Mycobacterium bovis BCG infection of the brain following intravesical BCG treatment

Background Intravesical Bacille Calmette-Guerin (BCG) therapy with live-attenuated form of Mycobacterium bovis ( M. bovis ) is used as a treatment of early-stage bladder cancers. Documented adverse reactions are usually local and time limited, with severe central nervous system (CNS) complications being exceedingly rare. We report an 88-year-old patient with papillary urothelial carcinoma who presented with recurring neurological complications for over a year after treatment with intravesical BCG therapy. Case Summary MRI at initial presentation revealed a dural-based left frontoparietal mass. Histological examination of the resected tissue revealed granulation tissue, necrosis, and lymphohistiocytic inflammation. Stains for organisms and cultures were negative, as was broad-range PCR. Two additional CNS resections performed followed detection of new lesions on follow-up. A mycobacterial culture from abscess fluid from the last resection recovered M. tuberculosis complex that, on region of detection signature pattern analysis, was identified as M. bovis BCG. Conclusion This case represents one of the rare documented reports of an M. bovis BCG CNS infection resulting from intravesical BCG treatment. BCG infection should be considered in the differential of CNS infections in patients with a history of BCG treatment so early life-saving therapy can be instituted.