Bacterial Causes of Rhombencephalitis
Listeria monocytogenes is the predominant bacterial cause of rhombencephalitis, accounting for the majority of infectious cases in this anatomic distribution. 1, 2, 3
Primary Bacterial Pathogen
Listeria monocytogenes is the most common bacterial cause of rhombencephalitis (inflammation of the hindbrain/brainstem and cerebellum). 2, 3
Clinical Context for Listeria Rhombencephalitis
Listeria primarily affects healthy young adults, though it also occurs in elderly, immunocompromised patients, and those with underlying conditions like cirrhosis. 2, 4
The disease typically presents with a biphasic time course: an initial flu-like prodrome followed by progressive brainstem dysfunction (cranial nerve palsies, cerebellar signs, altered consciousness). 2, 3
Approximately 75% of patients have CSF pleocytosis, and nearly 100% demonstrate abnormal brain MRI findings showing brainstem and cerebellar involvement. 2, 3
Positive CSF and blood cultures are the most specific diagnostic findings, though cultures may be negative in some cases. 1, 2
Treatment Implications
Empiric ampicillin therapy should be initiated immediately for suspected rhombencephalitis after obtaining CSF and blood samples, given Listeria's predominance and the high mortality without treatment. 2
Combination therapy with meropenem and trimethoprim-sulfamethoxazole has been successfully used in documented cases. 5
Prompt antimicrobial therapy is critical to prevent the high rates of mortality and morbidity associated with Listeria rhombencephalitis. 1
Other Bacterial Considerations
Mycobacterium tuberculosis
Tuberculosis can cause subacute to chronic rhombencephalitis, particularly in immunocompromised patients. 6
This presentation is part of tuberculous meningoencephalitis and should be considered in patients with appropriate risk factors and geographic exposure. 6
Treponema pallidum (Syphilis)
- Neurosyphilis can present with subacute CNS inflammation affecting the brainstem, though this is less common than Listeria. 6
Borrelia burgdorferi (Lyme Disease)
- Lyme neuroborreliosis can cause brainstem involvement in the context of CNS infection, particularly in endemic areas. 6
Critical Clinical Pitfalls
Do not wait for culture confirmation before starting treatment—empiric coverage for Listeria with ampicillin (plus acyclovir for HSV coverage) should begin immediately after diagnostic samples are obtained. 2
Negative cultures do not exclude Listeria—clinical suspicion based on biphasic presentation, MRI findings, and CSF pleocytosis should guide treatment decisions. 1
Consider Listeria exposure history: consumption of unpasteurized dairy products, deli meats, or other high-risk foods should heighten suspicion. 1
Immunosuppressive therapy alone is inadequate—cases initially misdiagnosed as autoimmune conditions (like Bickerstaff's brainstem encephalitis) may deteriorate without appropriate antimicrobial coverage. 5