An Unusual Case of Listeria monocytogenes-Associated Rhombencephalitis Complicated by Brain Abscesses in Italy, 2024

Listeria monocytogenes (Lm) is an extremely rare cause of brain abscesses, accounting for 1-10% of neurolisteriosis cases reported in the literature, associated with high mortality (approximately 23%). Data on diagnosis, management, and treatment is scarce. We report a case of listerial brain abscesses in an elderly patient in Italy who experienced progressively worsening bilateral ptosis.

Diagnostic evaluation included neuroimaging, blood cultures, and microbiological investigations, followed by antimicrobial treatment according to available evidence. The isolated Lm strain underwent whole genome sequencing. Dietary history was also collected.

Positive early blood cultures were pivotal in identifying Lm as the aetiological agent. Neuroimaging revealed brain abscesses consistent with neurolisteriosis. The clinical course was complicated by pneumonia and opportunistic co-infecting pathogens, and despite adequate treatment according to the available literature, the outcome was fatal. Genomic characterisation revealed that the patient was infected with an strain belonged to the sequence type 206 and clonal complex 14, described as hypervirulent. The patient reported consuming several foods known to be associated with an increased risk of listeriosis.

This case highlights the challenges involved in diagnosing and managing listerial brain abscesses, particularly in elderly patients. Even when the primary central nervous system infection is under control, the prognosis may be significantly impacted by comorbid conditions and hospital-related complications rather than the infection itself. Our findings underscore the need for improved preventive strategies and targeted risk communication regarding high-risk foods, particularly among elderly populations.