Disseminated <i>Mycobacterium bovis</i> ‐BCG Infection Following Intravesical BCG Administration in Solid Organ Transplant Recipients

BACKGROUND: Intravesical Bacillus Calmette-Guerin (BCG) is a live attenuated vaccine for tuberculosis. Intravesical BCG (iBCG) administration is a highly effective immunotherapy for non-muscle invasive bladder cancer (NMIBC). Although live attenuated vaccines are generally contraindicated in solid organ transplant recipients (SOTR), iBCG has been utilized for NMIBC in SOTR. We describe the clinical manifestations, management, and outcomes of disseminated Mycobacterium bovis-BCG infection (Mb-BCGi) following iBCG therapy in SOTR for NMIBC. METHODS: All adult patients (> 18 years of age) diagnosed with NMIBC who received iBCG across three tertiary referral and transplant centers between 2000 and 2025 were identified. The study cohort consisted of SOTR who had received iBCG for NMIBC and subsequently developed disseminated Mb-BCGi. English language literature review was performed to identify additional cases. RESULTS: A total of 4207 patients received iBCG during the study period. Thirty (0.71%) were SOTR, of whom two (6.7%) developed disseminated Mb-BCGi, including bloodstream infection and prostate abscesses. Literature review identified two additional disseminated Mb-BCGi cases in SOTR with lungs, bloodstream, and native kidney involvement, and one fatality. All cases required extended antimycobacterial therapy. Median times from SOT to Mb-BCGi and from iBCG to Mb-BCGi were 104 and 8 months, respectively. CONCLUSION: SOTR appear to be at a higher risk of disseminated Mb-BCGi following iBCG. Administration of iBCG in SOTR with NMIBC warrants careful risk-benefit assessment and subsequent close monitoring.