Mycobacterium bovis strain made avirulent by hundreds of culture cycles on unfavorable bile-glycerine medium. BCG is used as human immunization against TB; given via a single intradermal injection to newborns in developing and some Western countries and patients at risk for developing resistant TB. Maximum of 1 skin tuberculosis test should be performed in BCG-inoculated patient (this test is usu. negative) due to development of systemic reaction. BCG is also used as intravesical chemotherapy for superficial transitional cell carcinoma of bladder.