Central Nervous System Infections Caused by Bacillus Calmette-Guerin: Case Report and Narrative Literature Review

: Bacillus Calmette-Guerin (BCG) central nervous system (CNS) infections are one of the rarest complications following BCG exposure. A 77-year-old male, with bladder cancer previously treated with BCG instillation, presented with fever, confusion, and brain magnetic resonance imaging (MRI) consistent with encephalitis one month after the last BCG instillation. Cerebrospinal fluid (CSF) showed marked hypoglycorrhachia, hyperproteinorrachia, and lymphocytic pleocytosis. Despite CSF culture negativity, the presentation was considered suggestive of BCG-related encephalitis, and the empirical standard antitubercular treatment (rifampin, isoniazid and ethambutol), plus dexamethasone, was initiated. Following initial improvement, gait ataxia and hemiplegia were observed at the 4-month follow-up. MRI revealed an excluded enlarged left lateral ventricle with signs of ventriculitis, requiring surgical drainage. CSF collected during neurosurgery resulted positive on PCR for M. tuberculosis complex. Adjunctive linezolid was initiated, replaced by levofloxacin due to adverse events after 2 weeks. The patient was discharged following a normal CSF analysis. Oral antitubercular therapy was prescribed for 14 months and there were no signs of relapse at the 24-month follow-up. Previously, 16 cases of CNS BCGitis have been reported, without any cases of clinical relapse during antitubercular treatment. Furthermore, our study reports the use of linezolid as a 4th antitubercular drug for CNS BCGitis.