Vascular graft infections caused by Mycobacterium bovis BCG after BCG immunotherapy for non-muscle-invasive bladder cancer: Case report and review of literature

Abstract

Bacillus Calmette-Guerin (BCG) immunotherapy (i.e., intravesical instillation of live attenuated strain of Mycobacterium bovis) is a standard of care for non-muscle-invasive bladder cancer (NMIBC). The risk of infective adverse events is generally low as studies have reported an incidence of systemic BCG infections between 3% and 7%. In the majority of cases, BCG infections are disseminated (34.4%), genitourinary (23.4%), osteomuscular (19.9%), or vascular (6.7%). Regarding vascular involvement, mycotic aortic aneurysm, aorto-enteric fistula and vascular bypass graft infections have been described. A 73-year-old man with a prosthetic femoral-popliteal bypass was treated with BCG immunotherapy for a relapsed NMIBC. Two months later, the patient developed fever and hyporexia. PET-CT and CT scans of the abdomen showed an abscess surrounding the superficial femoral artery, while blood cultures yielded M. bovis BCG, and antitubercular therapy (with RMP + EMB + INH) was started. The prosthetic graft was removed and its cultures tested positive for M. bovis as well. A total of 14 cases of vascular prosthesis infections caused by M. bovis BCG following BCG instillation are so far reported. All the cases occurred in adult symptomatic men. Abdominal aorta was involved in the majority of cases. CT scan played a pivotal role in the diagnostic process. Mycobacterium bovis BCG was isolated from several different sources. Treatment required surgery and medical therapy, the latter showing wide variability. Previous BCG immunotherapy must be considered in the differential diagnosis in patients with infected vascular grafts. These infectious complications are rare and, while the infected grafts should be removed, there are no definite recommendations regarding the type of regimen and duration of treatment.

Keywords: BCG immunotherapy; Mycobacterium bovis BCG; Mycotic aneurysm; Vascular prosthesis.