(602) Mystery of the Mind: A Case of Clostridium septicum Meningitis in the Aftermath of Aneurysm Repair

Introduction: Clostridium species rarely cause central nervous system (CNS) infections, with high mortality, often linked to penetrating cranial trauma. This case describes a rare instance of C. septicum meningitis secondary to an infected aneurysm coil.

Description: A 70-year-old Hispanic woman presented to the ED with slurred speech, poor oral intake, and generalized weakness. Medical history included a clipped and coiled right middle cerebral artery (MCA) aneurysm, extracranial to intracranial bypass from proximal superficial temporal artery to MCA with saphenous vein graft, and SDH hematoma. On arrival, she was febrile (104°F), tachycardic (102 bpm), and exhibited left-sided weakness, right gaze preference, and photophobia. Her NIHSS score was 17. Labs were significant for leukocytosis (16.6 x 10³/mcL), hyponatremia (126 mEq/L), and elevated CRP (677.25 mg/L). CT head revealed post-surgical changes with air foci, asymmetric leptomeningeal enhancement, and calcified aneurysm. Ampicillin, Vancomycin, Acyclovir, and anticonvulsants were started. Lumbar puncture revealed cloudy yellow cerebrospinal fluid with elevated protein, low glucose, and neutrophilic pleocytosis. Blood cultures remained negative. A repeat CT head without contrast four hours later showed a progressive increase in air foci in the right temporal region with asymmetric leptomeningeal enhancement of the right frontal region and right MCA coils. Unfortunately, her AICD was not compatible with MRI, so an MRI brain could not be obtained. An EEG revealed changes consistent with encephalopathy. HSV, HIV, and fungal antigen tests were negative. Despite aggressive antimicrobial therapy and neurosurgery consult, the patient's condition rapidly deteriorated, putting her at high risk for surgery and leading to her demise. Postmortem cerebrospinal fluid cultures confirmed the presence of Clostridium septicum.

Discussion: Primary bacterial meningitis pathogens include S. pneumoniae (72%) and N. meningitidis (11%). Clostridium species rarely cause CNS infections but have a very high mortality of 74%. This patient's infection was likely from an aneurysm coil surgery in 2016, with no typical risk factors. Negative blood cultures made a gastrointestinal source unlikely. She was made comfortable, and no autopsy was performed.