A 46-year-old previously healthy man presented with 1 week of headache, nausea, 
vomiting and dizziness. He was found to have cranial nerve deficits, his 
cerebrospinal fluid (CSF) demonstrated a lymphocytic pleocytosis and brain MRI 
suggested rhombencephalitis. Although Gram stains and cultures of his CSF did 
not identify a pathogen, Listeria monocytogenes DNA was detected by the 
FilmArray Meningitis/Encephalitis panel within 2 hours of performing a lumbar 
puncture. He was treated with ampicillin and gentamicin and had a near-complete 
recovery. This case highlights the importance of recognising L. monocytogenes 
infection as a cause of acute cranial nerve impairment with MRI findings 
suggestive of brainstem encephalitis. It also highlights the frequently atypical 
CSF profile and low yield of culture in L. monocytogenes rhombencephalitis and 
the value of multiplex PCR testing of CSF to rapidly identify this pathogen and 
permit targeted therapy.