Listerial rhombencephalitis diagnosed by repeat blood culture despite negative CSF PCR: a case report.

BACKGROUND: Rhombencephalitis is a rare inflammatory disorder of the brainstem and cerebellum, most commonly associated with autoimmune, paraneoplastic, or vascular etiologies. Listeria monocytogenes is an uncommon but potentially severe infectious cause, and diagnosis may be challenging due to the limited sensitivity of cerebrospinal fluid testing. CASE SUMMARY: An adult patient presented with subacute, progressive brainstem symptoms. Neurological examination and magnetic resonance imaging findings were consistent with rhombencephalitis. Cerebrospinal fluid analysis demonstrated inflammatory changes; however, PCR testing for L. monocytogenes was negative. Additional cerebrospinal fluid findings included moderately elevated interleukin-6 and chemokine CXCL13 levels and detectable Epstein-Barr virus DNA. Blood cultures subsequently yielded L. monocytogenes, confirming the diagnosis. Targeted antimicrobial therapy was initiated, and adjunctive corticosteroids were administered because of severe neurological involvement. The patient showed clinical stabilization and neurological improvement during follow-up. CONCLUSION: This case demonstrates that listerial rhombencephalitis may occur even with negative cerebrospinal fluid PCR results and highlights the importance of empiric therapy covering Listeria until an alternative etiology is confirmed. Marked inflammatory and immunological cerebrospinal fluid abnormalities may accompany severe disease and should prompt careful clinical assessment.