Isolation of bacille Calmette-Guerin after immunotherapy for cancer

BCG, an attenuated mutant of Mycobacterium bovis, has been used to induce active immunity against tuberculosis. More recently, sc or intralesional injections of BCG have been given to patients with neoplasias. More than 2,650 patients with solid tumors or hematologic neoplasias received BCG immunotherapy at M. D. Anderson Hospital and Tumor Institute (Houston)-from 1974 and 1983. We reviewed all isolates of M bovis recorded by the clinical microbiology laboratory during that same period and found that there were nine single positive cultures, each one obtained from a different patient. The mean interval between the last BCG injection and the recovery of M bovis was 17.5 weeks; interestingly, in patient 8 (who had a protracted draining cellulitis and regional lymphadenopathy), the mycobacterium was recovered two years after the last BCG injection. All patients from whom M bovis was isolated had received BCG sometime in the past. Despite the fact that sputum, urine, and postmortem cultures were obtained from many other patients who had received BCG, only one instance of microbiologically-proven disseminated BCG infection was recorded. Our experience shows that viable organisms can be recovered for several months following BCG injections in cancer patients. As previously reported disseminated infection is extremely uncommon, even if the recipients are highly immunosuppressed. In addition, the isolation of M bovis in our patient population was related exclusively to BCG injections.