prognosis, as they often do not show clinical signs of infection, and as a result the diagnosis of a Clostridium septicum and associated malignancy can be delayed or even missed.