Quantitative Tuberculocidal Suspension Method
Purpose of Test
The Quantitative Tuberculocidal Suspension test method is a suspension-based method used to evaluate high-level disinfectants for registration the U.S. FDA. This method is also commonly used to evaluate the tuberculocidal efficacy of glutaraldehyde-based products for registration with the U.S. EPA and Health Canada.
Summary of Test
In this method, quadruplicate samples of the product are inoculated with a suspension of Mycobacterium bovis – BCG. The inoculated products are allowed to expose for a series of exposure times. After each exposure time, a sample of product is removed, neutralized and is quantitatively assayed for surviving Mycobacterium. A percent reduction is determined for the test samples, at each time point, as compared to a population control. The U.S. EPA requires an effective product demonstrate at least a 99.99% (4 log10) reduction of Mycobacterium and an average of <1 survivor at the effective time. For high-level disinfectants, the U.S. FDA requires an effective product demonstrate at least a 99.9999% (6 log10) reduction of Mycobacterium and an average of <1 survivor at the effective time. When the minimum reduction is not met at any of the times utilized in the study, a survivor curve can be constructed to predict the effective time of the product.