Crossing the Barrier: Eikenella corrodens Bacteremia Following CNS Infection in a Patient Treated with Nivolumab—A Case Report and Literature Review

Eikenella corrodens is a facultative anaerobic Gram-negative bacillus, part of the normal oropharyngeal flora, with opportunistic pathogenic potential particularly in immunocompromised hosts. The progression from localized intracranial infections such as cerebritis and subdural empyema to secondary bloodstream infection represents a rare but clinically significant pathway, especially in immuno-compromised patients. Here, we report a case of secondary E. corrodens bacteremia following left temporal cerebritis and ipsilateral subdural empyema in a 50-year-old man with advanced nasopharyngeal carcinoma treated with nivolumab. The patient presented neurological deficits and systemic inflammatory response, suggesting for a bacterial infection. Neuroimaging confirmed the intracranial infectious foci and blood cultures identified E. corrodens via MALDI-TOF MS and 16S rRNA gene sequencing. We discuss how cancer-associated immune dysregulation and immune checkpoint inhibition could modulate host susceptibility and clinical presentation of infection, potentially facilitating microbial dissemination across compromised blood–brain barriers. Additionally, we examine the cases of E. corrodens bacteremia secondary to CNS and head and neck infections. This case underscores the importance of heightened clinical vigilance for secondary bacteremia in oncologic patients with CNS infections and highlights the need for integrated microbiological and radiological assessment to optimize outcomes.