Standardization of tuberculocidal testing of disinfectants

The current AOAC tuberculocidal test has poor reproductibility caused by growth conditions of the test culture, lack of standardization of the challenge inoculum, poor growth in the recovery medium and the use of carriers. A procedure for growth of Mycobacterium bovis BCG is presented which yields cultures that can be easily standardized. Among currently used recovery media, Proskauer-Beck broth does not allow recovery of bovis BCG when 10 cfu or less are present and Middlebrook 7H9 broth provides the best recovery of cells.