For preceding treatment of pathological materials, the authors propose a decontaminating agent that contains plivasept at a concentration of 0.08%, the enzyme imozymase and sodium bicarbonate versus decontaminating agents containing chlorohexidine bigluconicum or plivasept alone. The authors' agent increases the proportion of Coch bacterial positive cultures and increases the informative value of luminescence microscopy by reducing the proportion of samples having single mycobacteria in the agent. The use of the proposed decontaminating agent saves the time of attending personnel by reducing the stages of preceding treatment of pathological materials.