A54-18 Status Epilepticus From Listeria Monocytogenes Meningoencephalitis With Concurrent Herpes Zoster CNS Infection

Abstract Listeria monocytogenes is an uncommon but lethal cause of meningoencephalitis, particularly in elderly and immunocompromised patients. Concurrent viral central nervous system (CNS) infection is rare and significantly complicates diagnosis and management. Prompt empiric recognition and comprehensive testing are essential, as both delayed diagnosis and inadequate antimicrobial coverage worsen outcomes. We report a rare case of Listeria meningoencephalitis with concurrent herpes zoster CNS infection and bacterial pneumonia in a severely immunocompromised host presenting with refractory status epilepticus. A 78-year-old woman with advanced HIV (CD4 count 14 cells/µL), type 2 diabetes, and hypertension was transferred in status epilepticus unresponsive to benzodiazepines and levetiracetam. Seizure control required near-maximal doses of propofol and midazolam under continuous EEG monitoring in consultation with an epileptologist. Initial laboratory evaluation revealed leukocytosis, thrombocytopenia, and hyperglycemia. The patient developed persistent fevers and worsening encephalopathy. Brain MRI demonstrated multifocal hyperintensities involving the right frontal white matter, corpus callosum, basal ganglia, and bilateral thalami, findings most consistent with infectious or inflammatory pathology. Lumbar puncture was initially deferred due to thrombocytopenia and ongoing seizure activity, but was later performed after platelet transfusion. Blood cultures flagged gram-negative bacilli that were ultimately identified as Listeria monocytogenes. A meningoencephalitis PCR panel detected both Listeria and herpes zoster viral DNA in cerebrospinal fluid, confirming dual CNS infection. Concurrent sputum cultures grew methicillin-sensitive Staphylococcus aureus and Klebsiella pneumoniae, reflecting a compounding pneumonia during her ICU course. High-dose intravenous ampicillin, acyclovir, and broad-spectrum antibacterial therapy were initiated. Despite appropriate therapy, her course was complicated by recurrent refractory seizures, autonomic instability, and eventual anoxic brain injury secondary to prolonged status epilepticus. This case shows multiple overlapping diagnostic and therapeutic challenges in the immunocompromised host. Profound CD4 depletion in advanced HIV increases susceptibility to simultaneous bacterial and viral CNS pathogens, and co-infection, though rare, should be suspected when clinical and radiologic features are discordant. The MRI pattern of thalamic and basal ganglia involvement is characteristic but not specific for Listeria and may overlap with viral encephalitides. Diagnostic delay due to thrombocytopenia highlights the importance of blood cultures, which are positive in up to 80% of CNS listeriosis and may establish diagnosis when CSF cannot be safely obtained. Early empiric ampicillin remains essential in elderly or immunocompromised patients with suspected meningitis, as cephalosporins lack Listeria coverage. This case shows the importance of broad diagnostic testing, early antimicrobial and antiviral therapy, and vigilant ICU management in complex opportunistic CNS infections. This abstract is funded by: None