Clinical Presentation, Management, and Outcomes of <i>Mycobacterium Bovis</i> Bacillus Calmette-Guérin (BCG) Infections: A Single-center Retrospective Review

Background Intravesical Mycobacterium bovis bacillus Calmette-Guérin (BCG) is standard therapy for high-risk nonmuscle-invasive bladder cancer. However, M bovis infections can occur and are not well understood. We aimed to characterize clinical phenotypes, diagnosis, management, and outcomes of culture-confirmed M bovis BCG infections following intravesical therapy for urothelial carcinoma. Methods A retrospective single-center review of adults with culture-confirmed M bovis infection after intravesical BCG (May 2009-July 2024) was conducted, abstracting clinical, microbiologic, treatment, and outcome data. Results Twenty-two White male patients (median age, 77 years) were included; 8 (36.4%) had localized genitourinary infection, 6 (27.3%) had dissemination limited to blood, and 8 (36.4%) had dissemination to other organs. Patients with bloodstream-only infection presented acutely (median 1.5 days after last BCG), whereas those with localized or organ-disseminated disease presented months to years after BCG, with the longest diagnostic delays in organ-disseminated infection. Despite all cases had culture-proven M bovis BCG infection, acid-fast smear, Mycobacterium tuberculosis complex polymerase chain reaction, and histopathology had limited sensitivity. All isolates were susceptible to rifampin, isoniazid, and ethambutol; all were resistant to pyrazinamide. Median treatment duration exceeded 9 months, 94.7% achieved cure, and attributable mortality was 5.0% (1 vascular graft infection). Conclusions M bovis BCG infections following intravesical therapy have favorable outcomes but are often associated with diagnostic delays and prolonged treatment. Early suspicion, comprehensive diagnostic evaluation, and timely surgical source control when indicated are critical. Management strategies should be tailored based on the extent of disease dissemination and individual host factors.