Testing a Method for Evaluation of the Viability of Biofilm-Forming Bacteria after Exposure to Disinfectants

A method for determining the viability of opportunistic pathogenic bacteria at the stage of biofilm formation after exposure to disinfectants with different active components was tested. The method is based on oxidation of tetrazolium salts by metabolically active cells with the formation of colored formazan derivatives and their quantitative spectrophotometry. The cell viability in the biofilm decreased after exposure to quaternary ammonium compounds and chlorine-containing disinfectants, but their effect was reversible. Dissemination of cells that had retained viability from the biofilm occurred after 24 h. The algorithm of testing, necessary controls, counting, and data interpretation are specified. The method can be recommended for use in laboratory diagnostics and clinical practice.