Neurolisteriosis in adults: a case series highlighting clinical and diagnostic challenges and review of Indian literature

Background Neurolisteriosis due to Listeria monocytogenes is uncommon but associated with high morbidity and mortality. Diagnosis is often delayed due to heterogeneous clinical presentations, overlap with non-infectious neurological conditions and limited sensitivity of early diagnostic tests. Methods We conducted a single centre retrospective chart review at a tertiary care teaching hospital between January 2024 to March 2026. Adult patients (≥ 18 years) with microbiologically confirmed neurolisteriosis cases were included. Clinical, radiological, microbiological, treatment, and outcome data were analysed descriptively. Results Of the 1633 CSF samples analysed, 110 (6.7%) were positive for bacterial meningitis, of which 3 (2.7%) were due to Listeria monocytogenes . The median age of patient was 57 years (range: 30–69) with female predominance. One patient had SLE on immunosuppressive therapy while other two were immunocompetent. The median symptoms duration prior to admission was 1 day with common presenting symptoms headache, fever and altered sensorium. Imaging demonstrated hyperintense meningeal or parenchymal enhancement. CSF revealed neutrophilic pleocytosis, elevated protein, and low glucose. CSF and blood cultures were positive in all cases. Delayed appropriate therapy led to deterioration, but targeted ampicillin-based treatment resulted in favourable outcomes. Conclusions Neurolisteriosis remains a significant diagnostic challenge due to its variable clinical presentation; therefore, maintaining a high index of suspicion and ensuring early recognition with prompt initiation of ampicillin-based therapy are essential for improving patient outcomes.