Community-Acquired Escherichia coli Meningoencephalitis and Brain Abscess in an Immunocompromised Patient: A Case Report and Literature Review

Gram-negative bacterial meningitis (GNBM) is rare, primarily affecting infants. <i>Escherichia coli</i> (<i>E. coli</i>) is the most common cause, with high mortality and poor clinical outcomes. We report a rare case of an immunocompromised 61-year-old male with a history of chronic lymphocytic leukemia who presented with altered mental status and fever. He was diagnosed with <i>E. coli</i> meningoencephalitis complicated by brain abscess, likely secondary to otitis media. Despite initial medical management, neurosurgical intervention was required due to abscess progression. The patient fully recovered following craniotomy, targeted antimicrobial therapy, and intravenous immunoglobulin administration. A comprehensive literature review was performed, including 142 cases of spontaneous community-acquired <i>E. coli</i> meningitis in adults from January 2000 to January 2024. The most common risk factors identified were urinary tract infection (24.4%), immunosuppression (22.1%), and diabetes mellitus (19.1%). Clinical manifestations frequently included fever (65.3%), altered mental status (50%), and neck stiffness (41.9%). Pneumocephalus was the only independent predictor of in-hospital mortality, with a 93% decrease in the odds of survival (odds ratio: 0.071; 95% CI: 0.005-0.942; p=0.045). Survivors had significantly lower CRP and higher cerebrospinal fluid (CSF) glucose levels compared to non-survivors. This case highlights the diagnostic and therapeutic challenges of community-acquired <i>E. coli</i> meningoencephalitis. Early recognition, appropriate antimicrobial treatment, and timely neurosurgical intervention are essential for optimal outcomes. Pneumocephalus, elevated CRP levels, and low CSF glucose may serve as predictors of poor prognosis.